JP3506504B2 - Digital video signal recording and playback device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital video signal recording / reproducing apparatus for recording / reproducing a digital video signal.

[0002]

2. Description of the Related Art FIG. 21 shows, for example, ISO-IEC / JTC1 / SC29 /
FIG. 11 is a block circuit diagram showing an encoding unit in a conventional video signal recording / reproducing apparatus shown in WG11 MPEG 92 / N0245 Test Model 2. In the figure, the digital video signal input from the input terminal 1 is input to the memory circuit 901.
The video signal 921 output from the memory circuit 901 is the first input of the subtractor 902 and the motion compensation prediction circuit 910.
Given to the second input of. The output of the subtractor 902 is D
It is input to the quantization circuit 904 via the CT circuit 903. The output of the quantization circuit 904 is the variable length coding circuit 90.
5 to the input of the transmission buffer 906.
The output of the transmission buffer 906 is output from the output terminal 2. On the other hand, the output of the quantization circuit 904 is the inverse quantization circuit 9
It is also input to the IDCT circuit 908 via 07. I
The output of the DCT circuit 908 is given to the first input of the adder 909. The output 922 of the adder 909 is provided to the first input of the motion compensation prediction circuit 910. The output 923 of the motion compensation prediction circuit 910 is given to the second input of the adder 909 and the second input of the subtractor 902.

FIG. 22 is a block circuit diagram showing a decoding section in a conventional video signal recording / reproducing apparatus. In the figure, the video signal input from the input terminal 20 is input to the reception buffer 1001. The output from the reception buffer 1001 is input to the variable length decoding circuit 1002, inversely quantized by the inverse quantization circuit 1003, inverse discrete cosine transform is performed by the IDCT circuit 1004, and the adder 100 is added.
6 to the first input. On the other hand, the receiving buffer 100
The output of 1 is also input to the prediction data decoding circuit 1005,
The output of the prediction data decoding circuit 1005 is given to the second output of the adder 1006. The output of the adder 1006 is output from the output terminal 30 via the memory circuit 1007.

FIG. 3 is a conceptual diagram showing motion compensation prediction in a conventional video signal coding system. FIG. 4 is a conceptual diagram showing the operation of the memory circuit 901 in the conventional video signal encoding system.

FIG. 23 is a block circuit diagram showing an example of the motion compensation prediction circuit 910 in the conventional video signal coding system. In the figure, the output 922 of the adder 909 is supplied to the input terminal 1201a, and the output 921 of the memory circuit 901 is supplied to the input terminal 1201b. A signal 922 input from the input terminal 1201a is input to the frame memory 1204a or the frame memory 1204b via the switch 1203. The reference image output from the frame memory 1204a is provided to the first input of the motion vector detection circuit 1205a. The video signal 921 input from the input terminal 1201b is applied to the second input of the motion vector detection circuit 1205a. The output of the motion vector detection circuit 1205a is input to the prediction mode selector 1206.

On the other hand, the reference image output from the frame memory 1204b is given to the first input of the motion vector detection circuit 1205b. Motion vector detection circuit 120
The video signal 921 input from the input terminal 1201b is applied to the second input of 5b. The output of the motion vector detection circuit 1205b is given to the second input of the prediction mode selector 1206. The video signal 921 input from the input terminal 1201b is applied to the third input of the prediction mode selector 1206. The first output of prediction mode selector 1206 is provided to the first input of switch 1207. The 0 signal is provided to the second input of the switch 1207. The second input of the switch 1207 is provided with the second output of the prediction mode selector 1206. The output 923 of the switch 1207 is output from the output terminal 1202.

Next, the operation will be described. As one of high-efficiency coding schemes for coding a video signal, there is a hybrid coding scheme in which inter-picture predictive coding using motion compensation prediction and intra-picture transform coding are combined. This conventional example also employs the above hybrid coding method. First,
The outline of the inter-picture predictive coding will be described.

FIG. 3 shows an outline of the above inter-picture predictive coding. Each image is an intra-picture coded image (hereinafter referred to as “I picture”), a unidirectional predictive coded image (hereinafter referred to as “P picture”).
Picture "), bidirectional prediction coded image (hereinafter,
"B picture").
For example, one image per N sheets is an I picture, and one image per M sheets.
When a picture is a P picture or an I picture, n and m are integers and 1 ≦ m ≦ N / M, the (N × n + M) th image is the I picture, and the (N × n + M × m) th image (M ≠ 1) is a P picture, and (N × n + M × m + 1) th to (N × n + M × m + M−1) th images are B pictures. At this time, the (N × n + 1) -th image to the (N × n + N) -th image are collected into a GOP (G
roup of Pictures).

FIG. 3 shows the case where N = 15 and M = 3. In the figure, I picture does not perform inter-picture prediction,
Only intra-image transform coding is performed. The P picture is predicted from the immediately preceding I picture or P picture. For example, the 6th image in the figure is a P picture, but this is predicted from the 3rd I picture. The 9th P picture in the figure is 6
No. P picture. The B picture is predicted from the immediately preceding and immediately following I or P pictures. For example,
In the figure, the 4th and 5th B pictures are predicted from both the 3rd I picture and the 6th P picture.
Therefore, the fourth and fifth images are encoded after the sixth image is encoded.

FIG. 21 is a block circuit diagram of the hybrid coding system. The digital video signal input from the input terminal 1 is input to the memory circuit 901. The memory circuit 901 rearranges the images in the order of encoding and outputs the images. That is, as described above, in FIG. 3, for example, the 1st B picture is coded after the 3rd I picture, so that the images are rearranged here. FIG. 4 shows the operation of this rearrangement. The image sequence input as shown in FIG. 4A is output in the order of FIG. Video signal 921 output from the memory circuit 901
Is a prediction image 923 output from the motion compensation prediction circuit 910 by the subtractor 902 in order to reduce the redundancy in the time axis direction.
After the difference between the images of
Is applied. The converted coefficient is quantized, variable-length coded, and then output via the transmission buffer 906. On the other hand, the quantized transform coefficient is dequantized and I
After the DCT is performed, it is added to the predicted image 923 by the adder 909 to obtain a decoded image 922. Decoded image 92
2 is a motion compensation prediction circuit 9 for encoding the next image.
Input to 10.

Next, the operation of the motion compensation prediction circuit 910 will be described.
This will be described with reference to FIG. The motion compensation prediction circuit 910
Frame memory 1204a and frame memory 1204b
The two reference images stored in the memory circuit 90 are used.
1 performs motion-compensated prediction of the video signal 921 output from No. 1 and outputs a predicted image 923.

First, when the image 922 encoded and decoded as described above is an I picture or a P picture,
This image 922 is stored in the frame memory 1204a or 1204b for encoding the next image. At this time, the switch 1203 is switched so as to select one of the frame memory 1204a and the frame memory 1204b that has been updated earlier in time. If the decoded image 922 is a B picture, the frame memory 1204a and the frame memory 1
No writing to 204b is performed.

By such switching, for example, as shown in FIG.
When the No. 1 and No. 2 B pictures are encoded, the frame memories 1204a and 1204b
The P-picture No. 0 and the I-picture No. 3 are stored in each of the frames, and when the P-picture No. 6 is encoded and decoded after that, the frame memory 1204a rewrites the decoded picture of the No. 6 P-picture. To be Therefore, the next 4
When the No. 5 and No. 5 B pictures are encoded, the No. 6 P picture and No. 3 I picture are stored in the frame memory, respectively. Further, when the 9th P picture is encoded and decoded, the frame memory 120
4b is rewritten with the decoded image of the 9th P picture.
Therefore, when the 7th and 8th B pictures are encoded, the 6th P picture and the 9th P picture are stored in the frame memory, respectively.

When the video signal 921 output from the memory circuit 901 is input to the motion compensation prediction circuit 910, 2
Two motion vector detection circuits 1205a and 1205b,
Based on the reference images stored in the frame memories 1204a and 1204b, respectively, a motion vector is detected and a motion compensation predicted image is output. That is, the video signal 921 is divided into a plurality of blocks, a block having the smallest prediction distortion in the reference image is selected for each block, the relative position of the block is output as a motion vector, and Is output as a motion compensation prediction image.

On the other hand, the prediction mode selector 1206 selects the one having the smallest prediction distortion from the two motion-compensated prediction images output from the motion vector detection circuits 1205a and 1205b and the average image thereof, and the prediction image is selected. Output as. At this time, if the video signal 921 is not a B picture, the motion compensation prediction image corresponding to the reference image input earlier in terms of time is always selected and output. In addition, the prediction mode selector 1206 selects one of the intra-picture coding that does not perform prediction and the inter-picture predictive coding that uses the selected predicted image, whichever has better coding efficiency. At this time, if the video signal 921 is an I picture, intra-picture coding is always selected. When intra-picture coding is selected, a signal indicating the intra-picture coding mode is output as the prediction mode,
When inter-picture predictive coding is selected, a signal indicating the selected predicted image is output as the prediction mode. The switcher 1207 outputs a 0 signal if the prediction mode output from the prediction mode selector 1206 is the intra-picture coding mode, and otherwise the prediction mode selector 1206.
The predicted image output from is output.

From the above, when the video signal 921 output from the memory circuit 901 is an I picture, the motion compensation prediction circuit 910 always outputs a 0 signal as the predicted image 923, so that the I picture performs inter-picture prediction. Instead, the image is intra-coded and encoded. Further, when the video signal 921 output from the memory circuit 901 is, for example, the No. 6 P picture in FIG. 3, the motion compensation prediction circuit 910 performs the motion compensation prediction from the No. 3 I picture in FIG. The image 923 is output. Further, when the video signal 921 output from the memory circuit 901 is, for example, No. 4 B picture in FIG. 3,
The motion compensation prediction circuit 910 performs motion compensation prediction from the I-picture No. 3 and the P-picture No. 6 in FIG.
Is output.

Next, the decoding operation will be described with reference to FIG. The image data encoded with high efficiency is input to the input terminal 2
The variable length data is input to 0 and input to the variable length decoding circuit 1002 via the reception buffer. The variable length data is dequantized into fixed length data, subjected to IDCT, and output to the adder 1006. On the other hand, the prediction data decoding circuit 1005 decodes the prediction image according to the motion vector output from the reception buffer 1001, and the adder 10
It outputs to 06.

In this case, the predictive data decoding circuit 1005 is provided with a frame memory for storing the I picture and P picture data decoded by the adder 1006, like the motion compensation predicting circuit 910, and at the time of P picture and B picture. , According to the input motion vector,
The predicted image is reproduced from the target I picture and P picture and output to the adder 1006. Note that the method of updating the reference image data at the time of the I picture and P picture is the same as that at the time of encoding, and therefore description thereof will be omitted.

In the adder 1006, the prediction data decoding circuit 1
The output of 005 and the output of the IDCT circuit 1004 are added and output to the memory circuit 1007. Here, at the time of encoding, the time-sequential video signals are rearranged in the order of encoding as shown in FIG.
Therefore, in the memory circuit 1007, the data input in the order shown in FIG. 4B is rearranged so that the image data is temporally continuous in the order shown in FIG.

[0020]

The conventional digital video signal recording / reproducing apparatus is constructed as described above, and when performing high-speed reproduction of several times speed using I pictures and P pictures, G
After the beginning portion of the OP is detected from the bit stream recorded on the medium such as the optical disk, the I picture data and the P picture data are read out. For this reason,
If the amount of data of the I picture and P picture becomes very large, or if it takes a lot of time to search the head portion of the GOP, the time for reading the data is insufficient, so all I pictures Therefore, there is a problem in that the P picture data cannot be read and high speed reproduction cannot be realized.

Further, in the conventional digital video signal recording / reproducing apparatus, since the data amount of the I picture is large, it takes time to input the data of the I picture even when performing the high speed reproduction using only the I picture. It is not possible to realize special playback that exceeds double. In this case, even faster special reproduction can be realized by reproducing the I picture once for several GOPs, but there is a problem that the contents of the image cannot be understood if the jump interval is long.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to perform high speed reproduction using an I picture and a P picture having a large amount of data and a reproduced image of high quality. It is an object of the present invention to obtain a digital recording / reproducing apparatus which can obtain

[0023]

[0024]

[0025]

According to a first aspect of the present invention, a digital video signal recording / reproducing apparatus divides one frame into n areas for an I picture when recording video data in GOP units. And encode each area,
GOP when recording each area at the beginning of 1 GOP
At the same time as scrolling and recording the position of the area to be recorded in units, the address information of each area of the I picture is simultaneously recorded as header information, and during special reproduction, only the I picture data is read out in area units, and the reproduced image When all the areas of the I picture cannot be read out within a certain time, the special reproduction image is output by interpolating with the data of the previous screen.

In the digital video signal recording / reproducing apparatus according to the second aspect of the present invention, when recording video data in GOP units, for I pictures, one frame is divided into n areas, and each area is divided into n areas. It is encoded, divided into error correction block units, and 1G in order from the area at the center of the screen.
At the same time as recording at the beginning of the OP, address information of each area of the I picture is simultaneously recorded as header information, and at the time of special reproduction, only the data of the I picture is read in error correction block units and output as a reproduced image for a fixed time. If you cannot read all I-pictures in
The special reproduction image is output by interpolating the data of the previous screen.

[0027]

[0028]

In the digital video signal recording / reproducing apparatus according to the third aspect of the present invention, when recording video data in GOP units, for I pictures and P pictures, one frame is divided into n areas and frame units are used. Each area is encoded by, and when scrolling the position of the area to be recorded first in a frame unit when recording each area at the beginning of 1 GOP, at the same time, the address information of each area of I picture and P picture is header information. Are recorded at the same time, the data of the I picture and the P picture are read out in area units at the time of special reproduction, and are output as a reproduced image.
When all the areas of the picture or P picture cannot be read, the special reproduction image is output by interpolating with the data of the previous screen.

In a digital video signal recording / reproducing apparatus according to a fourth aspect of the invention, when recording video data in GOP units, for I pictures and P pictures, one frame is divided into n areas, and each area is divided into n areas. Each area is coded, divided into error correction block units, and sequentially recorded from the area in the center of the screen at the head of 1 GOP. At the same time, the address information of each area of the I picture is simultaneously recorded as header information. Only the I picture data is read in error correction block units and output as a reproduced image,
When all I pictures cannot be read within a fixed time, the special reproduction image is output by interpolating with the data of the previous screen.

[0031]

[0032]

[0033]

SUMMARY OF] According to the digital video signal recording and reproducing apparatus according to the invention of claim 1, at the time of special reproduction, reproduced image is reproduced by the I-picture unit which is divided into n areas, it can be read within a predetermined time Areas that did not exist are interpolated by the data on the previous screen, but the position of the area is G when recording.
Since it is scrolled in OP units, one screen can be played back on average.

According to the digital video signal recording / reproducing apparatus of the second aspect of the present invention, during special reproduction, the I picture in which the reproduced image is divided into n areas is reproduced in error correction block units, and within a fixed time. The area that could not be read is interpolated by the data of the previous screen, but the area located in the center of the screen is preferentially reproduced, so that the interpolated reproduced image is not unsightly.

[0035]

[0036]

According to the digital video signal recording / reproducing apparatus of the third aspect of the present invention, during special reproduction, the reproduced image is reproduced in units of I picture and P picture divided into n areas and read out within a fixed time. Areas that could not be interpolated are interpolated by the data of the previous screen, but since the position of the area is scrolled in frame units of I and P pictures during recording, one screen can be reproduced on average.

According to the digital video signal recording / reproducing apparatus of the fourth aspect of the present invention, at the time of special reproduction, the I picture and the P picture in which the reproduced image is divided into n areas are reproduced in error correction block units and fixed. The area that could not be read in time is interpolated by the data of the previous screen, but the area located in the center of the screen is preferentially reproduced, and the interpolated reproduced image is not unsightly.

[0039]

【Example】

Example 1. Next, a first embodiment of the present invention will be described.
FIG. 1 is a block circuit diagram of a recording system of the digital video signal recording / reproducing apparatus of the first embodiment. In the figure, the digital video signal output from the input terminal 1 is input to the formatting circuit 3. Formatting circuit 3
The video signal output from is supplied to the first input to the subtractor 4 and the second input to the motion compensation prediction circuit 11.
The output of the subtractor 4 is input to the quantization circuit 6 via the DCT circuit 5. The output of the quantizing circuit 6 is given to the first input of the buffer memory 12 via the variable length coding circuit 7.

On the other hand, the output of the quantization circuit 6 is also input to the IDCT circuit 9 via the inverse quantization circuit 8. IDC
The output of the T circuit 9 is given to the first input of the adder 10. The output of the adder 10 is the first of the motion compensation prediction circuit 11.
Given to the input of. The first output of the motion compensation prediction circuit 11 is given to the second input of the adder 10 and the second input of the subtractor 4. Further, the second output of the motion compensation prediction circuit 11 is given to the second input of the buffer memory 12.
The output of the buffer memory 12 is input to the modulation circuit 14 via the format encoder 13. Modulation circuit 14
Output is recorded on a medium such as an optical disk via the output terminal 2.

FIG. 2 is a block circuit diagram showing a decoding unit in the video signal recording / reproducing apparatus of the first embodiment. In the figure, video information read from a medium such as an optical disk is input from an input terminal 20 and a demodulation circuit 21. The output from the demodulation circuit 21 is input to the format decoder 23 via the buffer memory 22. The first output of the format decoder 23 is input to the variable length decoding circuit 23, inversely quantized by the inverse quantization circuit 25, subjected to inverse discrete cosine transform by the IDCT circuit 26, and then the first output of the adder 28. Given to input. On the other hand, the output of the format decoder 23 is also input to the prediction data decoding circuit 27, and the output from the prediction data decoding circuit 27 is given to the second input of the adder 28. Adder 2
The output of 8 is output from the output terminal 30 via the unformatting circuit 29.

Next, the operation will be described. The digital video signal is input from the input terminal 1 line by line and supplied to the formatting circuit 2. Here, in the motion-compensated prediction, as in the conventional example, 1 GOP is set to 15 frames as shown in FIG. 3, one I picture, four P pictures (P1 to P4), and ten B pictures (B1). ~ B1
Predictive coding is performed as 0). In this case, the formatting circuit 2 rearranges the video data, which is continuously input as in the conventional example, in the order shown in FIG. Furthermore, the data input in line units is rearranged in block units of 8 × 8 pixels,
A macro block as shown in FIG. 5 (a total of 6 blocks of four adjacent luminance signal Y blocks and two color difference signals Cr and Cb blocks positionally corresponding to these) is formed,
Output data in macroblock units. Here, a macroblock is the minimum unit of motion compensation prediction, and a motion vector for motion compensation prediction is obtained in macroblock units.

In the formatting circuit 3, I
As for the picture, as shown in FIG. 6, one frame of video data is divided into five areas every 720 pixels × 96 lines in the vertical direction, and 8 × 8 pixels are blocked in this area. Construct and output a macroblock. In this case, the five divided areas are areas 1, 2, 3, 4, 5 from the top as shown in FIG. On the other hand, P-pictures and B-pictures are blocked without being divided into areas and are output in macroblock units.

The output of the formatting circuit 3 is input to the subtractor 4 and the motion compensation prediction circuit 11, and the subtractor 4, the DCT circuit 5, the quantization circuit 6, the variable length coding 7,
The operations of the inverse quantization circuit 8, the IDCT circuit 9, the adder 10, and the motion compensation prediction circuit 11 are the same as those in the conventional embodiment, and therefore their explanations are omitted.

The video data output from the variable length coding circuit 7 and the motion vector output from the motion compensation prediction circuit 11 are input to the buffer memory 12. In the buffer memory 12, 1 GOP worth of video data and motion vectors are recorded, and the data are sequentially output to the format encoder 13. The output of the format encoder 13 is input to the modulation circuit 14, added with an error correction code and the like, and recorded on a medium such as an optical disk.

Here, the format encoder 13 rearranges the video signals of 1 GOP worth of data into a data array as shown in FIG. Here, the I picture is divided into five areas as shown in FIG. 6, and the I picture data for the areas 1 to 5 is I (1), I (2), I (3), I.
Assuming that (4) and I (5), in FIG. 7, I picture data is placed at the beginning of a data string for 1 GOP, and I (3), I (2 ), I
(4), I (1), and I (5) are recorded in this order.

Further, in FIG. 7, the address where the data of each I picture area is stored at the head of the GOP is written as header information. As the header information, the number of bytes occupied by the data in each of the five divided areas in the data format of FIG. 7 is recorded. Therefore, at the time of reproduction, the end position of each area can be determined as a relative address from the head of the GOP based on the number of bytes occupied by each area recorded in the header information. As a result, it is possible to jump to the head address of the GOP in units of a fixed time during special reproduction, and read the I picture data in units of areas according to the header information from the head of the GOP.

In a general video signal recording / reproducing apparatus, an I picture is recorded in a frame unit as a data format at the time of recording. On the other hand, in FIG. 7, since the area located in the center of the screen is preferentially placed at the beginning of 1 GOP among the I picture data divided into 5 parts, a part of the I picture within a certain time Even when only the area of 1 can be decoded, it is possible to output the reproduced image of at least the central portion of the screen.

Next, the operation during reproduction will be described with reference to FIG. The video signal that has been subjected to error correction processing in the demodulation circuit 21 and recorded in the buffer memory 22 in the format of FIG. 7 is divided into a motion vector and video data by the format decoder 23, and the prediction data decoding circuit 27 and the variable length decoding are performed, respectively. It is output to the circuit 24. Here, the operation during the normal reproduction is the same as that of the conventional example, and the description thereof is omitted.

At the time of high-speed reproduction, with respect to data recorded on a medium such as an optical disk in units of 1 GOP, the data portion of an I picture is read in units of areas according to header information by jumping to the head of GOP in units of a fixed time. , And demodulated by the demodulation circuit 21 and input to the buffer memory 22. However, when all the I-pictures cannot be read within a certain time because the information amount of the I-picture is large, the area in the middle of reading is read to the end and then jumped to the beginning of the next GOP and read. Only the data in the area where it was possible is buffer memory 2
Enter 2. In this case, the format decoder 23 decodes only the area of the I picture that can be read and outputs it as a high-speed playback image. Therefore 1 GOP
When 15 is set to 15 frames, a special speed image of 15 times speed can be obtained.

FIG. 8 shows a reproduced image when only 1 GOP I picture is reproduced to perform high speed reproduction. in this case,
When the information amount of the I picture is large and it is not possible to read all the I picture areas from the medium within a fixed time, for the areas that could not be read, the data of the area one screen before is retained and output. By doing so, the high-speed reproduced image is combined. In FIG. 8, the area 5 of the (n + 1) th GOP and the (n + 3) th GO
When the areas 1 and 5 of P cannot be read, the reproduced image of the previous screen is held as it is.

As described above, as shown in FIG. 7, the I-picture used for special reproduction is arranged so that the center area of one screen is preferentially recorded on the medium at the head of one GOP. Therefore, even if all the I-pictures cannot be read out within a certain time, the central portion of the screen is preferentially reproduced, so that the content of the reproduced image is easy to understand.

In the first embodiment, when all the I pictures could not be read, the reproduced image was interpolated in area units. However, it is not always necessary to interpolate in area units.
It may be performed in error correction block units.

In this case, in the data array as shown in FIG. 7, the demodulation circuit 24 divides the data into packets of several bytes and adds an error correction code to each packet. FIG. 9 shows an example in which the data of five areas that are continuously input is divided into packets in error correction block units. FIG. 9A shows a data string before packet division.
FIG. 9B shows the data after packet division. The five areas of the I picture are divided into packets of a certain capacity, and I
The area (3) is divided into packets 1 to i, and I
(4) is input after being divided into packets i to j.

At the time of high-speed reproduction, with respect to data recorded on a medium such as an optical disk in units of 1 GOP, the data portion of the I picture is read in units of areas according to the header information by jumping to the beginning of the GOP in units of a fixed time. , And demodulated by the demodulation circuit 21 and input to the buffer memory 22. However, when all the I pictures cannot be read within a certain time because the information amount of the I picture is large, the process jumps to the beginning of the next GOP even during the reading of data for one area. Further, error correction processing is performed on the data that can be read, and only the data that can be error corrected is input to the buffer memory 22. In this case, the format decoder 23 identifies the address of the I picture area that was partially decoded,
The read data is decoded in macro block units and output as a high-speed playback image. In this case, the macroblock that could not be decoded retains and outputs the data of the previous screen.

In the first embodiment, the data in each area of the I picture was continuously divided into packets.
The data may be divided so that one packet does not include data of two or more areas. In this case, since the data for one area is closed by an integer multiple of the error correction block, it is possible to rearrange the data in area units immediately after performing the error correction processing. However, when the data in each area is divided into packets, the last packet in each area is only partially filled with data, and the remaining part is data masked (for example, masked to all "1"). Need to be kept.

Further, in the first embodiment, as shown in FIG. 7, the priorities are set in the order of the areas 3, 2, 4, 1, and 5, but the order does not necessarily have to be in this order.
The order of 4, 2, 5, 1 is also acceptable.

Further, in the first embodiment, as shown in FIG. 6, the I picture is divided into five areas in the horizontal direction and recorded, but it is not always necessary to divide the I picture into five areas and the international standard MPEG (Moving) is used. It may be divided into n units (n> 1) and recorded in units of slices defined by the Picture Expert Group.
Here, the slice has a one-dimensional structure of an arbitrary number (1 or more) of macroblocks in length, and is a band that continues to the left end one line down when reaching the right end of the screen.

Example 2. Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 10 is a diagram showing the special reproduction method of the second embodiment. In the second embodiment, the special reproduction is performed by the reproduction method shown in FIG. 8, but the special reproduction may be performed so that the reproduced image shown in FIG. 10 is output. In this case, the format decoder 23 synthesizes one screen by reproducing one area each from I pictures of five consecutive GOPs as shown in FIG. For example, in FIG.
In 0 (a), a reproduced image for one screen is composed from the I pictures of the nth to n + 4th GOPs. Area 1 is the n + 4th, area 2 is the n + 3th, area 3 is the n + 2th, and area 4 is the 4th. The I picture of the nth GOP is reproduced in the (n + 1) th area 5. Further, when attention is paid temporally to the area 5 in FIG. 10, as the reproduced image data, I pictures of GOPs of n, n + 1, n + 2 ... Are reproduced.

When all the I pictures cannot be read within a certain time because the information amount of the I picture is large, the data of the previous screen is held as it is and output to synthesize the high speed reproduced image. FIG. 11 shows area 5 of the (n + 1) th GOP and area 1 of the (n + 3) th GOP.
It is a reproduced image when and 5 cannot be read. In this case, in the data array, as shown in FIG. 7, the area located in the center on one screen is preferentially recorded on the medium, so that even if all I pictures cannot be read out in time, Since the central part of the image is reproduced with priority, the reproduced image does not become uncomfortable. Even if the data cannot be read from two or more areas, 1
Since the screen is divided into five areas and the frames reproduced in each area are different, it is difficult to understand that data is missing in the reproduced image.

Example 3. Next, a third embodiment of the present invention will be described with reference to the drawings. FIG. 12 is a diagram showing an arrangement structure of digital video data according to the third embodiment. In the first embodiment, the data array was written in the order of areas 3, 2, 4, 1, and 5 for the I picture as shown in FIG.
The array structure shown in 2 may be used. In FIG. 12, 1
When recording I picture data at the beginning of a GOP data string, the beginning area number is scrolled for each GOP. That is, as shown in FIG. 12, in the n-th GOP, I (5), I (1), I (2), I (3),
When I picture data is recorded in the order of I (4), n + 1
In the th GOP, I (1), I (2), I (3), I
The order is (4) and I (5). Further n + 2nd GO
In P, I (2) is at the head and the GOP number is n +
When 3, n + 4 ...
(3), I (4), I (5), I (1) ... Are scrolled and recorded.

Further, at the head of the GOP, the address where the data of each I picture area is stored and the information for discriminating the kind of the head area are written as header information.
As the header information, the number of the area recorded at the head and the amount of data occupied by the data of each area divided into 5 in the data format of FIG. 11 are recorded in the number of bytes. Therefore, at the time of playback, depending on the number of the first area recorded in the header information and the number of bytes occupied by each area,
The data order of the I picture area and the end position of each area on the medium can be determined as a relative address from the head of the GOP. This makes it possible to jump to the head address of the GOP at a fixed time unit during special playback, and
I picture data can be read from the beginning of P according to the header information in units of areas.

In this case, since the recording position of the I-picture area divided into 5 is scrolled in GOP units, even if only a partial area of the I-picture can be decoded during special reproduction, the area that cannot be decoded Does not concentrate on a fixed position on the screen.

At the time of high-speed reproduction, for data recorded on a medium such as an optical disk in units of 1 GOP, the data portion of the I picture is read in units of areas according to the header information by jumping to the beginning of the GOP in units of constant time. , And demodulated by the demodulation circuit 21 and input to the buffer memory 22. However, when all the I-pictures cannot be read within a certain time because the information amount of the I-picture is large, the area in the middle of reading is read to the end and then jumped to the beginning of the next GOP and read. Only the data in the area where it was possible is buffer memory 2
Enter 2. In this case, the format decoder 23 decodes only the I picture area that can be read and outputs it as a high-speed playback image. Therefore, when 1 GOP is set to 15 frames, a special reproduction image of 15 times speed can be obtained.

FIG. 13 shows a reproduced image when only 1 GOP I picture is reproduced to perform high speed reproduction. In this case, I pictures are assumed to have been recorded on the medium in the order shown in FIG. Here, when the information amount of the I picture is large and all the I pictures cannot be read within the time, the data of the previous screen is held as it is and output to synthesize the high speed reproduction image. FIG. 13 shows n
When the area 5 of the + 1st GOP and the areas 1 and 2 of the n + 3th GOP are not completely read, the data of the previous screen is held as it is.

As described above, as shown in FIG. 12, since the recording order of I pictures used for special reproduction is scrolled in GOP units, only a partial area of the I picture can be decoded during special reproduction. Even if it cannot be done, areas that cannot be decoded do not concentrate on a fixed position on the screen.

Example 4. Next, a fourth embodiment of the present invention will be described with reference to the drawings. FIG. 14 is a diagram showing the arrangement structure of digital video data according to the fourth embodiment. In this case, the I picture and the P picture have 720 pixels × 9 as shown in FIG.
It is divided into 5 areas of 6 lines, and each area is blocked and coded in macroblock units. However, since the P picture is divided into five banks, the motion compensation prediction is performed and encoded so that the search range of the reference pattern of the motion compensation prediction is closed within the area. Here, the five divided areas are areas 1, 2, 3, 4, 5 from the top as shown in FIG. In addition, for B pictures, motion compensation prediction is performed and coded without being divided for each area.

In the format encoder 13, 1 GO
The data for P is rearranged in a data array as shown in FIG. 14 and output to the modulation circuit 14. Where I
For pictures and P-pictures, one screen is divided into five areas as shown in FIG.
I pictures and P1, P2, P3, P4 for ~ 5
The picture data is converted into I (1) to I (5) and Pi.
Assuming (1) to Pi (5) (i = 1 to 4), in FIG. 14, the I picture, P1, P2, and P are arranged so that the area in the center of the screen is prioritized from the head of the data string for 1 GOP.
Data of 3, P4 pictures is recorded in the order of areas of 3, 2, 4, 1, 5. Furthermore, FIG.
In No. 4, the data amount of each area is recorded as header information in the head portion of 1 GOP so that the address of the data of each I picture and P picture area can be identified.

At the time of high-speed reproduction, for data recorded on a medium such as an optical disk in units of 1 GOP, the data portion of I pictures and P pictures is area-jumped according to the header information by jumping to the head of GOP in units of a fixed time. The data is read out in units, demodulated by the demodulation circuit 21, and input to the buffer memory 22. However, when all the I pictures and P pictures cannot be read within a fixed time because the information amount of the I picture and P picture is large, the data in the area being read is read to the end and then the next GOP is read. The data is jumped to the beginning and only the data in the area that can be read is input to the buffer memory 22. In this case, the format decoder 23 decodes only the I and P picture areas that can be read and outputs it as a high-speed playback image. Therefore 1 GOP is 1
When 5 frames are used, a special reproduction image of 3 times speed can be obtained.

Since the area located in the center of the screen among the I pictures divided into 5 is preferentially arranged at the head of 1 GOP, only the partial area of the I picture or P picture is decoded during special reproduction. Even if it is not possible, it is possible to output the reproduced image of at least the central portion of the screen. Furthermore, I, P1, P2, P3, P
Since the four pictures are recorded on the medium in the order, even if all the data cannot be read, the reference data cannot be reproduced by the prediction data decoding circuit 27.

FIG. 15 shows a reproduced image when only I picture and P picture in 1 GOP are reproduced and high speed reproduction is performed. In this case, if all the I-picture and P-picture areas cannot be read from the medium within a fixed time because the information amount of the I-picture and P-picture is large, the areas that could not be read are:
High-speed playback images are combined by holding and outputting the data of the area one screen before as it is. In FIG. 15, when the areas 3, 4, and 5 of P4 of the nth GOP could not be read, the data of the previous screen is held as it is.

As described above, as shown in FIG. 14, by arranging the I picture and P picture used for special reproduction at the beginning of 1 GOP in units of area, the I picture or P picture is reproduced during special reproduction. And output the special reproduction image. Further, even when all I-picture or P-picture areas cannot be read out temporally, a reproduced image can be output by interpolating the data of the previous screen in area units.

In the fourth embodiment, when all I pictures and P pictures could not be read, the reproduced image was interpolated in area units. However, it is not always necessary to perform in area units, and error correction block units are not necessary. You may go in.

In this case, in the data array as shown in FIG. 14, the demodulation circuit 24 divides the data into packets of several bytes and adds an error correction code to each packet. FIG. 16 shows an example in which the data of five areas that are continuously input is divided into packets of error correction block units. FIG. 16A shows a data string before packet division, and FIG. 16B shows data after packet division.
In FIG. 16, the packet is divided into packets i to j in the area P1 (3).

At the time of high-speed reproduction, for data recorded on a medium such as an optical disk in units of 1 GOP, the data portion of the I picture is read in units of areas according to the header information by jumping to the beginning of the GOP in units of constant time. , And demodulated by the demodulation circuit 21 and input to the buffer memory 22. However, when the information amount of the I picture is large and all the I pictures and P pictures cannot be read within a fixed time, the processing jumps to the beginning of the next GOP even while reading the data for one area. Further, error correction processing is performed on the data that can be read, and only the data that can be error corrected is stored in the buffer memory 2
Enter 2. In this case, the format decoder 23 identifies the addresses of the I picture and P picture area that could be decoded halfway, decodes the data that can be read in macroblock units, and outputs it as a high-speed playback image. In this case, the macroblock that could not be decoded retains and outputs the data of the previous screen.

In the fourth embodiment, the motion vector search range is closed within each area in the motion compensation prediction of P1 to P4, but it is not always necessary to close the search range.

Example 5. Next, a fifth embodiment of the present invention will be described with reference to the drawings. FIG. 17 is a diagram showing the trick-play method of the fifth embodiment. In the fifth embodiment, special reproduction is performed by the reproduction method as shown in FIG. 15, but special reproduction may be performed so that a reproduction image as shown in FIG. 17 is output. In this case, the format decoder 23 synthesizes one screen by reproducing each area from consecutive 5 frames as shown in FIG. In FIG. 17A, a reproduced image for one screen is composed from I pictures and P1 to P4 pictures. Also, in FIG. 17A, a P4 picture is reproduced in area 1, a P3 is reproduced in area 2, a P2 is reproduced in area 3, a P1 is reproduced in area 4, and an I picture is reproduced in area 5. Further, when attention is paid to area 5 in FIG. 17 in terms of time,
The video data to be reproduced is the I picture of the nth GOP, the I picture of P1, P2, P3, P4, and the n + 1th GOP.
The picture is P1, ...

Further, when all the I and P pictures cannot be read within a fixed time because the information amount of the I picture and P picture is large, the data of the previous screen is held as it is and outputted. Combine reproduced images. Areas 1, 4, and 5 of P4 of the nth GOP in FIG.
Shows a reproduced image when is not read. in this case,
As shown in FIG. 14, since the data string is preferentially recorded on the medium in the area located at the center of one screen, even if all I and P pictures cannot be read out in terms of time, the screen Since the central part of the image is reproduced with priority, the reproduced image does not become uncomfortable. Even if the data cannot be read from two or more areas,
Since one screen is divided into five areas and the frames reproduced in each area are different, it is difficult to understand that data has been lost in the reproduced image.

Example 6. Next, a sixth embodiment of the present invention will be described with reference to the drawings. FIG. 19 is a diagram showing the arrangement structure of digital video data according to the sixth embodiment. In the fourth embodiment, the data array was written in the order of areas 3, 2, 4, 1, and 5 for I picture and P picture as shown in FIG. 14, but the array structure as shown in FIG. Good.

In FIG. 19, when recording I picture data and P picture data in the head portion of the data string for 1 GOP, the head area number is scrolled for each frame. That is, as shown in FIG. 12, the n-th GOP
Then I (1), I (2), I (3), I (4), I
When I picture data is recorded in the order of (5), P1 pictures are P1 (2), P1 (3), P1 (4), and P1.
(5), P1 (1). Further, in the P2 picture, P2 (3) is the head, and in the P3 and P4 pictures, the head area is sequentially scrolled and recorded as P3 (4) and P4 (5).

Further, at the head of the GOP, the address where the data of each I picture and P picture area is stored and the information for discriminating the kind of the head area of each frame are written as header information. Here, as the header information, the number of the area recorded at the beginning of each frame and the number of bytes of the data amount of each area divided into 5 are recorded as the header information. As a result, at the time of special reproduction, the GOP start address is jumped to in a fixed time unit, and the GOP
Data can be read from the beginning of each area in units of areas according to the header information.

In this case, since the recording positions of the I-picture and P-picture area divided into five are scrolled in frame units, only a partial area of the I-picture and P-picture can be decoded during special reproduction. Even in this case, the undecodeable area does not concentrate at a fixed position on the screen.

At the time of high-speed reproduction, data recorded on a medium such as an optical disk in units of 1 GOP is read out in data units of I pictures and P pictures in area units according to header information, demodulated by a demodulation circuit 21, and buffer memory 22. To enter. However, when all the I pictures and P pictures cannot be read within a certain time because the information amount of the I picture and P picture is large, after reading the data to the end for the area in the middle of reading,
It jumps to the beginning of the next GOP and inputs only the data of the area that can be read to the buffer memory 22.
In this case, the format decoder 23 decodes only the I and P picture areas that can be read and outputs it as a high-speed playback image.

FIG. 20 shows a reproduced image when only I picture and P picture in 1 GOP are reproduced and high speed reproduction is performed. In this case, since the data amounts of I and P pictures are large, all I pictures and P pictures are
If the picture cannot be read, the data of the previous screen is held and output as it is to synthesize the high-speed playback image. In FIG. 20, when the areas 3, 4, and 5 of P4 of the nth GOP could not be read, the data of the previous screen is held as it is.

As described above, as shown in FIG. 19, since the recording order of I pictures used for special reproduction is scrolled in GOP units, only a partial area of the I picture can be decoded during special reproduction. Even if it cannot be done, areas that cannot be decoded do not concentrate on a fixed position on the screen.

[0086]

[0087]

[0088]

Effects of the Invention] According to the digital video signal recording and reproducing apparatus according to the invention of claim 1, by dividing the I-picture into n areas at the beginning of 1 GOP, to scroll through the order of recording the I-picture area in the GOP Since data is recorded as well as address information of each area, data is decoded in I picture area units during special playback, and areas that cannot be read within a certain period of time are interpolated by the data of the previous screen. And the order in which the I picture area is recorded in GOP units is scrolling,
The reproduced images for one screen can be averaged and output.

According to the digital video signal recording / reproducing apparatus in the second aspect of the invention, the I picture is divided into n areas at the head of 1 GOP, and the data is recorded so as to be closed in error correction block units in each area. In addition, since the address information of each area is also recorded, data is decoded in error correction block units of the I picture during special reproduction, and macro blocks that cannot be read within a fixed time are interpolated by the data of the previous screen. be able to.

[0090]

[0091]

According to the digital video signal recording / reproducing apparatus of the third aspect , the I picture and the P picture are divided into n areas at the head of 1 GOP, and the I picture and the P picture area are recorded in each frame. The order is scrolled and recorded, and the address information of each area is also recorded. Therefore, during special reproduction, data is decoded in area units of I picture and P picture, and the area that cannot be read within a certain time Interpolation can be performed using screen data, and since the order in which I and P picture areas are recorded is scrolled in GOP units, reproduced images for one screen can be averaged and output.

According to the digital video signal recording / reproducing apparatus in the fourth aspect of the present invention, the I picture and the P picture are divided into n areas at the head of 1 GOP, and each area is closed in error correction block units. Since the data is recorded and the address information of each area is also recorded, the data is decoded in error correction block units of the I picture at the time of special reproduction,
Areas that cannot be read within a fixed time can be interpolated by the data of the previous screen.

[Brief description of drawings]

FIG. 1 is a block diagram showing a recording system of a digital video signal recording / reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a reproducing system of the digital video signal recording / reproducing apparatus in the first embodiment.

FIG. 3 is a conceptual diagram for explaining the predictive coding according to the first embodiment.

FIG. 4 is a conceptual diagram for explaining predictive coding in the first embodiment.

FIG. 5 is a conceptual diagram for explaining a macroblock in the first embodiment.

FIG. 6 is a conceptual diagram for explaining screen division in the first embodiment.

FIG. 7 is a conceptual diagram for explaining a data array in the first embodiment.

FIG. 8 is a conceptual diagram for explaining a reproduction method of special reproduction in the first embodiment.

FIG. 9 is a conceptual diagram for explaining the arrangement of error correction blocks in the first embodiment.

FIG. 10 is a conceptual diagram for explaining a reproduction method of special reproduction in Example 2 of the present invention.

FIG. 11 is a conceptual diagram for explaining a reproduction method of special reproduction when data interpolation is performed in the second embodiment.

FIG. 12 is a conceptual diagram for explaining a data array according to the third embodiment of the present invention.

FIG. 13 is a conceptual diagram for explaining a reproduction method of special reproduction in the third embodiment.

FIG. 14 is a conceptual diagram for explaining a data array according to the fourth embodiment of the present invention.

FIG. 15 is a conceptual diagram for explaining a reproduction method of special reproduction in Example 4.

FIG. 16 is a conceptual diagram for explaining the arrangement of error correction blocks in the fourth embodiment.

FIG. 17 is a conceptual diagram for explaining a reproduction method of special reproduction in Example 5 of the present invention.

FIG. 18 is a conceptual diagram for explaining a reproduction method of special reproduction when data interpolation is performed in the fifth embodiment.

FIG. 19 is a conceptual diagram for explaining a data array according to the sixth embodiment of the present invention.

FIG. 20 is a conceptual diagram for explaining the reproduction method of special reproduction in the sixth embodiment.

FIG. 21 is a block diagram showing a configuration example of a recording system in a conventional video signal encoding system.

FIG. 22 is a block diagram showing a configuration example of a reproduction system in a conventional video signal encoding system.

FIG. 23 is a conceptual diagram for explaining the operation of the memory circuit in the conventional video signal encoding system.

[Explanation of symbols]

3 Formatting circuit, 4 Subtractor, 5 DCT
Circuit, 6 quantization circuit, 7 variable length coding circuit, 8 inverse quantization circuit, 9 IDCT circuit, 10 adder, 11
Motion compensation prediction circuit, 12 buffer memory, 13 format encoder, 14 modulation circuit, 21 demodulation circuit, 22 buffer memory, 23 format decoder, 24 variable length decoding circuit, 25 inverse quantization circuit, 26
IDCT circuit, 27 Predictive data decoding circuit, 28
Adder, 29 unformatting circuit.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI H04N 5/93 H04N 5/93 Z 7/30 7/133 Z 7/32 7/137 Z (72) Inventor Masamasa Kasezawa Kyo Nagaoka Ichibaba Zoujo 1 Mitsubishi Electric Co., Ltd. Video System Development Laboratory (72) Inventor Masato Nagasawa Nagaokakyo Baba Zoujo 1 Mitsubishi Electric Co., Ltd. Video System Development Laboratory (56) Reference JP-A-5-128810 ( JP, A) JP 4-79681 (JP, A) JP 3-74982 (JP, A) JP 7-123359 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H04N 5/76-5/956 G11B 20/10-20/12

Claims (4)

(57) [Claims] 1. A digital video signal recording / reproducing apparatus for recording / reproducing a digital video signal highly efficient encoded by using motion compensation prediction and DCT on a medium such as an optical disk, and an I-picture which is at least intra-frame encoded at the time of recording. With regard to the above, when the video data for one frame is divided into n (n> 1) and encoded and the I picture divided into n is recorded in area units, the order of the areas to start the recording is the motion compensation prediction. Means for scrolling and recording in GOP units, and also for simultaneously storing position information in which areas 1 to n in the GOP are recorded on the medium, and at the time of special reproduction, at least the I picture is read from the medium, and a buffer memory If it is not possible to read all of the I picture area by storing in the A digital video signal recording / reproducing apparatus characterized by comprising means for interpolating an area which could not be read from data of one screen before. 2. The I picture data divided into each area and coded is divided into blocks for error correction and recorded, and at the time of special reproduction, all the I picture areas cannot be read out. If outputs only DCT blocks can be decrypted by the error correction block, the error correction block can not be read, according to configured claim 1 by including means for interpolating from the previous screen data Digital video signal recording / reproducing device. 3. An I picture for intra-frame coding, a P picture for forward motion compensation prediction, and an I picture and a B picture for temporally preceding and following temporally preceding and following the I picture and P picture for performing motion compensation prediction are mixed. In a digital video signal recording / reproducing apparatus for recording / reproducing a high-efficiency-encoded digital video signal in a unit of a few frames on a medium such as an optical disk, one frame is recorded at least for I pictures and P pictures. Video data of n is divided into n (n> 1) and is coded in units of n divided areas. For the I picture and P picture divided into n, I picture is given priority,
When recording the I and P pictures divided into n units in area units, the position of the area where recording is started is scrolled and recorded in I and P picture frame units, and the areas 1 to n in the GOP are recorded. A means for simultaneously storing the position information recorded on the medium, and at the time of special reproduction, at least the I picture or P picture is read from the medium, stored in the buffer memory, and outputted as a special reproduction image in frame units, The I picture or
A digital video signal recording / reproducing apparatus characterized by comprising a means for interpolating the area which could not be read from the data of the previous screen when all areas of the P picture could not be read. 4. The I-picture and P-picture data divided and coded for each area are divided and recorded in units of blocks for error correction, and all the I-picture areas can be read during special reproduction. If not possible, only the DCT block that can be decoded in units of the error correction block is output, and the error correction block that cannot be read is provided with a means for interpolating from the data of the previous screen. 3. A digital video signal recording / reproducing apparatus according to item 3 .