JP2565218B2 - Magnetic recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in the following order.

A. Industrial field B. Outline of invention C. Prior art D. Problems to be solved by the invention (Fig. 4) E. Means for solving problems F. Action G. Example ( 1 to 3) H. Effects of the Invention A. Field of Industrial Application The present invention relates to a magnetic recording / reproducing apparatus, and more particularly to a video tape recorder (VTR) for digitally recording or reproducing an audio signal. It is suitable for application.

B. Summary of the Invention The present invention provides the maximum allocation when the sampling number of the audio signal is allocated differently in each frame in the magnetic recording / reproducing apparatus that digitally records or reproduces the audio signal in the television signal. For frames to which a smaller number of samplings have been assigned, the smaller amount is obtained from the immediately preceding frame and recorded / reproduced on / from the magnetic tape to dubbing audio signals between VTRs that handle television signals of different formats. , And the dubbing of an audio signal between VTRs handling the same type of television signal, and the dubbing of an audio signal from an audio tape recorder (ATR) to a VTR.

C. Conventional Technology In editing a VTR, in addition to dubbing the entire television signal, only the video signal among them may be dubbed, or only the audio signal among them may be dubbed. Of these, when recording the playback audio signal from the audio tape recorder (ATR) as the case of dubbing and editing the audio signal,
When recording a playback audio signal from a VTR of a television system (for example, PAL system) different from a VTR for recording (for example, NTSC system), or when recording a playback VTR of the same system (for example, NTS)
There are various modes such as the case of recording a reproduction audio signal from the C system).

By the way, in VTR and ATR, audio signals are sent to PCM (P
ulse Code Modulation) is available for recording and playback. Considering the above-mentioned dubbing as the sampling frequency at that time, each method of VTR (NTSC method, PAL method) and
It is desirable that the same frequency is used in ATR, and that the sampling frequency satisfies the sampling theorem and that the number of samplings for each frame is an integer so that editing can be performed in frame units.

Therefore, the frame frequency of PAL system is 25 [Hz] and NTS
Corresponding to the frame frequency of C method being 30 [Hz], the sampling frequency of the audio signal was selected to be 48 [kHz] or 44.1 [kHz] in the VTR for business and the ATR for business (note that Let's take 48 [kHz] as an example.

D. Problems to be Solved by the Invention However, in reality, the frame frequency in the NTSC system is strictly selected to be 29.97 [Hz] instead of 30 [Hz]. This is because in the case of a color television signal, if the frame frequency is selected to be 30 [Hz], the trap of the audio signal becomes incomplete due to the beat component with the color subcarrier, so the frame frequency is shifted by 1/1000 and this inconvenience occurs. This is because I tried to avoid it.

In this way, since the frame frequency is 29.97 [Hz], the sampling frequency of the audio signal in the NTSC VTR is not 48 [kHz], strictly speaking, so that the sampling number in the frame is an integer. It has been selected to be 47.952 [kHz] with a shift of 1/1000.

The sampling frequency of the audio signal is NT
Since it is different from SC type VTR and PAL type VTR or ATR, for example, when supplying playback PCM audio signal from PAL type VTR or ATR to NTSC type VTR for recording,
47.952 PCM audio signal sampled at [kHz]
It will be recorded as a PCM audio signal sampled at [kHz], which is the same as recording with a time axis compression of 1/1000. Therefore, when the PCM audio signal after recording is reproduced, the audio signal advances by 1/1000 with respect to the video signal.

In order to solve such inconvenience, PAL system VTR or AT
When dubbing a PCM audio signal from an R to an NTSC VTR, it is conceivable to perform it through a frequency converter that converts 48 [kHz] to 47.952 [kHz]. However, if an attempt is made to obtain a conversion device between frequencies having a difference of only 1/1000, the conversion device becomes complicated and expensive in practice, which is not desirable.

Therefore, regardless of the frame frequency, the sampling frequency of the audio signal in the NTSC VTR is the same as that in the PAL VTR or ATR (that is, 48 [kHz]).
Then, it is possible to make it convenient for dubbing PCM audio signals. But in this case NTSC
Since the frame frequency of the system is 29.97 [Hz], the number of samplings per frame is 1601.6 according to equation (1), which does not satisfy the condition of integer number.

48000 ÷ 29.97 ≈ 1601.6 (1) Therefore, the number of samplings of 3 consecutive frames is 1602 in order to satisfy the condition of integer number and to realize the sampling frequency of 48 [kHz]. In addition, by selecting the number of samplings of the remaining 2 frames to 1601, 1601.6 per frame as a whole
It is considered that it is sufficient to realize 160 pieces and arrange them so that 1601 frames are not continuous.

However, even when dubbing between VTRs of the NTSC system, if the sampling number of each frame is changed at a cycle of every 5 frames in this way, there will be a problem when dubbing in 1-frame units as in editing. For example, as shown in FIG. 4, the phase of 5 frames, which is a unit for changing the sampling number on the reproducing side, may deviate from the phase of 5 frames on the recording side. In this case, the corresponding recording side may have 1602 sampling frames.

Generally, when a PCM digital signal is recorded, a process of rearranging the data array by interleaving, shuffling, etc. is performed in units of one frame in consideration of interpolation when data is lost. In the case where the number of samplings on the recording side is larger than the number of samplings on the reproducing side, the recording side VTR must be provided with all the data of the frame NF on the reproducing side and the first data fD of the next frame (N + 1) F. The process cannot be executed. Since the reproducing side is also interleaved and shuffled in units of one frame, it is necessary to reproduce the entire frame in order to extract the first data fD of the next frame (N + 1) F. Therefore, in such a case, the recording side VTR cannot start the recording operation of the frame NF unless the reproducing side VTR reproduces the frame NF and the next frame (N + 1) F. It is conceivable that there will be an inconvenience that processing will be delayed.

As a method of removing such inconvenience, the frame NF
It is possible to reproduce the next frame (N + 1) F at the same time. However, in the digital data, one frame is often allocated to four tracks. Therefore, if two tracks are reproduced at the same time, four tracks are recorded. Since it has to be provided separately, it is possible that the structure becomes large and complicated.

The present invention has been made in consideration of the above points, and when dubbing a PCM audio signal between VTRs of different systems,
In the case of dubbing a PCM audio signal between VTRs of the same method, or in the case of dubbing a PCM audio signal between ATR and VTR, it is intended to provide a magnetic recording / reproducing device capable of dubbing appropriately. is there.

E. Means for Solving the Problems In order to achieve the above object, the present invention is determined by a sampling frequency (48 [kHz]) in a magnetic recording / reproducing apparatus for digitally recording or reproducing an audio signal in a television signal. Audio signal AAIN, DAIN
A plurality of (5) frames whose sampling number is an integer are set as one cycle, and the number of samplings per frame in one cycle matches the number of samplings per frame (1601.6) determined by the sampling frequency. , And so that the number of samplings of each frame forming one cycle matches any one of a plurality of preselected integers (1601, 1602) close to the number of samplings per frame determined by the sampling frequency, The assigning means 40 that assigns the sampling number to each frame according to a predetermined procedure, and the maximum number (1602) of the sampling number (1601, 1602) assigned to each frame by the assigning means 40 is set to the audio signals AAIN and DAIN. Each frame is used as a recording / reproducing unit for the digital data obtained based on the magnetic tape 1. Each frame assigned sampling number (1601, 1602 pieces) is insufficient to the maximum number (1602 pieces) (N + 2) F, (N + 4) F (second
For the figure), the shortfall is the previous frame (N + 1)
Recording and reproducing means 40 for recording and reproducing audio signals AAIN and DAIN obtained from F and (N + 3) F on the magnetic tape 1 are provided.

F. Action Regardless of the frame frequency, the sampling frequency of the audio signal is selected as the sampling frequency (48 [kHz]) of the audio signal of the VTR or ATR of the other method and the VT of the other method is selected.
Made it easy to accept dubbing between R and ATR.

However, in this case, the number of samplings per frame is not an integer. Therefore, an integer number (5) is set as a cycle, and an integer number (1601 or 1602) of sampling numbers is assigned to each frame so that the sampling number is completed for each frame. I tried to meet the demand to let me.

The number of samplings recorded on the magnetic tape 1 is the same as the maximum assigned sampling number (16
02) and the shortfall is obtained as a dummy from the previous frame. By using the dummy sampling, if one frame can be reproduced by the reproducing side VTR in the dubbing of the audio signal, the recording operation can be performed by the recording side VTR, and as a result, the signal processing can be promptly performed.

G. Examples Hereinafter, the present invention will be described with reference to the drawings by recording signals of NTSC system
An embodiment applied to the VTR to be reproduced will be described in detail. In FIG. 1, when the analog audio signal AAIN is given, the switching circuit 12 of the audio signal recording system 10 is switched to the analog-digital conversion circuit 11 side. In the analog-digital conversion circuit 11, for example, 48 [kHz ] After the analog audio signal AAIN is converted into digital data at the sampling frequency, it is applied to the time axis compression circuit 13 via the switching circuit 12, where it is time axis compressed and temporarily stored in the buffer memory 14. There is.
Further, in the audio signal recording system 10, when the digital audio signal DAIN is given, the switching circuit 12 is switched to the interface circuit 15 side in advance, and the interface circuit 15, the switching circuit 12, and the time axis compression circuit 13 are connected. It is adapted to be stored in the buffer memory 14 via the.

The buffer memory 14 has a capacity capable of storing data corresponding to a unit sampling number for performing data interleaving and shuffling processing. The digital data read from the buffer memory 14 is delayed by the delay circuit 16 and the switching circuit 17.
Are sequentially supplied to the memory 18 via the switching circuit 17.

An encoding circuit 19 is provided in association with the memory 18, and the encoding circuit 19 interleaves and shear-links the digital data of the memory 18, as well as an error correction code, an error detection code (error correction during reproduction). , For correction), and the like, and thereafter, recording is performed on the magnetic tape 1 via the recording circuit 20 and the recording head 21.

In the audio signal reproducing system 30, the reproduced data picked up from the magnetic tape 1 by the reproducing head 31 is given to the error correction / correction circuit 33 via the reproducing circuit 32.

The error correction / correction circuit 33 corrects and corrects the data based on the error correction code and the error detection signal added to the reproduced data, and then deinterleaves and deshuffles the data and stores it in the memory 34. The data stored in the memory 34 is sequentially read out via the buffer memory 35 having a capacity corresponding to the number of unit samplings, and given to the time axis expansion circuit 36.

The time axis expansion circuit 36 expands the read data in a time axis so as to have a cycle corresponding to the sampling frequency, and gives it to the digital-analog conversion circuit 38 or the interface circuit 39 via the switching circuit 37. Thus, Digital-
Reproduction analog audio signal AA from analog conversion circuit 38
OUT is output, and the playback digital audio signal DAOUT is output from the interface circuit 38.

The apparatus shown in FIG. 1 is controlled by a sequence control circuit 40 as a whole. Thus, the sequence control circuit 40 controls the data recorded on the magnetic tape 1 for all frames as shown in FIG.
Control so that the number is 02.

Here, the sampling frequency is selected as 48 [kHz], but in the case of NTSC system, the frame frequency is 29.97 [H].
z], the number of samplings per frame is 160
1.6 pieces. Therefore, originally, for example, 1 in 5 frame periods.
The first, second and fourth frames NF, (N + 1) in the cycle
1602 sampling numbers are assigned to F and (N + 3) F, and the third and fifth frames (N + 2) F and
1601 sampling numbers may be assigned to (N + 4) F.

Therefore, as shown in FIG. 2, the sequence control circuit 40 controls by adding one piece of dummy data DMY to a total of 1602 frames for which the number of samplings is 1601.

In order to realize such a recording operation, the sequence control circuit 40 is adapted to be provided with a frame signal FRM transmitted for each frame of a video signal,
The recording system 10 is controlled as follows.

The sequence control circuit 40 includes an encoding circuit 19 every time 1602 pieces of sampling data are stored in the memory 18.
From the frame delimiter signal FD. The sequence control circuit 40 determines whether or not to start the switching operation of the switching circuit 17 when the frame division signal FD is given.

The sequence control circuit 40 has a built-in quinary counter and performs a counting operation each time the frame signal FRM arrives. Immediately after the above frame delimiter signal FD is given, the counting operation is performed to update the updated count value. 3 and 5, that is, the third frame (N
In the case of +2) F and the fifth frame (N + 4) F, the switching command signal COM is sent to the switching circuit 17 to be temporarily connected to the delay circuit 16, and the address is controlled by the address signal ADR to end the previous frame. Sampling data LS of FIG. 2 (FIG. 2) is taken into the memory 18 as dummy data DMY, and after being taken in, the switching circuit 17 is set to the buffer memory.
After returning to the 14 side, 1601 pieces of sampling data assigned to the frame are loaded into the memory 18.

On the other hand, the sequence control circuit 40, when the count value of the built-in counter becomes 1, 2, 4 by the first counting operation after the arrival of the frame delimiter signal FD,
That is, the first, second, and fourth frames N
When it reaches F, (N + 1) F, or (N + 3) F, the switching operation is not started, and the sampling data from the buffer memory 14 is assigned to the memory 18 in the frame 1602.
Store them individually.

Thus, as shown in FIG. 2, the sequence control circuit 40 records the 1602 sampling data of the frame having the allocated sampling number of 1602 on the magnetic tape 1 as it is and the allocated sampling number of 1601. Regarding the frame, the last data LS of the immediately preceding frame is added as dummy data DMY, and a total of 1602 sampling data are recorded on the magnetic tape 1.
At this time, the sequence control circuit 40 is an encoding circuit.
A frame flag FF is given to 19 to record together.

On the other hand, the sequence control circuit 40 controls the reproduction system 30 as follows. The sequence control circuit 40 extracts the frame flag FF from the reproduction audio signal RP, and the frame being reproduced has an assigned sampling number of 1601.
, Or 1602 frames. The sequence control circuit 40 causes the memory 34 to output all 1602 pieces of data including dummy data for the first frame in which the number of allocated samplings in the reproduced frame is 1601. When a frame whose assigned sampling number is 1601 is detected in the subsequent frames, the sequence control circuit 40 controls the read address ADP so as to thin out the dummy data DMY and output 1601 data from the memory 34. ing.

In the configuration of FIG. 1, an analog audio signal
When AAIN is given, analog-digital conversion circuit 11
Is converted into a digital signal in the time axis compression circuit 13
After being subjected to time-axis compression processing in, the data is stored in the buffer memory 14. This stored data is stored in the memory 18 by 1602 in correspondence with each frame of the video signal by the switching control from the sequence control circuit 40, and the third and fifth frames (N + 2) in one cycle of five frames are stored.
1602 pieces of F and (N + 4) F including the last data of the previous frame are stored in the memory 18. The 1602 pieces of data are recorded on the magnetic tape 1 by the recording head 21 via the recording circuit 20 after the error correction code, the error detection code, the synchronizing signal and the like are added in the encoding circuit 19.

This signal is picked up by the reproduction head 31, and given to the error correction and correction circuit 33 through the reproduction circuit 32.
Then, the error is corrected and corrected and stored in the memory 34 as a time-series digital signal. Dummy data is thinned out and read from the memory 34 under the control of the read address of the sequence control circuit 40, and the dummy data is read out.
Are stored in a predetermined unit at a time, and are then expanded in the time axis so as to be included in the sampling frequency in the time axis expansion circuit 36 and given to the digital-analog conversion circuit 38. Therefore, the analog audio signal AAOUT is converted and output.

Thus, the same analog audio signal AAOUT as the input analog audio signal AAIN is output.

The same operation is performed when the digital audio signal DAIN is given, and the same output digital audio signal DAOUT as the input digital audio signal DAIN can be output.

Further, even when the audio signal is dubbed between the NTSC VTRs shown in FIG. 1, the reproducing VTR and the recording VTR respectively perform the reproducing operation and the recording operation as described above. Therefore, even if the playback side VTR has 1601 allocated sampling numbers in the first frame NF played back, the thinning operation is prohibited.
In the VTR, the dummy data of the first frame NF is sent as it is, as shown by hatching in FIG.

In this way, if the playback side VTR sends the dummy data of the first frame NF as it is, the allocated sampling number in the first frame NF is 1601 in the playback side VTR (Fig. 3 (A)) and 1602 in the recording side VTR. Even in the case of (FIG. 3 (C)), the next frame (N + 1) is generated as in the conventional device.
The recording side VTR can execute the recording operation without waiting for the first data of F.

As described above, according to the apparatus of FIG. 1, since the sampling frequency is selected to be the same as the sampling frequency of the audio signal in the PAL system or ATR, it is possible to record without using the frequency conversion circuit. Moreover, even if the sampling frequency is selected, the synchronization between the video signal and the audio signal can be maintained in units of 5 frames, and the processing of the audio signal can be executed quickly.

In addition, in the above-mentioned embodiment, in order to realize the number of samplings per frame of 1601.6, 1602 is allocated to 3 out of 5 consecutive frames, but 1601 is allocated to the other 2 frames. However, the present invention is not limited to this, and for example, 1604 may be assigned to 3 frames of 5 consecutive frames, and 1600 may be assigned to the other 2 frames. In this case, 1600 frames are assigned to the previous frame. More four dummy data may be added and recorded. Also, 1602 pieces are assigned to 2 out of 5 consecutive frames, and 1600 pieces and 1601 pieces are given to each of the other frames.
, 1603 may be assigned, and in this case, the number of differences from the maximum assigned sampling number 1603 may be added and recorded as dummy data.

H. Effects of the Invention As described above, according to the present invention, the sampling frequency of the audio signal is selected so as to be the same as the sampling frequency of the audio signal of the VTR or ATR of the other system without being restricted by the frame frequency. At the same time, by using the dummy data obtained from the immediately preceding frame so that the same sampling number is recorded and reproduced for each frame, the sampling number can be completed for each frame, and the audio signal of the dubbing Processing can be performed quickly, thus VTR of the same method
Thus, it is possible to obtain a magnetic recording / reproducing apparatus having a simple structure capable of appropriately dubbing audio signals between VTRs of different systems and between VTRs and ATRs.

[Brief description of drawings]

FIG. 1 is a block diagram showing a magnetic recording / reproducing apparatus according to the present invention, FIG. 2 is a schematic diagram for explaining recorded data on a magnetic tape by the apparatus shown in FIG. 1, and FIG. 3 is used for dubbing the apparatus shown in FIG. FIG. 4 is a schematic diagram for explaining the correspondence relationship between the reproduced data and the recorded data, and FIG. 4 is a schematic diagram for explaining the correspondence relationship between the reproduced data and the recorded data when the conventional apparatus is used for dubbing. 1 ... Magnetic tape, 10 ... Recording system, 13 ... Time axis compression circuit, 14 ... Buffer memory, 16 ... Delay circuit, 17 ... Switching circuit, 18 ... Memory, 19 ... Encoding circuit, 21 ...... Recording head, 30 ...... Reproducing system, 31 ...... Reproducing head, 33 …… Error correction, correction circuit, 34 …… Memory, 35 …… Buffer memory, 36 …… Time axis expansion circuit, 40 …… Sequence control circuit .

Claims (1)

(57) [Claims] 1. A magnetic recording / reproducing apparatus for digitally recording or reproducing an audio signal in a television signal, wherein a plurality of frames each having an integer number of samplings of the audio signal determined by a sampling frequency are set as one cycle. The number of samplings per frame in a cycle matches the number of samplings per frame determined by the sampling frequency, and the number of samplings of each frame forming one cycle is determined by the sampling frequency. To match any one of a plurality of preselected integers close to the number of samples per frame,
Assignment means for assigning a sampling number to each frame according to a predetermined procedure, and a magnetic tape of digital data obtained based on the audio signal, the maximum number of sampling numbers assigned to each frame by the assigning means. As a recording / reproducing unit for each of the above-mentioned frames, the number of samplings allocated to each of the above-mentioned frames is short of the maximum number, and the shortage is obtained from the immediately preceding frame, and the audio signal is recorded / reproduced on / from the magnetic tape. A magnetic recording / reproducing apparatus comprising: a reproducing unit.