JP2001298735A - Low delay video image transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of delay time caused by compression and decoding processing of a video signal, by reducing the processing time while maintaining reproduced video image quality, in the case that a conventional video transmission system in compliance with the MPEG standards (ISO 13818-2, ISO 11172-2) that are the international standards of video image compression is used for a 2-way application for a video conference or the like. SOLUTION: The low delay video image transmission system is provided with an MPEG coding section 10 consisting of an encode section 11 that encodes a received input video signal while its coding unit is fixed to fields only and generates and outputs an MPEG stream, of a matrix memory 12 that stores the priority of slices and blocks for encoding, and of a VBV delay comparison section 13 and with an MPEG decoder 20 consisting of a decode section 21 that receives and decodes an MPEG stream and outputs decoding end position information, of a field memory 22 that outputs desired supplement data according to the decoding end position information, and of a supplement section 23 that superimposes decoded field data ad the supplement data.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-delay video transmission system, and more particularly to a low-delay video processing in video compression based on the MPEG standard.

[0001]

2. Description of the Related Art The MPEG standard which is an international standard for video compression
When a video transmission system conforming to (ISO13818-2, ISO11172-2) is used as a bidirectional application such as a video conference, a delay time caused by a video signal compression and decoding process poses a problem. As measures for reducing the processing time, reduction of the VBV buffer size, prohibition of bidirectional prediction, switching to a simple profile, and the like have been put to practical use. A method of realizing a low delay by adopting a stream configuration for continuously transmitting P frames having no GOP structure is also conceivable. However, when a scene is changed, a significant deterioration in image quality due to an increase in prediction error is caused. In order to avoid this and protect the image quality, a processing method for forcibly inserting an I-frame at the time of detecting a scene change and restoring the GOP structure can be considered, but in this case, the amount of codes generated by intra-encoding increases, and Since the delay encoding / decoding operation cannot be performed in time, it is necessary to perform an error concealment process for a frame loss by a decoder that supports low delay. Another method for reducing the delay is to use M
There is also a method using a low-delay mode defined by the PEG standard. In this case, the encoder is allowed to skip a frame that has been determined to be too late for encoding / decoding. Also in this case, it is necessary for the decoder corresponding to the low delay to detect the loss of the frame to be decoded / displayed and perform the error concealment process. As error concealment processing of a decoder, redisplay of a frame decoded immediately before is currently known.

[0002]

When an attempt is made to achieve a low delay in a frame-based coding processing system that is currently in practical use, an encoder / decoder uses a frame as a coding unit based on a frame. A buffer delay occurs due to the VBV delay calculated in this manner, and the rate-determining condition for reducing the delay occurs. Further, as a method of repeating a previous decoding screen as an error concealment process when decoding or display of a frame is not in time in a decoder, in a field-based encoding / decoding system, field switching occurs, and Makes people feel uncomfortable.

[0003]

In order to solve this problem, a low-delay video transmission system according to claim 1 of the present invention comprises: an MPEG encoder for encoding a video signal to generate an MPEG stream; MPE generated above
And an MPEG decoder for decoding the G stream and reproducing the video signal. The low-delay video transmission system according to claim 2 of the present invention is the low-delay video transmission system according to claim 1, wherein the MPE
The G encoder encodes the input video signal by fixing the encoding unit to only the field, generates an MPEG stream, and performs low-delay output for outputting the MPEG stream.
It has an encoding part.

According to a third aspect of the present invention, there is provided the low-delay video transmission system according to the first aspect, wherein the MPEG encoder fixes the input video signal to a coding unit of only a field. MPEG
An encoder for calculating a VBV delay value for a field to be encoded in the process of performing MPEG encoding, performing a low delay output for generating and outputting a stream, and outputting the calculated VBV delay value as a current VBV delay value; It is characterized by the following.

According to a fourth aspect of the present invention, there is provided the low-delay video transmission system according to the third aspect, wherein the MPEG encoder further includes: A matrix memory for storing priorities of slices, blocks, and the like; and a VBV delay comparing unit for comparing a current VBV delay value output from the encoding unit with an externally specified VBV delay upper limit value. It is characterized by the following.

A low-delay video transmission system according to a fifth aspect of the present invention is the low-delay video transmission system according to the third or fourth aspect, wherein the encoding unit of the MPEG encoder is further externally input. When a field closing command is received, the coding of the field currently being coded is suspended in the minimum coding unit, and only the portion where the coding is completed is M
A field closing operation of outputting an MPEG stream after adjusting the PEG syntax, giving priority to the information on where the range that could not be encoded when the encoding of the field was interrupted falls within the field and the type of the field. Interrupt information output operation to output to the outside as degree information, with priority to preferentially encode the unencoded portion of the range in the field according to the priority information stored in the external or internal storage means Field encoding operation and MP for encoding an input video signal in accordance with the MPEG standard and outputting it as an MPEG stream
An EG stream output operation is performed.

A low-delay video transmission system according to claim 6 of the present invention is the low-delay video transmission system according to any one of claims 1 to 5, wherein the MPEG decoder comprises:
A decoding unit that receives and decodes the MPEG stream and outputs decoding completion position information, a field memory that outputs desired complementary data according to the decoding completion position information, and a decoding unit that decodes the decoding field data and the complementing data. And a complementary unit for superimposition.

According to a seventh aspect of the present invention, there is provided the low-delay video transmission system according to the sixth aspect, wherein the decoding unit of the MPEG decoder further comprises: And an incomplete field detection operation for detecting an incompletely coded incomplete field, decoding only a decodable part when the MPEG stream includes an incompletely coded field, and Incomplete field decoding operation to output, decoding only the decodable part when the MPEG stream contains incompletely coded fields, including the position information and field type of the undecodable range A decoding completion position information output operation for outputting as decoding completion position information;
A decoding operation for decoding a PEG stream in accordance with the MPEG standard.

According to an eighth aspect of the present invention, there is provided a low-delay video transmission system according to the seventh aspect, wherein the field memory stores the reproduced video signal in a form capable of being separated for each field, The field type is specified from the input decoding completion position information and the range in which decoding was not possible is determined. From the storage contents stored in advance, the decoding in the field storage data matching the field type was not performed. It is characterized in that data of a portion that matches the range is extracted and output as complementary data.

[0010] According to a ninth aspect of the present invention, in the low delay video transmission system according to the eighth aspect of the present invention, the complementary section may be partially decoded field data. A complete field reproduction video signal is generated from the data and the complementary data read from the field memory. With these configurations, the processing delay time, which is a problem when a two-way application such as a video conference is configured using a video transmission system compliant with the MPEG standard, which is the international standard for video compression, can be fixed by a field in the encoder , And further, the coding is terminated by setting the upper limit of the VBV delay.
By using (field closure), incomplete field detection in the decoder, and field complementation processing, the processing delay time can be reduced while minimizing the degradation of playback video quality. Becomes Also, by fixing the coding unit to a field for the purpose of achieving a low delay, coding can be performed at fine time intervals, and the buffer delay generated in the encoder / decoder due to the VBV delay can be further reduced. This can be shortened, and the processing delay in the system encoder placed downstream of the encoder can be reduced by subdividing the coding units.

Further, the low-delay video transmission system according to the present invention can be used in combination with the conventional means for reducing the VBV buffer size and prohibiting bidirectional prediction. Makes it possible to reduce the processing delay time while minimizing the degradation of the playback video quality

Further, the low-delay video transmission system according to the present invention also detects a state in which decoding cannot be performed in time due to low delay. For this purpose, the upper limit of the VBV delay is specified in advance. It is possible to avoid sending useless data to the decoder, and it is also possible for the encoder to interrupt the useless processing and start the next processing.

In summary, the present invention provides an encoding section for encoding an input video signal by fixing the encoding unit to only fields, generating and outputting an MPEG stream, and a slice or block for encoding. An MPEG encoding unit composed of a matrix memory for storing the priority of the MPEG-2 stream, a VBV delay comparing unit, a decoding unit for receiving and decoding the MPEG stream and outputting decoding completion position information, It has an MPEG decoder composed of a field memory for outputting desired complementary data according to information, and a complementer for superimposing decoded field data and complementary data.

With this configuration, the input video signal injected into the encoding unit is encoded according to the MPEG standard after the encoding unit is fixed to a field. The encoding unit encodes the VBV through a process of performing MPEG encoding in field units based on the designated VBV buffer size.
The V delay value is integrated and output to the VBV delay comparing section as the current VBV delay value. Further, the encoding unit preferentially encodes a data portion in a high priority field according to the priority information read from the matrix memory. The VBV comparison unit sequentially compares the designated VBV delay upper limit value and the current VBV delay value notified from the encoding unit, and issues a field closing instruction to the encoder when the two match. Upon receiving the field closing instruction, the encoding unit terminates the encoding process at the end of the minimum encoding unit (slice, macroblock, etc.) currently encoded, prepares the MPEG syntax as field data, and outputs the MPEG stream. Output as This allows the encoder to generate an MPEG stream with low delay time,
In the decoding process in the decoder, the output of the field data for which the decoding time is insufficient can be substantially suppressed. The encoding unit outputs to the matrix memory information including the position and range of the minimum coding unit and the field type that have not been coded due to the incomplete field on the matrix memory, and the matrix memory stores the information. . This is used to increase the encoding priority of the relevant part in the subsequent encoding processing, and prevents the quality of the reproduced video signal from being degraded at the decoder. That is, the MPEG decoder includes a decoding unit, a field memory, and a complementing unit 23, and the decoding unit repeats a process of decoding a field with respect to an input MPEG stream according to the MPEG standard and outputting it as a reproduced video signal. However, if the decoding cannot be completed in the process, the decoding is abandoned at that point, and the decoded data up to the last slice where decoding is completed is output to the complementing section as decoded field data, and decoding is completed in the field memory. The decoding completion position information including the extracted range and the distinction between the top field and the bottom field is output, and the decoding-completed past field data stored in the field memory is read. The decoding unit is MP
Even when it is detected that the field is skipped in the EG stream, the decoding completion position information including the decoding completion position as the whole field and the decoding completion position information including the field type are output to the field memory and stored. The stored data for the same type of field is read out. The field memory stores the reproduction field data output from the complement unit in a form that can be separated into a top field and a bottom field, and when decoding completion position information is output from the decoding unit, decodes the field type and decoding from the decoding completion position information. It detects where the unsuccessful range is, reads out the data of the corresponding range in the stored field data for the same type of field, and outputs the data to the complementing unit. The complementing unit combines the decoded field data output from the decoding unit with the complementary data output from the field memory to output a complete field signal as a reproduced video signal. The display device is MPE
The reproduced video signal output from the G decoder is displayed.

[0015]

(Embodiment 1) Hereinafter, a low-delay video transmission system according to Embodiment 1 of the present invention will be described with reference to FIGS. 1, 2, 3, and 4. FIG. I will explain it. The input video signal a input to the MPEG encoder 10 is compressed by the encoding unit 11 according to the MPEG standard to generate an MPEG stream b.
At this time, the coding unit is fixed to the field. At this time, in order to further increase the effect of reducing the delay, the designation of the VBV buffer size related to the maximum value of the VBV delay is set to a small appropriate value, for example, 35% of the standard maximum value.
It is better to prohibit bidirectional prediction. Further, FIG.
As shown in (a), the VBV delay upper limit value d is set to an appropriate value, for example, 50% of the maximum value derived from the set VBV buffer size. Encoding unit 11
Calculates the current VBV delay value c and sends it to the VBV delay comparison unit 13 in the process of performing the encoding process on each input field. The VBV delay comparator 13 compares the current VBV delay value c sequentially transmitted from the encoder 11 with the preset VBV delay upper limit d.
The field closing instruction e is sent to the encoding unit 11 only when they match with each other as shown in FIG.

As shown in FIG. 2C, when the encoding unit 11 receives the field closing command e, the encoding unit 11 completes the encoding of the appropriate encoding unit currently encoded, for example, the slice unit. , The encoding process was terminated, and the MPEG syntax as a field was adjusted.
As shown in (d), it is transmitted as an MPEG stream b. At this time, the slice data to be included in the MPEG data of the field portion exists only halfway, and the field structure is closed to become the header of the next field. Of course, if the encoding of the field is completed without reaching the VBV delay upper limit value d and the code generation amount is small, the field closing instruction e is not issued and the field becomes complete. When the coding is aborted, the data of the uncoded portion is not transmitted. Therefore, if this is repeated, the prediction error in the decoder 20 increases, which causes image quality deterioration. To prevent this, encoding with priority by the matrix memory 12 is performed. The matrix memory 12 stores field position information in a form that can be recognized as a top field and a bottom field. When the coding is discontinued, the encoding unit 11 sends the position in the field where the coding is completed and the field type to the matrix memory 12. In the matrix memory 12, as shown in FIG. 3, a check is made on three slice positions that have not been transmitted according to this information, and the encoding priority of these slices is raised. The encoding unit 11 reads the priority information f from the matrix memory 12 at the start of encoding, and adjusts the encoding configuration in the field so that a slice with a high priority can be encoded as much as possible. The MPEG stream b applied to the MPEG decoder 20 is subjected to a decoding process in the decoding unit 21 in accordance with the MPEG standard. If there is complete slice data for reproducing the field to be decoded in the MPEG stream, it operates as a conventional decoder and outputs it to the display device 30 as a reproduced video signal. When outputting a reproduced video signal, the reproduced field data is stored in an area of the field memory 22 where the signal of the corresponding field is stored. If a partially closed field or a skipped field is syntactically detected during the decoding process, the field complementing process is started. The decoding unit 21 decodes only the decodable part and sends it to the complementing unit 23 as decoded field data g.
The range and field type that could not be decoded are sent to the field memory 22 as decoding completion position information h. The field memory 22 determines from the decoding completion position information h where to read the data of the part that has given up decoding in the decoding unit 21, reads the complementary data i, and sends it to the complementing unit 23. The complementing unit 23 stores the decoded field data g received from the decoding unit 20 in the field memory 22.
And completes with the supplementary data i received from the server and outputs it as one complete field. At this time, similarly to the above, the output data (reproduced video signal j) is stored and stored at an appropriate position on the field memory 22 so that it can be used in the subsequent field complementing process. Another example is a case where the field data sent from the MPEG encoder 10 is complete, but the decoding process takes time, so that the display cannot be made in time even if decoding is performed with a specified VBV delay. is there. Also in this case, the MPEG decoder 20
Performs the same field complementing process as described above to ensure the quality of the reproduced video signal j. FIG. 4 shows a pattern of complementation for an incomplete field.

Although the bottom field is omitted in FIG. 4 for simplicity, in practice, the top field and the bottom field usually appear alternately, so that one is skipped in time. In the P field 1 in FIG. 4A, the slice in the first row is intra-coded, but the field closing instruction e is issued during the slice coding in the fourth row.
Simultaneously with the completion of the encoding of the slice in the fourth row, the P field 1 is forcibly closed, and the slices in the fifth to seventh rows are transmitted as incomplete fields that are not encoded. Therefore, the corresponding position (the slice position on the fifth to seventh rows) of the matrix memory 12 shown in FIG. 4B is checked, and the priority is increased by one. At this time, FIG.
The P field 1 of the reproduced video signal j which is the output of the MPEG decoder 20 shown in (c) is complemented by the complementary data i retrieved and read from the corresponding position in the field memory 22 for the slices 5 to 7. You. In the next P field 2, the slice in the second row is not intra-coded,
Intra-coding is started from slice 5 in accordance with the priority information f of the matrix memory 22, but since the field closing instruction e is received while coding the slice in the sixth row, the coding of the slice in the sixth row is completed at the same time. , P field 2 are forcibly closed, and the slice in the seventh row is transmitted as an uncoded incomplete field. Reflecting this, the check of the slices 5 to 6 on the matrix memory 22 is deleted, and instead, the slice position of the 7th row that could not be coded is checked again, and the priority is further reduced by one. Can be raised. Since the next P field 3 can be encoded as a complete field, all the checks in the matrix memory 22 are deleted.
Next, in the P field 4 to be encoded, since the matrix memory 22 is empty, the intra encoding at the position following the P field 1 may be continued.

As described above, the low-delay video transmission system according to the first embodiment uses MPEG as a system component.
It has an encoder and an MPEG decoder, and is configured to decode the MPEG stream generated by the MPEG encoder with the MPEG decoder. That is, the input video signal input to the encoding unit 11 is encoded in accordance with the MPEG standard after the encoding unit is fixed to a field, and at that time, the encoding unit 11 performs the encoding on a field basis based on the specified VBV buffer size. MPE
Through the process of performing G encoding, the VBV delay value is integrated and output as the current VBV delay value to the VBV delay comparing unit 13. The encoding unit 11 stores the high-priority field in the high-priority field according to the priority information read from the matrix memory 12. , The data part is encoded with priority, and VBV
The comparing unit 13 sequentially compares the specified VBV delay upper limit value and the current VBV delay value notified from the encoding unit 11 and issues a field closing instruction to the encoder 11 when both match, Upon receiving the field closing instruction, the encoding unit 11 terminates the encoding process at the end of the minimum encoding unit such as a slice or a macroblock which is being encoded at that time, and outputs the MPE as field data.
After the G syntax has been adjusted, the stream is output as an MPEG stream.
Can generate an MPEG stream with a low delay time, and can substantially suppress the output of field data for which the decoding time is insufficient in the decoding process in the MPEG decoder 20. The encoding unit 11 is a matrix memory 1
2 and outputs the information including the position and range of the minimum coding unit and the field type which have not been coded due to the incomplete field on the matrix memory 12, and the matrix memory 12 stores the information. By using it to raise the encoding priority of the part in the subsequent encoding process, it is possible to prevent the quality of the reproduced video signal from being degraded at the decoder. That is, the MPEG decoder 2 composed of the decoding unit 21, the field memory 22, and the complementing unit 23
0, the decoding unit 21 repeats the process of decoding the input MPEG stream according to the MPEG standard and decoding the field according to the MPEG standard and outputting it as a reproduced video signal. However, if the decoding cannot be completed in the process, the decoding unit gives up decoding at that time. The decoded data up to the last slice for which decoding has been completed is output to the complementing unit 23 as decoded field data, and the decoding completion position including the range in which decoding has been completed and the distinction between the top field and the bottom field are stored in the field memory 22. Output information to field memory 2
The decoding unit 21 reads out the decoded past field data stored in 2 and decodes the decoding completion position as the whole field even when the decoding unit 21 detects that the field is skipped in the MPEG stream. Completion position information and decoding completion position information including a field type are output to the field memory 22, and stored data for the same type of stored field is read out. The field memory 22 is output from the complementing unit 23. The reproduction field data is stored in a form that can be separated into a top field and a bottom field, and when decoding completion position information is output from the decoding unit 21, where is the field type from the decoding completion position information and the range where decoding is not possible? Is detected, and the stored field for the same type of field is detected. The data in the corresponding range in the field data is read out and output to the complementing unit 23. The complementing unit 23 combines the decoded field data output from the decoding unit 21 with the complementary data output from the field memory 22 to complete the data. The display device 30 displays the reproduced video signal output from the MPEG decoder 20 and outputs the reproduced video signal from the MPEG decoder 20 as described above. Signal quality deterioration can be prevented.

Therefore, in the low-delay video transmission system according to the first embodiment of the present invention, a two-way application such as a video conference is configured using a video transmission system conforming to the MPEG standard which is an international standard for video compression. The processing delay time, which is a problem in such a case, is determined by fixing the field in the encoder, stopping the encoding by setting the VBV delay upper limit, detecting the incomplete field in the decoder,
And the field complementing process, the processing delay time can be reduced while minimizing the degradation of the reproduced video quality. Here, in the MPEG standard, there is a mechanism in which a coding unit can be adaptively switched from a frame to a field or from a field to a frame according to the intensity of the movement of an input video signal. The purpose of this is to improve the quality of the reproduced video because it is suitable for encoding of the video, but in view of this, by having the field fixing function, the processing delay time can be reduced by the reproduction video. It is possible to be able to shorten it while keeping quality deterioration to a minimum

In the first embodiment of the present invention,
The coding unit in the coder can be fixed to the field for the purpose of achieving a low delay, so that the coding can be performed at a fine time interval of about half of the frame base, resulting from the VBV delay. The buffer delay occurring in the encoder / decoder can be further reduced, and the processing delay in the system encoder placed at the subsequent stage of the encoder for the purpose of multiplexing or packetizing a plurality of MPEG streams. Can also be reduced by subdividing the coding units.

The low-delay video transmission system of the present invention is not incompatible with the conventional means for reducing the VBV buffer size and prohibiting bidirectional prediction, and can be used in combination. In particular, VBV
There is a method of specifying the buffer size, which is used for the purpose of optimizing the buffer amount in the decoder and relates to the calculation of the VBV delay. In this case, the encoder uses the VBV delay. V derived from buffer size
Encoding is performed with the BV delay as the maximum value of the VBV delay. However, even if the decoder buffer is properly processed, decoding may not be performed in time for the purpose of low delay. However, the present invention can be applied to such a case and exerts its effects.

Further, the low-delay video transmission system of the present invention detects a situation in which decoding cannot be performed in time due to a reduction in delay. For this purpose, it is necessary to further specify an upper limit of a VBV delay. However, by specifying the upper limit of the VBV delay, it is possible to avoid sending unnecessary data to the decoder in advance, and to interrupt the unnecessary processing in the encoder and start the next processing. In this case, the encoder can not only skip the interrupted field unconditionally, but also transmit the encoded data up to the time when the encoding is completed in units of the minimum encoding unit. The decoder can be configured to decode a decodable portion when receiving incomplete coded data, and display a deficient portion in combination with past decoded data.

In the decoder, even when the field cannot be decoded in time, only the decodable part is decoded,
The missing portion may be displayed in combination with the past decoded data. Here, the past decoded data refers to decoded data at a position corresponding to a field with a lack of data among field data already decoded / displayed and stored in the storage means. In this case, the data to be complemented from the field memory must correspond to the same type of field as the field to be complemented. However, even if a field skip or incomplete field occurs due to this series of Can minimize discomfort.

[0024]

As described above, according to the low-delay video transmission system according to the present invention, M which is an international standard for video compression.
When an interactive application such as a video conference is configured using a video transmission system conforming to the PEG standard, an MPEG encoder that encodes a video signal to generate an MPEG stream, and an MPE generated as described above.
An MPEG decoder for decoding a G stream and reproducing a video signal is provided. The processing delay time in encoding and decoding is set in the encoder, the field is fixed, and the VBV delay upper limit value is set. In this case, the processing delay time is kept to a minimum while maintaining the reproduction video quality at a minimum. The effect that can be shortened is obtained.

According to the low-delay video transmission system of the present invention, the coding unit in the encoder can be fixed to a field for the purpose of achieving a low delay.
As a result, encoding can be performed at a fine time interval (about half of the frame base), the buffer delay caused by the encoder / decoder due to the VBV delay can be further reduced, and the encoder can be encoded at a shorter time. The processing delay in the system encoder placed at the subsequent stage can also be reduced by subdividing the coding units.

Further, the low-delay video transmission system according to the present invention can be used in combination with the conventional means for reducing the VBV buffer size and prohibiting bidirectional prediction. The subdivision makes it possible to reduce the processing delay time while minimizing the degradation of the reproduced video quality.

The low-delay video transmission system according to the present invention also detects a state in which decoding cannot be performed in time due to a low delay. For this purpose, the upper limit of the VBV delay is further specified by specifying the upper limit of the VBV delay. It is possible to avoid sending useless data to the decoder, and it is also possible for the encoder to interrupt the useless processing and start the next processing.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a low-delay video transmission system according to a first embodiment of the present invention.

FIG. 2 is a diagram for explaining an encoding process in the low-delay video transmission system according to the first embodiment of the present invention.

FIG. 3 is a diagram for explaining a matrix memory in the low-delay video transmission system according to the first embodiment of the present invention.

FIG. 4 is a diagram for explaining an encoding process and a decoding process in the low-delay video transmission system according to the first embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 10 MPEG encoder 11 Encoding unit 12 Matrix memory 13 VBV delay comparing unit 20 MPEG decoder 21 Decoding unit 22 Field memory 23 Complementary unit 30 Display device a Input video signal b MPEG stream c Current VBV delay value d VBV delay upper limit value e Field closing instruction f Priority information g Decoding field data h Decoding completion position information i Complementary data j Reproduction video signal

Claims (9)

[Claims] 1. A video signal is MPEG-encoded, and MPEG
A low-delay video transmission system, comprising: an MPEG encoder that generates a stream; and an MPEG decoder that decodes the generated MPEG stream and reproduces a video signal. 2. The low-delay video transmission system according to claim 1, wherein the MPEG encoder encodes the input video signal by fixing an encoding unit to only a field, and generates and outputs an MPEG stream. A low-delay video transmission system, comprising: a field fixed encoding / encoding unit that performs low-delay output. 3. The low-delay video transmission system according to claim 1, wherein the MPEG encoder encodes the input video signal by fixing an encoding unit to only a field, and generates and outputs an MPEG stream. An encoding unit that calculates a VBV delay value for a field to be encoded in a process of performing low-delay output and performing MPEG encoding, and outputting the calculated VBV delay value as a current VBV delay value. Delayed video transmission system. 4. The low-delay video transmission system according to claim 3, wherein said MPEG encoder further comprises a matrix memory for storing priorities of slices, blocks, and the like when encoding is performed by said encoding unit. A low-delay video transmission system, comprising: a VBV delay comparing unit that compares a current VBV delay value output from the encoding unit with an externally specified VBV delay upper limit value. 5. The low-delay video transmission system according to claim 3, wherein the encoding unit of the MPEG encoder further comprises:
Field closing operation of interrupting the encoding of the field currently being encoded in the minimum encoding unit, outputting only the completed portion as an MPEG stream after adjusting the MPEG syntax, and interrupting the encoding of the above fields The interruption information output operation of outputting information as to where in the field the range that could not be coded at the time of performing and the type of the field as priority information to the outside, the priority information stored in the external or internal storage means, Priority field encoding operation for preferentially encoding the unencoded portion of the range in the field according to the degree information, and encoding the input video signal in accordance with the MPEG standard,
And performing an MPEG stream output operation for outputting as an EG stream. 6. The low-delay video transmission system according to claim 1, wherein the MPEG decoder receives and decodes the MPEG stream, and outputs decoding completion position information. A low-delay video transmission system, comprising: a field memory that outputs desired complementary data according to the decoding completion position information; and a complementing unit that superimposes the decoded field data and the complementary data. 7. The low-delay video transmission system according to claim 6, wherein the decoding unit of the MPEG decoder further detects a skipped field and an incomplete field partially encoded. Incomplete field detection operation, Incomplete field decoding operation of decoding only the decodable part when the MPEG stream contains incompletely encoded fields and outputting it as decoded field data, MPEG stream incomplete A decoding completion position information output operation of decoding only a decodable portion when the encoded field is included, and outputting as decoding completion position information including position information and a field type of a range that cannot be decoded, And a decoding operation for decoding the input MPEG stream in accordance with the MPEG standard. A low-delay video transmission system, characterized in that: 8. The low-delay video transmission system according to claim 7, wherein the field memory stores the reproduced video signal in a form that can be separated for each field.
The field type is specified from the inputted decoding completion position information, and the range in which decoding was not possible is determined. From the stored contents stored in advance, the decoding was not performed in the field storage data matching the field type. A low-delay video transmission system for extracting data corresponding to a range and outputting the data as complementary data. 9. The low-delay video transmission system according to claim 8, wherein the complementing unit comprises: the decoding field data that is partially decoded field data; and the complementing data read from the field memory. A low-delay video transmission system for generating a full-field reproduced video signal from a video signal.