JPS58116888A - Controller for memory - Google Patents

Abstract

PURPOSE:To control writing and reading operation and to shorten the switching time of reproduced pictures by providing a memory having a capacity greater than one screen and less than 2 screens to write and read a digital video signal of still picture information to be transmitted in time series. CONSTITUTION:On the same track of a video disk 1, a digital signal for plural channels is recorded successively in time series; and the recorded signal is reproduced by a pickup circuit 2 and applied to a decoder 4 through an FM modulating circuit 3, and respective audio signals are converted into analog signals, which are outputted to output terminals 5-7. Further, a channel signal except the 1st signal is applied to the memory 8, whose writing and reading operation is controlled by a control signal from a control signal generating circuit 9. This memory 8 has a capacity greater than one screen and less than two screens and picture information read out of the memory 8 is converted by a D/A converter 10 into an analog signal, which is outputted from an encoder 11 to shorten the switching time of picture reproduction.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a memory control device that increases the memory capacity of a memory for writing and reading digital video signals related to still image information transmitted in time series by more than one screen.
Another object of the present invention is to provide a memory control device that can shorten the switching time of reproduced images by controlling memory writing and reading to a value smaller than two screens.

A digital video signal related to color still image information is added as auxiliary information to a digital audio signal obtained by digital reclus modulation of an audio signal using pulse code modulation (POM), and the signal is intermittent on the same spiral track. Digital audio discs are known that are recorded as changes in bit strings. Since a plurality of music programs are usually recorded on the same surface of such a digital audio disc, a plurality of color still image information are also recorded corresponding to the music programs.

In addition to a decoder for demodulating and reproducing digital audio signals, a reproducing apparatus for reproducing such a digital audio disc includes a still image decoder for demodulating and reproducing the digital video signal. This still image decoder has two frame memories, and when a digital video signal related to still image information of one program consisting of a disk is being played back, the reproduced digital video signal is stored in the first frame memory. , continue reading the digital video signal related to the still image information of the previous program stored in the second frame memory until the storage in the first frame memory is completed;
By switching between these two 7-frame memories, the playback screen can be instantly switched from static to 11. For this reason, there is a drawback that the still image decoder is expensive.

On the other hand, the aim is to lower the price of still image decoders.

If there is only one frame memory, either do not read it out while reading the playback digital video signal so that the playback image does not take effect, or read it out while reading it at the same time. There are two possible methods: In this case, if it takes, for example, 6 seconds to store the digital video signal for one frame in the frame memory, the memory storage information and time of the frame memory change as shown in FIG. 1, for example. h in the figure
PIs PL PS each indicates still image information. The memory storage information is only the still image information P1 at 0 seconds, and as time passes, the proportion of still image information P1 to the total memory storage information decreases linearly, while the still image information P2 remains at the same rate. The proportion of still image information P2 increases, and when 6 seconds have elapsed, one screen worth of still image information P2 is stored. When 6 seconds have passed, writing of the next still image information P5 will start, and in the same way as above, when another 6 seconds have passed (12 seconds from the time of first storage), one screen worth of still image information P3 will be written. ends.

Therefore, if one frame memory is controlled to read and write at the same time, the playback screen will be 0 seconds), 2 seconds, 3 seconds, 3.5 seconds, 4.5 seconds, 5 seconds, 6 seconds, and At each time point of 7 seconds, Fig. 2 (Al, (B
l, (C1, (DI, (El, Gl, (
As shown in G) and C), the still image information P1 to P
It takes 6 seconds for the screen to change to 2. However, 1 this 6
The screen switching time of seconds is the digital video signal transmission period of still image information for one frame, which is relatively long and therefore undesirable, and different still image information may be continuously recorded every 6 seconds. When playing back a disc like this, the disadvantage is that a complete still image can only be displayed on the entire playback screen for a moment.

The present invention eliminates the above drawbacks.

One embodiment will be described with reference to FIGS. 3 to 5.

FIG. 3 shows a block system diagram of a disc playback device equipped with an embodiment of the device of the present invention. In the figure, 1 is a disk.For example, the amount of information for one channel is at a sampling frequency of 4y,
zsxHz,! : A digital signal of 16 bits is sequentially and chronologically recorded for four channels on the same track. here.

Assuming that the above disc is a digital audio disc previously proposed by the applicant, three channels out of the four channels of digital signals have a sampling frequency of 4.
The signal is a digital audio signal of 7.25 KHz and 16 bits, and the remaining channel is a digital video signal with a sampling frequency of 4.5 KHz and 8 bits. This digital video signal is related to, for example, color still image information with 625 scanning lines, including a luminance signal and a 2m color difference signal ('R-Y) @ (
3 obtained by digital pulse modulation of B-Y) respectively.
This is a time-series composite signal of various digital signals.

Here, the transmission time of the 17th part of the above digital video signal will be explained. First, the field frequency of the luminance signal is 55 Hz, and the sampling frequency is 12 MH2.
, the number of quantization bits is 8 bits, λ84×10' bits are required to transmit one frame. Therefore, the digital video signal that can be recorded on the disc 1 is for one channel, with a sampling frequency of 94.5 KHz and a quantization number of 8 bits.

1 second shift 5ilX10 (=94SX10 x8
) beep)/required.

On the other hand, the two types of color difference signals each have a sampling frequency of 3MH, for example.
z is a digital color difference signal with a quantization number of 8 bits, so the number of bits required to transmit one frame is 7, respectively, that of the digital luminance signal. Therefore, the time required to transmit one frame of a digital luminance signal and two types of digital color difference signals sequentially in time series is 5.0 BX (1 + - + -) = 7.62 (seconds) 4 However, if we exclude the horizontal synchronization signal, vertical synchronization signal, color burst signal, and overscan signals from being transmitted, the amount of information will be reduced by about 20%, so in the end, the result is 6 (= 1.62XO1). seconds.

The disc 1 on which such a signal is recorded changes in light intensity or in the capacitance formed between the disc 1 and the electrode of the playback needle (not shown) depending on the presence or absence of recording pits. The signal is then picked up and reproduced by the pickup circuit 2, which converts it into an electrical signal. The reproduction signal output from the pickup circuits 2 and 11 is sent to the FM demodulation circuit 3.
After being quietly reproduced as a digital signal, it is supplied to the Tecoder 4, where the three channels of digital audio signals mentioned above are each converted into an analog audio signal and then output separately to the output terminals 5, 6 and T. .

On the other hand, the fourth channel signal is extracted from the decoder 4 and supplied to the memory 8, where writing and reading are controlled by control signals from the control signal generating circuit 9. The digital video signal written in this memory 8 and read out at the same time from an address different from the write address is transferred to the DAII" converter 1o.
The signal is digital-to-analog converted into an analog video signal (still image signal in this case), and then supplied to the encoder 11. The encoder 11 uses the above-mentioned analog video signal, horizontal and vertical synchronization signals from the synchronization signal input terminal 12, and color synchronization signals to generate a color burst signal and a reproduced color video signal conforming to the standard television system. The signal is then output from the output terminal 13 to a monitor television receiver (not shown). This allows the color still image reproduced from the disc 1 to be displayed on the monitor.

In this embodiment, the memory capacity of the memory 8 is selected in advance to be one and a half frames (here, 1.5 frames), and writing and reading are performed as detailed below. Now disk 1 contains still image information PI, P2.
P3. It is assumed that P4 is recorded without interruption in chronological order, and 0 seconds is defined as the point in time when writing for one frame of the static image signal of still image information P1 is completed.

After that, the write information and read information in the memory 8 are as schematically shown in FIG. 4. In FIG. 4, the diagonally solid line portion indicates the amount of memory from which reading is being performed in the memory 8, and the vertical solid line portion represents the amount of memory from which writing is being performed in the memory 8. Therefore, from 0 seconds to 3 seconds, still image information P1 for one screen is continuously read out from the memory 8, and at the same time, the still image information P2 being played back from the disk 1 is sequentially written. Therefore %0 seconds.

The playback screen at 2 seconds and 3 seconds is shown in FIG. 5(A).

(Bl, (01), only the still image information P1 is generated.

Next, during the period from 3 seconds to 10 seconds, the still image information P2 being played back from the disk 1 is continuously written, and the writing ends at 6 seconds. on the other hand.

At the same time, the readout memory amount of the still image information P1 starts to decrease monotonically over 3 seconds, and the readout of the still image information P2 starts, and at the time of 6 seconds, the still image information P1 is not read out at all, and only P2 is read out. Only. Therefore, for example, the playback screen at each time point of 5 seconds, 4.5 seconds, and 5 seconds is shown in FIG. 5 (DI, (Ili)).

As shown in (F), the reproduced image of the still image information P1 is gradually missing, and correspondingly, the display area of the reproduced image of the still image information P2 is also gradually missing. Then, at the time of 6 seconds, only still image information P2 is displayed.

Incidentally, at the time of 45 seconds, half of the image based on the still image information P1sP2 is displayed as shown in FIG. 5 (IC).

Thereafter, in the same manner as above, the still image information P2 continues to be played for 3 seconds from 6 seconds to 9 seconds, and at the same time the next still image information P3 is written to the memory 8. (Hitoshi indicates the information on the playback screen at the 7 second point, indicating that only the still image information P2 is being played back.) Then, for 3 seconds from 9 seconds to 12 seconds, the still image information P5 continues to be stored in the memory 8. At the same time as the still image information P2 is written, reading of P3 stored in the memory starts.
The amount of read memory decreases linearly, and 12
At the second point, the playback screen completely switches to only the still image information P3. Note that the still image at the time of the screen change to +;11 is, for example, omitted from the upper part of the still image, while the next still image is displayed from the upper part of the screen.

In this way, according to this embodiment, when a disc on which a plurality of pieces of still image information are recorded without interruption in chronological order is played back, the same still image information continues to be played for 3 seconds. In the next 3 seconds, the screen switches to the next still image information and repeats.

Note that the present invention can be applied not only to the digital audio disc previously proposed by the present applicant, but also to the case of reproducing a recording medium on which a digital still image signal is recorded.

As described above, the memory control device according to the present invention selects the memory amount of the memory to be larger than one screen and smaller than two screens, and stores the first digital data for one screen in the memory. After writing the video signal over a certain period of time, it starts writing the second digital video signal for one screen of the first screen, and the amount of memory due to the writing of this second digital video signal and the first digital video The reading of the first digital video signal for one screen is continued until the sum of the signal and the storage memory amount reaches the memory capacity, and from this point on, writing of the second digital video signal for one screen is completed. 1, write and read control is performed so that the read memory amount of the first digital video signal is gradually decreased to zero, and the read memory amount of the second digital video signal is gradually increased.
Since the switching time from the reproduced image based on the first digital video signal to the reproduced image based on the second digital video signal is made shorter than the above-mentioned fixed period,
You can view the next reproduced still image in a shorter time than when using memory that only has the memory capacity for one screen, and you can also view a still image for a continuous period of time, whereas previously you could only view it for a moment. In addition, compared to a conventional device that uses two memories with the memory capacity for one screen and alternately switches their output, the memory capacity of the memory is small, so it can be constructed at a low cost. This device has the characteristics of being suitable for use in the still image decoder of the digital audio disc playback device proposed earlier.

[Brief explanation of drawings]

FIG. 1 is a diagram schematically showing an example of the transition relationship between memory storage information and hour j of a conventional device, and FIG. FIG. 3 is a block diagram of a TisF playback device equipped with an embodiment of the device of the present invention, and FIG. 4 is a schematic diagram of an embodiment of the time transition relationship between write information and read information of the memory of the device of the present invention. The diagrams shown in FIG. 5 (Al to 5) are diagrams showing the playback screen at each point in FIG. 4. 1... Disc, 4... Decoder, S, 6.7...
・Analog audio signal output terminal, 8... memory,
9... Control signal generation circuit, 10... DA converter, 1
1...Encoder, 12...Synchronization signal input terminal, 1
3... Playback color video signal output terminal.

Claims (1)

[Scope of Claim] An apparatus for controlling the writing and reading of digital video signals in a memory in a transmission system that transmits digital video signals related to still image information for one screen over a certain period of time in time series. The memory amount of the above memory is selected to be larger than one screen and smaller than two screens, and one screen's worth of I/O is stored in the memory.
II After writing the digital video signal over the above-mentioned fixed period, writing of the second digital video signal for the next one screen is started. The first digital video for one screen is stored until the sum of the memory amount by the writing K of the second digital video signal and the storage memory amount of the first digital video signal becomes full. Continue reading out the video signal, and gradually reduce the readout memory amount of the first digital video signal to zero until writing of one screen of the second digital video signal is completed. At the same time, writing and reading control is performed so as to gradually increase the readout memory amount of the second digital video signal. A memory control device characterized in that the switching is performed in a shorter time than the above-mentioned fixed period.