JP2006014153A - Packet-error monitoring mpeg decoder, mpeg image transmitting system and mpeg image transmission method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a packet-error monitoring MPEG decoder capable of solving the turbulence of an image, such as a color missing, an MPEG image transmitting system and an MPEG image transmission method. <P>SOLUTION: An RTP-header monitor processor 5 receives an RTP packet from an IP-packet receiving processor 4, and the sequence numbers of an RTP header made increment for each packet are monitored. The quantity of data sent from an MPEG encoding processor 1, and the quantity of data received by an MPEG decoding processor 7 are conformed, by delivering dummy-packet data held by an RTP-packet data holder 6 to the several-minute MPEG decoding processor 7 for the missed packet, when a packet missing is detected. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an MPEG-2 over IP system that transmits MPEG-2 video compression technology in real time over an IP network, and more particularly to a packet error monitoring type MPEG decoder, an MPEG video transmission system, and an MPEG video transmission method.

  In the broadcast market and surveillance market, MPEG-2 (ISO / IEC13818) is widely recognized as a standard for high-quality video compression technology. More recently, an MPEG-2 over IP system that performs real-time transmission of MPEG-2 video compression technology over an IP network has come into widespread use. However, the IP network is not necessarily a high-quality network, and there is actually a network in which the quality is deteriorated due to the performance of network constituent devices and the load of traffic on the network.

  The main causes of IP network quality degradation are the routers, switches, and bridges that make up the network, the routing processing load, and the buffering processing load. However, these processing loads and the network could not be guaranteed. When trying to process traffic, packets that cannot be processed may be lost, which results in packet loss.

  As described above, the MPEG decoder used on the IP network needs to consider a recovery method for packet loss.

As a prior art example, there is a “lost data compensation method in packet data communication” that completely complements data related to packet loss when packet loss occurs during packet data communication using a protocol that does not have a retransmission function (for example, , See Patent Document 1). Also, the correspondence between the encryption key that is periodically updated at the time of decryption and the packet that should be decrypted with the encryption key is matched to enable establishment of encrypted communication “communication network, terminal interface device, node device, transmission Control method, storage medium, and program "(for example, see Patent Document 2).
JP 2003-163714 A JP 2003-283539 A

  As described above, in the above-described prior art, there are cases in which IP packets are lost due to the performance of various network devices such as routers and switches constituting the IP network and insufficient network bandwidth, resulting in packet loss. is there.

  In real-time video distribution using the MPEG over IP system, since real-time performance is important, TCP (Transport Control Protocol) / IP (Internet Protocol) that compensates for data by retransmission by establishing a connection with a communication partner is used. In general, UDP (User Datagram Protocol) / IP is used for high-speed data transfer, but packet loss is lost because packets are not retransmitted unlike TCP. Thus, when packet loss occurs, it is inevitable that block noise peculiar to MPEG appears in the image.

  Further, in the MPEG over IP system, when packet loss occurs, the amount of data transmitted from the MPEG encoding processing unit 1 of the MPEG encoder in FIG. 2 and the amount of data received by the MPEG decoding processing unit 7 of the MPEG decoder Therefore, the MPEG encoding / decoding rate between the MPEG data transmission / reception does not match, the color loss of the image occurs, or the data reception buffer of the MPEG decoding processing unit 7 underflows. When the packet loss occurred, such as failure, stable MPEG decoding processing could not be performed.

  The present invention has been made in view of the above circumstances. The RTP header monitoring processing unit receives an RTP packet from an IP packet reception processing unit, monitors the sequence number of the RTP header incremented for each packet, and When the missing packet is detected, the dummy packet data held in the RTP packet data holding unit is transferred to the MPEG decoding processing unit by the number of missing packets, and the data amount sent from the MPEG encoding processing unit and the MPEG decoding processing unit It is an object of the present invention to provide a packet error monitoring type MPEG decoder, an MPEG video transmission system, and an MPEG video transmission method capable of eliminating image disturbance such as color loss by matching the received data amounts.

  In order to achieve this object, the invention according to claim 1 is a packet error monitoring type MPEG decoder used in an MPEG video transmission system using RTP packets, which is transmitted from an MPEG encoder via an IP network. An IP packet reception processing unit for receiving packet data, an RTP header monitoring processing unit for monitoring the sequence number of the RTP header of the received packet data, an RTP packet data holding unit for generating and holding dummy packet data in advance When the RTP header monitoring processing unit detects a loss of packet data, the MPEG decoding processing unit acquires dummy packet data for the number of lost packet data from the RTP packet data holding unit and inserts the acquired dummy packet data; , Have packet When they occur, and wherein the MPEG2 TS data amount sent from the MPEG encoder, to match the MPEG2 TS data amount received by the MPEG decoding unit.

  According to a second aspect of the present invention, in the first aspect of the present invention, the IP packet reception processing unit processes each header of ETHER, IP, and UDP from packet data received from the MPEG encoder via the IP network, and RTP The packet data is output to the RTP header monitoring processor.

  According to a third aspect of the present invention, in the first aspect of the invention, the RTP header monitoring processing unit separates the RTP header and the MPEG2 TS data from the RTP packet data received from the IP packet reception processing unit, and the sequence of the RTP header It is characterized by determining whether or not a packet loss has occurred from the number.

  According to a fourth aspect of the invention, in the third aspect of the invention, when the RTP header monitoring processing unit determines that there is a packet loss, the dummy packet data corresponding to the skipped sequence number is transferred from the RTP packet data holding unit. After obtaining and outputting to the MPEG decoding processing unit, the received MPEG2 TS data is output to the MPEG decoding processing unit.

  The invention according to claim 5 is characterized in that, in the invention according to claim 3, the RTP header monitoring processing unit outputs the received MPEG2 TS data to the MPEG decoding processing unit when it is determined that there is no packet loss. To do.

  The invention according to claim 6 is the invention according to any one of claims 1 to 5, wherein the RTP header monitoring processing unit holds the sequence number of the RTP header every time RTP packet data is received. And

  The invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein the RTP header monitoring processor is configured such that the sequence number m received this time is a value larger by one than the previously received sequence number n. It is determined that there is no packet loss. If m is 2 or more larger than n, it is determined that there is a packet loss. If there is a packet loss, the dummy packet data held in the RTP packet data holding unit is m -(N + 1) times of output is output to the MPEG decoding processing unit, and the data corresponding to the packet loss is inserted as dummy packet data.

  The invention according to claim 8 is the invention according to any one of claims 1 to 7, wherein the RTP header monitoring processor monitors reverse reception of packets and duplicate reception of the packets.

  According to a ninth aspect of the invention, in the first aspect of the invention, the RTP packet data holding unit receives from the IP packet reception processing unit MPEG2 TS data for one RTP packet that is first received from the MPEG encoder when the MPEG decoder is activated. It receives and retains MPEG2 TS data.

  The invention according to claim 10 is the invention according to claim 1 or 9, wherein the RTP packet data holding unit uses, as dummy packet data, a packet generated by rewriting a packet identifier in the header of the MPEG2 TS data with NULL data. It is characterized by storing.

  The invention described in claim 11 is characterized in that, in the invention described in claim 1, the MPEG decoding processing unit outputs an analog video signal by performing MPEG decoding based on the MPEG2 TS data received from the RTP header monitoring processing unit. To do.

  The invention according to claim 12 is an MPEG video transmission system in which an MPEG encoder and an MPEG decoder are connected via an IP network and uses an RTP packet. The MPEG encoder inputs video from an analog video source. MPEG encoding processing unit that performs MPEG encoding of video, and RTP, UDP, IP, and ETHER headers are added to MPEG2 TS data MPEG-encoded by the MPEG encoding processing unit, and the MPEG decoder is connected via the IP network. An IP packet transmission processing unit for transmitting packet data to the MPEG decoder, the IP decoder receiving the packet data transmitted from the MPEG encoder via the IP network, and the received packet data RTP header sequence RTP header monitoring processing unit that monitors the service number, RTP packet data holding unit that generates and holds dummy packet data in advance, and RTP header monitoring processing unit detects lost packet data when the packet data loss is detected. MPEG2 TS data amount transmitted from the MPEG encoder when a packet loss occurs, having an MPEG decoding processing unit that acquires dummy packet data for the number of times from the RTP packet data holding unit and inserting the acquired dummy packet data And the amount of MPEG2 TS data received by the MPEG decoding processing unit.

  The invention according to claim 13 is an MPEG video transmission method which uses an RTP packet and is used in an MPEG video transmission system in which an MPEG encoder and an MPEG decoder are connected via an IP network, and the MPEG encoder is analog. MPEG encoding processing step that inputs video from video source and performs MPEG encoding of video, and MPEG encoder adds MPEG, TS header, RTP, UDP, IP, and ETHER headers. An IP packet transmission processing step for transmitting packet data to the MPEG decoder via the IP network, and an IP packet reception processing for the MPEG decoder to receive packet data transmitted from the MPEG encoder via the IP network. An RTP header monitoring processing step for monitoring the sequence number of the RTP header of the packet data received by the MPEG decoder, an RTP packet data holding step for the MPEG decoder to generate and hold dummy packet data in advance, and MPEG An MPEG decoding processing step of acquiring dummy packet data for the number of lost packet data and inserting the acquired dummy packet data when the decoder detects a loss of packet data in the RTP header monitoring processing step; When packet loss occurs, the amount of MPEG2 TS data transmitted from the MPEG encoder is matched with the amount of MPEG2 TS data received by the MPEG decoding processing unit.

  According to the present invention, the first effect is that the amount of MPEG-2 TS data transmitted from the MPEG-2 encoder when packet loss occurs matches the amount of MPEG-2 TS data received by the MPEG-2 decoder. Therefore, the MPEG encoding and decoding rates can be matched, and image disturbance such as color loss can be eliminated.

  The second effect is that the amount of data received by the MPEG decoder is stabilized when a packet loss occurs, so that the MPEG decoder receive buffer retention amount is constant, and the buffer underflow can be suppressed to prevent a forced reset, etc. It can be prevented.

  The third effect is that since the sequence number of the RTP header is monitored, it can be determined whether or not the RTP packet has been lost.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings.

(Characteristics of the invention)
The present invention eliminates the loss (packet loss) of IP packets due to IP network quality degradation in an MPEG (Moving Picture Experts Group) video transmission system (MPEG over IP) using RTP (Real-time Transport Protocol: RFC1889) packets. It is detected by monitoring the sequence number of the RTP header, and when packet loss occurs, it is possible to perform stable video transmission by minimizing video disturbance by inserting dummy packet data for the number of lost packets. It is a feature.

  In FIG. 1, an RTP / UDP (User Datagram Protocol) / IP packet transmitted from the IP packet transmission processing unit 2 of the MPEG encoder arrives at the IP packet reception processing unit 4 of the MPEG decoder via the IP network 3, and RTP The header monitoring processing unit 5 monitors the sequence number of the RTP header, and if a loss of the RTP packet is detected, the dummy packet data held in advance by the RTP packet holding unit 6 is passed to the MPEG decoding processing unit 7. Thus, stable MPEG decoding can be realized by compensating the data amount due to packet loss.

First, the structure of the Example of this invention is demonstrated below.
Referring to FIG. 1, an MPEG over IP system as an embodiment of the present invention is shown. In this embodiment, a case where a TS (Transport Stream) system of MPEG-2 (Moving Picture Experts Group phase 2) is used will be described.

  The MPEG encoding processing unit 1 inputs video from an analog video source such as NTSC (National Television Standards Committee) or PAL (Phase Alternation by Line) and performs MPEG encoding (digital compression) of the video.

  The IP packet transmission processing unit 2 adds RTP, UDP, IP, and ETHER headers to the MPEG-2 TS data MPEG-encoded by the MPEG encoding processing unit 1 (see FIG. 4) via the IP network 3. The packet data is transmitted to the MPEG decoder.

  The IP packet reception processing unit 4 processes the ETHER, IP, and UDP headers from the received packet data, and passes the RTP packet data to the RTP header monitoring processing unit 5.

  The RTP header monitoring processing unit 5 first separates the RTP header and MPEG-2 TS data from the RTP packet data received from the IP packet reception processing unit 4. Next, it is determined whether or not a packet loss has occurred by looking at the sequence number (Sequence number) in the RTP header (see FIG. 3). If it is determined that there is no packet loss, the received MPEG-2 TS data is transferred to the MPEG decoding processing unit 7. If it is determined that there is a packet loss, the dummy packet data corresponding to the skipped sequence number (packet loss) is acquired from the RTP packet data holding unit 6 and transferred to the MPEG decoding processing unit 7, and then the currently received MPEG -2 Transfers TS data to the MPEG decode processing unit 7.

  The RTP packet data holding unit 6 receives MPEG-2 TS data for one RTP packet first received from the MPEG encoder when the MPEG decoder is activated from the IP packet reception processing unit 4 and holds it.

  The MPEG decoding processing unit 7 performs MPEG decoding based on the MPEG-2 TS data received from the RTP header monitoring processing unit 5 and outputs an NTSC or PAL analog video signal.

Next, the operation of the embodiment of the present invention will be described below.
The operation of the MPEG decoder of FIG. 1 is shown in the flowchart of FIG. The MPEG decoder of FIG. 1 is activated and the MPEG-2 TS data of the RTP packet first received from the MPEG encoder is held in the RTP packet holding unit 6 of FIG. 1 (S1).

  The MPEG-2 TS data held here will be described. As shown in FIG. 4, the payload portion from which the RTP header of the RTP packet is removed is MPEG-2 TS data. One MPEG-2 TS data is 188 bytes including a 4-byte header, and whether the MPEG-2 TS data is a video data packet or an audio data packet or PCR (Program Clock Reference: time). There is a PID (packet identifier) indicating whether it is reference information, but since it is used as dummy packet data, a packet generated by rewriting this PID with NULL data (FFh) is stored as dummy packet data in order to prevent malfunction. To do.

  Next, every time an RTP packet is received, the sequence number of the RTP header is held in the RTP header monitoring processor 5 of FIG. 1 (S2). The RTP header is 12 bytes as shown in FIG. 3, and the sequence number is monitored here. This sequence number is 2-byte data and is a cyclic value that increments a value from 0000h to FFFFh for each RTP packet. Here, the previously received sequence number is “n”, and the currently received sequence number is “m”.

  Next, if the sequence number m is 1 larger than the received sequence number n, there is no packet loss (S3 / NO), and if m is 2 or greater than n, it is determined that there is a packet loss (S3). / YES). That is, if there is a packet loss, it means that there are “m− (n + 1)” times of packet loss. Therefore, the dummy packet data held in the RTP packet holding unit 6 of FIG. n + 1) times are passed to the MPEG decoding processing unit 7 in FIG. 1 (S4), and the data corresponding to the packet loss is inserted as dummy packet data (S5). Therefore, it is possible to eliminate the mismatch between the transmission data amount of MPEG-2 TS data from the MPEG-2 and the reception data amount at the MPEG-2 decoder.

  As described above, according to the first embodiment, the amount of MPEG-2 TS data transmitted from the MPEG-2 decoder when packet loss occurs matches the amount of MPEG-2 TS data received by the MPEG-2 decoder. Therefore, MPEG encoding and decoding rates can be matched, and image disturbance such as color loss can be eliminated.

  Further, according to the first embodiment, since the amount of data received by the MPEG decoder is stabilized when packet loss occurs, the reception buffer retention amount of the MPEG decoder becomes constant, and the occurrence of buffer underflow is suppressed, resulting in buffer failure. Forced reset etc. can be prevented.

  Further, according to the first embodiment, since the sequence number of the RTP header is monitored, it can be determined whether or not the RTP packet is lost.

  The present invention is not limited to the first embodiment described above, and is effective for all IP transmission systems using, for example, MPEG-4 and other RTP packets. Further, in the present invention, the embodiment has been described with respect to the processing when packet loss occurs. However, the processing of the RTP header monitoring processing unit 5 in FIG. It can respond by doing.

  As mentioned above, although the Example of this invention was described, it is not limited to the said Example, A various deformation | transformation is possible in the range which does not deviate from the summary.

  The present invention can be used for video / audio distribution using an MPEG over IP system, camera monitoring of roads / railways / rivers / parking lots, and remote lectures.

It is a block diagram which shows the structure of the MPEG decoder based on the Example of this invention. It is a block diagram which shows the structure of the MPEG decoder based on a prior art. It is a figure which shows the RTP header format which concerns on the Example of this invention. 3 is a diagram illustrating MPEG-encoded MPEG-2 TS data according to an embodiment of the present invention. FIG. 4 is a flowchart illustrating an operation of an MPEG decoder according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 MPEG encoding process part 2 IP packet transmission process part 3 IP network 4 IP packet reception process part 5 RTP header monitoring process part 6 RTP packet data holding part 7 MPEG decode process part

Claims (13)

A packet error monitoring type MPEG decoder used in an MPEG video transmission system using RTP packets,
An IP packet reception processing unit for receiving packet data transmitted from the MPEG encoder via the IP network;
An RTP header monitoring processor for monitoring a sequence number of an RTP header of the received packet data;
An RTP packet data holding unit that generates and holds dummy packet data in advance;
When the RTP header monitoring processing unit detects a loss of packet data, the MPEG decoding process for acquiring dummy packet data for the number of lost packet data from the RTP packet data holding unit and inserting the acquired dummy packet data And
A packet error monitoring type MPEG decoder characterized in that, when packet loss occurs, the amount of MPEG2 TS data transmitted from the MPEG encoder matches the amount of MPEG2 TS data received by the MPEG decoding processing unit.   The IP packet reception processing unit processes ETHER, IP, and UDP headers from packet data received from the MPEG encoder via the IP network, and outputs RTP packet data to the RTP header monitoring processing unit. The packet error monitoring type MPEG decoder according to claim 1.   The RTP header monitoring processing unit separates an RTP header and MPEG2 TS data from the RTP packet data received from the IP packet reception processing unit, and determines whether a packet loss has occurred from a sequence number of the RTP header. The packet error monitoring type MPEG decoder according to claim 1.   If the RTP header monitoring processing unit determines that there is a packet loss, the dummy packet data corresponding to the skipped sequence number is acquired from the RTP packet data holding unit and output to the MPEG decoding processing unit. 4. The packet error monitoring type MPEG decoder according to claim 3, wherein the received MPEG2 TS data is output to the MPEG decoding processing section.   4. The packet error monitoring type MPEG decoder according to claim 3, wherein the RTP header monitoring processing unit outputs the received MPEG2 TS data to the MPEG decoding processing unit when it is determined that there is no packet loss.   6. The packet error monitoring type MPEG decoder according to claim 1, wherein the RTP header monitoring processing unit holds a sequence number of an RTP header every time the RTP packet data is received. The RTP header monitoring processing unit determines that there is no packet loss when the sequence number m received this time is a value larger than the previously received sequence number n by one, and when m is a value greater than or equal to two by n Judge that there was a loss,
If there is packet loss, dummy packet data held in the RTP packet data holding unit is output m- (n + 1) times to the MPEG decoding processing unit, so that the packet loss data is output as dummy packet data. 7. The packet error monitoring type MPEG decoder according to claim 1, wherein the packet error monitoring type MPEG decoder is inserted as follows.   The packet error monitoring type MPEG decoder according to any one of claims 1 to 7, wherein the RTP header monitoring processing unit monitors reverse reception of packets and duplicate reception of the packets.   The RTP packet data holding unit receives MPEG2 TS data for one RTP packet first received from the MPEG encoder when the MPEG decoder is activated from the IP packet reception processing unit, and holds the MPEG2 TS data. 2. The packet error monitoring type MPEG decoder according to claim 1, wherein:   The packet error according to claim 1 or 9, wherein the RTP packet data holding unit stores a packet generated by rewriting a packet identifier in the header of the MPEG2 TS data with NULL data as dummy packet data. Supervised MPEG decoder.   2. The packet error monitoring type MPEG decoder according to claim 1, wherein the MPEG decoding processing unit outputs an analog video signal by MPEG decoding based on the MPEG2 TS data received from the RTP header monitoring processing unit. An MPEG video transmission system in which an MPEG encoder and an MPEG decoder are connected via an IP network and uses an RTP packet,
The MPEG encoder is
An MPEG encoding processor that inputs video from an analog video source and performs MPEG encoding of the video;
An IP packet transmission processing unit for adding RTP, UDP, IP, and ETHER headers to MPEG2 TS data MPEG-encoded by the MPEG encoding processing unit and transmitting packet data to the MPEG decoder via the IP network; Have
The MPEG decoder
An IP packet reception processing unit for receiving packet data transmitted from the MPEG encoder via the IP network;
An RTP header monitoring processor for monitoring a sequence number of an RTP header of the received packet data;
RTP packet data holding unit for generating and holding dummy packet data in advance;
When the RTP header monitoring processing unit detects a loss of packet data, the MPEG decoding process for acquiring dummy packet data for the number of lost packet data from the RTP packet data holding unit and inserting the acquired dummy packet data And
An MPEG video transmission system characterized in that, when a packet loss occurs, the amount of MPEG2 TS data transmitted from the MPEG encoder matches the amount of MPEG2 TS data received by the MPEG decoding processing unit. An MPEG video transmission method that uses an RTP packet and is used in an MPEG video transmission system in which an MPEG encoder and an MPEG decoder are connected via an IP network.
MPEG encoding processing step in which the MPEG encoder inputs video from an analog video source and performs MPEG encoding of the video;
An IP packet in which the MPEG encoder adds RTP, UDP, IP, and ETHER headers to MPEG2 TS data MPEG-encoded by the MPEG encoding processing unit, and transmits packet data to the MPEG decoder via the IP network. A transmission processing step;
An IP packet receiving process step in which the MPEG decoder receives packet data transmitted from the MPEG encoder via the IP network;
An RTP header monitoring processing step in which the MPEG decoder monitors a sequence number of an RTP header of the received packet data;
An RTP packet data holding step in which the MPEG decoder generates and holds dummy packet data in advance;
When the MPEG decoder detects a loss of packet data in the RTP header monitoring processing step, the MPEG decoding processing step of acquiring dummy packet data for the number of lost packet data and inserting the acquired dummy packet data; Have
An MPEG video transmission method characterized by matching the amount of MPEG2 TS data transmitted from the MPEG encoder with the amount of MPEG2 TS data received by an MPEG decoding processor when packet loss occurs.

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