Video packer communications system

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Industrial application field]

The present invention relates to a video packet communication method in which a video signal is packetized for each layer and transmitted on the transmitting side, and a video signal for each layer is extracted from the received packet on the receiving side, decoded separately, synthesized, and output. The present invention relates to a video packet communication method for switching the packetization target range of video signals for each layer depending on the presence or absence of packet discard.

【0002】

[Conventional technology]

Conventionally, in video packet communication, there is known a method of compensating for packet discard using a transmission class (service quality class based on packet discard) in a network for a layered coded output. As an example, here, embedded coding in the LSB-dropping method described in the Journal of the Institute of Electronics, Information and Communication Engineers B Vol.J71-B No.12 pp.1500-1510, 1988.12 "Examination of discarded packet compensation in video packet communication" The outline of is shown.

【0003】

FIG. 8 is a block diagram of the embedded coding method. In FIG. 8, since the coded output of the R-bit quantizer is deleted by the lower m bits and returned to the predictor, the predictor always operates with the decoding signal of R'= Rm bits. If the upper R'bit and lower m bit of the coded output are packetized independently and only the lower m bit is controlled to receive packet discard, even if the lower m bit is dropped next due to 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 m-bit deletion is superimposed on the output signal. During communication, packets with only lower m bits are assembled and transferred in a transmission class with a relatively large discard rate realized on the ATM, and packets with upper R'bits are assembled and transferred in a transmission class with a relatively small discard rate on the ATM. Transfer with. At this time, as described above, even if the lower m bits are discarded, the upper R'bits are transmitted, so that the asynchronous operation of the adaptive parameters in the encoder and decoder does not occur for the upper R'bits, and the overall operation is not performed. It is possible to suppress the deterioration of image quality to a relatively small level. In the predictor in the ADPCM method, the difference between the input signal and the prediction signal is taken and quantized by the adaptive quantization step width.

【0004】

[Problems to be Solved by the Invention]

Since the above-mentioned conventional method is based on the premise that a plurality of transmission classes in a network can compensate for the quality, there is a problem that it cannot be applied to a network in which a plurality of transmission classes cannot be realized.

【0005】

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

【0006】

[Means for solving problems]

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

【0007】

[Action]

The transmitting side assembles the video signal into packets for each layer and sends it, and when the receiving side notifies the packet to be discarded, the transmitting side stops sending the video signal of the layer having a small influence on the video quality as a packet. .. After that, when the receiving side notifies that the packet discard has not occurred, the transmitting side resumes 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 the video signals of multiple layers is decomposed, the video signals for each layer are taken out, the video signals of the multiple layers are decoded, and the video signals are returned to the video signals. On the other hand, when packet discard is detected, the sender is notified that packet discard has occurred.

【0008】

[Example]

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

【0009】

FIG. 1 shows a system configuration according to an embodiment of the present invention, in which 1 and 2 are communication devices A and communication devices B and 3 are communication networks. The communication device 1 is derived from the transmission system of the video input unit 11, the coding unit 12, the packet assembly unit 13, the transmission unit 14, and the reception system of the reception unit 15, the packet decomposition unit 16, the decoding unit 17, and the video output unit 18. Become. Similarly, the communication device 2 is described from the video input unit 21, the coding unit 22, the packet assembly unit 23, the transmission system of the transmission unit 24, and the reception unit 25, the packet decomposition unit 26, the decoding unit 27, and the video output unit 28. Become. 100, 200 are input signals, 101, 201 are priority coded outputs, 102, 202 are non-priority coded outputs, 103, 203 are transmission packets A, 104, 204 are transmission packets B, 105, 205 are reception packets A, 106 and 206 are received packets B, 107 and 207 are priority decoding inputs, 108 and 208 are non-priority decoding inputs, and 109 and 209 are output signals. Further, 300 is a packet discard notification, and 301 is a packet discard detection signal.

【0010】

The case where the video input from the communication device A1 is output to the communication device B2 will be described below. The processing flow of the communication device A1 at this time is shown in FIG. 2, and the processing flow of the communication device B2 is shown in FIG.

【0011】

In the communication device A1, video is input from the video input unit 11 (step F1), and the input signal 100 is transferred to the coding unit 12. In the coding unit 12, the input signal 100 is coded separately in two layers according to the degree of influence on the video quality, and the one having a large influence on the video quality is set as the priority coding output 101, and the degree of influence is changed. The smaller one is output to the packet assembly unit 13 as the non-priority coded output 102 (step F2). First, the packet assembly unit 13 assembles the transmission packet A103 based on the priority coded output 101 (step F3) and transfers the transmission packet A103 to the transmission unit 14. The transmission unit 14 transmits 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), and if not, the packet assembling unit 13 assembles the transmission packet B104 based on the non-priority coded output 102. (Step F6), the packet is transferred to the transmission unit 14, and the transmission unit 14 transmits the transmission packet B104 to the communication network 3 (step F7). If the receiving unit 15 receives the packet discard, the packet assembly unit 13 is notified as the packet discard notification 300 (step F8). When the packet assembly unit 13 finds that the packet discard notification 300 has been received, it stops assembling the non-priority coded output 102 into a packet (skips steps F6 and F7). The above processing is continued until the transmission is completed (step F9).

【0012】

When it is found that the communication device B2 has received the packet addressed to the self-communication device in the communication network 3 (step G1), the received packet corresponds to the transmission packet A103, the reception packet A205, and the reception packet B206 corresponding to the transmission packet B104. The receiver 25 determines which is the case (step G2). In the case of the received packet A205, the receiving unit 25 transfers this to the packet decomposition unit 26, and the packet decomposition unit 26 decomposes the received packet A205 (step G3). Then, the packet decomposition unit 26 checks whether or not the packet is discarded (step G4), and if there is a packet discard, notifies the transmission unit 24 as a packet discard detection signal 301 (step G5). The transmission unit 24 notifies the communication device A1 of the packet discard detection signal 301 via the communication network 3 (step G6). Next, the packet decomposition unit 26 takes out the priority decoding input 207 in the received packet A205 and transfers it to the decoding unit 27. If there is no packet discard in step G4, the packet decomposition unit 26 transfers the priority decoding input 207 included in the received packet A205 to the decoding unit 27 without notifying the packet discard detection signal 301. The decoding unit 27 decodes the priority decoding input 207 (step G7) and transfers it as an output signal 209 to the video output unit 28 (step G8). The video output unit 28 displays the output signal 209 (step G11).

【0013】

On the other hand, when the received packet is the received packet B206, the receiving unit 25 forwards the received packet B206 to the received packet decomposition unit 26. The received packet decomposition unit 26 decomposes the received packet B206 (step G9), transfers the non-priority decoding input 208 included therein to the decoding unit 27, and the decoding unit 27 decodes the non-priority input 208 (step G10). Then, the decoding unit 27 transfers the decoding result as an output signal 209 to the video output unit 28 (step G8). The video output unit 28 displays the output signal 209 (step G11). The communication device B2 continues the above processing until the packet reception is completed (step G12).

【0014】

When the video input from the communication device B2 is output to the communication device A1, it is processed in the same flow.

【0015】

FIG. 4 shows a detailed block diagram of the packet assembly unit 13, in which 1310 is buffer A, 1311 is a read / write unit for buffer A1310, 1320 is buffer B, 1321 is a read / write unit for buffer B1320, and 133 is a header addition. Part 1, 134 is a sequence number counter A. The processing flow in the packet assembly unit 13 is shown in FIG.

【0016】

The packet assembly unit 13 writes the priority coded output 101 output from the coding unit 12 to the buffer A1310 via the buffer A read / write unit 1311 (step H1), and similarly reads the non-priority coded output 102 to the buffer B. Write to buffer B1320 via write section 1321 (step H2). The header addition 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). The buffer A read / write unit 1311 reads the priority coded output 101 in the buffer A1310 from the buffer A1310 (step H5), adds a header by the header addition unit 133, and assembles the transmission packet A103 (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 transmitted packet A103.

【0017】

Next, it is checked whether or not the packet discard notification has been received (step H7), and if not, the buffer B read / write unit 132 reads the non-priority coded output B102 in the buffer B1320 (step H8) and adds a header. In part 133, a header including an identifier indicating that the transmission packet B is added is added to assemble the transmission packet B104 (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 assembly unit 13 performs the above processing until a series of packet transmissions is completed (step H10).

【0018】

FIG. 6 shows a detailed block diagram of the packet decomposition unit 26. 261 is a header separation unit, 262 is a discard detection unit, 2630 is a buffer C, and 2631 is a buffer C read / write unit.

【0019】

Here, it is assumed that the received packet A205 is first received and then the received packet B206 is received, and the processing in the packet decomposition unit 26 will be described. FIG. 7 shows the processing flow of the packet decomposition unit 26 at this time.

【0020】

The header separation unit 261 separates the header of the received packet (step I1), and examines either packet A205 or packet B206 from the identifier indicating the packet type in the header ((step I2). In the case of received packet A205. , The header distribution unit 261 transfers the sequence number contained in the header to the discard detection unit 262 (step I3). The discard detection unit 262 adds 1 to the sequence number of the previously received packet A205. (Step L4), and if not, it is determined that the packet has been discarded, and the packet discard detection signal 301 is notified to the transmitter 24 (Step I5). Next, the received packet A205 is sent. The included video signal is written to the buffer C2630 via the buffer C read / write unit 2631 (step I6). If the sequence number is a value obtained by adding 1 to the sequence number of the previously received packet A205, the step The video signal contained in the received packet A205 is written to the buffer C2630 without notifying the packet discard detection signal 301 of the I5 (step I6). As a result, the priority decoding input 207 of the received packet A205 is stored in the buffer C2630. To.

【0021】

Next, when the received packet B206 is received, the video signal included in the received packet B206 is similarly written to the buffer C1630 via the buffer C read / write unit 2631. As a result, the non-preferred decoding input 208 of the received packet B206 is stored in the buffer C2630. If the end of packet reception is not specified at this point (step I7), the above processing is continued.

【0022】

In this embodiment, the case of two-layer coding is described as an example of the hierarchical coding method, but the same processing can be performed for the three-layer or higher layer coding method. In this case, the plurality of layers may be divided into two types, priority / non-priority, or the layer to be packetized may be selected according to the number of times packet discard is detected. For example, if the frequency of packet discard is low, the packet assembly with the highest priority is stopped, and as the frequency increases, the packet assembly with a higher priority layer is also stopped.

【0023】

[Effect of the invention]

According to the present invention, when packet discard occurs in the network, non-priority class packet assembly can be stopped. Therefore, the traffic of the entire network is reduced and the packet discard rate is lowered, so that the priority class packet discard is less likely to occur and the deterioration of the video quality is reduced.

[Simple explanation of drawings]

[Figure 1]

This is a system configuration according to an embodiment of the present invention.

[Figure 2]

It is a flowchart which shows the transmission operation in a communication device.

[Fig. 3]

It is a flowchart which shows the reception operation in a communication device.

[Fig. 4]

It is a detailed block diagram of a packet assembly part.

[Fig. 5]

It is a flowchart which shows the operation of a packet assembly part.

[Fig. 6]

It is a detailed block diagram of a packet decomposition part.

[Fig. 7]

It is a flowchart which shows the operation of a packet decomposition part.

[Fig. 8]

It is a block diagram of the conventional embedded coding system.

[Explanation of symbols]

1 or 2 communication device 3 Communication network 11, 21 Video input section 12, 22 Coding section 13, 23 Packet assembly 14, 24 transmitter 15, 25 receiver 16, 26 Packet decomposition section 17, 27 Decryptor 18, 28 Video output section 100, 200 input signals 101, 201 Priority coded output 102, 202 Non-preferred coded output 103, 203 Outgoing packet A 104, 204 Outgoing packet B 105, 205 Received packet A 106, 206 Received packet B 107, 207 Priority decryption input 108, 208 Non-preferred decryption input 109, 209 output signal 300 packet discard notification 301 Packet drop detection signal