JP2751510B2 - Video decoding device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moving picture decoding apparatus for decoding moving picture information transmitted in a band-compressed manner.

2. Description of the Related Art In recent years, transmission of digital moving images and encoding and decoding thereof have been studied mainly in the field of communications. 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 of a conventional moving picture coding apparatus.

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

The relative operation of each of these components will be described.

First, the original image is input to the preprocessing means 31. Preprocessing means 31 performs sub-sampling and blocking of the original image,
Obtain a block signal. The determination means 32 determines whether to encode the block signal by inter-frame encoding or intra-frame encoding. In the case of inter-frame coding, a block difference signal between the block signal and the prediction signal predicted by the motion compensation inter-frame coding unit 37 is sent to the orthogonal transform coding unit 33.
In the case of intra-frame encoding, the block signal is sent to the orthogonal transform encoding unit 33 as it is.

If an uncorrectable error occurs on the transmission line during the time when frames using interframe coding are continuous, the error continues to propagate to subsequent frames. Insert the configured refresh frame. Also, when there is a normal scene change, the first frame becomes a refresh frame.

On the other hand, the motion detecting means 38 detects the motion information between the previous frame and the block signal by referring to the prediction signal in the frame buffer of the previous frame in the motion compensation interframe coding means 37.

The orthogonal transform coding means 33 performs a two-dimensional orthogonal transform on the block signal or the block difference signal and converts it into a transform coefficient. As for the transform coefficients, the spatial correlation of the image signal is removed, and the energy of some coefficients is concentrated. The quantization means 34 performs quantization by weighting the coefficient in which the energy is concentrated among the transform coefficients. The variable length coding means 39 performs code allocation such that the average code length becomes shorter for each of the quantized outputs. After that, the main information to which the code is assigned is transmitted by the channel coding means.
At 40, it is combined with the encoding method determination information from the determination means 32, the motion information from the motion detection means 38, and the sub-information such as the quantization step information from the quantization means 34, and further, an error correction code and the like are added. Out to the transmission path.

On the other hand, the inverse quantization means 35 inversely quantizes the quantized output using the quantization step information from the quantization means 34, and generates a local decoding transform coefficient. The orthogonal transform decoding means 36 performs orthogonal transform decoding of the local decoding transform coefficient to obtain an Ibe decoding output.

When the local decoding output is determined to be inter-frame coding by the determination unit 32, the local decoding output is added to the prediction signal and sent to the motion compensation inter-frame coding unit 37. If the encoding is determined to be intra-frame encoding, it is sent to the motion-compensated inter-frame encoding means 37 as it is. The motion compensation inter-frame encoding means 37 performs motion compensation using the motion information detected by the motion detection means 38,
Output the prediction signal.

FIG. 4 is a block diagram of a conventional moving picture decoding apparatus.

In FIG. 4, reference numeral 51 denotes communication path decoding means, 52 denotes error detection and correction means, 53 denotes separation means, 54 denotes decoding means, 55 denotes variable length decoding means, 56 denotes inverse quantization means, and 57 denotes orthogonal transform decoding. Decoding means 58 is a motion compensation inter-frame / intra-decoding means.

Next, the mutual operation of these components will be described.

The image information arriving from the transmission path is transmitted to the communication path decoding unit 51.
Performs error detection and correction. The error-corrected information is separated into main information and sub-information by separation means 53, and
The information corresponding to the block is detected. The separated main information and sub-information are each sent to the decoding means 54. In this example, the decoding means 54 comprises a variable length decoding means 55, an inverse quantization means 56, an orthogonal transform decoding means 57, and a motion compensation inter-frame / intra-decoding means 58. The main information sent to the decoding means 54 first converts the information to which the code has been assigned by the variable length decoding means 55 into a decoded and quantized output. In the inverse quantization means 56, the quantized output is inversely quantized using the quantization step information of the sub-information to produce a decoded transform coefficient. The orthogonal transform decoding means 57 performs orthogonal transform decoding of the decoded transform coefficient to obtain a decoded block signal.

The motion-compensated inter / intra-frame decoding means 58 has at least two
It has a frame buffer for frames. In the motion-compensated inter / intra-frame decoding means 58, the coding means of the decoded block output detects inter-frame coding or intra-frame coding using the coding method determination information of the sub-information. In the case of intra-frame encoding, the output of the decoded block is directly written as a decoded block signal at a designated position in the frame buffer of the current frame. In the case of inter-frame coding, a decoded block signal is created by adding the block signal at the position specified by the motion information in the buffer of the previous frame and the decoded block output using the motion information of the sub-information, and Writes to the specified position in the frame buffer.

When a reproduced image signal for one frame is thus formed in the frame buffer in the motion compensation inter / intra-decoding means 58, the contents of the frame buffer are updated in the order of the previous frame and the current frame according to the display timing. By repeatedly outputting, a moving image can be reproduced.

SUMMARY OF THE INVENTION However, in the above configuration, when an error that occurs during transmission cannot be corrected by a channel decoder, an image of a frame including incorrect image information cannot be correctly decoded. Therefore, the image is disturbed. Furthermore, in the case of using inter-frame coding or in the case of dropping frames by pre-processing means at the time of coding and interpolating dropped frames at the time of decoding, refer to incorrect image information in subsequent frames. There is a problem that an image is disturbed due to the propagation of an error at a certain location, and the image is disturbed until a periodically inserted refresh frame arrives.

In view of the above problems, the present invention interpolates an erroneous block using an error-free block of the previous and next frames even when an uncorrectable error occurs during transmission, so that a moving image that can reproduce a good image can be obtained. An image decoding device is provided.

Means for Solving the Problems In order to solve the above problems, a moving picture decoding apparatus of the present invention comprises: an error detection and correction means for detecting and correcting an error in band-compressed image information; Separation means for separating information, decoding means for decoding main information using sub-information, image storage means for storing a plurality of decoded image frames, and error correction among error correction means among a plurality of image frames Motion detecting means for detecting motion information between the preceding and succeeding error-free image frames of the image frame having the error, and error compensation for interpolating the error image information of the image frame having the error using the motion information It is provided with an inter-frame decoding means, and the rear image frame for detecting the motion information is obtained by decoding the intra-frame encoded image information by the inter-frame encoding device. It is a sign.

The video decoding device of the present invention has the above-described configuration,
If an uncorrectable error is detected during transmission, motion information is obtained between the frame immediately before the frame in which the erroneous image information is present and the intra-frame arriving after that, and the motion information is used. Even if erroneous image information is interpolated with other information and an uncorrectable error occurs, the reproduced image is not disturbed.

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

FIG. 1 is a block diagram of a moving picture decoding apparatus according to one embodiment of the present invention.

In FIG. 1, 1 is a channel decoding means, 2 is an error detection and correction means, 3 is a separating means, 4 is a decoding means, 5 is a variable length decoding means, 6 is an inverse quantization means, and 7 is an orthogonal transform decoding. Means 8, a motion compensation inter-frame / intra-decoding means, 9 an image storage means, 10 a motion detection means, and 11 an error compensation inter-frame decoding means.

FIG. 2 is a block diagram of the image storage means of the moving picture decoding apparatus according to one embodiment of the present invention.

In FIG. 2, 21 is a frame buffer group, 22 is a previous refresh frame, 23 is an error frame, 24 is a frame immediately before an error frame, 25 is a refresh frame after, 26 is an error block, and 27 is an error block. Block.

The operation of each component of the video decoding apparatus related to each other will be described below. The moving picture coding apparatus of the present embodiment is the same as that shown in the conventional example.

The image information coded by the moving picture coding apparatus and arrived via the transmission path is subjected to error detection and correction by the communication path decoding means 1. Here, when an error that cannot be corrected occurs, the decoding of the corresponding block is stopped, and the error detection and correction means 2 sends the position of the error block to the motion detection means 9 and the motion compensation inter / intra-decoding means 8. And the processing moves to the next block.

When the error correction is normally performed, the image information is separated into main information and sub-information by the separation unit 3. The separated main information and sub-information are sent to the decoding means 4, respectively. In this embodiment, the decoding means 4 comprises a variable length decoding means 5, an inverse quantization means 6, an orthogonal transform decoding means 7, and a motion compensation inter / intra-frame decoding means 8. The main information sent to the decoding means 4 first converts the information to which the code has been assigned by the variable length decoding means 5 into a decoded and quantized output. The inverse quantization means 6 inversely quantizes the quantized output using the quantization step information of the sub-information to produce a decoded transform coefficient. The orthogonal transform decoding means 7 performs orthogonal transform decoding on the decoded transform coefficients to obtain a decoded block output.

The motion compensation inter-frame / intra-decoding means 8 has at least 2
It has a frame buffer for frames. In the motion-compensated inter / intra-frame decoding means 8, the coding means of the decoded block output detects the inter-frame coding or the intra-frame coding using the coding method determination information of the sub-information. In the case of intra-frame encoding, the output of the decoded block is directly written as a decoded block signal at a designated position in the frame buffer of the current frame. In the case of inter-frame coding, a decoded block signal is created by adding the block signal of the previous frame specified by the motion information in the frame buffer 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 / intra-frame decoding means 8 uses the error block position information from the error detection and correction means 2,
The block signal of the previous frame specified by the motion information detects the erroneous block 26 or the block 27 referring to the erroneous block, and if so, does not write the current frame into the frame buffer.

When the reproduced image signal for one frame is formed in the frame buffer in the motion compensation inter / intra-decoding means 8 in this manner, the reproduced image signal is stored in the image storage means 9 while being updated in the order of the previous frame and the current frame. You. Image storage means 9
Is composed of at least two periodically inserted refresh frames and a frame buffer corresponding to the number of frames existing between them. In the case of this embodiment, if one refresh frame is inserted into six frames, the image storage means 9 has a frame buffer group 21 for at least seven frames. When the reproduced video signals are sequentially stored in the image storage means 9 and all the reproduced video signals of the frames existing between the refresh frames are decoded and stored, they are sequentially read out according to the display timing and display is started.

When an uncorrectable error is detected by the error detection and correction means 2, the error detection and correction means 2 informs the motion detection means 10 of the position of the error block 26 composed of erroneous data. The motion detecting means 10 detects the error frame 23 where the error block exists and its position, and notifies the error-compensating inter-frame decoding means 11 thereof. When the next refresh frame 25 arrives at the image storage means 9, the motion detection means 10 determines whether the frame 24 immediately before the erroneous frame 23 and the refresh frame
The motion information near the position where the error block 26 exists is detected between the 25 and the error compensation interframe decoding means 11 is notified. The error-compensation interframe decoding means 11 uses the error block position and motion information to
Is interpolated from the frame 24 immediately before the error frame 23, and an interpolation block is recorded at a corresponding position of the error frame 23 in the image storage means 9. In this way, even if an uncorrectable error occurs by compensating the error block by using another block, the reproduced image is not disturbed.

After that, the inter-frame coding block 27 that referred to the error block 26 after the error frame 23 is decoded by the error-compensation inter-frame decoding unit 11 using the interpolation block. Record at the appropriate location. When all the reproduced video signals of the frames existing between the refresh frames 22 and 25 are decoded, they are sequentially read out according to the display timing and display is started.

In this embodiment, the example in which the coded image signal is transmitted to the decoding device via the transmission path has been described. However, the image signal coded by the coding device is recorded on a storage medium such as an optical disk and reproduced. Needless to say, the same effect can be obtained for other devices, such as when the storage medium is read by the device and decoded by the decoding device.

As described above, the moving picture decoding apparatus of the present invention detects an error of band-compressed image information, an error detection and correction unit that corrects, and a separation unit that separates sub-information and main information from image information. Decoding means for decoding main information using sub-information; image storage means for storing a plurality of decoded image frames;
Motion detecting means for detecting motion information between two error-free image frames, and error-compensating inter-frame decoding means for interpolating, using the motion information, error pixels uncorrectable by the error detecting and correcting means between the two image frames. When an uncorrectable error is detected during transmission, motion information is obtained between a frame immediately before a frame in which erroneous image information is present and an intra-coded frame arriving after that, and Since the erroneous image information is interpolated using other information using the information, it is possible to provide a moving picture decoding apparatus which does not disturb the reproduced image even if an uncorrectable error occurs.

[Brief description of the drawings]

FIG. 1 is a block diagram of a video decoding device according to one embodiment of the present invention, FIG. 2 is a configuration diagram of image storage means of the video decoding device according to one embodiment of the present invention, and FIG. FIG. 4 is a block diagram of a conventional moving picture decoding apparatus, and FIG. 4 is a block diagram of a conventional moving picture decoding apparatus. 1 ... channel decoding means, 2 ... error detection and correction means, 3
... separating means, 4 ... decoding means, 5 ... variable length decoding means, 6 ... inverse quantization means, 7 ... orthogonal transform decoding means,
8 ... motion-compensation inter-frame / intra-decoding means, 9 ... image storage means, 10 ... motion detection means, 11 ... error-compensation inter-frame decoding means.

Claims (1)

(57) [Claims] 1. An apparatus for decoding image information band-compressed by an inter-frame encoding apparatus that performs intra-frame encoding at least periodically, wherein an error in the band-compressed image information is detected and corrected. Error detection and correction means, separation means for separating the image information into sub-information and main information, decoding means for decoding the main information using the sub-information, image storage for storing a plurality of decoded image frames A motion detecting means for detecting motion information between preceding and succeeding error-free image frames of an image frame having an error which cannot be corrected by the error detecting and correcting means among the plurality of image frames; Error-compensation inter-frame decoding means for interpolating the error image information of the image frame having the above-mentioned motion information using the motion information. Laem is
A moving picture decoding apparatus characterized in that the picture information that has been intra-coded by the inter-frame coding apparatus is decoded.