JPH05153574A - Moving picture data decoder - Google Patents

Abstract

PURPOSE:To correct smoothly a defect of a picture due to a code error against a peripheral picture by replacing a block having an uncorrectable code error caused therein with a block picture generated by a preceding motion vector decided based on a preceding frame picture and decoding the picture. CONSTITUTION:When a code error detection correction circuit 23 detects a block whose code error in reproduced data S21 cannot be corrected, a moving picture data decoder 20 outputs a switching signal S23 to changeover circuits 30,31 to stop the write of decoded picture data S29 and a current motion vector S30 to a frame memory 29 and a motion vector memory 32. Furthermore, the device 20 outputs a signal S23 to the memory 32 and a changeover circuit 33 to read a motion vector in a relevant block of a preceding frame stored in the memory 32 and gives it to a motion compensation circuit 34. Then prediction picture data S33 predicted from the preceding motion vector is sent to the frame memory 29. Thus, the defect of the picture due to a code error is smoothly corrected against the peripheral picture.

Description

Detailed Description of the Invention

[0001]

[Table of Contents] The present invention will be described in the following order. Field of Industrial Application Conventional Technology Problems to be Solved by the Invention Means for Solving the Problems (FIG. 3) Action (FIGS. 4 to 6) Example (FIGS. 1 to 6)

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moving picture data decoding apparatus, which is a so-called compact disk or a so-called DAT.
(Digital audio tape recorder) It is suitable for application when reproducing moving image data from a recording medium such as a cassette or a hard disk.

[0003]

2. Description of the Related Art Conventionally, since the amount of information is extremely large for digitally recording a moving image, a recording medium having an extremely high continuous transmission speed is required for recording / reproducing this. For example, when a video signal according to the NTSC system is digitally recorded, a so-called video disc having a large amount of recorded information is used for recording / reproduction.

However, in order to record moving image data having the same amount of generated information as a so-called video disc for a long time on a smaller recording medium (that is, a small amount of recorded information), a video signal is encoded with high efficiency. A means for recording and efficiently decoding the read signal is indispensable.

In order to meet such a demand, a high-efficiency coding system for image signals has been proposed, one of which is MPE.
There is a G (Moving Picture Experts Group) method.
In this MPEG system, first, the redundancy in the time axis direction is reduced, the difference between images is taken, and thereafter, the redundancy in the spatial axis direction is reduced, so that the discrete cosine transform (DCT) is performed.
It is designed to do.

[0006]

However, such an M
In the PEG system, a decoding device is provided in front of the decoding. However, when an error that cannot be corrected by the error code correction capability of this decoding device occurs, a partial loss of the image occurs at that position, and it remains as it is. Displaying an image makes it unsightly.

Therefore, in general, an error is corrected by fitting a past frame image as a partial image located at the same position as the missing image part into the missing part. This method is effective for an image portion where there is no movement, but when there is movement, it is not possible to connect the missing portion and the peripheral portion smoothly, and the missing portion is conspicuous and a good result cannot always be obtained.

The present invention has been made in consideration of the above points, and moving image data capable of reproducing an image much closer to the original image even when a transmission error in which a decoding error cannot be corrected on the decoding side occurs. It is intended to propose a decoding device.

[0009]

In order to solve such a problem, in the present invention, moving image data S2 sequentially input
In the moving picture data decoding apparatus 20 which decodes 1, the code error of the moving picture data S21 is corrected, the reproduced digital signal S22 is output, and when a code error that cannot be corrected is detected in the moving picture data S21, the error detection signal S2 is detected.
Error detection / correction means 23 for outputting 3; demultiplexing means 24 for separating the reproduction digital signal S22 into motion vector data S30 and image data S24; and prediction image data based on the error detection signal S23 and motion vector data S30 Predicted image generation means 31, 3 for generating S28
2, 33, 34 and image synthesizing means 28, 29 for synthesizing the image data S24 and the predicted image data S28,
When a code error that cannot be corrected in the moving image data S21 is detected, the predicted image generating means 31, 32, 33, 34 generate the predicted image data S28 based on the motion vector S31 corresponding to the moving image data S21. To generate.

[0010]

In decoding the moving image data S21, if a code error that cannot be corrected is detected, the predicted image data S28 generated based on the motion vector S31 corresponding to the moving image data S21 is missing an image. By replacing the part, even when the motion of the decoded moving image data S21 is large, the loss due to the code error can be corrected inconspicuously.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a moving image data encoding device (encoder) as a whole, which is input image data S1 obtained by converting an analog moving image signal into digital data.
Is input from the input terminal 2. At this time, the input image data S1 is composed of an intra frame I, a predict frame P, and a bidirectional frame B as shown in FIG.

Here, the intra frame I (I ₀ , I ₁ ...
...) is a frame that is compressed and transmitted only within the frame, and is a predict frame P (P ₀ , P _1).
......) is a frame whose motion is predicted from one direction,
By Day Rexinal Frame B (B ₀ , B ₁ , B ₂ ,
B ₃ ......) is a frame motion prediction from both directions.

The difference data generation circuit 3 inputs the input image data S1 from the input terminal 2 and the frame memory 4
Further, the previous frame image data S2 of the previous frame stored in the frame memory 4 is input. Here, the difference data generation circuit 3 uses the input image data S
1 and the previous frame image data S2 is obtained to generate difference data S3, and the discrete cosine transform DCT
(Discrete cosine transform) Output to the circuit 5.

The discrete cosine transform circuit 5 uses the two-dimensional correlation of the image to perform discrete cosine transform of the difference data S3 in a unit of a small block, and the resulting transformed data S4 is a quantizer Q (quantizer). 6
It is designed to output to. The quantizing circuit 6 quantizes the transformed data S4 with a predetermined quantizing step size, and outputs the quantized data S5 obtained at the output end to the variable length coding VLC (variable length code) circuit 7.

The variable length coding circuit 7 outputs variable length coded data S6 obtained by subjecting the quantized data S5 to variable length coding to the multiplexer 8. Multiplexer 8
Is the motion vector data S input from the encoder 9.
When 7 is multiplexed with the variable length coded data S6, it is sent out as transmission data S8 via the buffer circuit 10.

The moving picture data encoding apparatus 1 also has a local decoding circuit system 11 for locally decoding the quantized data S5 transmitted as the transmission data S8 and supplying it to the frame memory 4. ing. Local decoding circuit system 1
When the quantized data S5 is input to the dequantization circuit (Q ^-1 ) 12, the dequantized data S5 is dequantized to a representative value and converted to dequantized data S10 to convert the unquantized converted data. Decode and inverse discrete cosine transform (DCT ^-1 )
Supply to the circuit 13.

Discrete cosine inverse conversion circuit 13
Is the inverse quantized data S1 decoded by the inverse quantization circuit 12.
0 is converted into decoded image data S11 by a conversion process reverse to that of the discrete cosine conversion circuit 5, and is output to the frame data generation circuit 14. Here, the frame data generation circuit 14 adds the frame image data S2 fed from the frame memory 4 and the decoded image data S11 to restore the image data output as the transmission data S8, and sequentially stores it in the frame memory 4. Has been done.

Further, when the moving picture data coding device 1 inputs the input picture data S1 to the motion vector calculating circuit 18 and obtains a motion vector, it is supplied to the motion compensating circuit 19 and the encoder 9 as the motion data S15. ing. Here, the motion compensation circuit 19 uses the frame memory 4
The decoded image data S16 is read from the motion prediction data S17 for motion compensation of the decoded image data S16.
Is output to the frame memory 4.

The encoder 9 is adapted to encode the motion data S15 obtained by the motion vector calculation circuit 18 and output it as the motion vector data S7 to the multiplexer 8.

On the other hand, reference numeral 20 in FIG. 3 indicates a moving image data decoding device (decoder) as a whole, which reproduces the reproduction data S21 read from the recording medium from the input terminal 21 through the buffer circuit 22 and detects a code error. / Correction circuit 2
It is designed to be input in 3.

Here, the code error detection / correction circuit 23 detects and corrects an error included in the image data from the reproduction data S21 and outputs the corrected reproduction image data S22 to the demultiplexer circuit 24. Further, the code error detection / correction circuit 23 outputs a switching signal S23 for controlling the switching of the image data output when detecting a block in which the code error cannot be corrected.

The demultiplexer circuit 24 separates the motion vector data from the reproduced image data S22, and the variable length decoding circuit (VLC ^-1 ) as the difference image information data S24.
25, and the decoded image data S25 before being encoded by the variable-length code encoding circuit 7 is decoded and the inverse quantization circuit (Q
^-1 ) 26.

The dequantization circuit 26 uses the decoded image data S2.
5 is inversely quantized into a representative value and converted into inversely quantized data S26, the discrete cosine inverse conversion circuit 27 converts it into decoded image data S27 by a conversion process reverse to that of the discrete cosine conversion circuit 5, and frame data is generated. Circuit 2
It is designed to output to 8.

The frame data generation circuit 28 also uses the motion compensation data S28 read from the frame memory 29.
Is added with the decoded data S27 to decode the decoded image data S29, and the decoded image data S29 is output from the frame memory 29 via the switching circuit 30.

Here, the switching circuit 30 is on / off controlled by a switching signal S23 supplied from the code error detection / correction circuit 23, and reproduced data S21 by the code error detection / correction circuit 23.
If an uncorrectable code error is detected, the decoded image data S29 is not stored in the frame memory 29.

When the vector data is separated from the reproduced image data S22, the demultiplexer circuit 24 supplies it as current motion vector data S30 to the motion vector memory 32 via the switching circuit 31.

Here, when the code error detection / correction circuit 23 does not detect an uncorrectable code error in the reproduction data S21, the switching circuit 31 stores the current motion vector data in the motion vector memory 32 which holds the motion vectors for the past three frames. S30 is supplied.

The switching circuit 33 is so controlled as to be switched by the switching signal S23 supplied from the code error detection / correction circuit 23, and the reproduction data S21 of the current frame.
If no uncorrectable code error is detected, the current motion vector S30 is supplied to the motion compensation circuit 34, or if an uncorrectable code error is detected, the previous motion vector stored in the motion vector memory 32 is detected. Data S
31 is supplied to the motion compensation circuit 34.

The motion compensation circuit 34 includes a frame memory 29.
When the reference frame data S32 is input from, the predicted block image is generated based on the current or previous motion vector S30 or S31 and is stored in the frame memory 29 as the predicted image data S33.

When an uncorrectable code error occurs, the frame memory 29 replaces the predicted image data S33 generated by the previous motion vector S31 as the image data of the corresponding block portion and stores it. The output image data S34 is output.

In the above structure, the moving picture data decoding device 20 reads out the reproduction data S21 from the recording medium in sequence and inputs it to the code error detection / correction circuit 23 via the buffer circuit 22.

When the code error detection / correction circuit 23 can correct the code error of the reproduced data S21, the moving picture data decoding apparatus 20 decodes the corrected image data S22 corrected based on the error detection / correction code. A multiplexer circuit 24, a variable length code decoding circuit 25, an inverse quantization circuit 26, and a discrete cosine inverse conversion circuit 27 are sequentially supplied to a frame data generation circuit 28.

The frame data generation circuit 28 motion-compensates the intra-frame I0 stored in the frame memory 29 as a reference frame to obtain motion compensation data S2.
Decoded image data S29 by adding the decoded data S27 to 8
Of the frame memory 2 through the switching circuit 30
9 and sequentially decodes the image data of the predictive frame P0 and the bidirectional frames B0, B1 ... And outputs it as decoded image data S34.

On the other hand, the moving picture data decoding device 20
If the block that cannot correct the code error of the reproduction data S21 is detected by the code error detection / correction circuit 23,
The switching signal S23 is output to the switching circuits 30 and 31, and the writing of the decoded image data S29 and the current motion vector S30 to the frame memory 29 and the motion vector memory 32 is stopped.

Further, the moving picture data decoding apparatus 20 sends the switching signal S23 to the motion vector memory 32 and the switching circuit 33.
Output to the motion vector memory 32, the motion vector in the corresponding block of the past frame stored in the motion vector memory 32 is read out and supplied to the motion compensation circuit 34, and the predicted image data S33 predicted from the past motion vector is sent to the frame memory 29. To do.

When the moving picture data decoding device 20 detects a code error that cannot be corrected in the intra frame I ₁ as shown in FIG. 4, for example, the first and second prediction frames stored in the motion vector memory 32 are detected. P ₀ and P ₁
Predicted image data S33 of the second predicted frame P ₁ to the intra frame I ₁ is generated by inter-frame prediction using the motion vector V (P ₀ P ₁ ) between them (FIG. 5).

The frame memory 29 uses a motion compensation circuit 34 to detect a block which is missing due to an uncorrectable code error.
It is replaced with the predicted image data S33 generated in step S31 and output as the decoded image data S34. As a result, when a code error occurs in the conventional intra frame I, it is possible to effectively avoid deterioration of the image quality even in these frames, which may cause the code error to propagate to other frames.

Similarly, when the moving picture data decoding apparatus 20 detects a code error that cannot be corrected in the second prediction frame P _1, it detects a motion vector V (I) between the intra frame I ₀ and the first prediction frame P _{0. 0} P ₀ ) is used to perform inter-frame prediction to replace the predicted image data S33 of the second prediction frame P ₁ from the intra frame I ₀ .

Similarly, the first and second prediction frames P
_{When a} code error that cannot be error-corrected is detected in the fourth bi-directional frame B ₃ predicted from both ₀ and P ₁ , the moving picture data decoding apparatus 20 causes the intra frame I ₀ and the second frame By Day Rexinal Frame B ₁
Between the first prediction frame P ₀ and the motion vector V (I ₀ B ₁ ) between the first prediction frame P ₀ and the second bidirectional frame B ₁ between the first and second motion vectors V (I ₀ B ₁ ). The fourth bi-directional frame B ₃ is predicted and replaced from both the prediction frames P ₀ and P ₁ (FIG. 6).

According to the above construction, in the moving picture data decoding apparatus for decoding moving picture data in block units and reproducing it, when a code error that cannot be corrected is detected in the reproduced moving picture data, By replacing the image of the corresponding block with the predicted image generated from the past frame based on the motion vector in the past frame, the loss due to the coding error is not conspicuous even when decoding the image with large motion. In comparison, the image quality can be further improved.

In the above-described embodiment, the case where the motion prediction of the image is performed in frame units has been described, but the present invention is not limited to this and can be applied to a system in which motion prediction is performed in field units.

Further, in the above-mentioned embodiment, the case of applying to the system using the discrete cosine transform DCT and the motion prediction between frames has been described, but the present invention is not limited to this and the prediction processing between frames is performed. It is suitable to be applied to a moving picture data decoding device that executes.

Further, in the above embodiment, the sequence of the configuration shown in FIG. 2, that is, I ₀ , B ₀ , B ₁ ,
The case of P ₀ , B ₂ , B ₃ , P ₁ , B ₄ , B ₅ , I ₁ has been described, but the present invention is not limited to this, and the intra frame I, the predecessor frame P, and the bidirectional unit are not limited thereto. It can also be applied to the case of sequences in various combinations with the Nari frame B.

Further, in the above embodiment, the case where the motion vectors for the past three frames are stored in the motion vector memory 32 has been described, but the present invention is not limited to this, and the case where the motion vectors for the past plural frames are stored. Widely applicable to.

Furthermore, in the above-mentioned embodiment, the case where a code error occurs in a single frame has been described, but the present invention is not limited to this and can be applied to the case where a code error occurs continuously. For example, when a code error that cannot be corrected is generated in the predict frame P ₁ and the intra frame I ₁ , the motion vector V (I ₀ P ₀ ) between the intra frame I ₀ and the predict frame P ₀ is used. good.

[0047]

As described above, according to the present invention, the moving image data in which an uncorrectable code error has occurred is replaced with the predicted image data generated by the corresponding motion vector and is decoded, whereby the decoded image Regardless of the presence or absence of motion, the missing part of the image due to a code error can be smoothly corrected with respect to the peripheral image.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of a moving image data encoding apparatus of the present invention.

FIG. 2 is a schematic diagram for explaining the inter-frame motion prediction.

FIG. 3 is a block diagram showing a configuration of an embodiment of a moving image data decoding apparatus of the present invention.

FIG. 4 is a schematic diagram for explaining inter-frame motion prediction in the case where a block that cannot be error-corrected is detected in the intra frame I ₁ .

FIG. 5 is a schematic diagram for explaining motion compensation using a motion vector.

FIG. 6 is a schematic diagram for explaining inter-frame motion prediction when a block that cannot be error-corrected is detected in the bi-directional frame B ₃ .

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Moving image data encoding device, 20 ... Moving image data decoding device, 21 ... Input terminal, 22 ... Buffer circuit, 23 ... Code error detection / correction circuit, 24 ... Demultiplexer circuit, 25 ...... Variable length decoding circuit, 26 ……
Inverse quantization circuit, 27 ... Discrete cosine inverse conversion circuit, 28 ... Frame data generation circuit, 29 ... Frame memory, 30, 31, 33 ... Switching circuit, 32 ...
Motion vector memory, 34 ... Motion compensation circuit.

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] October 21, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0033

[Correction method] Change

[Correction content]

When the code error detection / correction circuit 23 can correct the code error of the reproduced data S21, the moving picture data decoding apparatus 20 decodes the corrected image data S22 corrected based on the error detection / correction code. A multiplexer circuit 24, a variable length decoding circuit 25, an inverse quantization circuit 26 and a discrete cosine inverse conversion circuit 27 are sequentially supplied to a frame data generation circuit 28.

Claims (1)

[Claims] 1. A moving image data decoding apparatus for decoding moving image data that is sequentially input, in which a code error of the moving image data is corrected, a reproduced digital signal is output, and an error correction code is not added to the moving image data. Error detection / correction means for outputting an error detection signal when an error is detected, demultiplexing means for separating the reproduced digital signal into motion vector data and image data, and prediction based on the error detection signal and motion vector data The predictive image generating means for generating image data and the image synthesizing means for synthesizing the image data and the predictive image data are provided, and the predictive image generating means detects a code error that cannot be error-corrected in the moving image data. In this case, the predictive image data is generated based on the motion vector corresponding to the moving image data. Video data decoding device.