JPH03139083A - Dynamic image encoding device - Google Patents

Abstract

PURPOSE:To execute the interpolation of erroneous image information by detecting a frame whose relativity is small between the front frame and the rear frame from dynamic image information, and bringing a frame immediately before it to in-frame encoding. CONSTITUTION:An original image is inputted to a pre-processing means 1 and a correlation detecting means 3. The means 1 executes sub-sampling and blocking of the original image, and obtains a block signal. The means 3 detects a correlation value between each frame and the frame immediately before each frame, and transmits the frame number immediately before the detected frame to a control means 4, in the case the correlation value is smaller than a prescribed threshold. The means 4 inserts a refresh frame at every prescribed time interval. In the case these is a scene change, the means 4 determines in- frame encoding of all blocks of the frame immediately before and immediately after the scene change. A block control means 2 determines an encoding method of a block signal of the frame with respect to all the frames except the frame designated by the means 4. In accordance with the determination of the means 2 and 4, an adaptive encoding means 5 encodes adaptively each block.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a video encoding device that performs band compression transmission encoding of a video signal.

2. Description of the Related Art In recent years, transmission of digital moving images and their encoding and decoding have been studied mainly in the communication field. An example of the basic operation of these video encoding/decoding devices will be described below with reference to the drawings.

FIG. 3 is a block diagram showing the configuration of a conventional video encoding device.

In FIG. 3, 31 is a preprocessing means, 32 is a determining means,
33 is orthogonal transform encoding means, 34 is quantization means, 35 is inverse quantization means, 36 is orthogonal transform decoding means, 37 is motion compensation interframe encoding means, 38 is motion detection means, 39
40 is a variable length encoding means, and 40 is a channel encoding means.

First, the original image is input to preprocessing means 31 .

The preprocessing means 31 performs sub-sampling and blocking of the original image to obtain a block signal. The determining means 32 determines whether the block signal is encoded by interframe encoding or intraframe encoding. In the case of interframe coding, a block difference signal between the block signal and the predicted signal predicted by the motion compensated interframe coding means 37 is sent to the orthogonal transform coding means 33. In the case of intraframe encoding, the block signal is sent as is to the orthogonal transform encoding means 33.

When frames using interframe coding are consecutive, if an uncorrectable error occurs in the transmission path during that period, that error will continue to propagate to subsequent frames, so only blocks periodically coded within the frame can be used. Insert a configured refresh frame. Also, when there is a scene change, the first frame becomes a refresh frame.

On the other hand, the motion detection means 38 refers to the block signal and the prediction signal in the frame buffer of the previous frame in the motion compensated interframe encoding means 37 to detect motion information between the previous frame and the previous frame.

The orthogonal transform encoding means 33 performs two-dimensional orthogonal transform on the block signal or the block difference signal and converts it into transform coefficients.

The spatial correlation of the image signal is removed from the transform coefficients, and energy is concentrated in some coefficients. The quantization means 34 performs quantization by weighting coefficients in which energy is concentrated among the transform coefficients. The variable length encoding means 89 assigns codes to each quantized output so that the average code length becomes short. Thereafter, the main information to which the code has been assigned is sent to the channel encoding means 40, which includes sub-information such as encoding method determination information from the determining means 32, motion information from the motion detecting means 38, and quantization step information from the quantizing means 34. It is combined with information, further added with an error correction code, etc., and sent out to a transmission path.

On the other hand, the dequantization means 35 dequantizes the quantized output using the quantization step information from the quantization means 34 to create local decoding transform coefficients. The orthogonal transform decoding means 36 performs orthogonal transform decoding on the locally decoded transform coefficients to obtain a locally decoded output.

If the determination means 32 determines that the local decoding output is interframe encoding, the local decoded output is added to the predicted signal and sent to the motion compensated interframe encoding means 37. If it is determined that intra-frame encoding is required, the motion compensated inter-frame encoding means 37
sent to. The motion compensation interframe encoding means 37 performs motion compensation using the motion information detected by the motion detection means 88, and outputs a predicted signal.

FIG. 4 is a block diagram showing the configuration of a conventional moving image decoding device.

In FIG. 4, 51 is a channel decoding means, 52 is an error detection and correction means, 53 is a separation means, 54 is a decoding means, and 55
58 is a variable length decoding means, 58 is an inverse quantization means, 57 is an orthogonal transform decoding means, 58 is a motion compensation inter/intraframe decoding means, 59 is an image storage means, 80 is a motion detection means, 61
is an error-compensated interframe decoding means.

FIG. 5 is a diagram for explaining the operations of the image storage means, motion detection means, and error compensation interframe decoding means of a conventional moving picture decoding device.

In FIG. 5, 71 is the first group of frame buffers, 72Gt
lliI constant time interval refresh frame, 73
74 is an error frame, 74 is a frame immediately before the error frame 73, 75 is a subsequent refresh frame at a constant time interval, 76 is an error block, 77 is a block that refers to the error block, and 78 is motion information.

Regarding the moving picture decoding apparatus configured as described above, the detailed operation of the conventional moving picture decoding apparatus will be explained below using FIGS. 4 and 5.

The image information encoded by the moving image encoding device and arriving via the transmission path is subjected to error detection and correction in the communication path decoding means 51. Here, if an uncorrectable error occurs, the decoding of the corresponding block is stopped, and the error detection and correction means 52 determines the position of the error block from the motion detection means 59 and the motion compensated inter/intra frame decoding means 58. and moves on to processing the next block.

If the error correction is successfully performed, the image information is transferred to the separation means 5.
3, the information is separated into main information and sub information. The separated main information and sub information are each sent to decoding means 54. In this conventional example, the decoding means 54 is variable length decoding means 56. Inverse quantization means 6e, orthogonal transform decoding means 57. It consists of motion compensated inter/intra frame decoding means 58. The main information sent to the decoding means 54 is first sent to the variable length decoding means 55.
The code-assigned information is converted into a decoded and quantized output.

The inverse quantization means 56 inversely quantizes the decoded and quantized output using the quantization step information of the side information to create decoded transform coefficients. The orthogonal transform decoding means 57 performs orthogonal transform decoding on the decoded transform coefficients to obtain a decoded block output.

The motion-compensated inter/intra-frame decoding means 58 has a small frame buffer (both have a frame buffer for two frames). Then, from the decoded block output, it is detected whether the encoding means is interframe encoding or intraframe encoding.In the case of intraframe encoding, the decoded block output is directly used as a decoded block signal and is sent to the specified position of the frame buffer of the current frame. In the case of interframe coding, a decoded block signal is created by adding the block signal of the previous frame specified by the motion information of one group of frame buffers of the previous frame and the decoded block output using the motion information of the sub information. , writes to the specified position in the frame buffer of the current frame.

At this time, the motion compensated inter/intraframe decoding means 58 uses the error block position information from the error detection and correction means 52 to determine whether the block signal of the previous frame specified by the motion information is the error block 78 or the block to which the error block refers. 77 is detected, and if this is the case, the current frame is not written to the frame buffer.

When the reproduced image signal for one frame is thus formed in the frame buffer in the motion compensated inter/intra frame decoding means 58, it is stored in the image storage means 59 while being updated in the order of the previous frame and the current frame. be done. Image storage means 5
9 consists of at least two refresh frames inserted periodically and frame buffers corresponding to the number of frames existing between them. In this example, e
If one refresh frame is inserted into a frame, the image storage means 59 has one group of frame buffers 71 for at least seven frames.

When one raw video signal is sequentially stored in the image storage means 59 and all the reproduced video signals of frames existing between refresh frames are decoded and stored, according to the display timing,
These are sequentially read out and displayed.

When the error detection and correction means 52 detects an uncorrectable error, the error detection and correction means 52 notifies the motion detection means 60 of the position of the error block 76 that is composed of erroneous data. The motion detection means 80 detects the error frame 73 in which the error block exists and its position, and notifies the error compensation interframe decoding means 61 of the detected error frame 73 and its position. When the next refresh frame 75 arrives at the image storage means 59, the motion detection means 60 detects the frame 74 immediately before the error frame 73.
The motion information 78 near the position where the error block 76 exists between the refresh frame 75 and the refresh frame 75 is detected and notified to the error compensation interframe decoding means 61. The error compensation interframe decoding means 61 uses the error block position and motion information 78 to interpolate the error block 76 of the error frame 73 from the frame 74 immediately before the error frame 73, and interpolates the error block 76 of the error frame 73 from the frame 74 immediately before the error frame 73 in the image storage means 59. Record the interpolation block at the position.

Thereafter, the error compensation interframe decoding means 61 decodes the interframe encoded block 77 that referred to the error block 76 after the error frame 73 using the interpolation block, and the frame buffer 1 group 71 of the image storage means 59 Record at the appropriate location. When all the reproduced video signals of the frames existing between refresh frames 72 and 75 are decoded,
According to the display timing, these are sequentially read out and displayed.

Problem to be Solved by the Invention However, in the above configuration, if there is a scene change, etc. between the frame immediately before the error frame and the refresh frame, there is no correlation between the frame immediately before the error frame and the refresh frame. Therefore, there was a problem that motion information could not be obtained and incorrect image information could not be interpolated.

In view of the above problems, the present invention provides a video encoding device that can reproduce a good image even when there is a scene change, etc. between the frame immediately before an error frame and a refresh frame, and the correlation between them is small. The purpose is to provide.

Means for Solving the Problems In order to achieve the above object, the video encoding device of the present invention includes a preprocessing means for dividing each frame of a video signal into blocks, and a preprocessing means for dividing each frame of a video signal into blocks. a correlation detection means for detecting a frame having a small correlation with the frame; a frame control means for determining an encoding method for a frame at a fixed time interval and a frame immediately before the frame having a small correlation; block control means for determining the encoding method for blocks of frames other than the frame immediately preceding the frame with low correlation; and adaptive encoding means for adaptively encoding each block according to determinations of the frame control means and the block control means. The configuration includes the following.

Effect of the Invention With the above-described configuration, the present invention detects a frame with a small correlation between the preceding and succeeding frames from video information, and performs intra-frame encoding on the immediately preceding frame, so that it is refreshed with the frame immediately before the error frame during decoding. Even if there is a scene change between frames, there is a correlation between the frame immediately before the erroneous frame, and motion information can be obtained, making it possible to interpolate erroneous image information. .

Embodiment Hereinafter, a moving picture encoding device according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a moving picture encoding device in an embodiment of the present invention.

In FIG. 1, 1 is preprocessing means, 2 is block control means, 3 is correlation detection means, 4 is frame control means, 5 is adaptive encoding means, 8 is orthogonal transform encoding means, 7 is quantization means, 8 is an inverse quantization means, 9 is an orthogonal transform decoding means, 10
11 is a motion compensation interframe encoding means, 11 is a motion detection means, 12 is a variable length encoding means, and 13 is a channel encoding means.

In this embodiment, the adaptive encoding means 5 includes the orthogonal transform encoding means 6. Quantization means7. Inverse quantization means8. Orthogonal transform decoding means 9. Motion compensated interframe coding means 10. Motion detection means 11. It is composed of variable length encoding means 12.

First, the original image is input to the preprocessing means 1 and the correlation detection means 3. The preprocessing means 1 performs subsampling and blocking of the original image to obtain a block signal. Correlation detection means 3
Then, the correlation value between each frame of the input moving image signal and the immediately preceding frame is detected, and if the correlation value is smaller than a certain threshold value, the frame number immediately preceding the detected frame is transmitted to the frame control means 4.

When frames using interframe coding are consecutive, if an uncorrectable error occurs in the transmission path during that period, that error will continue to propagate to subsequent frames. It is necessary to insert a refresh frame that is configured. In the case of this example,
The frame control means 4 determines to insert a refresh frame at a rate of one frame into the θ frame.

In addition, when there is a scene change, in order for the decoding device to interpolate errors that occur between the regular refresh frame immediately before the scene change and the scene change, it is necessary to It is necessary to insert the frame immediately before the change as a refresh frame. The correlation value between the frame immediately before and the frame immediately after a scene change is generally small, so
The correlation detection means 3 detects this, and the frame control means 4 receives this and decides to perform intra-frame encoding on all blocks of the frame immediately before and after the scene change.

The block control means 2 determines, for all frames other than the frame designated by the frame control means 4, whether to encode the block signal of the frame by interframe encoding or intraframe encoding.

In accordance with the decisions of the frame control means 4 and the block control means 2, the adaptive encoding means 5 generates a block difference signal between the block signal and the prediction signal predicted by the motion compensated interframe encoding means 10 in the case of interframe encoding. It is sent to orthogonal transform encoding means 6.

In the case of intraframe encoding, the block signal is sent as is to the orthogonal transform encoding means 8.

On the other hand, the motion detection means 11 refers to the block signal and the predicted signal in the frame buffer of the previous frame in the motion compensated interframe encoding means 10 to detect motion information between the previous frame and the previous frame.

The orthogonal transform encoding means 6 performs two-dimensional orthogonal transform on the block signal or block difference signal and converts it into transform coefficients. The spatial correlation of the image signal is removed from the transform coefficients, and energy is concentrated in some coefficients. The quantization means 7 performs quantization by weighting coefficients in which energy is concentrated among the transform coefficients.

The variable length encoding means 12 assigns codes to each quantized output so that the average code length becomes short.

Thereafter, the code-assigned main information is transmitted to the channel encoding means 13.
Then, it is combined with sub-information such as the encoding method determination information from the block control means 2, the motion information from the motion detection means 11, and the quantization step information from the quantization means 7, and is further added with an error correction code, etc. Sent to the transmission path.

On the other hand, the dequantization means 8 dequantizes the quantized output using the quantization step information from the quantization means 7 to create local decoding transform coefficients. The orthogonal transform decoding means 9 performs orthogonal transform decoding on the locally decoded transform coefficients to obtain a locally decoded output.

When the block control means 2 and the frame control means 4 determine that interframe coding is to be performed, the local decoded output is added to the prediction signal and sent to the motion compensated interframe coding means 10. If it is determined that intra-frame encoding is to be performed, the signal is directly sent to the motion compensated inter-frame encoding means 10. The motion compensation interframe encoding means 10 performs motion compensation using the motion information detected by the motion detection means 11, and outputs a predicted signal.

The configuration and operation of a moving picture decoding apparatus according to an embodiment of the present invention that decodes data encoded by a moving picture encoding apparatus are the same as those of a conventional moving picture decoding apparatus (FIG. 4).

FIG. 2 shows image storage means and motion detection means of a moving picture decoding device when decoding data encoded by the moving picture encoding device in an embodiment of the present invention.

FIG. 3 is a diagram for explaining the operation of error compensation interframe decoding means.

In FIG. 2, 21 is a frame buffer group, 22 is a previous refresh frame at a constant time interval, 23 is an error frame, 24 is a frame immediately before the error frame 23, 2
6 is the frame immediately before the scene change, 26 is the subsequent refresh frame at a certain time interval, 27 is the error block,
28 is a block that refers to the error block 27, and 29 is motion information.

The error compensation operation of the moving picture decoding apparatus at the time of a scene change will be described below with reference to FIGS. 2 and 4.

In the conventional video decoding device shown in FIG. 4, if there is a scene change between the frame in which the error detection and correction means 52 detects an uncorrectable error and the next refresh frame at a constant time interval, the error detection and correction means 52 notifies the motion detection means 60 of the location of the error block 27 which is composed of incorrect data. The motion detection means 60 detects the error frame 23 in which the error block 27 exists and its position, and notifies the error compensation interframe decoding means 81 of the detected error frame 23 and its position.

In the video encoding device according to the embodiment of the present invention, the frames immediately before and after the scene change are also encoded as refresh frames, so the next refresh frame, that is, the frame 25 immediately before the scene change, arrives in the image storage means 59. ! At that point, the motion detection means 60 detects motion information 29 near the position where the error block 27 exists between the frame 24 immediately before the error frame 23 and the frame 25 immediately before the scene change, and performs error compensation interframe decoding. Notify the means 61. The error compensation interframe decoding means 61 uses the error block position and motion information 29 to interpolate the error block 27 of the error frame 23 from the frame 24 immediately before the error frame 23, and interpolates the error block 27 of the error frame 23 from the frame 24 immediately before the error frame 23 in the image storage means 59. Record the interpolation block at the position.

Thereafter, the error compensation interframe decoding means e1 decodes the interframe encoded block 28 that referred to the error block 27 from the error frame 23 onward using the interpolation block, and Record at the appropriate location. When all the reproduced video signals of the through frames existing between refresh frames 22 and 25 are decoded,
According to the display timing, these are sequentially read out and displayed.

In this embodiment, an example has been described in which an image signal is encoded by a moving image encoding device and transmitted to a decoding device via a transmission path. It goes without saying that similar effects can be obtained with other devices, such as when recording, reading out the storage medium with a playback device, and decoding with a decoding device.

Effects of the Invention As described above, the video encoding device of the present invention includes a preprocessing means that divides each frame of a video signal into blocks, and a frame that has a small correlation with the previous frame among each frame of the video signal. a frame control means for determining an encoding method for a frame at a fixed time interval and a frame immediately before a frame with a small correlation; , and adaptive encoding means for adaptively encoding each block according to determinations of the frame controlling means and the block controlling means, and comprising: Detects frames with small correlation between the previous and subsequent frames from the information,
Since the frame immediately before the error frame is intra-frame encoded, even if there is a scene change between the frame immediately before the error frame and the refresh frame during decoding, there is a correlation between the frame immediately before the error frame and the refresh frame, and the movement Since the information can be obtained, it is possible to interpolate erroneous image information, thereby providing a moving image encoding device.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a video encoding device according to an embodiment of the present invention, and FIG. 2 is a video decoding device when decoding data encoded by the video encoding device of the same embodiment. Figure 3 is a block diagram showing the configuration of a conventional video encoding device, and Figure 4 is a diagram showing the configuration of a conventional video encoding device. FIG. 5 is a block diagram showing the configuration of a video encoding device, and FIG. 5 is an image storage means of a video encoding device when decoding data encoded by a conventional video encoding device. FIG. 3 is a diagram for explaining the operation of a motion detection means and an error compensation interframe decoding means. 1... Preprocessing means, 2... Block control means,
3... Correlation detection means, 4... Frame control means, 6... Adaptive encoding means, 8... Orthogonal transform encoding means, 7... Quantization means, 8... Inverse quantization means, θ...orthogonal transform decoding means, 10...
Motion compensated interframe coding means, 11...Motion detection means, 12...Variable length coding means, 13.
...Communication channel encoding means.

Claims (1)

[Scope of Claims] Preprocessing means for dividing each frame of a moving image signal into blocks; correlation detecting means for detecting a frame having a small correlation with the previous frame from among each frame of the moving image signal; a frame control means for determining an encoding method for a frame at each interval and a frame immediately before the frame with low correlation; The present invention is characterized by comprising: block control means that determines a block encoding method; and adaptive encoding means that adaptively encodes each of the blocks according to determinations of the frame control means and the block control means. Video encoding device.