JP4034438B2 - Error code replacement method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a compressed image data processing method and apparatus, and more particularly to a method and apparatus for decoding bitstream data compliant with the MPEG standard and outputting the data in the order of display. The present invention relates to a replacement method and a replacement device for replacing error data specified by an error detection signal with a sequence error code when a detection signal is input.
[0002]
[Prior art]
For example, in an apparatus that handles MPEG signals such as a television receiver conforming to the MPEG standard, if an error is further detected after error correction by the error correction circuit, this error is output along with the stream as an error detection signal. . Further, in the subsequent error signal replacement circuit, it is replaced with a sequence error code to be detected by the subsequent decoder circuit. As a result, the decoder circuit can know the presence of the error data, and can appropriately proceed with the signal processing.
[0003]
The error data replacement process at this time includes a method of deleting the error data specified by the error detection signal and inserting a 4-byte sequence error code, or a method of replacing the data with the sequence error code from the position where the error is detected. .
[0004]
[Problems to be solved by the invention]
However, when the error detection signal is detected, the error data is deleted and a 4-byte sequence error code is inserted. If the error data is shorter than 4 bytes, it is replaced with a sequence error code rather than the input stream. Since the amount of data in the stream thus generated increases, the STD-buffer overflows.
[0005]
Also, if the error detection signal is shorter than 4 bytes when the error detection position is replaced with the sequence error code, the error data will be longer than 4 bytes, and normal data will be destroyed. . At this time, if the destroyed data is the head of a synchronization word such as a picture header, there is a problem that the return from the error for one picture is delayed. In order to avoid this, if only the part where an error has occurred is replaced with a sequence error code, there is a problem that a pseudo pattern of a synchronization word occurs.
[0006]
In order to solve such a problem, the present invention is a replacement device for replacing error data specified by an error detection signal with an error code signal when an error detection signal is generated in an MPEG standard encoded signal. It is an object of the present invention to provide a replacement device that does not perform replacement when destroying a signal or the like.
[0007]
[Means for Solving the Problems]
One means for solving the problem is an error code replacement device that receives encoded data accompanied by an error detection signal and performs a replacement process of the error data specified by the error detection signal. Receiving means for receiving accompanying encoded data, synchronizing word signal detecting means for detecting a synchronizing word signal from the encoded data received by the receiving means, and detection position of the synchronizing word signal detected by the synchronizing word signal detecting means The error data is replaced with a sequence error code, so that the synchronization signal is replaced with the sequence error code, so that an error code replacement prohibited section in which the synchronization signal is destroyed is set. If the error data is detected outside, the error data An error code replacement device comprising replacement means for replacing the error data with the sequence error code when the error data is detected within the error code replacement prohibited section. is there.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
A block diagram of an error code replacement apparatus according to the present invention is shown in FIG.
FIG. 1 shows the configuration of an image processing apparatus that receives an MPEG standard encoded signal, such as a television receiver. In the image processing apparatus according to the present invention, a tuning circuit 11 that receives a signal input from an antenna unit, an error correction circuit 12 connected thereto, a replacement circuit 1, a decoder circuit 13 connected thereto, An image processing unit 14 that receives a signal from the decoder circuit and performs predetermined image processing.
[0018]
In such an image processing apparatus, a signal supplied from the antenna unit is tuned by the tuning circuit 11 and is supplied to the error correction circuit 12 as an MPEG standard encoded signal. Here, error correction processing of the encoded signal is performed and output, but if there are more errors, this error detection signal becomes active at the timing when this error data exists, and error data exists. An error detection signal is given to the replacement circuit 1 along with the encoded signal so as to report that it is present.
[0019]
This error detection signal is shown in FIG. 2, and the data 25 is recognized as an error signal when the error detection signal 28 becomes active.
In the replacement circuit 1, the input data is encoded encoded data and an error detection signal added to each data byte along with the encoded data. These input data are input to the shift register 101 and at the same time, the synchronization word detection circuit 102 detects a synchronization word signal (specific pattern: 00, 00, 01) from the encoded data.
[0020]
The data input to the shift register is output after a certain period of delay, and the error signal detection circuit 103 detects an error detection signal added to the encoded data from this output. Here, when an error detection signal is detected by the error signal detection circuit 103, the error code generation circuit 104 generates a sequence error code (00, 00, 01, B4) from the head position of error signal detection.
[0021]
On the other hand, the output from the shift register 101 is input to the selector circuit 105, and when the error detection signal is active, there is error data in the data, so this error data is generated by the error code generation means 104. It is replaced with the sequence error code that has been output.
[0022]
Here, as shown in FIG. 6, the error code generation circuit 104 applies the encoded data output from the shift register 101 (six stages here) based on the detection position of the synchronization word from the synchronization word detection circuit 102. An error code replacement prohibition section 33 of a 3-byte period is set. If error data is detected by an error detection signal outside this section, the data is replaced with the sequence error code (00, 00, 01, B4), but the error data is detected within the error code replacement prohibition section 33. In this case, for example, the data is replaced by (00) without performing the replacement by the sequence error code.
[0023]
As another embodiment of the present invention, as shown in FIG. 2, when the bit length of the error data 25 specified by the error detection signal in the encoded data 21 exceeds the length of the sequence error code, the sequence error In order to invalidate the latter half of the error data 25 after the error code 26 of the encoded data 23 including the code, a part 27 of the encoded data valid signal is made inactive. As a result, the error data 25 is converted into the sequence error code 26, and other unnecessary data is substantially deleted.
[0024]
The present invention can avoid the following problems by adopting the embodiment as described above. FIG. 3 is a diagram illustrating a case where error data is replaced and inserted into a sequence error code, FIG. 4 is a diagram illustrating a case where a malfunction occurs in the operation by replacing the error data with a sequence error code, and FIG. 5 is a sequence of error data. It is a figure which shows the case where a malfunction arises by replacing with an error code.
[0025]
In FIG. 3, when the encoded data 31 includes error data 33 and 34 specified by the error detection signal, when the sequence error code is inserted, the encoded data 32 becomes too larger than the initial size. The buffer capacity overflows.
[0026]
However, according to the above-described replacement method of the present invention, since the code data is not inserted, the entire bit length does not become longer than the initial length, and such a problem can be avoided.
[0027]
Further, in FIG. 4A, when the encoded data 41 accompanied by the 3-byte error detection signal includes the picture start code 44 (00, 00, 01, 00), the error specified by the error detection signal 43 is detected. If the data is converted into an error code signal (00, 00, 01, B4), the first bit data of the picture section start code is destroyed (45), and the picture start code 44 becomes unreadable.
[0028]
Further, in FIG. 4B, a fake picture start code 55 is generated in the converted data after the error data 53 of the encoded data 51 accompanied by the error detection signal is replaced by the bit length together with this bit length. This causes a malfunction.
[0029]
According to the present invention, since the replacement prohibition section 33 is provided as described above, the replacement process is not performed when an error detection signal is generated during this period, so that the picture start code shown in FIG. 4 (b) can be avoided such as the occurrence of the pseudo picture start code.
[0030]
Further, FIG. 6 illustrates a situation where the replacement prohibition signal 81 becomes active and the destruction 73 of the picture header 74 is avoided. In this figure, the encoded data 61 includes error data 62, but since this is close to the picture header 63, if this is simply encoded (72), the picture header 74 will be destroyed ( 73). Therefore, the replacement is stopped for a certain period by the replacement prohibition signal 81, and then the replacement process is resumed.
[0031]
Also, here, only the case where the burst length of the error data specified by the error detection signal is shorter than the code length (4 bytes) of the sequence error code has been described, but the burst length of the error data specified by the error detection signal is When the length is longer than the sequence error code, it is needless to say that only the head portion of the error data is replaced with the sequence error code and the other error data portions are deleted (masked) as shown in FIG.
[0032]
【The invention's effect】
As described above in detail, according to the present invention, the synchronization word is prevented from being destroyed by the replacement process of the error data with the sequence error code, and the stable detection of the synchronization word is ensured, thereby stabilizing the operation. A replacement circuit that can be provided can be provided.
[Brief description of the drawings]
FIG. 1 is a block diagram of an image receiving device including an error code replacing device according to the present invention.
FIG. 2 is a diagram showing replacement of error data with a sequence error code.
FIG. 3 is a diagram illustrating a case where replacement insertion of error data into a sequence error code is performed.
FIG. 4 is a diagram illustrating a case where a malfunction occurs in operation by replacing error data with a sequence error code.
FIG. 5 is a diagram illustrating a case where a malfunction occurs in operation by replacing error data with a sequence error code.
FIG. 6 is a diagram illustrating a case where replacement is stopped according to an error code replacement prohibition section.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Replacement apparatus 11 ... Tuning circuit 12 ... Error correction circuit 13 ... Decoder circuit 14 ... Image processing part 21 ... Encoded data 22 containing error data ... Encoded data valid signal 23 ... Encoded data valid signal error data Is deleted from the encoded data 24 ... The encoded data valid signal 31 ... The encoded data 32 including the error data ... The sequence error code 41 ... The encoded data 42 including the error data ... The encoded data in which the picture start code is destroyed 51: Encoded data 52 including error data 52: Encoded data 61 in which pseudo picture start code is generated ... Encoded data 71 including error data ... Encoded data 81 in which picture start code is destroyed 81 ... Replacement prohibiting signal 91 ... Error Encoded signal 92 including data is delayed Encoded signal 93 ... Replacement prohibition section 94 ... Encoded data 95 in which error data replacement is prohibited ... Encoded data in which error data is replaced with a sequence error code

Claims (4)

An error code replacement device that receives encoded data accompanied by an error detection signal and performs replacement processing of error data specified by the error detection signal,
Receiving means for receiving encoded data with the error detection signal;
Synchronization word signal detection means for detecting a synchronization word signal from the encoded data received by the reception means;
Based on the detection position of the synchronization word signal detected by the synchronization word signal detection means, the synchronization signal is destroyed because the synchronization signal is replaced with the sequence error code by replacing the error data with a sequence error code. An error code replacement prohibition section is set, and when the error data is detected outside the error code replacement prohibition section, the error data is replaced with the sequence error code, and the error data within the error code replacement prohibition section A replacement means that does not replace the error data with the sequence error code,
An error code replacement device characterized by comprising: A tuning circuit for tuning a signal input from an antenna;
An error correction circuit for error correction of the tuning signal and supplying encoded data to the receiving means;
2. The error code replacement device according to claim 1, further comprising a decoding circuit for decoding the encoded data output from the replacement means. An error code replacement method for receiving encoded data accompanied by an error detection signal and performing replacement processing of error data specified by the error detection signal ,
Receiving the encoded data with the error detection signal;
A synchronization word signal detection step of detecting a synchronization word signal from the encoded data received by the reception step;
Based on the detected position of the detected synchronization word signal, an error code replacement prohibition section in which the synchronization signal is destroyed because the synchronization signal is replaced with the sequence error code by replacing the error data with a sequence error code is set. When the error data is detected outside the error code replacement prohibited section, the error data is replaced with the sequence error code, and when the error data is detected within the error code replacement prohibited section, the error data is replaced with the sequence error code. An error code replacement method comprising a replacement step of not replacing error data with the sequence error code. The error code replacement method is as follows:
A step of tuning a signal input from the antenna,
A step of supplying the encoded data to the receiving step the tuning signal to correct the error,
4. The error code replacement method according to claim 3 , further comprising the step of decoding the encoded data output from the replacement step .

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