JP2001169277A - Data transmission/reception system, data receiver and program recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem such that an effective transmission speed is lowered because of the transmission delay of a network itself when a compensation means for transmission errors and omissions by retransmission is used in the network transmission. SOLUTION: This data receiver is provided with a buffer 101 for restoring video and sound data for which the data of respective frames are divided into a plurality of data units, identifiers for the respective frames are attached and also redundant data for error detection are attached, a buffer 102 for outputting the data of the frame directly before the frame restored by the buffer 101, a transmission error/omission detection part 104 for detecting whether an error or an omission is present in the data constituting the video and sound data on the basis of the identifiers and the redundant data and a selector 103 for selecting the data from the buffer 101 and/or the buffer 102 and preparing the frame without data omissions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission / reception system for transmitting / receiving a video signal conforming to the DV system between two remote locations via a network, for example.
The present invention relates to a data receiving device.

[0002]

2. Description of the Related Art With the recent expansion of a network transmission band for data communication, a video signal is transmitted using a common network for data communication instead of a method of transmitting a video signal using a transmission line dedicated to video. It is becoming possible.

In transmitting data through a network, it is necessary to deal with transmission errors and omissions occurring on the network. In a network for data communication, redundant information for detecting transmission errors and omissions and a serial number are added to the data to be transmitted and then transmitted, and the receiving side reports the occurrence of transmission errors and omissions with this redundant information and Find out based on your serial number.

[0004] When a transmission error or loss is found, the receiving side requests retransmission to the transmitting side, and the transmitting side retransmits the same information in response to the transmission error or loss so that there is no transmission error or loss. Data transmission is taking place (for example, IETF RFC
793 Transmission Control Protocol).

FIG. 6 is a block diagram showing an example of a data transmission system for performing retransmission. Data transmitted from the transmission unit 1001 is transmitted to the reception unit 1002 via the network 1000.
The received data is stored in the buffer 1003 and sent to the transmission error / loss detection unit 1004. When a transmission error or loss is detected by the transmission error / loss detection unit 1004, a retransmission request is issued from the retransmission request unit 1005 to the transmission unit 1001.

[0006]

However, when the transmitting side and the receiving side are separated from each other by several hundred kilometers to several thousand kilometers, the transmission delay of the network becomes large, and it takes time to correct transmission errors and omissions by retransmission. The time may be so large that it cannot be ignored for the restoration of the video / audio signal.

This is the same as the decrease in the effective transmission speed. As a result, the receiving side must prepare a buffer 1003 having a sufficient size so that the video signal is not interrupted. For this reason, the delay time in the buffer on the receiving side causes a delay that greatly exceeds the transmission delay time of the network, and cannot be used for applications requiring immediacy.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem. Even when a transmission error or loss occurs in the transmission of video and audio data, the transmission of the video and audio data can be performed without requesting retransmission. An object of the present invention is to provide a data transmission / reception system with a small delay time by complementing data based on data transmitted without data, and a data receiving device that receives video and audio data and complements the data.

[0009]

Means for Solving the Problems The first invention (claim 1)
) Includes a data transmitting device that transmits video and audio data conforming to the DV system, and a data receiving device that receives the video and audio data transmitted by the data transmitting device. Dividing the data of each frame constituting the audio data into a plurality of data units, attaching an identifier for each frame, attaching redundant data for error detection, transmitting the video / audio data, A receiving device, a restoration unit for restoring the video and audio data transmitted by the data transmission device, and a previous frame output unit for outputting the video and audio data of at least one frame before the frame to be restored by the restoration unit; Based on the identifier and the redundant data of the video and audio data transmitted by the data transmission device, the video and audio data Error / drop detection means for detecting whether there is an error and / or drop in the data to be formed, and an output from the restoration means and / or the previous frame output means based on a detection result performed by the error / drop detection means. Selecting means for selecting data and generating a frame without data loss.

According to a second aspect of the present invention (corresponding to claim 2), the restoration means has a buffer function, and the buffer function is such that the error and / or the loss is detected by the error / loss detection means. A data transmission / reception system according to the first aspect of the present invention, wherein when detected, the data is used for outputting an audio data portion of a portion where the error and / or omission is detected.

According to a third aspect of the present invention (corresponding to claim 3), the previous frame output means can restore the video and audio data of at least one frame before the frame restored by the restoration means. A data transmission / reception system according to the first or second aspect of the present invention, characterized in that:

According to a fourth aspect of the present invention (corresponding to claim 4), when the error / missing is detected by the error / missing detecting means, the selecting means detects the error and / or missing. For the video block constituting the data unit thus selected, a video block corresponding to a frame immediately before the frame containing the video block from the previous frame output means is selected, and the error and / or Regarding the ID part and the audio auxiliary data part of the audio block constituting the data unit in which the loss has been detected, the ID corresponding to the immediately preceding frame from the previous frame output means is output.
And the audio auxiliary data section is selected, and as for the audio data section, another audio data section of the same frame from the restoration means is selected. It is a data transmission / reception system of the description.

According to a fifth aspect of the present invention (corresponding to claim 5), the data transmitting apparatus assigns the same identifier to each of a plurality of predetermined frames, and the previous frame output means outputs the frame to be restored by the restoration means. The video / audio data of the previous frame having the same identifier as the attached identifier is output, and when the error and / or the loss is detected by the error / drop detection unit, the selection unit outputs the error and / or the drop. For the video block constituting the data unit in which the missing is detected, one of the frames including the video block from the previous frame output unit is output.
The corresponding video block of the immediately preceding frame is selected, and the ID part and the audio auxiliary data part of the audio block constituting the data unit in which the error and / or omission has been detected are output from the previous frame output means. Selecting the corresponding ID part and the audio auxiliary data part of the frame having the same identifier as the identifier of the frame containing the data unit in which the error and / or the loss is detected, and for the audio data part, The data transmitting / receiving system according to any one of the first to third aspects of the present invention, wherein another audio data portion of the same frame from the means is selected.

According to a sixth aspect of the present invention (corresponding to claim 6), the video / audio data transmitted by the data transmission device is divided into a plurality of sub-sequences composed of a plurality of the data units. When the error and / or omission is detected by the error / omission detecting means and the selecting means selects the audio data section, the selecting means selects the data unit at which the error and / or the omission is detected. And selecting an audio data part having a high correlation with the data unit in which the error and / or the missing is detected in a subsequence 2n (n is an integer) away from the subsequence including A data transmission / reception system according to any one of the first to fifth aspects of the present invention.

According to the above configuration, when a transmission error occurs, the entire data unit is discarded, for example, UD
By combining with a transmission protocol such as P, even if a transmission error or loss occurs, the data contained in the data unit transmitted without error is used to supplement the data unit lost due to the transmission error or loss. In addition, data transmission can be performed without using a means of retransmission.

According to a seventh aspect of the present invention (corresponding to claim 7), a DV
Data of each frame constituting the video and audio data is divided into a plurality of data units, each frame is provided with an identifier, and redundant data for error detection is provided. Restoring means for restoring the video and audio data to which is attached, a previous frame output means for outputting the video and audio data of at least one frame before the frame to be restored by the restoration means, and An error / loss detection means for detecting whether an error and / or loss exists in the data constituting the video / audio data based on an identifier and the redundant data; and a detection result performed by the error / loss detection means. , Selecting data from the restoration means and / or the previous frame output means to create a frame without data loss. Further comprising a selection means for a data receiving apparatus according to claim.

According to an eighth aspect of the present invention (corresponding to claim 8), the restoration means has a buffer function, and the buffer function is such that the error and / or the loss is detected by the error / loss detection means. A data receiving device according to a seventh aspect of the present invention, wherein when detected, the data is used for outputting an audio data portion of a portion where the error and / or omission is detected.

According to a ninth aspect of the present invention (corresponding to claim 9), the preceding frame output means can restore the video / audio data of at least one frame before the frame restored by the restoration means. A seventh or eighth aspect of the present invention is the data receiving apparatus according to the present invention.

A tenth aspect of the present invention (corresponding to claim 10) is:
When the error and / or omission is detected by the error / omission detection means, the selection means outputs the previous frame output to the video block constituting the data unit in which the error and / or omission is detected. Means for selecting the corresponding video block of the frame immediately before the frame containing the video block from the means, and the ID part of the audio block constituting the data unit in which the error and / or omission was detected And for the audio auxiliary data section, select the ID section and the audio auxiliary data section corresponding to the previous frame from the previous frame output means,
The data receiving apparatus according to any one of the seventh to ninth aspects, wherein the audio data section selects another audio data section of the same frame from the restoration means.

The eleventh invention (corresponding to claim 11) provides:
The video and audio data is data to which the same identifier is attached for each of a plurality of predetermined frames, and the previous frame output unit has the same identifier as the identifier attached to the frame restored by the restoration unit. The video / audio data of the previous frame is output, and when the error and / or the missing is detected by the error / missing detecting means, the selecting means selects the data unit in which the error and / or the missing is detected. For the video block to be composed, the video frame corresponding to the frame immediately before the frame containing the video block from the previous frame output means is selected, and the error and / or omission is detected. Regarding the ID part and the audio auxiliary data part of the audio block constituting the data unit, And selecting the corresponding ID part and the audio auxiliary data part of the frame having the same identifier as the identifier of the frame containing the data unit in which the error and / or the loss has been detected, from the audio output means. The data receiving device according to any one of the seventh to ninth aspects of the present invention, wherein the other of the same frame from the restoring means is selected from other audio data portions.

According to a twelfth aspect of the present invention (corresponding to claim 12),
The video / audio data is divided into a plurality of sub-sequences composed of a plurality of the data units, and the error / loss detection unit detects the error and / or the loss, and the selection unit outputs the audio / video data. When selecting a data part, the selecting means may select the error and / or error in a subsequence 2n (n is an integer) away from the subsequence including the data unit in which the error and / or the missing is detected. A seventh to eleventh audio data part having a high correlation with the data unit in which the loss is detected is selected.
The data receiving device according to any one of the present inventions.

A thirteenth aspect of the present invention (corresponding to claim 13) is:
A computer-readable recording program and / or data for causing a computer to execute all or a part of the functions of all or a part of the data receiving apparatus according to any one of the seventh to twelfth aspects of the present invention. A program recording medium characterized by being possible.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.

(Embodiment 1) FIG. 1 is a block diagram of a data receiving device of a data transmitting / receiving system according to Embodiment 1 of the present invention. In FIG. 1, a data receiving device 10
0 is composed of a buffer 101, a buffer 102, a selector 103, and a transmission error / loss detection unit 104. The buffer 101 has a capacity of one frame, and receives data transmitted by being divided into data units from a data transmitting device. Further, the buffer 101 restores data from the data transmission device.

The buffer 102 has a capacity of one frame similarly to the buffer 101, and receives the contents of the data received by the buffer 101 from the buffer 101 in units of one frame time, that is, one frame time later. The selector 103 sequentially outputs 10 from the buffer head of the buffer 101.
5, the random access output 106 of the buffer 101, and the sequential output 107 of the buffer 102 are input, and one of them is selected and output based on the detection result of the transmission error / loss detection unit 104.

The transmission error / dropout detection unit 104
In the same manner as described above, data is received from the data transmission device, and transmission errors / losses are detected in data unit units. When a transmission error and / or loss is detected, an instruction is sent to the selector 103 so that an appropriate supplementary operation is performed. In order to detect a transmission error, a data transmission apparatus adds redundant error detection data in data unit units, and a transmission error / dropout detection unit 104 uses the redundant error detection data, as is generally performed widely. This is possible. In order to detect the loss, the data transmission apparatus may add a monotonically increasing serial number, for example, in data unit units, and the transmission error / loss detection unit 104 may detect a missing or duplicate serial number. it can.

FIG. 2 is an explanatory diagram showing the structure of DV video / audio data. First, the data for one frame is 52
In the case of the 5/60 system, it is composed of 10 subsequences as shown in FIG. 2A, and in the case of the 625/50 system, FIG.
As shown in FIG. The subsequence numbers are sequentially assigned to the respective subsequences from 0 to 9 or 0 to 11 from the top.

Next, each subsequence is shown in FIG.
As shown in (c), it is composed of 150 blocks. The block number in the subsequence is 0
149 are assigned. Among them, nine audio blocks are included in one subsequence, and the block numbers are 6, 22, 38, 54, 70, and 8 respectively.
6, 102, 118 and 134.

The audio block has a length of 80 bytes as shown in FIG.
D section, followed by a 5-byte audio auxiliary data section, 72
It consists of a byte audio data part.

When transmitting the DV video / audio data through a network, the video / audio data is divided into a plurality of data units in block units. For example, when the data unit is divided into data units each composed of 15 blocks, in the 525/60 system, 1
The frame data is composed of 100 data units. When there are no transmission errors in the network and all 100 data units arrive, the original data of one frame is reproduced in the buffer 101 of the data receiving apparatus 100.

However, if a transmission error occurs even in one bit of a certain data unit, the data unit is discarded, and information contained in 15 blocks in the data unit is lost. Therefore, complement is performed from information included in the data unit that has arrived without a transmission error.

First, regarding video data, since correlation between frames is generally high, complement is performed with information of a block including video information of the previous frame. In the DV system, video information is completed within a frame, and the position occupied by a block in the data of one frame, that is, the position from the beginning of the data of one frame is determined on the screen of the reproduced video. And has a one-to-one relationship. So, to compensate for the lost video data block, just one
What is necessary is just to replace with the block before a frame.

Next, as for the audio data, the sampling frequency is set sufficiently higher than the frequency range of the actual audio, so that the correlation with the value of the adjacent sample is high, so that the interpolation is performed with the value of the adjacent sample. . Since the data of adjacent samples of the audio data in the DV system is included in different sub-sequences of the same frame, data of one frame must be at least 10 (in the case of the 525/60 system) or 12 (in the case of the 625/50 system). If the data unit is divided into the above-mentioned data units and transmitted, if there is at most one transmission error in the frame, data of adjacent samples can always be obtained.

However, the audio data block including the audio data includes an ID part and an audio auxiliary data part as shown in FIG. Since these parts include information different from the audio data block of another sub-sequence of the same frame, the ID part of the audio data block of the previous frame, like the video data,
Complementation is performed in the audio auxiliary data section.

Based on the above, the transmission error / loss detection unit 104 in FIG. 1 instructs the selector 103 to select the input of the sequential output 105 from the buffer 101 when there is no error or loss.

On the other hand, when an error or omission is detected, the selector 103 informs the selector 103 of the omission of the block of the video data and the buffer 10 holding the data of the previous frame.
An instruction is given to select an input of the sequential output 107 from the buffer 102 in order to take out a video data block from 2 and complement it. ID of the missing audio data block
Instructs to select the input of the sequential output 107 from the buffer 102 to take out the data from the buffer 102 holding the data of the previous frame as well as the block of the video data and complement the data with respect to the audio auxiliary data part I do. With respect to the audio data part, it instructs to select an input of the random access output 106 from the buffer 101 to take out and complement a block of audio data of another subsequence of the same frame.

With the above operation, when a transmission error / loss occurs, complement is performed.

In the first embodiment, the buffer 102 receives the content of the data received by the buffer 101 from the buffer 101 with a delay of one frame time. Instead of receiving the data, the data is received from the data transmitting device in the same manner as the buffer 101, and the data is transmitted such that the same data as the sequential output 105 is output with a time delay of one frame from the sequential output 105 from the buffer 101. It may be means having a function of restoring data from the device. in short,
The buffer 102 only needs to output the same data as the sequential output 105 from the buffer 101 as the sequential output 107 one frame time later than the sequential output 105.

In the first embodiment described above, the data receiving apparatus constituting the data transmitting / receiving system of the present invention
Alternatively, in the data receiving apparatus of the present invention, the buffer 101 as an example of a restoration unit, the buffer 102 as an example of a previous frame output unit, the transmission error / drop detection unit 104 as an example of an error / drop detection unit, and an example of a selection unit. As selector 1
03 was used for each.

(Embodiment 2) By the way, the ID part of each block contains sequence number information circulating in 12 frames. By checking the continuity, in the data transmission / reception system shown in the first embodiment, it is determined whether or not transmission errors or omissions occurring in a network or the like have been complemented by a data reception device at a subsequent stage of the data transmission / reception system. Can be detected.

In order to check network quality, it is often the case that clues for detecting transmission errors / drops are used. However, there are cases where it is desirable that this detection does not work depending on the application field, such as when a device that causes a malfunction due to discontinuity of the sequence number is connected.

FIG. 3 is a block diagram of a data receiving device of the data transmitting / receiving system according to the second embodiment of the present invention. 3, components that perform the same functions as in FIG. 1 are given the same numbers as in FIG. 1, and descriptions thereof are omitted. In FIG. 3, a buffer 301 has a capacity of 11 frames and has a capacity of 1 frame.
The contents of the data received by the buffer 102 are received from the buffer 102 with a frame time unit, ie, one frame time later. That is, data of a frame that is 12 frames or less than the data held in the buffer 101 is held.

In the second embodiment, when an error or loss is detected, the transmission error / loss detection unit 104 stores an ID portion in the audio data block loss and a buffer 301 for the audio auxiliary data portion. 12 held
It instructs to select the input of the sequential output 302 of the buffer 301 in order to take out and complement the data of the ID part and the audio auxiliary data part before the frame. Other parts are the same as in the first embodiment.

By the above operation, when a transmission error / loss occurs, complement is performed. Further, continuity of the sequence number information included in the ID part of each block output from the data receiving apparatus of the present embodiment is maintained regardless of the presence or absence of the complement operation.

(Embodiment 3) FIG. 4 is an explanatory diagram showing an arrangement of audio blocks of one frame of the DV system in the 525/60 system. One horizontal row indicates one subsequence. In the 525/60 system, one frame is composed of 10 subsequences. Further, one audio sequence includes 9 audio blocks. Therefore, 90 audio blocks are included in one frame.

Each of the sub-sequences is composed of a total of 150 blocks, and the audio block includes 6, 22, 38, 54, 70, 86, 10
It is at the 2,118,134th position. The subsequence is also divided into the first five subsequences and the second five subsequences, and corresponds to independent channels of audio.

The audio data is not placed on the above audio blocks in order from the beginning, but is placed via an operation called shuffling. For example, regarding the audio data up to the 45th sample from the beginning of the frame, the leading D0 data is placed in the audio block of block number 6 of subsequence number 0, but the next D1 data is placed in the block of subsequence number 2 It is placed on the audio block of number 54. The next D2 data returns to the block number 104 of the subsequence number 4, and the next D3 data returns to the block number 1 of the subsequence number 1. As described above, the audio data is arranged on the block while changing the position in various ways.

Although the positions of all audio blocks are determined by the standard, the following conditions must be satisfied in order to complement audio data in a data receiving device. That is, audio blocks in a complementary relationship are included in one frame, audio blocks of even subsequences are audio blocks of even subsequences, and audio blocks of odd subsequences are audio blocks of odd subsequences. It is a complement to the block.

In the former condition, the contents may change between frames. Therefore, in order to perform an operation of complementing audio data across frames, it is necessary to check the matching of the contents between frames, and the processing contents are complicated. Because it becomes. Also, the latter condition is because at least avoiding complementation from adjacent subsequences makes it possible to avoid the influence of approaching transmission errors / drops.

In the third embodiment of the present invention, 525/60
In the system, when the sub-sequence number of the audio block to be complemented is i and the block number in the sub-sequence of the audio block is n, i is 0,
In the case of 1, 5, and 6, audio data of block number m represented by (Expression 2) (where mod is an operator for obtaining a remainder) included in the subsequence of subsequence number j represented by (Expression 1) Copy the audio data part of the block.

[0051]

## EQU1 ## j = i + 2

[0052]

[Mathematical formula-see original document] m = ((n + 42) mod 144) +6 Note that in (Expression 2), if n is 1, then (n + 42)
The value of mod 144 is 43, and the value of m is 49.
When n is 102, the value of (n + 42) mod 144 is 0, and the value of m is 6.

On the other hand, if i is 2, 3, 4, 7, 8,
In the case of 9, the audio data part of the audio data block of the block number m shown in (Formula 4) included in the subsequence of the subsequence number j shown in (Formula 3) is copied.

[0054]

## EQU3 ## j = i-2

[0055]

[Mathematical formula-see original document] m = ((n + 90) mod 144) +6 Thus, the complementary operation can be performed while satisfying the above condition.

The above complementary operation is performed when the selector 103 described in the first or second embodiment selects an output from the buffer 101, the buffer 102, or the buffer 301.

(Embodiment 4) FIG. 5 is an explanatory diagram showing an arrangement of audio blocks of one frame of the DV system in a 625/50 system. One horizontal row indicates one subsequence. In the 625/50 system, one frame is composed of 12 subsequences. Further, one audio sequence includes 9 audio blocks. Therefore, in one frame, there are 108 audio blocks.
Will be included.

Each sub-sequence is composed of a total of 150 blocks, and the audio block has 6, 22, 38, 54, 70, 86, 10
It is at the 2,118,134th position. The subsequence is also divided into the first six subsequences and the second six subsequences, and corresponds to independent channels of audio.

In the fourth embodiment of the present invention, 625/50
In the system, when the sub-sequence number of the audio block to be complemented is i and the block number in the sub-sequence of the audio block is n, i is 0,
1,2,3,6,7,8,9 and n is 6,22,3
In the case of 8, 54, 70 and 86, the audio data part of the audio data block of the block number m shown in (Equation 2) included in the subsequence of subsequence number j shown in (Equation 1) is copied.

[0060]

## EQU1 ## j = i + 2

[0061]

M = ((n + 42) mod 144) +6 Also, i is 4, 5, 10, 11 and n is 6, 22,
In the case of 38, 54, 70, 86, the audio data part of the audio data block of the block number m shown in (Equation 2) included in the subsequence of subsequence number j shown in (Equation 5) is copied.

[0062]

## EQU5 ## j = i-4

[0063]

M = ((n + 42) mod 144) +6 Also, i is 0, 1, 6, 7 and n is 102, 11
In the case of 8, 134, the audio data part of the audio data block of the block number m shown in (Formula 4) included in the subsequence of the subsequence number j shown in (Formula 6) is copied.

[0064]

## EQU6 ## j = i + 4

[0065]

M = ((n + 90) mod 144) +6 Further, when i is 2, 3, 4, 5, 8, 9, 10, 11 and n is 102, 118, 134, The audio data part of the audio data block of the block number m shown in (Equation 4) included in the subsequence of the shown subsequence number j is copied.

[0066]

## EQU5 ## j = i-4

[0067]

[Mathematical formula-see original document] m = ((n + 90) mod 144) +6 Thus, the complementary operation can be performed while satisfying the conditions described in the third embodiment.

The above-described complementary operation is performed when the selector 103 described in the first or second embodiment selects an output from the buffer 101, the buffer 102, or the buffer 301.

As described above, according to the present embodiment, information of a data unit lost due to a transmission error or loss can be complemented based on information already transmitted without a transmission error or loss. This makes it possible to reduce the delay time involved in transmission as compared with a method of compensating for transmission errors or loss due to retransmission, and in particular, a data transmission / reception system and data reception apparatus suitable for long-distance data transmission with a large amount of delay in a network It is possible to provide.

Note that all or some of the components of the data transmitting device and the data receiving device of the above-described embodiment are
It may be hardware or software having the same function as the corresponding function of the hardware.

A program and / or a program for causing a computer to execute all or some of the functions of all or some of the elements of the data receiving apparatus according to the above-described embodiment.
Or a program recording medium on which data is recorded,
A program recording medium readable by a computer, wherein the read program and / or data executes the function in cooperation with the computer also belongs to the present invention.

[0072]

As is apparent from the above description, the present invention provides a method for transmitting video and audio data without error without requiring retransmission of the video and audio data even when a transmission error or loss occurs in the transmission. It is possible to provide a data transmission / reception system with a small delay time by complementing data based on the obtained data, and a data receiving device that receives video and audio data and complements the data.

[Brief description of the drawings]

FIG. 1 is a block diagram of a data receiving device of a data transmitting / receiving system according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a structure of video and audio data of a DV system.

FIG. 3 is a block diagram of a data receiving device of the data transmitting / receiving system according to the second embodiment of the present invention.

FIG. 4 is an explanatory diagram showing an arrangement of audio blocks of one frame of a DV system in a 525/60 system.

FIG. 5 is an explanatory diagram showing an arrangement of audio blocks of one frame of a DV system in a 625/50 system.

FIG. 6 is a block diagram of an example of a data transmission system according to a conventional example.

[Explanation of symbols]

 101 buffer 102 buffer 103 selector 104 transmission error / dropout detector

Claims (13)

[Claims] 1. A data transmitting apparatus for transmitting video and audio data conforming to the DV system, and a data receiving apparatus for receiving the video and audio data transmitted by the data transmitting apparatus, wherein the data transmitting apparatus includes: The data of each frame constituting the audio data is divided into a plurality of data units, an identifier for each frame is attached, and redundant data for error detection is attached, and the video / audio data is transmitted. A receiving unit configured to restore the video and audio data transmitted by the data transmitting device; a previous frame output unit that outputs the video and audio data of at least one frame before the frame to be restored by the restoration unit; The video / audio data is transmitted based on the identifier and the redundant data of the video / audio data transmitted by the data transmission device. Error / drop detection means for detecting whether there is an error and / or loss in the data constituting the data, and from the restoration means and / or the previous frame output means based on the detection result performed by the error / drop detection means. A data transmission / reception system, comprising: selection means for selecting the data and generating a frame without data loss. 2. The reconstructing means has a buffer function. When the error / missing is detected by the error / missing detecting means,
2. The data transmission / reception system according to claim 1, wherein the data transmission / reception system is used for outputting an audio data portion of a portion where the error and / or lack is detected. 3. The apparatus according to claim 1, wherein said previous frame output means is means capable of restoring said video and audio data of at least one frame before the frame restored by said restoration means. The data transmission / reception system according to 1. 4. When the error and / or missing is detected by the error / missing detecting means, the selecting means selects a video block constituting the data unit in which the error and / or missing is detected. Selecting a video block corresponding to a frame immediately before the frame containing the video block from the previous frame output unit, and configuring the data unit in which the error and / or omission has been detected. Regarding the ID part and audio auxiliary data part of the block, the I frame corresponding to the previous frame from the previous frame output means is
4. A method according to claim 1, wherein a D section and the audio auxiliary data section are selected, and for the audio data section, another audio data section of the same frame from the restoration means is selected. Data transmission / reception system. 5. The data transmitting apparatus assigns the same identifier to each of a plurality of predetermined frames, and the previous frame output means has the same identifier as the identifier assigned to the frame restored by the restoration means. And outputting the video and audio data of the frame, and when the error / loss is detected by the error / loss detection means, the selection means configures the data unit in which the error and / or loss is detected A video block corresponding to a frame immediately before the frame containing the video block from the previous frame output means, and selecting the data from which the error and / or omission was detected. For the ID part and audio auxiliary data part of the audio block that constitutes the unit, Means for selecting the corresponding ID part and the audio auxiliary data part of the frame having the same identifier as the identifier of the frame containing the data unit in which the error and / or the omission has been detected, for the audio data part 4. The data transmission / reception system according to claim 1, wherein another audio data portion of the same frame from the restoration unit is selected. 6. The video / audio data transmitted by the data transmission device is divided into a plurality of sub-sequences composed of a plurality of the data units, and the error and / or the error are detected by the error / loss detection means. When a loss is detected and the selection means selects the audio data portion, the selection means calculates 2n (n is an integer) from the subsequence including the data unit in which the error and / or the loss is detected. ) In a separate subsequence,
The data transmission / reception system according to any one of claims 1 to 5, wherein an audio data portion having a high correlation with the data unit in which the error and / or the lack is detected is selected. 7. Video / audio data conforming to the DV system, wherein data of each frame constituting the video / audio data is divided into a plurality of data units, an identifier for each frame is added, and error Restoring means for restoring the video and audio data to which redundant data for detection is attached; and a preceding frame output means for outputting the video and audio data of at least one frame before the frame restored by the restoring means; An error detecting whether the data constituting the video / audio data has an error and / or an omission based on the identifier of the video / audio data and the redundant data /
Drop-out detection means; and selection means for selecting data from the restoration means and / or the previous frame output means based on a detection result performed by the error / drop-out detection means to create a frame without data loss. A data receiving device comprising: 8. The restoration means has a buffer function, and the buffer function is provided when the error and / or the loss is detected by the error / loss detection means.
8. The data receiving apparatus according to claim 7, wherein the data receiving apparatus is used for outputting an audio data part of a part where the error and / or the missing part is detected. 9. The apparatus according to claim 7, wherein said previous frame output means is means capable of restoring said video / audio data of at least one frame before the frame restored by said restoration means. A data receiving device according to claim 1. 10. When the error and / or omission is detected by the error / omission detecting means, the selecting means includes: for an image block constituting the data unit in which the error and / or omission is detected; Selecting a video block corresponding to a frame immediately before the frame containing the video block from the previous frame output unit, and configuring the data unit in which the error and / or omission has been detected. Regarding the ID part and audio auxiliary data part of the block, the I frame corresponding to the previous frame from the previous frame output means is
10. The D section and the audio auxiliary data section are selected, and as for the audio data section, another audio data section of the same frame from the restoring means is selected. Data receiver. 11. The video / audio data, wherein the same identifier is assigned to each of a plurality of predetermined frames, wherein the previous frame output means includes an identifier assigned to a frame restored by the restoration means. The video / audio data of the previous frame having the same identifier is output, and when the error / missing is detected by the error / missing detecting means, the selecting means detects the error and / or missing. For the video block that constitutes the data unit, a video block corresponding to the frame immediately before the frame containing the video block is selected from the previous frame output unit, and the error and / or missing data is selected. Of the audio block constituting the data unit in which the ID is detected and the audio auxiliary data section. Selecting the corresponding ID part and audio auxiliary data part of the frame having the same identifier as the identifier of the frame including the data unit in which the error and / or the loss has been detected from the previous frame output means. 10. The data receiving apparatus according to claim 7, wherein another audio data part of the same frame from the restoration unit is selected as the audio data part. 12. The video / audio data is divided into a plurality of sub-sequences composed of a plurality of the data units, and the error / loss is detected by the error / loss detection means, When the selection unit selects the audio data portion, the selection unit includes a sub-sequence 2n (n is an integer) away from the sub-sequence including the data unit in which the error and / or the omission is detected. The data receiving apparatus according to any one of claims 7 to 11, wherein an audio data portion having a high correlation with the data unit in which the error and / or the missing is detected is selected. 13. A computer which records a program and / or data for causing a computer to execute all or a part of the functions of all or part of the data receiving apparatus according to claim 7. A program recording medium readable by a computer.