JPS6325752B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a memory control device that allows the memory capacity of a memory for writing and reading out digital video signals related to still image information transmitted in time series to be larger than one screen, and It is an object of the present invention 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 the number of screens.

A digital video signal related to color still image information is added as auxiliary information to the digital audio signal obtained by digital pulse modulation such as pulse code modulation (PCM), and the signal is intermittent on the same spiral track. A digital audio disk that records changes in pit rows is known. Since a plurality of music programs are usually recorded on the same surface of such a digital audio disk, a plurality of color still image information are also recorded corresponding to the music programs.

In addition to a decoder for demodulating and reproducing the digital audio signal, 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 a certain program is being played back from the disk, the reproduced digital video signal is stored in the first frame memory. , the digital video signal related to the still image information of the previous program stored in the second frame memory is continued to be read out until the storage in the first frame memory is completed, and these two frame memories are switched. This allows the still images on the playback screen to be switched instantly. Therefore, the still image decoder has the drawback of being expensive.

On the other hand, if the purpose of reducing the cost of a still image decoder is to use only one frame memory, it is necessary not to read out the reproduced digital video signal and output the reproduced image while the reproduced digital video signal is being written. Possible methods include performing reading and writing at the same time. In this case, if it takes, for example, 6 seconds to store one frame worth of digital video signals in the frame memory, the memory storage information and time of the frame memory change as shown in FIG. 1, for example.
In the figure, P ₁ , P ₂ , and P ₃ each indicate still image information.
Memory storage information is only still image information _P1 at 0 seconds, and still image information increases as time passes.
While the proportion of P ₁ in the total memory storage information decreases linearly, the proportion of still image information P ₂ increases at the same rate, and after 6 seconds, still image information P ₂ has filled up one screen. be remembered. After 6 seconds have passed, writing of the next still image information P ₃ will start.
In the same manner as above, when another 6 seconds (12 seconds from the time of first storage) have elapsed, writing of one screen worth of still image information _P3 is completed.

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, and 4.5 seconds.
At each time point of 2 seconds, 5 seconds, 6 seconds, and 7 seconds, the screen becomes as shown in FIG. 2 A, B, C, D, E, F, G, and H, and the screen changes from still image information P ₁ to P ₂ . It takes 6 seconds to switch. However, this screen switching time of 6 seconds is the digital video signal transmission period of still image information for one frame, which is relatively long and therefore undesirable.Moreover, different still image information is continuously recorded every 6 seconds. When playing back such a disc, it has the disadvantage that a single complete still image can be displayed to fill the playback screen in an instant.

The present invention eliminates the above-mentioned 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 same figure,
Reference numeral 1 denotes a disk, on which, for example, the information amount for one channel is a digital signal having a sampling frequency of 47.25 KHz and a quantization number of 16 bits, and four channels are sequentially recorded on the same track in time series. Here, assuming that the above-mentioned disk is a digital audio disk proposed earlier by the applicant, the above-mentioned 4.
Three of the channels of digital signals are digital audio signals with a sampling frequency of 47.25 KHz and a quantization number of 16 bits, and the remaining one channel is a digital video signal with a sampling frequency of 94.5 KHz and a quantization number of 8 bits. This digital video signal is related to color still image information with, for example, 625 scanning lines, and is obtained by digital pulse modulation of a luminance signal and two types of color difference signals (RY) and (BY), respectively. This is a time-series composite signal of three types of digital signals.

Here, the transmission time for one frame of the above-mentioned digital video signal will be explained. First, the field frequency of the luminance signal is 50Hz, and the sampling frequency is
Assuming 12MHz and 8-bit quantization,
3.84×10 ⁶ bits are required to transmit one frame. Therefore, the digital video signal that can be recorded on disk 1 is for one channel, has a sampling frequency of 94.5 KHz, and a quantization number of 8 bits, so it is 756 x 10 ³ (=94.5 x 10 ³ x 8) bits per second. Transmitted per second. Therefore, the transmission of one frame of the digital luminance signal requires 5.08 (-3.84×10 ⁶ /756×10 ³
) seconds are required.

On the other hand, since each of the two types of color difference signals is a digital color difference signal with a sampling frequency of 3 MHz and a quantization number of 8 bits, the number of bits required to transmit one frame of each is 1/1/1 that of the digital luminance signal. It becomes 4. Therefore, the digital luminance signal, 2
The time required to transmit one frame of digital color difference signals in time series is 5.08 x (1 + 1/4 + 1/4) = 7.62 (seconds), but horizontal synchronization signal, vertical synchronization signal, color burst signal , overscan, etc. are removed, the amount of information is reduced by about 20%, so the total time is about 6 (=7.62×0.8) seconds.

The disc 1 on which such a signal is recorded changes depending on the presence or absence of recording pits in the intensity of the light or in the capacitance formed between the disc 1 and the electrode of the reproducing needle (not shown). The signal is then picked up and reproduced by a pickup circuit 2 which utilizes it and converts it into an electrical signal. Pickup circuit 2
The reproduced signal extracted from the FM demodulator 3 is converted into a reproduced digital signal and then supplied to the decoder 4, where the digital audio signals of the three channels described above are converted into analog audio signals, respectively, and then sent to output terminals 5, 6 and 7 are output separately.

On the other hand, the digital video signal of the fourth channel 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. A digital video signal written to this memory 8 and read out at the same time from an address different from the write address is digital-to-analog converted by the DA converter 10 and converted into an analog video signal (here, a still image signal). The signal is then supplied to the encoder 11. The encoder 11 generates a reproduced color video signal compliant with the standard television system from the above-mentioned analog video signal, horizontal and vertical synchronization signals from the synchronization signal input terminal 12, and a color burst signal which is a color synchronization signal. The signal is output from the output terminal 13 to a monitor television receiver (not shown). Thereby, the color still image reproduced from the disk 1 can be displayed on the monitor.

Therefore, in this embodiment, the memory amount of the memory 8 is set in advance for one and a half screens (here, 1.5 frames).
Writing and reading are performed as detailed below. It is assumed that still image information P ₁ , P ₂ , P ₃ , and P ₄ are recorded on disk 1 in sequence without interruption in chronological order, and the still image information
Assuming that the point in time when writing for one frame of the digital video signal of _P1 is completed is 0 seconds as a reference, the written information and read information in the memory 8 will be as schematically shown in FIG. 4 thereafter. 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, one screen worth of still image information _P1 continues to be read out from the memory 8.
At the same time, the still image information _P2 being reproduced is sequentially written from the disk 1. For this reason, 0
The playback screen at seconds, 2 seconds, and 3 seconds is the fifth
As shown in Figures A, B, and C, only still image information _P1 is reproduced.

Next, for times from 3 seconds to 6 seconds, disk 1
The still image information _P2 that is being reproduced continues to be written, and the writing ends at 6 seconds. on the other hand,
At the same time, the readout memory amount of still image information _P1 starts to decrease monotonically from 3 seconds, and the still image information
Reading of _P2 is started, and at the time of 6 seconds, still image information _P1 is not read out at all, and only _P2 is read out. Therefore, for example, the playback screen at each point of 3.5 seconds, 4.5 seconds, and 5 seconds, as shown in _FIG . As a result, the display area of the reproduced image of the still image information _P2 gradually increases. Then, at the time of 6 seconds, only the still image information _P2 is displayed. In addition,
At 4.5 seconds, still image information is displayed as shown in Figure 5E.
The images from P ₁ and P ₂ are displayed in half.

Thereafter, in the same manner as above, the still image information P ₂ continues to be played for 3 seconds from 6 seconds to 9 seconds, and at the same time the next still image information P ₃ is written to the memory 8 (note that the 5th still image information Figure H shows information on the playback screen at 7 seconds, indicating that only still image information _P2 is being played back.) Then, for 3 seconds from 9 seconds to 12 seconds, the still image information _P3 was continuously written to the memory 8, and at the same time it was stored until then.
While the reading of P ₃ starts, the still image information P ₂
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 switching described above 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 any interruption in time is played back, the same still image information continues to be played for 3 seconds, The screen is repeatedly switched to the next still image information in the next three seconds.

The present invention can be applied not only to the digital audio disk previously proposed by the applicant, but also to the reproduction of a recording medium on which digital still image signals are 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 video for one screen in the memory. After writing the signal over a certain period of time, writing of the second digital video signal for the next screen is started, and at the same time,
Continuing to read out the first digital video signal for one screen until the sum of the memory amount by writing the second digital video signal and the storage memory amount of the first digital video signal becomes full; From this point until the writing of one screen of the second digital video signal is completed, the first
Writing and reading 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 image to the reproduced image using the second digital video signal is made shorter than the above fixed period, the switching time is shorter than when using memory that only has the memory capacity for one screen. You can view the next reproduced still image, and still images that could only be viewed for a moment can be viewed continuously for a certain period of time. Compared to conventional devices that alternately switch the output, the amount of memory is small, so it can be constructed at low cost, and can be used in still image decoders of digital audio disk playback devices, etc., which the applicant proposed earlier. It has features such as being suitable.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing an example of the transition relationship between memory storage information and time in a conventional device, and FIGS. 2A to 2H
are diagrams showing playback screens for explaining the operation of FIG. 1, respectively;
FIG. 3 is a block system diagram of a disk 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 temporal relationship between write information and read information of the memory of the device of the present invention. The figures shown in FIGS. 5A to 5H are views showing the playback screen at each point in time in FIG. 4, respectively. 1... Disk, 4... Decoder, 5, 6, 7... Analog audio signal output terminal, 8... Memory, 9
...Control signal generation circuit, 10...DA converter, 11...
Encoder, 12... Synchronization signal input terminal, 13... Playback color video signal output terminal.

Claims (1)

[Claims] 1. In a device that controls the writing and reading of digital video signals into and from 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, Larger than the screen,
and after writing the first digital video signal for one screen into the memory over the above-mentioned fixed period, write the second digital video signal for the next one screen. At the same time, one screen's worth of data is stored until the sum of the memory amount due to the writing of the second digital video signal and the storage memory amount of the first digital video signal becomes full. The reading of the first digital video signal is continued, and the reading memory amount of the first digital video signal is gradually reduced to zero from that point until writing of one screen of the second digital video signal is completed. At the same time, by performing write and read control to gradually increase the readout memory amount of the second digital video signal, from the reproduced image based on the first digital video signal to the reproduced image based on the second digital video signal. A memory control device characterized in that the switching time is shorter than the fixed period.