JP2007019889A - Data transfer system and its method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a packet data communication system for reducing missing due to the transmission of a media data frame constituting a packet and its method in a packet communication system. <P>SOLUTION: A packet transmission processor 10 leaves a portion of the latter half of a transmitted packeted media data frame and arranges the portion at the front of the next media data frame to be transmitted to thereby transmit a packet with the portion of the latter half of the media data frame overlapped, and a media data frame reproducing device 20 complements missing with the received overlapped media data frame with a time stamp of a received packet as reference if there is the missing in the portion of the last half of the media data frame and discards the media data frame if there is no missing. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a real-time data transmission method in a packet communication system, and more particularly to a packet data communication method and method for reducing deficiencies due to transmission of media data frames constituting a packet.

  When transmitting highly real-time media data such as voice and moving images over a packet network, the transmission side captures the media data in units of frames, and packetizes the media data frames for transmission. On the receiving side, media communication with high real-time property is realized by reproducing media data simultaneously with packet reception or holding in a short time buffer. In such packet communication, data transmitted in packets has a high degree of dependence on time rather than data reliability, so that some data loss is allowed. The packet structure in transmission is not limited to one media data frame as one packet, but is divided into multiple packets when the media data size is large, and multiple frames are simultaneously transmitted as one packet when the media data size is small. Is done.

  FIG. 7 is a schematic diagram showing a frame structure of a packet and transmission / reception thereof. In FIG. 7a, the amount of media input data D0 to D4 is different for each media data frame. Therefore, after compression processing, frame subdivision and multiple frame embedding are performed, packetized and sent to the network. Sent. When the frame and the packet are in a one-to-one relationship, the header and the encoded data C0 are transmitted as one packet. When the encoded data is large, it is divided into 0 and 1 for example, and transmitted as 2 packets. When the encoded data is small, it is continuously embedded after the header, and for example, C0 and C1 are transmitted as one packet. In FIG. 7b, when any transmitted packet is received without loss, it is rearranged by removing the data delay by buffer processing, decompressed for each frame, and restored to original media information without loss, Played.

  FIG. 8 is a packet arrangement pattern showing the state of a packet when a defect occurs in the transmitted packet. In FIG. 8a, the second of the transmitted three packets is missing. Accordingly, media data corresponding to the fifth to ninth frames is lost, but in the buffer on the receiving side, the continuity of these data is temporarily stored. In FIG. 8b, the received packet has a delay, and the real-time property of the arrangement pattern is not compensated. On the other hand, the packets in the reception buffer are rearranged based on the time stamp of the header, and the real-time property necessary for reproducing the media data is maintained.

As described above, although the real-time property necessary for the reproduction of the media data is maintained, the missing media data remains as it is, so that the media information reproduced depending on the missing amount is incomplete. Become. Patent Document 1 discloses a method for preventing deterioration of voice quality by shifting the time within a range in which real-time performance can be maintained and transmitting two or more identical voice packets on the voice packet transmission side regardless of the communication quality status of the communication line. Are listed.
JP 2001-268121 A

  The present invention has been made to solve such a problem, and provides a packet data communication method and method for reducing defects caused by transmission of media data frames constituting a packet in a packet communication system. Objective.

The packet data transmission method of the present invention is a packet data transmission method in a packet communication system including a packet transmission processing device and a media data frame reproduction device for transmitting and receiving packetized media data frames,
The packet transmission processing device leaves a part of the latter half of the transmitted packetized media data frame, and places the latter part of the media data frame by placing it at the beginning of the media data frame to be transmitted next. Send duplicate packets,
The media data frame reproducing device supplements the media data frame received in duplicate if there is a defect in the latter half of the media data frame based on the time stamp of the received packet. For example, the media data frame is discarded.

The packet transmission processing device of the packet data transmission method of the present invention includes an analog signal receiving circuit that receives an analog signal from a media information input device, a sampling circuit that samples the analog signal into media data, and the sampled signal A codec circuit that compresses the media data, and a packet transmission processing circuit that configures and transmits the compressed media data in packets in overlapping frames.
The media frame reproduction device includes a packet reception circuit that receives the transmitted packet, a media data frame reproduction circuit that performs a complementary process of a missing part of a media data frame of the received packet and a discarding process of an overlapping part. And a buffer circuit that holds the media data frame that has been subjected to the complementing process and the discarding process, and a decompression processing circuit that reads the held media data frame and decompresses it to the analog signal.

The packet transmission processing circuit of the packet data transmission system of the present invention further has a line monitoring means for monitoring the state of the communication line, adaptively variably processes the number of frames to be overlapped according to the line state,
The media frame reproduction circuit determines whether the media data frame is duplicated based on a time stamp in the header of the packet, and discards the duplicate media data frame.

A packet data transmission method of the present invention is a packet data transmission method in a packet communication system including a packet transmission processing device and a media data frame reproduction device for transmitting and receiving packetized media data frames,
Monitoring the state of the communication line of the packet communication system;
Based on the result of the monitoring, transmitting a packet in which the duplication of the media data frame is adaptively varied;
Receiving the transmitted packet, and discarding the media data frame if there is an overlap based on the time stamp in the header of the packet, and complementing the media data frame if there is not.

  According to the present invention, it is possible to adaptively vary the number of duplicate frames according to the line quality without burdening the header in the designation of duplicate frames. Further, since the missing size of media data can be reduced by avoiding duplication of received packets and supplementing the missing packets, the reproducibility of media data is improved.

  An embodiment of a packet data transmission system according to the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a packet communication system using a packet data transmission system according to the present invention. The packet communication system 100 includes a packet transmission processing device 10, a media data frame reproduction device 20, a packet communication network 30, a media information input device 40, and a media information output device 50.

  The packet transmission processing device 10 includes an analog signal receiving circuit 11, a sampling circuit 12, a codec circuit 13, and a packet transmission processing circuit 14, and the packet transmission processing circuit 14 further includes line monitoring means 15. The media data frame reproducing apparatus 20 includes a packet receiving circuit 21, a media data frame reproducing circuit 22, a buffer circuit 23, an expansion processing circuit 24, and an analog signal reproducing circuit 25.

  In FIG. 1, an analog signal receiving circuit 11 of a packet transmission processing device 10 receives an analog data signal of media information from a media information input device 40. The sampling circuit 12 samples the analog data signal and encodes media data. The encoded media data is compressed by the codec 13. In the packet transmission processing circuit 14, the compressed media data is collected in units of frames in the order of input data, constitutes a data portion that follows the header portion of the packet, and is transmitted to the packet communication network 30. At this time, the second half complement of the media data frame of the packet transmitted first is left and placed at the head of the media data frame to be transmitted next. In this way, the complementary media data frame in the latter half of the first packet is transmitted in duplicate. Thereafter, this operation is repeated.

  FIG. 2 is a structural diagram of a packet showing the overlap of media data frames. The packet has time stamp information in the header portion, and media data frames are arranged in the data portion. Since there is no duplication in the first packet, media data frames 1 to 4 are arranged in the data portion, and information of time stamp 1 is contained in the header portion. Since the next packet overlaps the complementary media data frame in the latter half of the previous packet, media data frames 4 to 7 are arranged in the data portion, and information on the time stamp 4 is entered in the header portion. Yes. The packet transmission processing circuit 14 monitors the line state by the line monitoring unit 15 that monitors the state of the communication line of the packet communication network 30, and adaptively variably processes the number of frames to be overlapped according to the line state.

  In FIG. 1 again, the packet receiving circuit 21 of the media data frame reproducing device 20 receives the packet transmitted from the packet transmission processing device 10 via the packet communication network 30. The transmitted packet is received with each communication delay, and depending on the communication state, the packet is lost in the middle and data loss occurs. Based on the time stamp of the packet received in such a situation, the media data frame reproduction circuit 22 reproduces the real time and complements the missing data, and temporarily stores the media data in the buffer circuit 23. The data temporarily stored in the buffer circuit 23 is read out to the decompression processing circuit 24 and restored based on the compressed data, is reproduced as an analog signal by the analog signal reproduction circuit 25, and is output to the media information output device 50 as media information. The

  FIG. 3 is a packet structure diagram showing a time stamp stored in the header part of the packet. An IP header, a UDP header, and a header for real-time communication are sequentially stored in the header portion of the packet, and media data is framed in the data input order in the data portion and stored in units of frames. The header for real-time communication consists of a sequence number, a time stamp, and an unspecified box. In this unspecified box, packet destination and header type information is stored. The sequence number is used for packet identification, and the time stamp indicates the start position of continuous media data playback. The media data frame reproduction circuit 22 reproduces the real time and complements the missing data based on the time stamp of the packet received by the packet reception circuit 21 and temporarily stores the media data in the buffer circuit 23. Next, the reproduction of the media data will be described in detail.

  FIG. 4 is a packet data array pattern diagram showing an array of data parts of transmitted, received and reproduced packets. In state 1, the start time stamp value indicating the start of the data portion of the six packets to be transmitted and the data size of the data portion are shown. The hatched portion at the rear of the data portion indicates a frame portion that is duplicated in the next packet to be transmitted, and the oblique line at the front portion of the data portion indicates a portion that is overlapped with the frame of the previously transmitted packet. Each packet is transmitted from the packet transmission processing device 10 at the same timing.

  The packet being transmitted is accompanied by fluctuations and delays, and the packet is lost or data is lost depending on the state of the line, and is not received as a normal packet by the media data frame reproduction device 20. The arrangement of packets in state 2 shows the case where the third and fifth packets are received missing. The media data frame reproduction circuit 22 complements the missing data based on the time stamps of these received packets. As shown in FIG. 2, when the data part is composed of 4 frames, if the time stamp of the second packet is 4, the media data frame 4 is duplicated and discarded, and the previous one is discarded. If the time stamp does not exist, it is regarded as a missing frame and the frame is transmitted in duplicate. The data part of state 3 discards the redundantly transmitted frame if the frame is duplicated, and if the frame is missing, it is a redundantly transmitted frame, and the media data frame It has been rearranged to reproduce the real-time nature of. The rearranged media data is temporarily stored in the buffer circuit 23 and converted into analog signal media information.

  FIG. 5 is a packet data arrangement pattern diagram showing an arrangement of data portions of received and reproduced packets when the number of overlapping frames is variable. The line monitoring means 15 of the packet transmission processing circuit 14 monitors the state of the communication line of the packet communication network 30 and adaptively variably processes the number of frames to be overlapped according to the line state. State 1 in FIG. 5 shows an arrangement of data portions in which a transmission state is determined on the transmission side, and a packet transmitted by changing the number of overlapping frames for each packet is received without loss. Accordingly, in state 2, the media data is temporarily stored in the buffer circuit 23 in a state where all the duplicate frames are discarded, and converted into analog signal media information.

  As for communication line errors, burst errors that occur continuously with respect to time are rare, and random errors that occur discontinuously are almost all. For this reason, in a communication line state in which random errors frequently occur, the amount of lost media data can be reduced by increasing the number of duplicate frames. The circuit configuration of the block diagram shown in FIG. 1 may be any circuit or device as long as it is a means for realizing the function, and it is also possible to realize the complement of the function by software. . Furthermore, the function realizing means may be realized by a plurality of circuits, and a plurality of functions may be realized by a single circuit.

  FIG. 6 is a flowchart showing media data frame processing according to the packet data transmission method of the present invention. The line monitoring means 15 included in the packet transmission processing circuit 14 of the packet transmission processing apparatus 10 monitors the communication line state of the packet communication network 30 (step 10). The packet transmission processing circuit 14 determines the number of duplicate frames based on the monitoring result of the line monitoring means 15 (step 20). A frame corresponding to the number of overlapping frames is set at the front of the data portion of the packet to create a transmission packet (step 30). The created packet is transmitted to the packet communication network 30 (step 40). The media data frame reproduction device 20 receives the transmitted packet from the packet communication network 30 (step 50). Whether the received media data frame is duplicated is checked based on the time stamp (step 60). If there is a duplicate in the received media data frame, the duplicate frame is discarded, the duplicate is eliminated, temporarily stored in the buffer, and the process is terminated (step 70, step 90, step 100). If there is no duplication, it is determined that a packet loss has occurred, complemented with the media data frame transmitted as duplication, temporarily stored in the buffer, and the process ends (steps 80 to 100).

  As described above, according to the present invention, it is possible to adaptively vary the number of duplicate frames according to the line quality without burdening the header in the designation of duplicate frames. Further, since the missing size of media data can be reduced by avoiding duplication of received packets and supplementing the missing packets, the reproducibility of media data is improved.

1 is a configuration diagram of a packet communication system of a packet data transmission system according to the present invention. FIG. 3 is a structural diagram of a packet showing an overlap of media data frames according to the present invention. The packet structure figure which shows the time stamp stored in the header part of a packet. The packet data arrangement pattern figure of a transmission, reception, and reproduction | regeneration packet. The packet data arrangement pattern figure in the duplication frame number variable of this invention. 5 is a flowchart illustrating processing of media data frames according to the present invention. The schematic diagram which shows the frame structure of the conventional packet, and its transmission / reception. The packet arrangement pattern figure which shows the state of the conventional reception packet.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Packet communication processing device 11 Analog signal receiving circuit 12 Sampling circuit 13 Codec circuit 14 Packet transmission processing circuit 15 Circuit monitoring means 20 Media data frame reproducing device 21 Packet receiving circuit 22 Media data frame reproducing circuit 23 Buffer circuit 24 Decompression processing circuit 25 Analog Signal regeneration circuit 30 Packet communication network 40 Media information input device 50 Media information output device 100 Packet communication system

Claims (4)

A packet data transmission method in a packet communication system including a packet transmission processing device and a media data frame reproduction device for transmitting and receiving packetized media data frames,
The packet transmission processing device leaves a part of the latter half of the transmitted packetized media data frame, and places the latter part of the media data frame by placing it at the beginning of the media data frame to be transmitted next. Send duplicate packets,
The media data frame reproducing device supplements the media data frame received in duplicate if there is a defect in the latter half of the media data frame based on the time stamp of the received packet. A packet data transmission method, wherein the media data frame is discarded. The packet transmission processing device includes an analog signal receiving circuit that receives an analog signal from a media information input device, a sampling circuit that samples the analog signal into media data, and a codec circuit that compresses the sampled media data And a packet transmission processing circuit configured to transmit the compressed media data as a packet in a partially overlapping frame unit,
The media frame reproduction device includes a packet reception circuit that receives the transmitted packet, a media data frame reproduction circuit that performs a complementary process of a missing part of a media data frame of the received packet and a discarding process of an overlapping part. And a buffer circuit that holds the media data frame that has been subjected to the complementing process and the discarding process, and a decompression processing circuit that reads the held media data frame and decompresses it to the analog signal. Item 2. A packet data transmission method according to Item 1. The packet transmission processing circuit further includes line monitoring means for monitoring the state of the communication line, adaptively variably processes the number of frames to be overlapped according to the line state,
3. The media frame reproduction circuit according to claim 1, wherein the media frame reproduction circuit determines that the media data frame is duplicated based on a time stamp of a header of the packet, and discards the duplicate media data frame. Packet data transmission method described in 1. A packet data transmission method in a packet communication system including a packet transmission processing device and a media data frame reproduction device for transmitting and receiving packetized media data frames,
Monitoring the state of the communication line of the packet communication system;
Based on the result of the monitoring, transmitting a packet in which the duplication of the media data frame is adaptively varied;
Receiving the transmitted packet, and discarding the media data frame if there is an overlap based on the time stamp in the header of the packet, and complementing the media data frame if there is not. Packet data transmission method.

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