JPH06339137A - Video packer communications system - Google Patents

Abstract

PURPOSE:To device a system that packet abort hardly takes place by stopping the transmission of a packet of non-priority class is stopped on the occurrence of packet abort in a communications network so reduce the traffic of the entire network. CONSTITUTION:A communications equipment 11 receives a video from a video input section 11 and uses a coding section 12 to code the input signal in two layers to provide a priority coding signal and a non-priority coding signal and a packet compositions section 13 forms a packet for each layer and it is sent from a transmission section 14. A reception section 25 of a communications equipment 2 receives the packet and a packet decomposition section 26 decomposes the received packet depending on layers and a decoding section 27 decodes the packet and a video output section 28 synthesizes the decoded signals to provide an output. When the packet decomposition section 26 detects packet abort, it is informed to the sender side. The packet composition section 13 stops the packet composition of the on-priority coding signals upon the receipt of notice of packet abort.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal in which a video signal is layered and transmitted at a transmitting side, and a video signal for each layer is taken out from a received packet at a receiving side, decoded, synthesized and output separately. More specifically, the present invention relates to a packet packet communication system that switches the packetization target range of a layered video signal depending on the presence or absence of packet discard.

[0002]

2. Description of the Related Art Conventionally, in video packet communication, a method of compensating for packet discard by using a transmission class (service quality class based on packet discard) in a network for a hierarchical encoded output is known. As an example, here, IEICE Transactions BVol. J71-B No.
12 pp. 1500-1510, 1988.12, e in the LSB-dropping method described in "Examination of Discarded Packet Compensation in Video Packet Communication"
An outline of mbedded coding is shown.

FIG. 8 is a block diagram of the embedded coding system. In FIG. 8, since the lower m bits of the encoded output of the R-bit quantizer are deleted and fed back to the predictor, the predictor always operates with a decoded signal of R ′ = R−m bits. If the upper R'bits and the lower m bits of the encoded output are packetized independently and the control is performed so that only the lower m bits receive the packet discard, even if the lower m bits are dropped due to the packet discard, the encoder, Asynchronous operation of the adaptive parameter in the decoder does not occur, and the characteristic is that quantization noise corresponding to simply deleting m bits is superimposed on the output signal. At the time of communication, a packet of only the lower m bits is assembled and ATM
The transfer class realized with the relatively high discard rate is transferred, the upper R'bit packets are assembled and transferred on the ATM with the transfer class relatively low. At this time,
As described above, since the upper R'bits are transmitted even if the lower m bits are discarded, the asynchronous operation of the adaptive parameters in the encoder and the decoder does not occur with respect to the upper R'bits, and the overall image quality is The deterioration can be suppressed to a relatively small level. The predictor in the ADPCM system takes the difference between the input signal and the predicted signal and quantizes the difference with the adaptive quantization step width.

[0004]

The above-mentioned conventional method is not applicable to a network in which a plurality of transfer classes cannot be realized because it is premised that a plurality of transfer classes in the network can compensate for the quality. was there.

The present invention solves the above-mentioned conventional problem. In the video packet communication, even when a plurality of transmission classes cannot be realized, a video signal having a relatively small effect on the video quality when the packet is discarded is transmitted. The purpose of this is to reduce the traffic of the entire network and make it difficult for packet discard to occur.

[0006]

In order to achieve the above object, the present invention provides a video packet communication system in which video is packetized and communicated between communication devices.
Means for inputting a video signal, means for separating the video signal into a plurality of layers according to the degree of influence on the video quality, and encoding
A means for assembling the encoded video signal as a packet for each layer, a means for transmitting the assembled packet, and a degree of influence on the video quality when the receiving-side apparatus notifies the occurrence of packet discard. The receiving side device has means for stopping transmission of a packet of a video signal of a small layer, the receiving side device, means for decomposing the received packet and taking out a video signal for each layer, and the means for extracting the packet. Means for decoding the video signal for each layer, a means for synthesizing and outputting the video signal decoded for each layer, a means for detecting the discard of the received packet, and a means for notifying the transmission side device of the occurrence of the packet discard. It is characterized by having.

[0007]

In the transmitting side, the video signal is assembled into a packet for each layer and transmitted, and when the receiving side notifies the packet discard, the video signal of the layer having a small influence on the image quality is packetized and transmitted. To cancel. Then, when the receiving side is notified that the packet discard has not occurred, the transmitting side restarts packetizing and transmitting the video signal of the layer having a small influence on the video quality. On the receiving side, if packet discard is not detected, the received packet composed of video signals of multiple layers is decomposed to take out the video signal of each layer, the video signals of multiple layers are decoded and returned to the video signal, On the other hand, when packet discard is detected, the sender is notified that packet discard has occurred.

[0008]

An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a system configuration of an embodiment of the present invention. Reference numerals 1 and 2 are a communication device A, communication devices B and 3 are communication networks. The communication device 1 includes a video input unit 11, an encoding unit 12, a packet assembly unit 13, a transmission system of a transmission unit 14, and a reception system of a reception unit 15, a packet decomposition unit 16, a decoding unit 17, and a video output unit 18. Become. Similarly, the communication device 2
Is a video input unit 21, an encoding unit 22, a packet assembling unit 2
3, a transmission system of the transmission unit 24, a reception unit 25, a packet decomposition unit 26, a decoding unit 27, and a video output unit 28. 1
00 and 200 are input signals, 101 and 201 are priority coded outputs, 102 and 202 are non-priority coded outputs, 103 and 2
03 is a transmission packet A, 104 and 204 are transmission packets B, 105 and 205 are reception packets A, 106 and 206
Is a received packet B, 107 and 207 are priority decoding inputs,
Reference numerals 108 and 208 are non-priority decoding inputs, and 109 and 209 are output signals. Also, 300 is a packet discard notification, 3
01 is a packet discard detection signal.

In the following, a case will be described in which an image input from the communication device A1 is output to the communication device B2. A processing flow of the communication device A1 at this time is shown in FIG.
The processing flow of No. 2 is shown in FIG.

In the communication device A1, an image is input from the image input unit 11 (step F1) and the input signal 100 is transferred to the encoding unit 12. In the encoder 12, the input signal 1
00 is divided into two layers and encoded according to the degree of influence on the video quality, the one having a great influence on the video quality is the priority encoded output 101, and the one having a small influence is the non-priority encoded output. The packet is output to the packet assembling unit 13 as 102 (step F2). In the packet assembly unit 13, first,
The transmission packet A 103 is assembled based on the priority coded output 101 (step F3) and transferred to the transmission unit 14. The transmission unit 14 sends the transmission packet A103 to the communication network 3 (step F4). Next, the receiving unit 15 checks whether the packet discard notification 300 has been received (step F5). If not, the packet assembling unit 13 sends the transmission packet B104 based on the non-priority encoded output 102.
Are assembled (step F6), transferred to the transmission unit 14, and the transmission unit 14 sends the transmission packet B104 to the communication network 3 (step F7). If the receiving unit 15 receives the packet discard, the packet assembling unit 13 is notified as the packet discard notification 300 (step F8). When it is determined that the packet discard notification 300 has been received, the packet assembling unit 13 stops assembling the non-priority coded output 102 into a packet (skipping steps F6 and F7). The above processing is continued until the transmission is completed (step F9).

When it is found that the communication device B2 has received a packet addressed to the own communication device in the communication network 3 (step G
1) The receiving unit 25 determines whether the received packet is the received packet A205 corresponding to the transmitted packet A103 or the received packet B206 corresponding to the transmitted packet B104 (step G2). Received packet A20
In the case of 5, the receiving unit 25 transfers this to the packet decomposing unit 26, and the packet decomposing unit 26 receives the received packet A205.
Is decomposed (step G3). Then, the packet disassembling unit 26 checks whether or not the packet has been discarded (step G4), and if there is a packet discard, notifies the transmitting unit 24 as a packet discard detection signal 301 (step G5). The transmitter 24 detects the packet discard detection signal 301.
To the communication device A1 via the communication network 3 (step G6). Next, the packet disassembling unit 26 receives the received packet A2.
The priority decoding input 207 in 05 is taken out and transferred to the decoding unit 27. If there is no packet discard in step G4, the packet disassembly unit 26 detects the packet discard detection signal 30.
The priority decoding input 207 included in the reception packet A 205 is transferred to the decoding unit 27 without notifying of 1. The decoding unit 27 decodes the priority decoding input 207 (step G7) and transfers it as the output signal 209 to the video output unit 28 (step G7).
8). The video output unit 28 displays the output signal 209 (step G11).

On the other hand, the received packet is the received packet B20.
In the case of 6, the reception unit 25 transfers the reception packet B206 to the reception packet decomposition unit 26. Received packet disassembly unit 2
In step 6, the received packet B206 is disassembled (step G
9), the non-priority decoding input 208 included in the decoding unit 2
7, and the decoding unit 27 decodes the non-priority input 208 (step G10). Then, the decoding unit 27 transfers the decoding result as the output signal 209 to the video output unit 28 (step G8). The video output unit 28 outputs the output signal 209.
Is displayed (step G11). The communication device B2 continues the above processing until the packet reception is completed (step G12).

When a video image input from the communication device B2 is output to the communication device A1, the same process is performed.

FIG. 4 is a detailed block diagram of the packet assembling unit 13, in which 1310 is a buffer A and 1311.
Is a read / write unit for the buffer A 1310, 1
320 is a buffer B, 1321 is a read / write section for the buffer B 1320, 133 is a header addition section, 1
34 is a sequence number counter A. A processing flow in the packet assembling unit 13 is shown in FIG.

The packet assembling unit 13 writes the priority coded output 101 output from the coding unit 12 into the buffer A 1310 via the buffer A read / write unit 1311 (step H1), and similarly outputs the non-priority coded output 102. The data is written in the buffer B 1320 via the buffer B read / write unit 1321 (step H2). The header adding unit 133 reads the counter value from the sequence number counter 134 (step H3) and increments the counter value of the sequence number counter 134 by 1 (step H4). Buffer A read / write unit 1311
Reads out the priority coded output 101 in the buffer A 1310 from the buffer A 1310 (step H5), adds the header in the header adding unit 133, and transmits the transmission packet A10.
3 is assembled (step H6). At this time, the sequence number read from the sequence number counter A134 and the identifier indicating the transmission packet A are written in the header. The sequence number indicates the order of the transmission packet A103.

Next, it is checked whether or not the packet discard notification has been received (step H7). If not, the buffer B read / write unit 132 determines that the buffer B 1320 has not been received.
Read out the non-priority encoded output B102 (step H
8), the header adding unit 133 adds a header including an identifier indicating that the packet is the transmission packet B, and the transmission packet B
Assemble 104 (step H9). When the packet discard notification is received (step H7), the packet assembly of the non-priority coded output 102 is not performed. The packet assembling unit 13 performs the above processing until the series of packet transmission is completed (step H10).

FIG. 6 is a detailed block diagram of the packet disassembling unit 26. 261 is a header separating unit, 262 is a discard detecting unit, 2630 is a buffer C, and 2631 is a buffer C reading / writing unit.

Here, the processing in the packet disassembling unit 26 will be described assuming that the received packet A 205 is received first, and then the received packet B 206 is received. FIG. 7 shows a processing flow of the packet disassembling unit 26 at this time.

The header separating unit 261 separates the header of the received packet (step I1), and determines the packet A205 or the packet B from the identifier indicating the packet type in the header.
Any one of 206 is checked ((step I2). In the case of the received packet A205, the header distribution unit 261 transfers the sequence number included in the header to the discard detection unit 262 (step I3). It is checked whether or not the sequence number is a value obtained by adding 1 to the sequence number of the previously received packet A205 (step L4). If not, it is determined that the packet is discarded and the packet discard detection signal 301 is transmitted. This is notified to the unit 24 (step I5) Next, the received packet A20
The video signal included in No. 5 is written in the buffer C2630 via the buffer C reading / writing unit 2631 (step I6). If the sequence number has a value obtained by adding 1 to the sequence number of the previously received packet A 205, the packet discard detection signal 301 of step I5
The video signal included in the received packet A205 is written in the buffer C2630 without the notification of (step I
6). As a result, the priority decoding input 207 of the received packet A205 is stored in the buffer C2630.

Next, when the reception packet B206 is received, the video signal included in the reception packet B206 is similarly written in the buffer C1630 via the buffer C reading / writing unit 2631. As a result, the non-priority decoded input 208 of the received packet B206 is stored in the buffer C2630. If there is no designation of ending packet reception at this point (step I7), the above processing is continued.

In the present embodiment, the case of the coding of two layers is described as an example of the hierarchical coding system, but the same processing can be applied to the hierarchical coding system of three or more layers. In this case, a plurality of layers may be divided into two types of priority / non-priority, or a layer to be packetized may be selected according to the number of packet discard detections. For example, when the frequency of packet discard is low, the packet assembly with the lowest priority is stopped, and as the frequency is increased, the packet assembly with the higher priority layer is also stopped.

[0023]

According to the present invention, when a packet is discarded in the network, it is possible to cancel the packet assembly of the non-priority class. Therefore, the traffic of the entire network is reduced,
Since the packet discard rate is lowered, the packet discard of the priority class does not occur, and the deterioration of the video quality is reduced.

[Brief description of drawings]

FIG. 1 is a system configuration of an embodiment of the present invention.

FIG. 2 is a flowchart showing a transmission operation in a communication device.

FIG. 3 is a flowchart showing a receiving operation in the communication device.

FIG. 4 is a detailed block diagram of a packet assembling unit.

FIG. 5 is a flowchart showing an operation of a packet assembling unit.

FIG. 6 is a detailed block diagram of a packet disassembly unit.

FIG. 7 is a flowchart showing an operation of a packet disassembling unit.

FIG. 8 is a configuration diagram of a conventional embedded encoding method.

[Explanation of symbols]

 1 and 2 communication device 3 communication network 11 and 21 video input unit 12 and 22 encoding unit 13 and 23 packet assembling unit 14 and 24 transmitting unit 15 and 25 receiving unit 16 and 26 packet disassembling unit 17 and 27 decoding unit 18 and 28 Video output unit 100, 200 Input signal 101, 201 Priority coded output 102, 202 Non-priority coded output 103, 203 Transmission packet A 104, 204 Transmission packet B 105, 205 Reception packet A 106, 206 Reception packet B 107, 207 Priority decoding input 108, 208 Non-priority decoding input 109, 209 Output signal 300 Packet discard notification 301 Packet discard detection signal

Claims (1)

[Claims] 1. A video packet communication method for packetizing and communicating video between communication devices, wherein a transmitting device has a plurality of means for inputting a video signal and a plurality of the video signals according to the degree of influence on the video quality. Means for separating into layers and encoding, means for assembling the encoded video signal as a packet for each layer, means for transmitting the assembled packets, and notification of occurrence of packet discard from the receiving side device In this case, the receiving side device has means for stopping the transmission of the packet of the video signal of the layer having a small influence on the image quality, and the receiving side device decomposes the received packet and divides the received packet by layer. Means for extracting the video signal, the means for decoding the extracted video signal for each layer, the means for synthesizing and outputting the video signal decoded for each layer, and the discarding of the received packet. Out comprises means for notifying the occurrence of a packet discard to the transmitting apparatus, a video packet communication method, wherein a.