JPH05260090A - Video transfer system - Google Patents

Abstract

PURPOSE:To suppress the deterioration of the video information caused by the disuse of a video packet and also to secure the real time properties of communication by detecting the congestion of a transmission line out of the packet received from the transmission line and then controlling the bit rate of a video coder in response to the detected congestion. CONSTITUTION:A connector 120 supplies the signal existing on a transmission line 123 to a transmission line interface control part 110. The part 110 fetches a packet where the destination address is coincident with its own address. Then the part 110 supplies the packet which reparts the congestion of the line 123 received from the side of the line 123 to a congestion informing packet processing part 420 among those fetched packets. Receiving the relevant packet, the part 420 supplied a signal to a video bit rate control part 500. The part 500 controls the video bit rate of a video coder 600 based on the signal received from the part 420.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video transfer system using packet switching.

[0002]

2. Description of the Related Art Conventionally, when video is transferred by a circuit switching system, the bit rate of the video encoder is controlled to be constant because the transmission speed of the line that can be used by the terminal is constant. It was

Further, in video transfer using packet switching, when one transmission line is used by a plurality of different terminals, the transmission width (bit rate) available at the terminals is not constant, and the transmission line The margin of the transmission width can be used. Therefore, variable bit rate coding that improves the video quality by changing the bit rate of the video encoder according to the state (change etc.) of the video to be transmitted without controlling the bit rate of the video encoder constant Being developed.

[0004]

In the case where the bit rate of the video encoder is fixed or the variable bit rate encoding is performed, in either case, when the packet switching system is used, the transmission width of the transmission line is As long as there is room, no problems will occur. However, if congestion occurs on the transmission path due to an increase in the transmission width from other communication points (data terminal or video / audio terminal, etc.), the transmission rate on the transmission path will be higher than the bit rate of the video encoder. The bit rate that can be transmitted is reduced. Therefore, if the video data is stored until the video data can be transmitted, there is a problem that the real time property of communication is likely to be lost. In addition, if video data that cannot be transmitted in real time is discarded in order to maintain real-time communication, there is a problem in that the video is significantly deteriorated due to the video data being discarded. Further, there is a problem that video packets being transferred are more likely to be discarded on the transmission path while the congestion continues.

The present invention has been made in view of the above,
The purpose is to prevent deterioration of video information due to video packet discard in video transfer when congestion occurs on the transmission line in video transfer using the packet switching method, and to maintain real-time communication. To provide a video transfer method.

[0006]

In order to achieve the above object, a video transfer system of the present invention is provided with a congestion annunciation packet receiving means for receiving a packet for announcing the congestion of a transmission path from the transmission path, and the congestion annunciation packet reception means. The gist of the present invention is to have bit rate control means for detecting congestion of the transmission line from the packet received by the means, and controlling the bit rate of the video encoder according to the congestion.

Further, in the video transfer system of the present invention, the transmission line state detecting means for detecting the state of the transmission line for identifying congestion in the transmission line, and the transmission line state detected by the transmission line state detecting means are used. The gist of the present invention is to have bit rate control means for controlling the bit rate of the video encoder in accordance therewith.

Further, in the video transfer system of the present invention, a transfer means for generating a transfer time measurement packet, setting a transmission time in the transfer time measurement packet and transmitting the packet, and a transfer time measurement packet transmitted from the transmitting means. And a reply means for receiving and replying to the transfer time measurement packet returned from the reply means, extracting the transmission time set in the packet, and calculating the transfer time from the transmission time and the current time. A transfer time measuring means for calculating a round trip transfer time of the measurement packet; and a bit rate control means for controlling a bit rate of the video encoder based on the round trip transfer time of the packet calculated by the transfer time measuring means. Is the gist.

Furthermore, in the video transfer system of the present invention, the packet discard detecting means for detecting the discard of the packet in the transmission path, and the bit rate of the video encoder based on the packet discard detected by the packet discard detecting means. And a bit rate control means for controlling the.

[0010]

In the video transfer system of the present invention, congestion of the transmission line is detected from the packet received from the transmission line, and the bit rate of the video encoder is controlled according to the congestion.

Further, in the video transfer system of the present invention, the state of the transmission line is detected in order to identify congestion in the transmission line,
The bit rate of the video encoder is controlled according to the detected state of the transmission path.

Further, in the video transfer system of the present invention, the transmission time is set in the transfer time measurement packet and transmitted, the transfer time measurement packet returned is received, and the transmission time set in the packet is transmitted. The round-trip transfer time of the packet is calculated from the current time, and the bit rate of the video encoder is controlled based on this round-trip transfer time.

Furthermore, in the video transfer system of the present invention, the discard of a packet on the transmission line is detected, and the bit rate of the video encoder is controlled based on the discard of the packet.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the structure of a video transfer system according to the first embodiment of the present invention. In FIG. 1, 101 is a terminal, 110 is a transmission line interface control unit, 120 is a connector, 123 is a transmission line, 420 is a congestion notification packet processing unit, 500 is a video bit rate control unit,
Reference numeral 600 is a video encoder, and 700 is a video packet assembling unit.

The operation will be described below with reference to FIG.

The connector 120 supplies the signal on the transmission line 123 to the transmission line interface control unit 110. The transmission path interface control unit 110 carries out a process of fetching a packet whose destination address matches its own address. The transmission path interface control unit 110 supplies, to the congestion notification packet processing unit 420, among the captured packets, the packet notifying the congestion of the transmission path transmitted from the transmission path side.

When the congestion notification packet processing unit 420 receives the congestion notification packet, the video bit rate control unit 50
Supply signal to 0. Congestion notification packet reception processing unit 42
The video bit rate control unit 500 receives the signal from 0,
The video bit rate of the video encoder 600 is controlled.

The method of controlling the image bit rate includes changing the quantization width, changing the number of dropped frames, changing the image resolution, changing the dominant block determination method, etc. Method is also acceptable and is not specified.

The operation of the video bit rate control unit 500 is as follows. The video bit rate control unit 500 sets the video bit rate of the video encoder 600 to 128 kbps, 64 kbps, 1 in 3 steps, for example, by the above method.
It can be controlled to 0 kbps.

First, the video encoder 600 has a capacity of 128 kb.
Suppose it is operating at ps. At that time, when the video bit rate control unit 500 receives the signal from the congestion notification packet processing unit 420, the video bit rate control unit 500 sets the video bit rate of the video encoder 600 to 64 kbps and further controls the video bit rate. When the unit 500 receives the signal from the congestion notification packet processing unit 420, the video bit rate control unit 500 sets the video bit rate of the video encoder 600 to 10 kbps. The video bit rate control unit 500 may decrease the video bit rate by one step each time one signal is supplied from the congestion notification packet processing unit 420, or m or more (m is a natural number) within a certain set time. When the signal from the congestion notification packet processing unit 420 is supplied, the video bit rate may be reduced by one step.

Further, the video bit rate control unit 500 increases the video bit rate by one step when the signal from the congestion notification packet processing unit 420 is not supplied within a certain set time. However, the video bit rate is 128 kbps
In this case, the video bit rate control unit 500 does not control the video bit rate any more. When the video bit rate is 10 kbps, the video bit rate control unit 500 does not control the video bit rate to be smaller than that.

In the above description, the settable video bit rate is set to three stages, but m stages (m is a natural number of 2 or more).
But it doesn't matter. Also, the unit for increasing or decreasing the video bit rate may be i stages (i is a natural number).

It should be noted that, here, when changing the bit rate of the video encoder, the method of notifying the video decoder of changing the bit rate is not specified. However, C
CITTH. When the H.261 standard video coding is performed, it is not necessary to notify the video decoder of the change in the video bit rate.

As a concrete example of the packet for notifying congestion, the TCP / IP protocol uses ICMP (Sou
rce Qunech message), ICMP (Time exceeded messa
ge).

FIG. 2 is a block diagram showing the configuration of a video transfer system according to the second embodiment of the present invention. In the embodiment shown in the figure, the transmission line interface control unit has a CSMA / C
When the D method is used, a signal collision is detected as a means for identifying the state of the transmission line, and when the degree of collision is large, it is considered that congestion has occurred and the video bit rate is controlled. Is. In FIG. 2, 101 is a transmission side terminal, 110 is a transmission line interface control unit, 12
0 is a connector, 123 is a transmission line, 115 is a collision detection unit, 5
00 is a video bit rate control unit, 600 is a video encoder, and 700 is a video packet assembling unit.

The operation will be described below with reference to FIG.

The transmission line interface control unit 110 uses the CS
It is assumed that the MA / CD method is used. The connector 120 detects the collision of the signal on the transmission path on the transmission path 123 and supplies the signal to the transmission path interface control unit 110. In the CSMA / CD method, the signal collision is detected by measuring the voltage level of the carrier wave on the transmission line. When the collision occurs, the transmission line interface control unit 110 causes the collision by the signal from the connector 120. Generate a detection signal. The transmission path interface control unit 110 supplies the collision detection signal to the collision detection unit 115. Collision detector 11
In No. 5, when the collision detection signal is supplied, the signal is supplied to the video bit rate control unit 500.

The collision detection unit 115 may supply one signal to the video bit rate control unit 600 each time the collision detection signal is received, or n or more (n is a value set as a natural number) within a certain time. When one of the collision detection signals is received, one of the signals may be supplied to the video bit rate control unit 500. The video bit rate control unit 500 controls the video bit rate of the video encoder 600 based on the signal from the collision detection unit 115. Video bit rate control methods include changing the quantization width, changing the number of dropped frames, changing the video resolution, and changing the dominant block determination method. Either method may be used. , Not specified.

The operation of the video bit rate control unit 500 in the second embodiment of FIG. 2 is the same as that shown in FIG. 1, but from the congestion notification packet processing unit 420 shown in FIG. The collision detection unit 115 instead of the signal
The only difference is that the signal from is supplied to the video bit rate control unit 500.

FIG. 3 is a block diagram showing the structure of a video transfer system according to the third embodiment of the present invention. In the embodiment shown in the figure, the transmission line interface control unit has a CSMA / C
When the D method is used, the usage rate of the transmission path is calculated to identify the status of the transmission path, and if the usage rate is high, it is considered that congestion has occurred and the video bit rate is controlled. It is a thing. In FIG. 3, 101 is a terminal, 110 is a transmission line interface control unit, 120 is a connector, 123 is a transmission line, 117 is a network usage rate calculation unit, 500 is a video bit rate control unit, 600 is a video encoder, and 700. Is a video packet assembly unit.

The operation will be described below with reference to FIG.

The video packet assembling unit 700 supplies the video packet to the transmission path interface control unit 110. The transmission line interface control unit 110 sends the video packet to the transmission line 123 through the connector 120. The operation of the transmission line interface control unit 110 is performed as follows in the CSMA / CD system. The transmission line interface control unit 110 uses the signal from the connector 120 to transmit the transmission line 123.
Always generate a carrier sense signal indicating whether or not a signal is present. This carrier sense signal is supplied to the network usage rate calculation unit 117. The network usage rate calculation unit 117 constantly monitors the carrier sense signal.

The network usage rate calculation unit 117 calculates the time when the carrier sense signal is supplied, for example, in units of 1 second (this may be x seconds: x is a positive number), and calculates the network usage rate. .. For example, if the signal is supplied for 1 second for 0.3 seconds, the network usage rate is 0.3 (30%). Network usage rate calculation unit 1
In No. 17, a signal is sent to the video bit rate control unit 500 when the set network usage rate is in the state described below.

[1] When the network usage rate exceeds a certain set value, [2] n times (n
Is a natural number) or more. When the network usage rate is higher than a certain set value, [3] When the average value of the network usage rate at a certain time is higher than a certain set value.

The operations of the video bit rate control unit 500, the video encoder 600 and the video packet assembling unit 700 in the third embodiment shown in FIG. 3 are the same as those in the second embodiment shown in FIG. is there.

FIG. 4 is a block diagram showing the structure of a video transfer system according to the fourth embodiment of the present invention. In the embodiment shown in the figure, the transmission line interface control unit has a CSMA / C
In the case of using the D method, when sending a packet from the terminal to the transmission path, the packet cannot be sent due to the number of retransmissions being exceeded, that is, by detecting an excessive collision error indicating packet discard, The state of the transmission line is identified and the video bit rate is controlled. In FIG. 4, 101 is a terminal,
110 is a transmission line interface control unit, 120 is a connector, 123 is a transmission line, 118 is a retransmission number excess detection unit, 50
0 is a video bit rate control unit, 600 is a video encoder,
A video packet assembling unit 700 is provided.

The operation will be described below with reference to FIG.

The video packet assembling unit 700 supplies the video packet to the transmission path interface control unit 110. The transmission line interface control unit 110 sends the video packet to the transmission line 123 through the connector 120. The operation of the transmission line interface control unit 110 is performed as follows in the CSMA / CD system. That is, if no signal is detected on the transmission path 123, the transmission path interface control unit 110 sends the video packet to the transmission path 123 via the connector 120, and a collision occurs while sending the video packet to the transmission path 123. When it detects "," it waits and then tries to retransmit. This retransmission is repeated until the transmission is completed or the number of retransmission attempts reaches a certain set value.

When the number of trials reaches the set value but cannot be transmitted, the packet is not transmitted and the number of retransmissions is exceeded. When this excess number of retransmissions occurs, the transmission line interface control unit 110 determines that the excess number of retransmissions is detected as an excess collision error.
The signal is supplied to 18. The retransmission number excess detection unit 118 supplies the video bit rate control unit 500 every time one excess collision error signal is supplied, or when n or more (n is a natural number) excess collision errors are supplied within a certain time. Supply a signal.

The operations of the video bit rate control unit 500, the video encoder 600 and the video packet assembling unit 700 in the fourth embodiment shown in FIG. 4 are the same as those in the second embodiment shown in FIG. is there.

In the fourth embodiment, an excessive collision error of a video packet is detected. However, when the terminal 101 can send a packet other than a video packet, a packet other than a video packet is detected. The detection of excessive collision error of may be calculated.

FIG. 5 is a block diagram showing the structure of a video transfer system according to the fifth embodiment of the present invention. The fifth embodiment is to detect the congestion of the transmission line, calculate the packet transfer time, and control the video bit rate according to the packet transfer time. In FIG. 5, 101 and 102 are terminals, 105 is a time measurement packet generation unit, 110 and 130 are transmission line interface control units, 123 is a transmission line, 210 is a time measurement packet return unit, 400 is a transfer time calculation unit, and 500 is A video bit rate control unit, 600 is a video encoder, and 700 is a video packet assembling unit.

The operation will be described below with reference to FIG.

Time measurement packet generator 11 of terminal 101
At 0, a time measurement packet is generated, the time when the packet is generated is incorporated into the time measurement packet, and the time measurement packet is supplied to the transmission path interface control unit 110.
The number of the time measurement packets generated per hour may be arbitrary. Next, the time measurement packet is supplied to the connector 120 with the destination address of the transmission path interface control section 130 incorporated in the transmission path interface section 110. The connector 120 supplies the time measurement packet to the transmission path 123.

The connector 121 supplies the signal on the transmission path 123 to the transmission path interface controller 130. Since the transmission path interface control unit 130 performs processing for fetching a packet whose destination address matches its own address,
Capture the time measurement packet. The transmission path interface control unit 130 supplies the time measurement packet to the time measurement packet return unit 210. Time measurement packet return unit 21
At 0, the receiving terminal 10 receives the supplied time measurement packet.
1, the transmission line interface control unit 130
Supply to. The time measurement packet supplied to the transmission path interface control unit 130 incorporates the destination address of the transmission path interface control unit 110, is supplied to the connector 121, and is further supplied to the communication path 123.

The connector 120 supplies the signal on the transmission path 123 to the transmission path interface controller 110. Since the transmission path interface control unit 110 performs processing for fetching a packet whose destination address matches its own address,
Capture the time measurement packet. The time measurement packet is transferred from the transmission line interface control unit 10 to the transfer time calculation unit 4
00 is supplied. The transfer time calculation unit 400 reads the time embedded in the time measurement packet and calculates the difference from the current time.

The calculated time is the round-trip transfer time of the time measurement packet. The transfer time calculation unit 400 has a threshold value of the round-trip transfer time, and supplies a signal to the video bit rate control unit 500 when the packet round-trip transfer time calculated from the time measurement packet is larger than the threshold. The video bit rate control unit 500 controls the video bit rate of the video encoder 600 based on the signal from the transfer time calculation unit 400. There are various methods of controlling the video bit rate, such as changing the quantization width, changing the number of dropped frames, changing the video resolution, and changing the dominant block determination method. Well, not specified.

The operation of the video bit rate control unit 500 in the fifth embodiment of FIG. 5 is the same as that shown in FIG. 1, but from the congestion notification packet processing unit 420 in the one shown in FIG. Transfer time calculation unit 4 instead of a signal
The only difference is that the signal from 00 is supplied to the video bit rate control unit 500.

In the fifth embodiment, the terminal for transmitting the image and the terminal for receiving the image are separately described, but one terminal may have both functions at the same time.

FIG. 6 is a block diagram showing the structure of a video transfer system according to the sixth embodiment of the present invention. In the embodiment shown in the figure, the video receiving terminal detects the discard of the video packet generated between the video transmitting terminal and the video receiving terminal from the sequence number, thereby detecting the congestion of the transmission path, and the video receiving The video bit rate is controlled in the video transmitting terminal by transmitting the video from the terminal to the video transmitting terminal.

In FIG. 6, 35 is an output terminal, 101,
102 is a terminal, 100 is a transmission packet header processing unit, 1
10, 130 are transmission line interface control units, 120,
121 is a connector, 123 is a transmission line, 200 is a received packet header processing unit, 300 is a discard notification packet generation unit, 4
Reference numeral 60 is a discard notification packet reception processing unit, 500 is a video bit rate control unit, 600 is a video encoder, and 700 is a video packet assembling unit.

The operation will be described below with reference to FIG.

In the packet header of the video packet supplied from the video packet assembling unit 700, the transmission packet header processing unit 100 incorporates a sequence number in the order of input and supplies it to the transmission line interface unit 110. Further, in the video packet, the destination address of the transmission path interface control unit 130 is incorporated in the transmission path interface unit 110,
It is supplied to the connector 120. The connector 120 supplies the video packet to the transmission path 123.

The connector 121 supplies the signal on the transmission path 123 to the transmission path interface controller 130. Since the transmission path interface control unit 130 performs processing for fetching a packet whose destination address matches its own address,
Capture the video packet. The transmission path interface control unit 130 supplies the captured video packet to the reception packet header processing unit 200. The reception packet header processing unit 200 reads the sequence number of the packet header of the input video packet, and detects the packet discard occurring between the transmission line interface control unit 110 and the transmission line interface control unit 130 from this sequence number. , And outputs the video packet to the output terminal 35.

Here, a method of detecting packet discard will be described. When the packets are supplied to the reception packet header processing unit 200 in the same order as the order number incorporated in the transmission packet header processing unit 100, the reception packet header processing unit 200 sequentially reads the sequence numbers and the sequence numbers are omitted. If not, consider the packet dropped.

If the packets are not supplied to the reception packet header processing unit 200 in the same order as the sequence number incorporated in the transmission packet header processing unit 100, the packet header is received in the reception packet header processing unit 200 incorporating the timer. If a packet with a missing sequence number is detected during processing and the packet with the missing sequence is not supplied within the set time, it is considered that the packet is discarded. In addition, even if the received packet header processing unit 200 processes the last supplied packet and does not input the packet within the set time, it may be considered that the packet is discarded.

When the packet header processing unit 200 detects packet discard, the discard notification packet generation unit 30
A signal is supplied to 0. Discard notification packet generator 300
Then, when the signal from the packet header processing unit 200 is supplied, a discard notification packet for notifying that the packet discard has occurred is generated, and the transmission path interface control unit 1
Supply to 30. The discard notification packet generation unit 300
Then, a discard notification packet for notifying that packet discard has occurred may be generated each time a signal is supplied from the packet header processing unit 200, or n number of signals may be output from the packet header processing unit 200 during a certain period of time. (N is a natural number)
When supplied as above, one discard notification packet may be generated for notifying that packet discard has occurred. The discard notification packet supplied to the transmission path interface control unit 130 incorporates the destination address of the transmission path control unit 110, is supplied to the connector 121, and is further supplied to the communication path 123.

The connector 120 supplies the signal on the transmission path 123 to the transmission path interface control section 110. Since the transmission path interface control unit 110 performs processing for fetching a packet whose destination address matches its own address,
The discard notification packet is fetched. The discard notification packet is supplied from the transmission path interface control unit 110 to the discard notification packet reception processing unit 460. When the discard notification packet reception processing unit 460 is supplied with the discard notification packet, it supplies a signal to the video bit rate control unit 500.
The video bit rate control unit 500 controls the video bit rate of the video encoder 600 based on the signal from the discard notification packet reception processing unit 460. There are various methods of controlling the video bit rate, such as changing the quantization width, changing the number of dropped frames, changing the video resolution, and changing the dominant block determination method. Well, not specified.

The operation of the video bit rate control unit 500 in the sixth embodiment shown in FIG. 6 is the same as that shown in FIG. 1, but from the congestion notification packet processing unit 420 in the one shown in FIG. The only difference is that the signal from the discard notification packet reception processing unit 460 is supplied to the video bit rate control unit 500 instead of the signal No.

In the present embodiment, the transmission line interface controller 110 uses the CSMA system or CSMA /
When the CD method is used, the transmission path interface control unit 110 may set the number of retransmissions of video packets. By changing the number of retransmissions, the possibility of discarding video packets can be changed.

In the present embodiment, the video transmission terminal and the reception terminal are separately described for the purpose of explaining the function, but one terminal may have both functions at the same time.

Furthermore, as another embodiment that can replace the sixth embodiment shown in FIG. 6, a sequence number is incorporated in the video packet in this sixth embodiment, and instead of detecting the discard of the video packet, transmission is performed. An input terminal may be provided in the packet header processing unit 100, a sequence number may be incorporated in a data packet other than a video packet, and discarding of a packet other than a video packet may be detected. That is, the video packet assembling unit 700 supplies the video packet to the transmission path interface control unit 110, and the reception packet header processing unit 2
In 00, the transmission packet header processing unit 100 processes the packet having the sequence number incorporated therein, but does not process the video packet and outputs it from the output terminal 35. In addition,
Packets that incorporate sequence numbers are, for example, voice packets,
There are packets only for discard detection.

Further, by combining the sixth embodiment with the sixth embodiment described above, the sequence number is incorporated into both the video packet and the packet other than the video packet, and the received packet header processing unit 200 Both packet discards may be detected by.

FIG. 7 is a block diagram showing the structure of a video transfer system according to the seventh embodiment of the present invention. In the embodiment shown in the figure, a terminal that detects packet discard from the sequence number controls the video bit rate of the terminal itself.

In FIG. 7, 10 is an input terminal, 35 is an output terminal, 101 and 102 are terminals, 100 is a transmission packet header processing section, 110 and 130 are transmission line interface control sections, 120 and 121 are connectors, and 123 is Transmission line, 2
00 is a received packet header processing unit, 500 is a video bit rate control unit, 600 is a video encoder, and 700 is a video packet assembling unit.

In the seventh embodiment shown in FIG. 7, in FIG.
Unlike the above-described another embodiment of the sixth embodiment shown in FIG. 7, the packet input from the input terminal 10 includes a video packet and may be any packet. When the received packet header processing unit 200 detects packet discard,
The reception packet header processing unit 200 supplies a signal to the video bit rate control unit 500 of the terminal 102.

Further, the video bit rate control unit 500 and the video encoder 600 in the seventh embodiment of FIG. 7 operate in the receiving terminal 102, but the operations are the same as those shown in FIG. 1 and others. 1, except that the signal from the reception packet header processing unit 200 is supplied to the video bit rate control unit 500 instead of the signal from the congestion notification packet processing unit 420 shown in FIG.

A plurality of the above-mentioned respective embodiments may be combined and used at the same time.

[0070]

As described above, according to the present invention,
Congestion of the transmission line is detected from the packet received from the transmission line, the bit rate of the video encoder is controlled according to the congestion, the state of the transmission line is detected, and the state of the detected transmission line is detected. Controls the bit rate of the video encoder, calculates the round-trip transfer time of the transfer time measurement packet, controls the bit rate of the video encoder based on this round-trip transfer time, or discards the packet in the transmission path. Is detected and the bit rate of the video encoder is controlled based on the discard of this packet, so if the congestion occurs on the transmission path, the bit rate of the video encoder is reduced and the data is transferred on the transmission path. Since it is possible to reduce the bit rate of the video packet to be transmitted, it is possible to transmit in real time on the transmission path, it is possible to maintain the real time of communication, and it is necessary to discard the video data. It does not occur, it can prevent the deterioration of video information, the transmission amount itself on the transmission line can be reduced, congestion on the transmission line can be relieved, and video packets being transferred can be discarded on the transmission line. Sex becomes smaller.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a video transfer system according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a video transfer system according to a second embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a video transfer system according to a third embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a video transfer system according to a fourth embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of a video transfer system according to a fifth embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration of a video transfer system according to a sixth embodiment of the present invention.

FIG. 7 is a block diagram showing a configuration of a video transfer system according to a seventh embodiment of the present invention.

[Explanation of symbols]

 100 transmission packet header processing unit 101, 102 terminal 105 time measurement packet generation unit 110, 130 transmission line interface control unit 115 collision detection unit 117 network utilization rate calculation unit 118 retransmission number excess detection unit 120, 121 connector 123 transmission line 200 reception Packet header processing unit 300 Discard notification packet generation unit 400 Transfer time calculation unit 420 Congestion notification packet processing unit 460 Discard notification packet reception processing unit 500 Video bit rate control unit 600 Video encoder 700 Video packet assembly unit

Claims (7)

[Claims] 1. A congestion annunciation packet receiving means for receiving a packet announcing the congestion of the transmission path from the transmission path, and a congestion of the transmission path is detected from the packet received by the congestion annunciation packet receiving means, and according to the congestion A video transfer method comprising: a bit rate control means for controlling a bit rate of a video encoder. 2. A transmission path state detecting means for detecting a state of the transmission path for identifying congestion in the transmission path, and a bit of a video encoder according to the state of the transmission path detected by the transmission path state detecting means. A video transfer method, comprising: a bit rate control unit for controlling a rate. 3. The transmission path status detecting means detects the status of the transmission path based on the degree of collision on the transmission path, the usage rate of the transmission path, or the discarding of packets due to the number of retransmissions of transmitted packets on the transmission path. The video transfer system according to claim 2, further comprising: 4. A transmission unit that generates a transfer time measurement packet, sets a transmission time in the transfer time measurement packet and transmits the packet, and a return unit that receives and returns the transfer time measurement packet transmitted from the transmission unit. And receiving the transfer time measurement packet returned from the reply means, extracting the transmission time set in the packet, and calculating the round-trip transfer time of the transfer time measurement packet from the transmission time and the current time. And a bit rate control means for controlling the bit rate of the video encoder based on the round-trip transfer time of the packet calculated by the transfer time measuring means. 5. A packet discard detecting means for detecting packet discard on a transmission path, and a bit rate control means for controlling a bit rate of a video encoder based on the packet discard detected by the packet discard detecting means. A video transfer method characterized by having. 6. The packet discard detecting means sets a sequence number to a packet to be transmitted, transmits the packet, and the packet transmitted from the transmitting means, and discards the packet from the sequence number of the packet. Packet discard detection means for detecting the packet discard notification packet, reply means for generating and returning a packet discard notification packet for notifying the discard of the packet, and receiving means for receiving the packet discard notification packet returned from the reply means. The video transfer system according to claim 5, wherein 7. The packet discard detecting means sets a sequence number to a packet to be transmitted, transmits the packet, and the packet transmitted from the transmitting means, and discards the packet from the sequence number of the packet. 6. The video transfer system according to claim 5, further comprising means for detecting