MXPA97008327A

MXPA97008327A - Method and apparatus for voiding the effects of color gypsymodifications for a signal vi

Info

Publication number: MXPA97008327A
Application number: MXPA/A/1997/008327A
Authority: MX
Inventors: O Ryan John; Quan Ronald
Original assignee: Macrovision Corporation
Priority date: 1995-05-09
Filing date: 1997-10-29
Publication date: 1998-01-01

Abstract

The present invention relates to the known process of color bands to prevent the recording of video signals, the burst of color present in each line of active video is modified so that any subsequent video tape record of the signal of video shows variations in color fidelity that appear as undesirable bands or color error bands. This process of color bands is first avoided when determining the location of the video lines that include the process of color bands, either by previous experimentation or by online detection. Afterwards, some or all of the lines that include the modified bursts of color are modified in order to convert all the recordable video signals. The modification is carried out in several ways, including the phase shift of the color band burst to the correct phase, replacing some of the color band bursts or a portion of the particular color band bursts in order to that they are no longer effective, and mixing the color band bursts with phase color band signals in order to eliminate most or all of the present phase error. Modified bursts of color are avoided, in other versions, by modifying the horizontal synchronization pulse signals immediately preceding the modified color bursts so that the modified bursts of color are not detected by a VCR and therefore do not have efec

Description

METHOD AND APPARATUS TO VOID THE EFFECTS OF COLOR DISCONTINUITY MODIFICATIONS FOR A VIDEO SIGNAL BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a method and apparatus for processing a video signal, and more particularly to remove (cancel) the effects of phase modulation of the color discontinuity component of the signal. Of video. DESCRIPTION OF THE PREVIOUS TECHNIQUE U.S. Patent No. 4,577,216, "Method and Apparatus for Processing a Video Signal", by John O.

Ryan, issued March 18, 1986 and incorporated for reference, states the modification of a color video signal to inhibit the development of acceptable video records of the same. A conventional television receiver produces a normal color image from the modified signal. However, the resulting color image from subsequent videotape records shows variations in color fidelity that appear as bands or color error strips.

Colloquially the modifications are called "color band system" or the "color band process". The commercial modalities of the teachings of this patent typically limit the number of video lines per field that have the color error or the color bands induced. Color video signals (both NTSC and PAL TV systems) include what is called a color discontinuity. The system of color bands modifies the discontinuity of color. The suppression of the color subcarrier signal in the TV transmitter requires that the color TV receiver include (in the NTSC) a 3.58 MHz oscillator, which is used during demodulation to reinsert the color subcarrier signal and re-store the color color signal in its original form. Both the frequency and the phase of this reinserted subcarrier signal are critical for color reproduction. Therefore, it is necessary to synchronize the 3.58 MHz local oscillator of the color TV receiver so that its frequency and phase are in accordance with the subcarrier signal in the transmitter. This synchronization is carried out by transmitting a small sample of the subcarrier signal of 3.58 MHz of the transmitter during the interval of the hind window of the pulse in horizontal white. Figure A shows a horizontal blank range for a color TV. The duration of the horizontal synchronization pulse, front view and blank interval is essentially the same as for black and white TV. However, during transmission on color TV (both broadcast and cable), from 8 to 10 subcarrier cycles of 3.58 MHz that are to be used as the color synchronization signal overlap in the rear viewpoint. This color synchronization signal is referred to as the "color discontinuity" or "discontinuity". The peak-to-peak amplitude of the color discontinuity (40 IRES for the NTSC TV as shown) is the same amplitude as for the horizontal synchronization pulse. Figure IB shows an enlarged view of a part of the waveform of figure A which includes the actual color discontinuity cycles. During the blank TV color intervals, such color discontinuity is transmitted after each horizontal synchronization pulse. In a commercial mode of the color band process, no modification of (bands) phase of color discontinuity appears in the video lines having a color discontinuity signal during the vertical white interval. These are lines 10 to 21 in a signal from the NTSC and the corresponding lines in a PAL signal. Modifications to the color bands occur in bands of four to five video lines of the observable TV field followed by bands of eight to ten video lines without the modulation of the color bands. The location of the bands is fixed ("static") of field-field. It has been found that this process of color bands is quite effective for cable television, especially when combined with the teachings of U.S. Patent No. 4,631,603 also invented by John O. Ryan and incorporated herein by reference. On the NTSC TV, the start of the color discontinuity is defined by the null crossing (positive or negative declivity) that precedes the first half of the subcarrier cycle (color discontinuity) that is 50% or greater than the amplitude of color discontinuity. It should be understood that the process of color bands displaces the phase of color discontinuity cycles in relation to their nominal (correct) position shown in Figure IB. The phase shifted color discontinuity is shown in Figure 1C. The amount of phase shift shown in Figure 1C is 180 ° (the maximum possible). In addition, the amount of phase shift in the color band process may vary from, for example, 20 ° to 180 °; the greater the phase shift, the greater the visual effect in terms of color shift. In a color band process for PAL TV, a somewhat larger phase shift (eg, 40 ° to 180 °) is used to be effective. Other variations of the color band process are also possible. U.S. Patent No. 4,626,890, "Method and Apparatus for Removing Phase Modulation of Color Discontinuity," by John O. Ryan, issued December 2, 1986 and incorporated for reference, discloses the removal of phase modulation from U.S. Patent No. 4,577,216. This withdrawal is useful in eliminating many of the effects of the process set forth in US Pat. No. 4,577,216 for registration. SUMMARY OF THE INVENTION The present inventors have determined that some improvements are possible over the teachings of the aforementioned U.S. Patent No. 4,626,890, which relates especially to the elimination or reduction of the effects of certain variants as described above of the process of color bands of U.S. Patent No. 4,577,216. In this way, according to the present invention, a circuit modifies and / or removes the process of color bands, or modifies the video signal so that the process of color bands is not evident, that is, it does not have influence on a TV set or VCR. In one embodiment, the locations of the video line of color band discontinuities are known. That is, it is known in which video lines the modified discontinuities of color bands occurred, as in the commercial modality described above of the color band process. These locations are stored in a preprogrammed memory that provides signals that indicate those video lines. Also, the same preprogrammed memory provides an indication of whether the discontinuity of color bands should be modified in whole or only a part. A modification circuit that also receives the video signal, and uses the information as the location of the discontinuities of color bands, removes and / or modifies the discontinuities of color bands or otherwise modifies the video signal (i.e. , modifies the horizontal synchronization pulse immediately preceding the discontinuity of color bands) so that the effect of the color band process is attenuated or eliminated. With respect to the present invention, it has been found that it is not necessary to completely eliminate the discontinuities of color bands; with commercially available, typical television sets and VCRs that eliminate some of the discontinuities of color bands or that attenuate the discontinuities of color bands either in terms of amplitude or duration, or that remove or attenuate a portion of each One or most of the discontinuities of color bands, it has been found effective to overcome the effect of the color band process, allowing a recordable (copyable) video signal to be produced. Sometimes the process of color bands is not fixed in the location of the line. Other times, even when it is fixed, it is not desired or it is not possible to provide the preprogrammed memory. Then, instead of a phase detector detecting, for each video line, the presence of a discontinuity of color bands, i.e., it detects color discontinuities having an induced phase modulation. After detection of the discontinuity of color bands, the modification circuit (as above) modifies either the discontinuity of color or other portions of the video signal (i.e. the horizontal synchronization pulse) in order to attenuate or eliminate the effect of discontinuity of color bands. It should be understood that the correction or replacement of discontinuities of color bands according to the invention does not require the complete elimination of phase shift (modulation); A reduction of the phase shift to a somewhat small value (eg 5 ° or less for the NTSC) has been found effective, since the typical observer will not perceive the concurrent color shift. In this way, the present method and apparatus have various modalities. There are several methods to determine the location of discontinuities of color bands, either by knowing their location from a previous analysis or by real detection. Various modalities are also exposed in the present to avoid the process of color bands. These, as described above, generally depend first on the determination of the locations of the video lines in the discontinuities of color bands, either by knowing their location from a previous analysis and scheduling the location in eg a memory programmable, or by detecting each discontinuity of individual color bands on a line-by-line basis of the video. Any of these methods for determining the location of discontinuity of color bands can be achieved by various circuits. As an alternative, one replaces all color discontinuities with correct phase discontinuities, generating the correct discontinuities by particular circuits different from those illustrated in Ryan's US Patent No. 4,626,890 as set forth below. A typical circuit that depends on the knowledge of the location of the discontinuity of color bands (for the case where the color line discontinuity video line locations are static) generates vertical and horizontal synchronization signals from the input video signal and from these it generates indicator signals indicating the particular video lines in each video field and particular portions of the line for which it is desired to provide a modification to the color discontinuity. The focus of the detector typically utilizes a phase detector that includes a subcarrier regeneration circuit such as a synchronized phase network, a crystal filter or a frequency multiplier circuit to determine the phase of the color discontinuity, and then compares this phase detected with the nominal phase (using a phase comparator) and provides an indicator signal when the discontinuity of color bands occurs, that is, when the phase of color discontinuity has been modulated to deviate from the normal phase. This indicator signal then controls the desired modification for that line. The actual modifications to the video lines to prevent the process of color bands fall into two main categories. In the first category, the discontinuity of color itself is altered in order to avoid (eliminate or attenuate) its effect in a typical VCR. In the second category, the horizontal synchronization pulse immediately preceding a discontinuity of color bands is altered, thus causing a VCR not to respond to the discontinuity of following color bands. The first approach (in which the discontinuity of color bands itself is modified) can be carried out in several ways. In one embodiment, discontinuity of color bands is replaced with blanks and is not replaced. Alternatively, the discontinuity of color bands is replaced with blanks and a new color discontinuity of the correct phase is inserted for the discontinuity. The discontinuity of color bands is alternately shifted from phase to phase correction. In another embodiment, the discontinuity of color bands is delayed in time with respect to the trailing edge of the preceding horizontal synchronization pulse, so that the discontinuity of color bands occurs outside the detection window of the color discontinuity circuitry. of VCR. In another embodiment, the phase error (displacement) present in the discontinuity of color bands is measured and a color discontinuity of a negative vector phase is added thereto, and after discontinuity of summed color it can be attenuated to a normal level . In another embodiment, a color discontinuity of very large amplitude of correct phase is added at the location of the discontinuity of color bands and then the color discontinuities added are attenuated to a normal level, thus effectively eliminating the effect of discontinuity of color. color bands. (This can be done on all video lines - those that have discontinuities of color bands as well as lines without discontinuity of color bands). In another embodiment, an inverted phase color discontinuity (opposite to that of the color band discontinuity) is added to substantially cancel out the discontinuity of color bands, and then a correct phase color discontinuity is added. In another related mode, the correct phase of a normal color discontinuity and the difference between the phase of that normal color discontinuity are determined and the phase of the discontinuity of color bands is measured. Next, a signal with a negative phase is generated as the difference and used to modify the discontinuity of color bands, in order to produce color discontinuities that are of "correction" phase in the same number of degrees as the correct discontinuity on the alternate lines. That is, in one example, the discontinuity phase of color bands is + 45 °. Then, one modifies a sufficient number of TV lines, each discontinuity of color bands having about half the discontinuity of color having a phase of + 90 °, while changing the other half of the color discontinuity so that it has a phase of -90 ° (the opposite phase angle). This correction is prorated using a typical VCR. In another embodiment, all the correct phase color discontinuities across the entire TV field are replaced with color discontinuities that have the phase of color band discontinuities or that have some chromatic saturation phase angles (arbitrary). Then, the chromatic saturation phase of each corresponding horizontal TV line is modified to be equal to the phase of the discontinuities of color bands or to be the phase angle of arbitrary chromatic saturation. It should be understood that in each of these modalities it has been found that it is not necessary to modify the entirety of a discontinuity of color bands in particular; it has been found that modifying a part as small as half a discontinuity of color bands effectively eliminates its effect for a typical VCR. Also, it has been found that it is not necessary to modify each discontinuity of color bands present in a video field; In a typical VCR, you can create a copyable record of a signal with as much as half of the discontinuities of original color bands still present for a typical commercial mode of the color band system. Another modality that involves modifications to the discontinuity of color bands per se heterodyne the discontinuity signal of color bands towards the correct phase. One can also use heterodination to effectively replace with targets as observed by the VCR. This results, for example, in the heterodination of the discontinuity of color bands towards a new frequency at which the VCR will not respond, that is, a frequency substantially greater or substantially lower than the normal TV subcarrier frequency. The other broad category of methods for avoiding the color band process uses various modifications to the horizontal synchronization pulses that precede at least some of the locations of color band discontinuities. If the VCR synchronization separator fails to detect a horizontal synchronization pulse, the VCR will not generate a discontinuity sampling pulse and therefore will not detect any discontinuity of bands of subsequent color. In this way, it has been found that removal of the horizontal synchronization pulse from a line of discontinuity of color bands results in a copyable video signal. Additionally, it has been found that the actual withdrawal of the horizontal synchronization pulse is not necessary; instead, the horizontal synchronization pulse can be attenuated, for example, in amplitude (duration) by narrowing it to the point where horizontal synchronization pulse is not detected by the corresponding synchronization separator circuitry in the VCR, and therefore neither the discontinuity of bands of subsequent color is detected. Also, it has been found that the removal of only some of the horizontal synchronization pulses coincident with the discontinuities of the color bands reduces the effectiveness of the color band process. Other modes for modifying the horizontal synchronization pulse include the DC level shift up the horizontal synchronization pulse, thus causing the VCR synchronization separator to fail to produce an output signal.

Another modality that refers to horizontal sync pulses is to blacken the screen or attenuate the amplitude of the horizontal sync pulses so that they are not detected by the VCR sync separator. Another embodiment that also refers to the horizontal synchronization pulses adds a delay of approximately 2 microseconds between the trailing edge of the horizontal synchronization pulse and the start of discontinuity of color bands; in this way the color discontinuity sampling pulse of the VCR erroneously shows the discontinuity of delayed color bands and loses it. Another aspect of this invention is directed to the inhibition of the elaboration of an acceptable video record of a video signal, that is, to the protection of a video copy by modifying the video signal, by means of phase modulation. of only a portion of the color discontinuity. It should be understood that although the description herein generally refers to NTSC TV, with relatively minor modifications of the type well known to one of ordinary skill in the art, the pulses and methods described herein are suitable for use with TV. of PAL, which similarly to the NTSC TV, has a color discontinuity immediately following a horizontal synchronization pulse. The main differences between NTSC and PAL television, that is, the number of lines per field and the number of fields per second, are not material to the present invention and the circuits described therein can be easily modified to accommodate PAL TV. BRIEF DESCRIPTION OF THE DRAWINGS Figures IA and IB show a standard TV waveform of the NTSC. Figure 1C shows a modification to the waveform of Figure IB, illustrating by this the process of color bands. Figures 2A to 2G show waveforms illustrating various ways of avoiding the process of color bands according to the invention. Figure 3 shows a block diagram of an apparatus according to the invention. Figures 4A to 4C show circuits for generating a correct color subcarrier frequency and other signals to avoid the process of color bands. Figures 5A and 5B and 6A and 6B show various circuits to avoid the process of color bands. Figure 7 shows a circuit for improving the reproducibility, for use with the elimination of horizontal synchronization pulses. Figure 8 shows another circuit to avoid the process of color bands. Figure 9 shows a circuit for the regeneration of the subcarrier. DETAILED DESCRIPTION The following describes a number of modalities to avoid the process of color bands. First there is a description regarding waveforms and processes; second, there is a description of the various related circuits. Description of the Process The following are various processes for avoiding the color bands according to the invention. 1. One or more synchronous color discontinuity phase networks (or other circuits) are used to find the middle phase of color discontinuity and then all color discontinuities (whether color bands or not) are replaced through of the entire video signal. This replacement may be only a portion of a particular color discontinuity. For example, of the eight to ten standard cycles of the NTSC color discontinuity, one can replace for example the first five cycles, the last five cycles, or any other group of for example four to six cycles. The replaced cycles do not need to be consecutive; one can replace alternate cycles, leaving "good" (corrected) cycles interspersed with "bad" cycles (colored bands). It is also possible to add corrected color discontinuity cycles out of their normal location and over the horizontal synchronization pulses, since these will be detected by a VCR. It should be understood that the recognition by the present inventors that only a portion of a particular color discontinuity needs to be replaced forms a part of the invention. In addition, the partial replacement is also applicable to other of the modalities described here below. 2. A horizontal line synchronized phase crystal or network (or an equivalent such as a discontinuity crystal filter) supplies a signal whose frequency is a multiple of 455 or 910 (on the NTSC TV) of the line frequency horizontal and subdivided into the color frequency, with the phase reset of each field based on an even or odd field identification. This color frequency is used to replace (in the detection described above) all or sufficient discontinuities of color bands in order to allow a copyable result. 3. A color synchronized phase network is used to identify the specific horizontal video lines that are color bands, and then the discontinuity of color bands is shifted phase (using for example a conventional phase shifter circuit) in order to obtain a usable record. 4. The horizontal lines of color bands are determined, and coincident with these lines of color bands are commuted to a discontinuity of phase shifted color to replace discontinuities of color bands or all discontinuities. 5. Either the detection of color band video lines (for example, through a synchronized color phase network) or the identification of video lines of other color bands and the delay of each line of active video and therefore of chromatic saturation in order to provide an copiable signal. 6. Either detect the color band lines (for example through a synchronized color phase network) or otherwise identify the color band lines, and phase shift the color saturation on the active lines where they are locate the process of color bands to make an copiable tape, free of color bands. The phase shift of the color saturation is carried out by a conventional circuit such as an operational amplifier having its inverted terminal connected through a resistor to the input signal and its non-inverted terminal connected through a capacitor to the entrance sign. The input terminal of its operational amplifier is connected to the inverted terminal through a resistor, and also a resistor of the same value is connected to the inverted input terminal of the operational amplifier and its output. 7. Locate video lines in which discontinuities of color bands appear, then measure the phase error of the discontinuity of color bands. This is done with a phase detector with discontinuity of color bands as an input and a regeneration circuit of the color subcarrier (eg a color glass call circuit) that supplies the second input. A color discontinuity of a negative vector phase is then added to correct the phase of the discontinuity and (in one version) readjust the amplitude of the discontinuity to a normal level of for example 40 IRÉ units. 8. Locate the video lines in which discontinuities of color bands appear, then effectively replace the color band discontinuities by adding a very large amplitude of the correct color discontinuity to the discontinuity of color bands and attenuate then the resulting added discontinuity, thus effectively eliminating any effect of the incorrect color bands. 9. Replace discontinuities of color bands by first locating discontinuities of color bands, then adding color discontinuities of an inverted phase to substantially cancel the discontinuities of color bands and add correct phase color discontinuities. This requires the deduction of the phase of discontinuities of color bands, by observation or by measurement as above. This process results in the replacement of discontinuities of color bands, without having to transfer the discontinuities. 10. Use a synchronized color frequency phase network (or other method) to find the correct phase of a normal color discontinuity signal and to find the phase difference between normal color discontinuity and band discontinuity signals color. By using this information, generate a signal with a negative phase of this difference and use this signal to modify all or part of the discontinuities of color bands with the negative phase discontinuity signal to produce color discontinuities that are correction of phase in the same number of degrees from the correct discontinuity of a line to the next line or within the portions of discontinuity in the same lines. A VCR tends to apportion the TV line to the next line, correcting more or less the phase discontinuity signals, and / or the plus / minus discontinuity phase portions within each TV line. Consequently, the resulting signal tends to produce fewer color errors than the signal of unmodified color bands. The variants of the methods described above are illustrated in Figures 2A and the following. Figure 2A illustrates (in simplified form) the horizontal synchronization pulse and the discontinuity of color bands in Figure 1C. The shaded area is the discontinuity area of color bands; the individual color discontinuity cycles are not shown here for simplicity. In the case of Figure 2A, the discontinuity of the color as a whole is shifted from phase to phase as indicated by shading. A method to avoid the process of color bands is illustrated in Figure 2B, where a portion (here, the right or back portion) of the discontinuity of color bands is modified to be in the correct phase and / or in the phase of discontinuity of bands of negative color, as illustrated by the absence of shading. As described above, it has been found that if about half or more of the duration of the discontinuity of color bands has its own corrected phase or is blank, the discontinuity of color bands is effectively prevented. That is, the color discontinuity of the NTSC is 8 to 10 cycles long; it has been found that the modification of 4 to 6 of these cycles is adequate. Figure 2C shows another method to avoid the process of color bands; here the central portion of the discontinuity of color bands goes blank. The first and second portions are corrected towards the correct phase; this shows that the discontinuity of color bands does not need to be presented in full in order to achieve an appropriate color operation of the VCR and / or the television set. Figure 2D shows a variant of Figures 2B and 2C, where the first and the last portion of the discontinuity of color bands have their phase corrected, but the central portion remains with the incorrect phase. As shown here, approximately 30% or 40% of the color discontinuity remains in the wrong phase but this still effectively prevents the process of color bands. In Figure 2E the discontinuity of color bands in whole has been blanked without providing any substitution. In this case, it has been found that there is no need for a discontinuity of color in each video line for the effective operation of most television sets and VCRs. In Figure 2F the first portion of the discontinuity of color bands has been blanked; instead of a few cycles of the correct phase color discontinuity overlapping the actual horizontal synchronization pulse. Even in this location, they will be detected by the color synchronization circuitry of the TV set or VCR. A portion of the discontinuity of color bands is still present, that is, the central portion; the last portion of the discontinuity of color bands has its corrected phase until it is normal. Figure 2G shows a last and obvious variant where the discontinuity of color bands entirely has its phase corrected, by replacing or altering the discontinuity of color bands until it is of correct phase. Other methods of cancellation include those that refer to the horizontal synchronization pulses: 11. Replace all the correct phase color discontinuities across the entire TV field with color discontinuities that have the phase of color band discontinuities. . Then modify each chromatic saturation phase of the corresponding active horizontal TV line until it is equal to the discontinuities of color bands. For example, if the phase of color band discontinuity is 180 ° outside the correct color discontinuity phase, then one modifies the color discontinuity of the correct color discontinuity phase by 180 °. One can also replace all discontinuities of color with discontinuities that have an arbitrary phase, and shift after phase the phase of chromatic saturation in the active portions of the TV lines so that they are equal to the arbitrary phase. This modification can be made by phase shift and / or delay circuits and / or inversion amplifiers. With this modification, the phase of chromatic saturation in each horizontal line of TV is 180 ° outside the discontinuity line modified as described above. To correct this discrepancy, one then modifies each of the horizontal active TV lines by shifting its chromatic saturation by 180 °. This can be done by inserting a shifted phase or delayed version of the horizontal, active, video, original TV lines in conjunction with the modified color discontinuity. Again, one can obtain a copyable record by modifying a sufficient number of correct color discontinuities and by shifting a sufficient number of horizontal TV lines from phase. 12. Remove the horizontal synchronization pulse so that the VCR discontinuity detection circuit (which normally depends on a preceding horizontal synchronization pulse) is disabled. One can effectively "withdraw" the horizontal sync pulses in several ways. For example, one can remove the immediately preceding horizontal synchronization pulses in at least some locations of the discontinuity of color bands. It has been found that removal of, for example, four horizontal synchronization pulses coincident with a band of color band discontinuity video lines results in an copiable record without adversely affecting the synchronization of the horizontal line of the VCR. The withdrawal of these horizontal synchronization pulses can also be done by narrowing the horizontal synchronization pulse coincident with the discontinuity lines of color bands. This narrowing is done until the effectiveness of the color bands is reduced to the point where it is possible to create an copiable record. As an example, one can reduce horizontal sync pulses to below 100 nanoseconds of amplitude. It has also been found that the removal of only some of the horizontal synchronization pulses coincident with the discontinuity lines of color bands reduces the effectiveness of the color band signal. For example, every other line where a discontinuity of color bands appears, the horizontal synchronization pulse of that line is removed. 13. The DC level shifts upwards from the horizontal sync pulses that precede the discontinuities of color bands. This causes the VCR synchronization separator to fail in the production of an output in response to these offset horizontal pulses of level. Other methods for effectively removing the horizontal synchronization pulses are to blacken the screen or attenuate the amplitude thereof to about 20 IRES or less so that the synchronization separator of the VCR does not detect these horizontal synchronization pulses of smaller amplitude, and in this way it does not create a discontinuity sampling impulse when discontinuities of color bands occur. These last two methods can lead to problems of "reproducibility" due to the missing horizontal synchronization pulses. "Playback capability" refers to the resulting video signal that includes significant visual defects due to "sliding" away from the active video as caused by the inappropriate separation of the horizontal synchronization pulse. This causes some of the synchronization separators in the receivers of televisions or VCRs to generate false horizontal synchronization pulses. To minimize such reproducibility problems one can: Add a voltage or constant voltage signal such as a ramp from 0 IRÉ to the start of the active TV line until approximately 10 IRÉ at the end of the TV line to all active lines of TV; and / or extending all the amplitudes of the other horizontal synchronization pulses to approximately 6 microseconds. 14. On video lines where discontinuities of color bands occur, add a delay of approximately 2 microseconds or more in such a way that the discontinuity sampling pulse of the VCR (triggered by the horizontal synchronization pulse) between the trailing edge of the horizontal synchronization pulse and the start of discontinuity of color bands erroneously show (omit) the discontinuity of delayed color bands. 15. Heterodyne the discontinuity signal of color bands towards the correct phase by mixing it with a signal in such a way that the resultant has the correct phase. 16. Heterodyne the discontinuity of color bands to a new frequency in such a way that the VCR does not respond to it. For example, the discontinuity of color bands could be shifted by their heterodyning to a 15 MHz signal or a 2 MHz signal. In any of the above embodiments, one can replace the color synchronized phase network with at least one stage of glass filtration such as a call circuit. General Circuit Figure 3 shows a block diagram of an apparatus according to the present invention, suitable for carrying out the methods described above to avoid the process of color bands. An "input video" of the input video signal is typically provided from a cable television source, but possibly from other sources such as prerecorded video tapes. (However, the process of color bands is generally unsuitable for a pre-recorded video tape). The input video signal is provided to a circuit that includes a color band location memory 12. This is typically a read-only programmed memory, for example, an EPROM, which includes data indicating which of the 525 lines of the NTSC television field are located discontinuities of color bands. This EPROM is programmed before the assembly of the circuit, and the knowledge of the location of the discontinuity of color bands is determined by observation. Accordingly, it could be determined that the color band pattern is the commercial mode as described above with four video lines having the discontinuity of color bands followed by eight video lines without the discontinuity of color bands, etc. The output signals from the location of color bands from memory 12 include a line location gate (LLG) signal which indicates on which lines the color discontinuity is located. The LLG signal is thus raised for the entire duration of a line having a discontinuity of color bands. A second output signal from the color band location memory 12 is a pixel location gate (PLG) signal which indicates exactly which portions of the color discontinuity are to be modified. The LLG signal is useful because, as explained above, in certain embodiments of the invention, only a portion of each color discontinuity is modified and other portions do not. In this way, typically, the PLG signal is only raised for a portion of a discontinuity of color bands, but of course it can be raised for the entire duration of a discontinuity of color bands where it is desired to modify and / or eliminate the discontinuity of color bands entirely. Again, the data for generating the PLG signal is stored in a part of the memory 12 that stores enough data to divide the discontinuity of color bands in, for example, 20 segments and to modify or not modify each of those segments. Since the color discontinuity in the NTSC television is eight to ten cycles of duration, each of these cycles can be treated individually by the PLG signal. An oscillator 16 provides an output signal having the subcarrier frequency signal (3.58 MHz for the NTSC). This oscillator (synchronization signal generator) can be, for example, a synchronized phase network, or a crystal filter oscillator, or it can derive the subcarrier frequency from the frequency of the horizontal synchronization pulse edges and then multiply the horizontal synchronization pulse frequency by the multipliers of frequency or by a synchronized phase network to cause the circuit to lock on the correct color subcarrier frequency. A phase detector circuit 18 provides an output signal, which is either logically high or low and is called the color band detecting (CSD) signal. In this way, when the signal is high it indicates that the discontinuity of color bands in a particular video line has been detected. This CSD detection signal is useful when the video line locations of color band discontinuities are not known. This is typically used when discontinuity locations of color bands are dynamic, i.e., non-static. In this way, the use of the phase detector is an alternative to the use of the LLG signal and typically both are not used in a single circuit. In this way, the circuit of Figure 3 is a generalized representation of several alternative circuits that share common elements and is shown here as a circuit for purposes of explanation. The phase detector circuit 18 includes a phase detector, the output signal of which is provided to a comparator for comparing the phase of a color discontinuity in particular with that of a normal color discontinuity. If the comparison does not indicate any difference, then the color band detector signal is low, that is, there is no discontinuity of color bands; if there is a difference, then the color band detector signal is a high signal indicating the presence of a discontinuity of color bands. The right-hand portion of Figure 3 shows a generic modification circuit 22. This circuit 22 may be any of a number of circuits, each of which carries out one of the types of modification to the video signal as shown in FIG. exposed above and described in detail below. In addition to receiving as inputs the indication of the presence of the color bands, that is, either the LLG signal or the CSD signal, and the PLG signal that indicates which portions of the color bands are to be modified as well as the subcarrier frequency signal, the modification circuit also receives the input video signal. The output signal of the modification circuit 22 is a "video output" of the video signal that is free of (or has only one attenuated) color band processes and is therefore copyable by a commercially available typical VCR . As described below, the modification circuit either attenuates or eliminates the color band process by directly modifying the discontinuity of color bands or alternatively operates in the horizontal synchronization pulse immediately preceding a discontinuity of color bands. color, and modifying the horizontal sync pulse causes the VCR to ignore the discontinuity of resulting color bands. Therefore, to the AND logically the output of the phase detector (the CSD signal) or the LLG signal with the PLG signal, one can select which video lines to modify and which portion of each line is to be modified. As described above, it has generally been found that it is suitable, for example, to modify a part as small as one half of a discontinuity of particular color bands in order to avoid the process of color bands with respect to band discontinuity. color. Furthermore, it has been found experimentally that for the typical commercial modalities of the color band process one can modify or eliminate as little as one half of the discontinuities of color bands and still effectively avoid the process of color bands, ie , provide a copyable video signal. It is understood that herein the terms "copiable" and "recordable" both mean that the resulting video signal, when recorded by a VCR and then reproduced, provides an observable television image without substantial color defects due to the process of color bands. In this way, these terms refer to the effective elimination (cancellation) of the effect of the color band process in terms of observability of the video signal. Significant axis circuits Figures 4A, 4B, 4C illustrate several exemplary circuits for generating the correct color subcarrier frequency and other signals to be used in order to replace the color discontinuity signal component in the output video of the device. Figure 4C also illustrates a circuit for generating synchronization signals in order to avoid the process of color bands to provide a copyable video signal thereof. In this way, Figures 4A, 4B, 4C and Figures 5A, 5B, 6A and 6B show several particular versions of the circuit of Figure 3. Video protected from the copy from a video source (such as cable television). ) is demodulated in a conventional manner (not shown) to provide a baseband video using well-known techniques. This video protected from the copy usually contains stable video with horizontal and vertical synchronization and subcarrier coherence, and includes the process of color bands as described above. The copy protection may also include pseudo-synchronization and AGC pulse pairs as described in US Pat. No. 4., 631,603 of Ryan referred to above and elevated rear gazebo pulses as described in U.S. Patent 4,819,098 also by John. O. Ryan and incorporated herein for reference. These pseudo-timing and AGC pulse pairs can be removed using techniques described in U.S. Patent No. 4,695,901 to John O. Ryan and also incorporated herein by reference. Also incorporated herein by reference are U.S. Patent No. 5,194,965 to Quan et al., U.S. Patent No. 5,157,510 to Quan et al., And U.S. Patent Application Ser. 08 / 062,866 filed by Wonfor et al., Which also disclose copy protection and cancellation techniques relevant to the present invention. This baseband video in the signal (see figure 4A) is introduced to the Al and A2 amplifiers. The output of the amplifier Al is coupled to the synchronization separator Ul which is for example part number LM1881 of National Semiconductor Corp. or an equivalent. The synchronization separator Ul generates a structure pulse on line 16, a horizontal synchronization pulse on line 18 and a discontinuity gate signal on line 20. Amplifier A2 operates as a synchronization end blocking amplifier. A one-shot U-89 generates a synchronization pulse sample pulse to cause the amplifier A2 to lock on the synchronization pulses at a specific voltage, i.e. The synchronization end lock is desirable since the input signal may include the pseudo-synchronization and AGC pulses described above, which would cause the hind viewer locking circuits to behave incorrectly. The output signal of amplifier A2 is about 1 volt peak-to-peak and the blanking level of the video output signal of amplifier A2 is blocked at approximately zero volts. The discontinuity gate inverter U20 is coupled to the control terminal of the switch SW1. The blocked video signal from the amplifier A2 is coupled to a first input of the switch SW1 and to the "Video Blocked" output line of FIG. 4C. The second input terminal of SW1 is coupled to the ground.

Switch SW1 drives the color discontinuity portion of the input video to produce a color discontinuity signal driven on line 30. Chromatic saturation amplifier A3 amplifies the color discontinuity signal operated on line 30, and its terminal output 34 is coupled to a first input terminal of AND gate U100. The other input terminal of the gate U100 is connected to the output terminal D5 of the EPROM U5 (see FIG. 4B). The EPROM U5 38 is a 525-line EPROM treated more fully later; its output terminal D5 provides a signal that is typically high during the active field and low during the vertical blanking interval. It is necessary that the signal in terminal D5 is "on" during the entire active TV field since it can be programmed to turn on during the time of the normal color discontinuity signal and / or be low for the duration of the time of discontinuities of color and / or low bands during the vertical blanking interval (VBI) lines without color discontinuity. The output signal from gate U100 on line 42 is the discontinuity from the input video, with possible restrictions to particular lines in the VBI. The synchronous color discontinuity phase network U2 has a long and slow time constant in its DC amplifier in such a way that its output signal is a constant phase, although there are discontinuities of color bands with phase discontinuity signals incorrectly in the video input 42. Alternatively, the PLL U2 may be a glass discontinuity continuation oscillator which is closed by injection, such as RCA CA1398, or a discontinuity call circuit such as a crystal filter. The output terminal 46 of the PLL U2 is coupled to a phase shifter 02, on line 50 is a stable 3.58 MHz sine wave, CW2, which is used in the circuitry of Figures 5A, 5B to produce recordable video signals. The above discussion assumes that the locations of discontinuities of color bands are known and fixed. If the location of the discontinuities of color bands moves at the location of the line over time, these color discontinuities are rather detected on a line-by-line basis. This detection is made by comparing the input video discontinuity signal to activate U100 with the output signal of circuit U2 using a phase detector (PD) Ull (see Figure 4C). The output signal from the phase detector Ull is coupled to a 3 MHz low pass filter (LPF) LPF3 to an input terminal of the switch SW20. Switch SW20 is controlled by a reverse lock pulse on line 24. Switch SW20 and capacitor C4 show and maintain the output of the 3MHz LPF3 low pass filter during the discontinuity gate interval. The non-inverse input signal to the amplifier A4 is therefore a line-by-line identification of the discontinuity phase. An incorrect discontinuity phase from a color band signal causes a different voltage to appear at the input terminal of the A4 amplifier than when the correct discontinuity phase occurs. The amplifier A4 operates a threshold detector that is activated as high when discontinuities of color bands occur. The output signal of amplifier A4 is therefore a color band detection signal (CSD) on line 62 which is used in the circuitry of FIGS. 5A, 5B to produce copyable signals. A second method for generating a stable color subcarrier is to derive a subcarrier signal from the horizontal synchronization portion of the video signal. This method is applicable when there is a consistency of synchronization-with-discontinuity, which is the case when the process of color bands is applied in cable television applications. To achieve this, a horizontal synchronization pulse signal on line 18 from the synchronization separator Ul is coupled to a non-reactivatable U3 trip of 45 microseconds to eliminate the horizontal synchronization pulses present during the vertical interval and / or the pseudo pulses when both are in the video input signal. The output terminal of a shot U3 (see Figure 4B) is coupled to a first input terminal of a 10-bit counter U4. The zeroing input terminal of the counter U4 is coupled to a structure pulse output terminal of the synchronization separator Ul via line 16 and a differentiation circuit including a capacitor Cl and a resistor Rl. The output signals of the 10-bit counter U4 are fed to a 10-bit bus to the EPROM circuit U5. The EPROM U5 is programmed to set high or low logic levels within the TV structure (525 lines in the NTSC). The output terminals of the EPROM U5 are DO to D7. The signal in terminal D3 can be raised all the time or raised during a portion of the TV field. The signal in terminal D3 controls the control of three states of the output of flip-flop U6 Q. the output terminal of the one-shot U3 is coupled to the clock input terminal of the phase detector bistable circuit U6. The horizontal synchronization edges of the one-shot U3 set the bistable circuit U6, while the output signal of the divider U7 resets the flip-flop U6. The output terminal of the flip-flop circuit U6 is coupled to a low-pass filter and to the LPF1 amplifier for filtering and amplification (see FIG. 4C). The filter output LPF1 is coupled to a VCO crystal voltage controlled oscillator operating at 14.318180 MHz. As a result of the input signal from the LPF1 filter, the VCO oscillator is blocked for horizontal video synchronization pulses. The output terminal of the VCO oscillator is coupled to a counter divided by 4 U8 to produce a subcarrier frequency signal on line 76. The counter divided by 4 U8 is reset at its CLR terminal each structure and results in an ambiguity of 0 ° or 180 ° in the correct phase of the subcarrier frequency on line 76. To correct this, the counter signal divided by 4 U8 is compared in phase by the phase detector U10 with the normal discontinuity of the input when shown in a video line that is known to have a normal discontinuity, that is, video line 14, and maintained through capacitor C3. If the phase is correct from the counter U8, the amplifier A5 emits a low state and the output of the exclusive OR gate U9 will not invert the phase of the output signal of the counter U8. If the phase of the output signal of the counter U8 is incorrect (180 °), the phase detector (PD) U10 supplies a voltage (through the low pass filter LPF2 and the switch SW10) to the amplifier A5 in such a way that the output of amplifier A5 is high. This then causes the output of the XOR gate U9 to reverse phase by 180 °. Switch SW10 is controlled by the signal at terminal D6 of EPROM U5. This circuit generates the correct subcarrier phase in the output terminal of the XOR U9 gate. The output signal of the XOR gate U9 is coupled to the phase shifter 0l. The output of 0I is a 3.58 MHz CW1 subcarrier signal on line 94 which is used in the circuitry of Figures 5A, 5B to generate one or more recordable output signals. The additional circuitry in Figure 4C includes a 10-bit counter U60, the output terminals of which are coupled to the horizontal line pixel location EPROM U70. The individual pixels are located by zeroing the 10-bit counter U60 with the horizontal ratio edge signals from the output terminal of the U3 one-shot and synchronizing the 10-bit counter U60 with the output signal of the VCO oscillator . The output signals of the 10-bit bus of the 10-bit counter U60 are coupled to the address lines of the U70 EPROM to generate outputs DDO to DD7. These outputs (pixel location gate signals) represent pixel locations within horizontal lines across the entire video field. In addition to the output signals of figure 4C above treated, several additional output signals from Figure 4C are used in the circuitry of Figures 5A, 5B. A first group of these includes: (1) the output signal DO of EPROM U5 which provides an indication of "all locations" of the pulses of color bands designated ACSL on line 100; (2) the output signal DI of the EPROM U5 which provides an indication of "some locations" of the pulses of color bands designated SCSL on the line 102; and (3) the output signal at terminal D4 of EPROM U5 which provides an output of "all active fields" designated AFL on line 104. These signals correspond to the line location gate signal of the figure 3. Additionally, there is: (1) a horizontal synchronization HSYNC output signal provided on line 18 by the horizontal synchronization output terminal of the synchronization separator Ul; (2) a BLOCKED VIDEO output signal on line 108 provided by the output terminal of blocking amplifier A2; and (3) an output signal of DISCONTINUITY GATE provided by a discontinuity gate output terminal 20 of the synchronization separator Ul. All these output signals are used for various parts of the circuitry described in Figures 5A, 5B, 6A, 6B. Figures 5A, 5B and 6A, 6B show various exemplary circuits for using the color subcarrier and other signals generated in Figure 4C for various methods that produce a video output signal recordable by a video cassette recorder. Therefore, Figures 5A, 5B and 6A, 6B are illustrative of various possible circuits; a current circuit would accordingly include only selected portions of what is shown in Figures 5A, 5B and 6A, 6B. The first of these circuits produces a copyable video output signal VIDOUT 1, at terminal 200. The user can select a suitable subcarrier signal generated in FIG. 4C by selecting either signal CW1 on lines 94 or signal CW2 in line 62 through the use of a jumper JP1. The bridge output terminal JP1 is coupled to a PAD attenuator which attenuates the selected subcarrier signal. The video blocked on line 108 and the attenuated subcarrier from the PAD attenuator are coupled to the first and second inputs of the SW100 switch. The switch SW100 is controlled by an output terminal of the AND gate U305, with a gate input terminal U305 coupled to the DDO output line of the EPROM U5 that contains a discontinuity gate signal of an amplitude dependent on the programming of the EPROM U5. The other input terminal of the AND gate U305 is selectively connected to the ACSL signal on line 100, the SCSL signal on line 102 or the CSD signal on line 62 using a bridge combination JP2 and bridge JP3. This circuit allows the user to select the video lines of the recordable video output VIDOUT 1 at terminal 200 which are about to receive the replacement color discontinuity signals. If the ACSL signal is selected, the recordable video output VIDOUT 1 includes corrected color discontinuities in all video lines where discontinuity of color bands is known. If the SCSL signal is selected, the recordable video output VIDOUT 1 includes corrected color discontinuities in a sufficient number of video lines to substantially reduce or nullify the effects of the color band process in the recorded video.

The ASCL signal is preprogrammed and indicates the video lines that as determined by observation have been preprogrammed in turn by the color band generator. (The color band generator is the device, not illustrated here, that puts the process of color bands in the video signal). In some cases it is known which lines have been preprogrammed, and then the CSD signal is used to determine which video lines need to have a corrected color discontinuity. If the CSD signal is selected using jumper JP3 to operate the AND gate U305, the circuit replaces all or at least most of the discontinuity of color bands in the recordable video output VIDOUT 1, such that the effects of discontinuities of color bands are essentially nullified. In each of the above techniques, the signal at the output terminal of the EPROM U5 is programmed to insert by sufficiently switching a portion of the correct discontinuity in each line to substantially reduce or nullify the process of color bands. A second circuit produces a recordable video output signal VIDOUT 2, at terminal 214. This circuit inserts by switching a phase shifter during video lines where a discontinuity of color bands is known, to shift the known phase error of the discontinuity of color bands. A first input signal to switch SW102 is blocked in the video of line 108 which contains discontinuities of color bands with a known value of phase shifted color discontinuity signals. The second input signal to the switch SW102 is the output signal of the phase shifter 03, which is a shifted phase version of the blocked video signal. The control terminal of the switch SW102 is connected to the output terminal of the AND gate U305 which provides the same synchronization pulses as the control switch SW100. These pulses allow the selection of a sufficient corrected color discontinuity of essentially the corrected phase in each line to substantially reduce or nullify the process of color bands. A third circuit for providing a copyable video output signal adds a large amplitude of a correct discontinuity signal to the color band video and then attenuates the resulting discontinuity to nominal discontinuity levels. This circuit is carried out as follows. The video signal blocked on line 108 is coupled to a first input terminal of totalization amplifier A36. The color subcarrier signal selected by the bridge JPl, either signal CW1 or CW2, through the attenuator PAD is coupled to an input terminal of the switch SW101. Switch SW101 selects the attenuated color subcarrier, which is at a normal discontinuity amplitude, during the moments determined by EPROM U305 as discussed above. The output terminal of the switch SW101 is coupled to the amplifier A35, which is a 10X amplifier that produces a color subcarrier discontinuity signal of 10 times the normal amplitude. This amplified color discontinuity signal is coupled to a second input terminal of the totalization amplifier A36, where it is summed with the video signal blocked on line 108 which contains discontinuities of color bands. The output terminal of the totalization amplifier A36 is coupled to a switched attenuator which includes the resistor R9, the resistor RIO and the switch SW104. The switch SW104 is controlled by the discontinuity gate signal from the synchronization separator A36 during the duration of the discontinuity gate signal. This in effect "submerges" any discontinuity of color bands present in the input video signal. The output of the switched attenuator is coupled to amplifier A44, which is a unit gain amplifier, to provide the VIDOUT 3 copyable video output in terminal 218. Note that switch SW104 causes the reduction of the discontinuity amplitude to be closed during some or all of the color band lines and also during a portion of the discontinuity. of color on each line to produce a recordable (copyable) signal. Note also that the addition of a large amplitude color discontinuity through the amplifier A36 followed by the reduction in amplitude of the discontinuity can be made to most video lines in a video field to produce a recordable signal. A fourth technique for providing a copyable video signal includes the removal of discontinuity of color bands and / or the horizontal synchronization pulses preceding the discontinuities of color bands. In doing so, the record VCR will not attempt to heterodyne the discontinuity line of correct color bands with an incorrect phase discontinuity signal. All or some of the lines with discontinuities of color bands that have horizontal synchronization pulses or discontinuities of color bands replaced with blanks result in a recordable copy. It should be noted that only some of the relevant horizontal synchronization pulses are narrowed or only some of the discontinuities of relevant color bands are narrowed to produce a recordable output. A circuit to implement this fourth technique is as follows. The video blocked on line 108 is coupled to resistor R107 which in turn is coupled to the gain amplifier of unit A55. A combination of NAND gate U110, AND gate U120, bridge JP5, bridge JP4, and gate OR U130, provides the synchronization signals to replace with blanks the discontinuity of color bands and / or the horizontal synchronization pulses preceding the discontinuities of color bands. Switch SW103 ground the input terminal of the gain amplifier of unit A55 as long as the selected pulses or discontinuity intervals are selected by the above-profiled elements. The synchronization components described above can replace the horizontal pulses or discontinuity signals of color bands with whites all or only during a portion of a discontinuity period of color bands or their accompanying horizontal synchronization pulse. The output terminal of the unit gain amplifier A55 provides the recordable video output VIDOUT 4 on terminal 220. FIGS. 6A, 6B illustrate other circuits for using the color subcarrier and the pulses generated by the circuitry of FIG. 4C for produce recordable (copyable) video output signals. A fifth technique for producing a recordable video signal eliminates the effect of the horizontal synchronization pulses associated with discontinuities of color bands, using a level shift of the horizontal synchronization pulses. The effects of the level shift are described in "Method and Apparatus for Deploying Anti-Copy Protection in Video Signals", United States Patent Number 5,194,965 issued to Quan et al, on March 16, 1993, and which is incorporated for reference. This fifth technique is carried out as follows. The video blocked on line 108 of FIG. 4C is coupled to the first input terminal of totalization amplifier A99. The other input terminal of the amplifier A99 is connected to an output terminal of the gate U120 which may contain a horizontal positive heading synchronization pulse coincident with a discontinuity of color bands. The output terminal of the gate U120 can also carry out part of a horizontal synchronization pulse coincident with some of the discontinuities of color bands. The selection of the lines that are affected is a function of the synchronization described in the previous technical proposal. In this way, the displacement level of the horizontal synchronization pulse can occur only on a portion of a specific line or on specific lines that have color discontinuities. The amount of level shift can be adjusted to produce the amount needed to produce a recordable video output. The output of the terminal totalization amplifier A99 250 provides the recordable video output signal with horizontal synchronization pulses displaced from the level. A sixth technique for producing a recordable video signal is to eliminate the effect of the horizontal synchronization pulses associated with the discontinuities of color bands by trimming the associated horizontal synchronization pulses. The sixth technique is carried out as follows. A timing trimming circuit includes an amplifier A91, a transistor QBCL and a resistor RS. The amplifier A91 inverts and attenuates the logic level of the output signal of the gate U120 described above. The output signal from amplifier A91 is typically approximately zero IRÉ at -10 IRÉ. When the blocked video signal is coupled through the resistor Rs, its horizontal sync pulses will be trimmed to -10 IRÉ during a portion of or all color band discontinuity lines, depending on the output of the logic level of the gate U120. In addition, each horizontal synchronization pulse can be trimmed for its total duration or part of its duration. The amount of clip duration depends on the ability to make a recordable copy. Amplifier A77 outputs the recordable VIDOUT 6 video signal with horizontal synchronization signals cut off. A seventh technique for producing a recordable video output is to eliminate the effect of the horizontal synchronization pulses associated with discontinuities of color bands by extending those horizontal sync pulses. This is carried out as follows. The video signal blocked on line 108 is coupled to a first input terminal of switch SW124. The second input terminal of the switch SW124 is coupled to an extended horizontal synchronization signal that is provided by the output terminal DD3 of the EPROM U70. The switch SW124 is controlled by the signal at the output terminal of the AND gate U123 that AND the horizontal blank signal at the DD4 terminal of the U70 EPROM and the output signal of the active field lines in line 64 .

This seventh technique uses the gate output signal U120 to control switch SW124. The resulting signal on any video line determined to have discontinuity signals of color bands with no color discontinuity, because the extended horizontal synchronization eliminates color discontinuity. The A88 unit gain amplifier couples the recordable video output with the horizontal synchronization signals extended to the VCR. Figure 7 shows a circuit to improve the reproduction capacity in conjunction with the elimination of horizontal synchronization pulses, to 1 add a displacement voltage to the video that has eliminated horizontal synchronization pulses. This added displacement voltage allows the synchronization separator on a TV or VCR not to be divided into video levels caused by missing horizontal sync pulses. To generate a constant voltage during the active lines of the active field, the active horizontal line pixel locations indicated by a signal on the DD5 terminal of the U70 EPROM are logically combined by the AND gate U467 with the signal in terminal D4, which indicates the active field line locations. The output of gate U467 is provided to a current reflector that includes transistors QA and Q_ through the resistor Rped. The collector of transistor QA feeds a current reflector including transistors QD and Qc. The collector of the transistors Qc then injects a constant voltage into the resistor Rss to add a constant voltage to the blocked video input. The output signal (via the buffer amplifier A40) is then fed into the various trimmer, shift or blank circuits of the horizontal synchronization pulse described herein. An eighth technique for producing a recordable video output is to delay the discontinuity of color bands in order to be outside the range of the discontinuity detection circuitry, to cause the color discontinuity to be "effectively" removed. The technique is carried out as follows. The video blocked on line 108 is coupled to a chromatic saturation bandpass filter including resistor Ro, inductor L4 and capacitor C4 and to a first input terminal of switch SW123. The output signal of the chromatic saturation step filter is stored and amplified by the amplifier A98. The output terminal of the amplifier A98 is coupled to the delay line 276 which retards the chromatic saturation output of the bandpass filter, for example, 2 microseconds. The output terminal of the delay line 276 is coupled to a second input terminal of the switch SW123. Switch SW123 is controlled by the output signal and gate AND U278. The horizontal synchronization pulses from the synchronization separator Ul are coupled to the input terminal of the U505 of a trip that generates a 4 microsecond pulse triggered by the trailing edge of the horizontal synchronization input signal. Gate AND U278 generates a control signal for switch SW123 from a logical combination of the output signal of U505 from a trip and the output signal from terminal DI of EPROM U5, which is a signal representing some Locations of color band lines (SCSL), as described above. The output signal of switch SW123 has a delayed color discontinuity in video lines that have discontinuities of color bands. The delayed color discontinuity is not detected by a VCR. Therefore, the VCR does not respond to lines that have a discontinuity of color bands. Amplifier A97 stores the output signal of switch SW123 and provides an output signal with discontinuities of delayed color bands that is recordable. A ninth technique for producing a recordable video signal uses signal multiplication (heterodination) to shift the discontinuity phase from color bands to correct and / or to displace the discontinuities of color bands outside the frequency range of the discontinuity detection circuitry, to cause the color discontinuity of the VCR to be "removed" effectively. The video blocked on line 108 is coupled to a first input terminal of a signal multiplier 282, the second input terminal is connected to a DC 1 volt signal most of the time, as controlled by signal SW122 . To control the discontinuity phase of color bands, the switch SW122 is coupled through the bridge JP207 to the signal eos (2pfsct + 0) of Figure 4 generated by the dual frequency amplifier A10 and the phase shifter 04, or To shift the discontinuity of color bands out of the frequency range, an eos signal (2pl8.6xl06t) from any oscillating source is used to heterodyne discontinuities of color bands. Switch SW122 is controlled by the output of AND gate U305. Due to the 1 volt DC in the switch SW122 and the control signal from the gate U305, the output signal of the multiplier 282 is "transparent" (equal to the signal in the line 108) for most of the time. However, during the time of color band discontinuity signals as determined by the output signal of gate U305, the output signal of multiplier 282 is equal to the frequency of color bands plus a phase angle of corrected color discontinuity or eos (2pfsct + 0A) and three times the discontinuity frequency of color plus another phase angle or eos (2p3fsct + 0B). The output multiplier is coupled to a low pass filter LPF4. The low pass filter LPF4 has a cutoff frequency of approximately 5 MHz so that the three times color discontinuity frequency is eliminated. The output signal of the low pass filter LPF4 is coupled to the amplifier A74 which stores the output signal of the low pass filter LPF4 and provides an output with discontinuity of color bands which is therefore recordable. If the second input terminal of the switch SW122 is coupled to a sine wave of 18.6 MHz, and the low pass filter LPF4 is designed to be cut at 16 MHz, the output signal of the multiplier 282 during the time of band discontinuity The color, as determined by the output of gate U305, will have discontinuity frequencies of approximately 15 MHz and 22 MHz. Such LPF4 will pass through the discontinuity of 15 MHz during the moments of color bands. When this signal is coupled to a VCR, the chromatic saturation input filter of the VCR will not respond at 15 MHz since it expects a 3.58 MHz discontinuity (and separates by filtering at a higher frequency). In this way, during the discontinuity lines of color bands, the discontinuity of color bands is canceled. Figure 8 shows a circuit for carrying out the above-described method to replace the correct phase color discontinuities with discontinuities of color bands and then modify the color saturation phase to that of color band discontinuities. The blocked video signal is provided to the phase shifter U75, which shifts the phase by an amount equal to the difference between that of the color band discontinuities and the correct color discontinuity phase. The switch SW124 controlled by the discontinuity gate signal, emits the blocked video that has in each line of the TV field a discontinuity of color having the phase of discontinuity of color bands. Similarly, the controlled switch U126 then emits the blocked video that each phase of the horizontal TV line displaced (including the active color saturation) has to match the phase shift of the discontinuity of color bands, whose signal is copiable. Figure 9 illustrates a circuit for the regeneration of the subcarrier without the use of a synchronized phase network or a voltage control oscillator, to be used in conjunction with the circuitry described above in one embodiment of the invention. The output signal from U3 of a shot of Figure 4B is given to U60 from a 32 μsec shot, the output signal of which is the equivalent of the horizontal line frequency, that is, a square wave with the horizontal line frequency. This signal is provided to a band pass filter BPF3 passing a 13th. Harmonic horizontal synchronization. In this way, this signal that is 13 times the horizontal frequency is fed to a limiting amplifier A47, which in turn is connected to the input terminal of a bandpass filter BPF4 that passes the seventh harmonic of the 13 times the horizontal frequency. This frequency, which is seven times the 13th. harmonic of the horizontal frequency, is provided to a second limiting amplifier A48, which in turn is connected to the input terminal of a bandpass filter BPFG, which passes a band of a fifth harmonic seven times the 13th . harmonic of the horizontal frequency, and which in turn is connected to another limiting amplifier A50 that is connected to the clock terminal of a counter divided by 2 U68. The non-inverting output terminal Q of counter U68 provides a signal of 3.57954 MHz, which, of course, is exactly the subcarrier frequency desired by the NTSC television. This signal in turn is the first input to a color phase identification circuit U70 (similar to that shown in Figure 4C) which provides as an output signal thereof (in response to the structure pulse provided in the other terminal input) the desired correct color phase and the frequency subcarrier for each TV field. A similar scheme can be made to regenerate the color subcarrier through the vertical synchronization signals through frequency multipliers and / or synchronized (crystal) phase network circuits. In the prior art copy protection method of US Pat. No. 4,577,216 to inhibit video recording by phase modulation means, typically for bands of four to five lines of an observable TV field the entire color discontinuity is modulated per phase for each line in the band. This band is then followed by a band of 8 to 10 video lines without the modulation of color discontinuity. However, for each line that has color discontinuity modulation, the color discontinuity is completely modulated by phase. In accordance with the present invention, only a portion of the color discontinuity for video copy protection is modulated per phase. It has been found that whenever a significant portion (but not necessarily all) of the color discontinuity of a video line has been modified, that video record is inhibited, in order to avoid the elaboration of an acceptable video record. . This method involves, as described above to avoid copy protection, the modulation of a phase of more than half but less than the total length of each discontinuity of color to another one different from the correct phase, thus inhibiting the elaboration of an acceptable video record. Phase modulation, as also described above, shifts the phase, for example, from 20 ° to 180 °. Approximately half or more of the duration of the discontinuity of color is subject to this modulation, for example, in the NTSC having 8 to 10 cycles of color discontinuity, 4 to 6 of these cycles are modified. Also, this method, as described above, can be used in a band of several consecutive horizontal video lines subject to phase modulation followed by a band of horizontal lines not subject to modulation. This exhibition is illustrative and not limiting; Subsequent modifications will be apparent to a person skilled in the art and an attempt is made to fall within the scope of the appended claims.

Claims

NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and therefore the property described in the following claims is claimed as property. A method for modifying a video signal containing a modification of color bands, the modification of color bands being to inhibit the processing of acceptable video records of the video signal, the method comprising the steps of: determining in which lines of the video signal the modification of color bands is presented; and modifying the modified video signal of color bands within at least some of those lines by which an acceptable video record of the video signal can be made. The method according to claim 1, characterized in that the determination step comprises the steps of: storing data in a memory indicating in which predetermined lines of the video signal the modification of color bands is presented; and access memory. The method according to claim 1, characterized in that the step of determining comprises the step of detecting a presence of the modification of line-by-line color bands. The method according to claim 3, characterized in that the detection step comprises the steps of: for each video line, comparing a phase of a color discontinuity of that line with a known phase; and if the phase of color discontinuity differs from the known phase, provide a signal in response indicating the presence of color band modification. The method according to claim 1, characterized in that the modification step includes modifying the lines in which the modification of color bands occurs, but sufficient lines in order that an acceptable video record can be made. The method according to claim 5, characterized in that the modification step includes: generating a color discontinuity frequency; replace at least one part but not all color discontinuities in not all lines with the color discontinuity frequency generated; and resetting a phase of the discontinuity frequency generated at intervals of a multiple of two fields of the video signal. The method according to claim 1, characterized in that the modification step comprises the steps of: generating a signal having the frequency of color discontinuity by multiplying a frequency of the horizontal synchronization pulses for the video signal; and replace at least part of the color discontinuity in at least some of the lines with the generated signal. The method according to claim 1, characterized in that the modification step comprises the phase shift of the color discontinuity. The method according to claim 1, characterized in that the step of modifying comprises: generating a phase-shifted color discontinuity signal; and insert the color discontinuity generated in the video signal. The method according to claim 1, characterized in that the step of modifying comprises: retarding at least a portion of the active video portion of each line, thereby modifying the effect of changing color bands. The method according to claim 10, characterized in that the delayed portion of the active video portion is a chromatic saturation signal. The method according to claim 6, characterized in that the generation step comprises providing a signal from a signal source. The method according to claim 1, characterized in that the modification step includes the steps of: determining a quantity of phase error in each line; add to the line a discontinuity of color of a phase opposite to that of the determined phase error; and after the addition steps, attenuate an amplitude of the color discontinuity portion of the signal to a normal level. The method according to claim 1, characterized in that the step of modifying comprises the steps of: generating a color discontinuity frequency having an amplitude greater than that of a normal color discontinuity; add the color discontinuity frequency generated to each line; and after the addition step, attenuate an amplitude of the color discontinuity portion of the line to a normal level. The method according to claim 1, characterized in that the modification step includes the steps of: generating a first color discontinuity signal having a phase opposite to that of the discontinuity phase of color band modification; generating a second color discontinuity signal having a correct phase; and adding the first and second color discontinuity signals to the color discontinuity portion of each video line. The method according to claim 1, characterized in that the modification step comprises the steps of: measuring an amount of the discontinuity phase modification of color bands for a line, relative to a normal color discontinuity; generating a color discontinuity frequency signal having a phase opposite to the determined amount of color band discontinuity phase modification; and adding the frequency of discontinuity of color generated to an immediately following line, thereby causing a phase of correction of color discontinuity from one line to the line immediately following. The method according to claim 14, characterized in that the measurement and addition steps are undertaken only for each other line having a modification of color bands. The method according to claim 1, characterized in that the modification step includes attenuating the color band modification portion of the color discontinuity portion of the signal. The method according to claim 1, characterized in that the modification step includes the elimination. The method according to claim 1, characterized in that the modification step includes: in those lines of the video signal in which the modification of color bands does not occur, modify the color discontinuity; and modify a phase of a color saturation in the video signal to one of the same as the color discontinuity. The method according to claim 1, characterized in that the modification step includes selecting a sufficient number that is less than all the lines to be modified to allow the acceptable video registration to be made. The method according to claim 1, characterized in that the modification steps include modifying only a portion of a color discontinuity in any particular video line, thereby leaving a remaining portion of the color discontinuity with the modified discontinuity of color bands. color. The method according to claim 1, characterized in that the modification step includes attenuating a horizontal synchronization pulse present in at least some of the lines. The method according to claim 23, characterized in that the attenuation step includes the withdrawal of the horizontal synchronization pulse. The method according to claim 23, characterized in that the attenuation step includes the narrowing of the horizontal synchronization pulse. 26. The method according to claim 23, characterized in that the attenuation step includes the level shift of the horizontal synchronization pulse. The method according to claim 23, characterized in that the attenuation step includes the attenuation of the amplitude of the horizontal synchronization pulse. The method according to claim 1, characterized in that it further comprises the steps of: adding a constant voltage signal to all the active video lines in the video signal; and extending a duration of the horizontal synchronization pulses different from those subject to the attenuation stage, up to at least 6 μsec. 29. The method according to claim 23, characterized in that the modification step comprises the line delay in at least 2 μsec. 30. The method according to claim 23, characterized in that the modification step comprises altering a frequency of the modified discontinuity of color bands so that it is different from that of a subcarrier frequency of the color discontinuity. The method according to claim 23, characterized in that the modification step comprises the heterodination of at least a portion of the modified discontinuity of color bands to a normal color discontinuity phase. 32. (Double Amended) An apparatus for modifying a video signal containing a modification of color bands to inhibit the processing of acceptable video records of the video signal, the apparatus comprising: a line location circuit; and a video line modifier operatively connected to receive an indicator signal from the line location circuit, wherein the indicator signal indicates in which lines the modification of color bands occurs. 33. The apparatus according to claim 32, characterized in that the indicating signal indicates in which lines the modification of color bands occurs. 34. The apparatus according to claim 33, characterized in that the indicating circuit includes a memory in which the data indicating which lines the modification of color bands is presented is stored. 35. The apparatus according to claim 33, characterized in that the indicating circuit includes a phase error detecting circuit. 36. The apparatus according to claim 35, characterized in that the phase error detecting circuit comprises: a synchronization circuit that generates a synchronization signal having a particular phase; and a phase comparator connected to receive the synchronization signal and the color discontinuity portion of the video signal. 37. The apparatus according to claim 32, characterized in that the modifier includes means for modifying less than all the lines in which the modification of color bands is present, but sufficient lines in order that the acceptable video registration can be made. 38. The apparatus according to claim 32, characterized in that the modifier includes: a color discontinuity frequency generator; means to replace at least part of the color discontinuity in not all lines with the color discontinuity frequency generated; and means for restoring a phase of the color discontinuity frequency generated at intervals of a multiple of two fields of the video signal. 39. The apparatus according to claim 32, characterized in that the modifier includes: a color discontinuity generator that multiplies a frequency of the horizontal synchronization pulses to generate a color discontinuity frequency; and means for replacing at least part of the color discontinuity in at least some of the lines with the frequency generated. 40. The apparatus according to claim 32, characterized in that the modifier induces a phase shifter of the color discontinuity. 41. The apparatus according to claim 32, characterized in that the modifier comprises: a phase-shifted color discontinuity signal generator; means for inserting a color discontinuity generated in the video signal. 42. The apparatus according to claim 32, characterized in that the modifier includes a delay element connected to retard at least a portion of the active video portion of each line, thereby modifying the effect of changing color bands. 43. The apparatus according to claim 42, characterized in that the delayed portion of the active video portion is a chromatic saturation signal. 44. The apparatus according to claim 38, characterized in that the generator comprises a synchronization signal generator. 45. The apparatus according to claim 32, characterized in that the modifier includes: means for determining an amount of phase modification of color bands in each line; means for adding to the line a color discontinuity of a phase opposite to that of the determined phase modification; and an attenuator that attenuates an amplitude of the color discontinuity portion of the signal to a normal level. 46. The apparatus according to claim 32, characterized in that the modifier comprises: a generator that generates a color discontinuity frequency having an amplitude of at least three times that of a normal color discontinuity; means for adding the color discontinuity frequency generated to each line; and an attenuator connected to attenuate an amplitude of the color discontinuity portion of the line to a normal level. 47. The apparatus according to claim 32, characterized in that the modifier includes: a generator that generates a first color discontinuity signal having a phase opposite to that of the modified color discontinuity phase of color bands; a second generator that generates a second color discontinuity signal having a correct phase; and means for adding the first and second color discontinuity signals to the color discontinuity portion of each video line. 48. The apparatus according to claim 32, characterized in that the modifier comprises: means for measuring a phase amount of a modified color discontinuity of color bands for a line, relative to a normal color discontinuity; a generator that generates a color discontinuity frequency signal having a phase opposite to the determined amount of the phase of a modified color discontinuity; and means for adding the frequency of discontinuity of color generated to an immediately following line, thereby causing a phase of correction of color discontinuity from one line to the line immediately following. 49. The method according to claim 48, characterized in that the measuring means and the addition means operate only for each other line having a modification of color bands. 50. The apparatus according to claim 32, characterized in that the modifier includes a color discontinuity attenuator. 51. The apparatus according to claim 32, characterized in that the modifier eliminates color discontinuity. 52. The apparatus according to claim 32, characterized in that the modifier includes: a phase shifter for displacing a color discontinuity phase in the video signal; a first switch connected to the phase shifter, thereby providing an output signal having in each video line the modification of color bands; and a second switch connected to an output terminal of the first switch, thereby providing a phase shifted video signal. 53. The apparatus according to claim 32, characterized in that the modifier includes means for selecting a sufficient number of lines to allow acceptable video recording to be made. 54. The apparatus according to claim 32, characterized in that the modifier includes a horizontal synchronization pulse attenuator. 55. The apparatus according to claim 54, characterized in that the attenuator removes the horizontal synchronization pulse. 56. The apparatus according to claim 54, characterized in that the attenuator includes the horizontal synchronization pulse narrow. 57. The apparatus according to claim 54, characterized in that the attenuator level shifts the horizontal synchronization pulse. 58. The apparatus according to claim 54, characterized in that the attenuating amplitude attenuates the horizontal synchronization pulse. 59. The apparatus according to claim 54, characterized in that it further comprises: means for adding a constant voltage signal to all the video lines active in the video signal; and means for extending a duration of the horizontal synchronization pulses different from those subject to attenuation, up to at least 6 μsec. 60. The apparatus according to claim 32, characterized in that the modifier comprises a delay element that delays the video line by at least 1 μsec. 61. The apparatus according to claim 32, characterized in that the modifier comprises a frequency modifier that alters a frequency of the color discontinuity of the color band modification to differentiate that of a subcarrier frequency from a normal color discontinuity. 62. The apparatus according to claim 32, characterized in that the modifier comprises a heterodyne circuit which heterodyne at least a portion of the color discontinuity of the color band modification to a normal color discontinuity phase. 63. A method for modifying a video signal, the video signal including a plurality of video lines, each video line including a color discontinuity having a predetermined phase, the method comprising the steps of: determining a duration of the discontinuity of color; and modifying a phase of a portion of said duration of each color discontinuity to be different from the predetermined phase, whereby the development of an acceptable video record of the video signal is inhibited or allowed as a function that is modify said portion of said duration. 64. The method according to claim 63, characterized in that the modification step includes the step of moving the predetermined phase by 180 °. 65. The method according to claim 63, characterized in that the modification step includes the step of displacing the predetermined phase by at least 20 °. 66. The method according to claim 63, characterized in that at least 60% of the duration of the color discontinuity is modulated in order to inhibit the acceptable registration of said modified signal. 67. The method according to claim 63, characterized in that a duration of the color discontinuity is eight to ten cycles of a color subcarrier signal, and the modification step includes the modification of more than four of the cycles. 68. The method according to claim 63, characterized in that in each video field, at least one band of video lines is subjected to the modification step, followed by a band of video lines that are not subject to the modification stage. . 69. A method for inhibiting the processing of an acceptable video record of a video signal, the video signal including a plurality of video lines, each video line including a color discontinuity having a predetermined phase, the method comprising the stages of: determining a length of color discontinuity; and modulating a phase or more than half and less than a full duration of each color discontinuity to be different from the predetermined phase, whereby the development of an acceptable video record of the video signal is inhibited. 70. The method according to claim 69, characterized in that the modulation step includes the step of moving the predetermined phase by 180 °. 71. The method according to claim 69, characterized in that the modulation step includes the step of displacing the predetermined phase by at least 20 °. 72. The method according to claim 69, characterized in that at least 60% of the duration of the color discontinuity is modulated. 73. The method according to claim 69, characterized in that a duration of the color discontinuity is eight to ten cycles of a color subcarrier signal and the modulation step includes the modulation of more than four of the cycles. The method according to claim 69, characterized in that in each video field, at least one band of video lines is subjected to the modulation step, followed by a band of video lines that is not subject to the modulation stage. . SUMMARY In the known process of color bands to avoid the recording of video signals, the discontinuity of color present in each line of active video is modified so that any subsequent videotape record of the video signal shows variations in the fidelity of the color that appear as undesirable bands or bands of color error. This process of color bands is first avoided when determining the location of the video lines that include the process of color bands, either by previous experimentation or by online detection. Then, some or all of the lines that include the modified color discontinuities are modified in order to convert all of the recordable video signals. The modification is carried out in several ways, including the phase shift of the color band discontinuity to the correct phase, replacing some of the color band discontinuities or a portion of the color band discontinuities in particular in order to that they are no longer effective, and mixing the color band discontinuities with phase color band signals in order to eliminate most or all of the present phase error. Modified color discontinuities are avoided, in other versions, by modifying the horizontal synchronization pulse signals immediately preceding the modified color discontinuities so that the modified color discontinuities are not detected by a VCR and therefore do not have effect.