JPH0322780A - Packet transmitter for video signal - Google Patents

Abstract

PURPOSE:To prevent picture quality from deteriorating by discarding packets in a 1st group which is not image information with high importance when a state wherein packets are discarded on a transmission line, etc., is entered. CONSTITUTION:A transmission part consists of an A/D conversion part 102, memories 103-105, a timing circuit 106, and a header addition part 107 and a reception part consists cf an analysis part 202, a synchronization timing circuit 203, a distribution part 204, memories 205-207, and a D/A converter 208. Here, even if a packet is lost in a transmission system, etc., packets in the 1st group are composed of video signal components which are small in picture element deterioration and packets in a 2nd group are composed of video signal components which deteriorate in picture quality greatly if a packet is lost. Then if the state wherein packet discarding occurs on the transmission line, etc., is entered, the packets in the 1st group which is not high-importance information are discarded first. consequently, the picture quality is prevented from deteriorating when packets are discarded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a transmission device that converts digital video signals into packets (cells) and transmits them.

Conventional technology A conventional device for variable rate encoding and transmitting a digital video signal includes, for example, a 400 Mb/s PCM multiplexing system ffi (Sumitomo Electric No. 131!) 1) 7). FIG. 13 shows the configuration of the device. Analog-digital (A
/D) Sampling frequency 9.9 in converters 1301 to 1304
It samples at 3 Mb/s and outputs an 8-bit fluorescent signal. In general, video signals have strong periodicity, and the DC balance of the transmission signal is not good, such as a periodic pattern occurring in the transmission signal and a high frequency of successive occurrences of logical values "0" and "1". Therefore, in order to improve the DC balance of the transmission signal, scramblers 1306 to 1308 are applied immediately after the video signal is A/D converted.

The audio signal is quantized into 14 bits by A/D converters 1310 and 1311 at a sampling frequency of 44.3 kHz.

The A/D converted 8-channel audio signals are multiplexed by an audio multiplexer 1312 and output to a multiplexer 1309 as a 9.93 Mb/s serial signal.

A multiplexer 1309 performs scrambling and adds data bits to the 9-bit image signal including the C bit to make a signal of 10 bits per channel, and further multiplexes the 4-channel image signal with 40 bits. The data bits are different for each image channel, the first channel has a frame synchronization signal (01 alternating pattern), the second and third channels each have a data signal of 9.93 Mb/s, and the fourth channel has a multiplexed signal. Assigning audio signals.

FIG. 14 shows the frame structure. The frame consists of 4 frames/1 multiframe, 10 bits/1 frame,
The transmission speed is 397.2 Mb/s.

This signal is converted into an optical signal by an optical transmitter 1313 and transmitted.

In the conventional digital video transmission device as explained above, the sampling of the video signal is not synchronized with the color subcarrier of the video signal, for example, 3fsc (fsc=3
．． Video signals sampled at 58MHz) cannot be transmitted.
Furthermore, although the information content of one channel is converted to 99.3 Mb/s, it is also possible to perform high-efficiency encoding (for example, predictive encoding) and transmit a video signal compressed to about 30 Mb/s. It's impossible. That is, there is no flexibility with respect to changes in the transmission capacity of video signals. In order to overcome these drawbacks, sATM (Asynchronous T
Transfer Node) transmission systems are attracting attention.

Figure 15 shows the concept of ATM transmission. (Nikkei Electronics 1988.1.11 No.438 ppl22
) ATM transfers fixed-length cells (packets) in time slots that repeat at a constant cycle.By increasing or decreasing the number of cells to be transferred, the effective communication speed can be changed.

Figure 16 shows STM (Synchronous T
This figure shows the difference in multiplex transmission methods between transfer ilode (transfer ilode) and ATM. ATM is an attempt to realize high-speed communication by boldly removing the parts that hindered high-speed communication in conventional packet switching systems and by incorporating technology cultivated through circuit switching.

X. Packet communication conforming to 25 is originally suitable for transmitting burst signals and is highly flexible. You can send as much information as you need, whenever you want. But plot col. Because of the complexity, there is a limit to the ability to transmit high-speed signals.

In ATM, information to be sent is divided into short blocks and multiplexed. A header indicating the destination etc. is attached to the block. A block with a header is called a cell.

Inside the network, the contents of the header are referenced, the cells are exchanged in units of cells, and the data is delivered to the other party. Continuous signals such as audio and video are also broken down into cells, which are then converted back into continuous signals on the receiving side. Conventional packet signals are also divided into short cells and sent out. On the other hand, S
TM is an antonym for ATM and stands for traditional time division multiplexing.

Research and development in the field of high-efficiency encoding of video signals is also part of ATMs.
It suddenly became lively with the appearance of This is because ATM solves the problems that have hitherto constrained high-efficiency encoding technology. The main premise of conventional high-efficiency coding is to keep the transmission speed constant. With additional ATMs, you can send the necessary information whenever you need it. That is, the transmission speed can be dynamically changed. This enables high-efficiency encoding with constant image quality.

Current standard television signals require a transmission capacity on the order of IOOMb/s if they are transmitted as they are without digital conversion and high-efficiency encoding. The basis of high-efficiency encoding is to reduce the amount of transmitted information by omitting redundant parts. For example, in the case of a still image in which the subject does not move, it is wasteful to send the same signal over and over again. Assuming ATM is used, moving images may be sent at a rate of about 100 Mb/s, and still images may be sent at a transmission speed of zero. However, in the past, it was necessary to reduce the transmission speed even when moving pictures, so the image quality of the pictures had to be sacrificed.

FIG. 17 shows a model for variable encoding of video signals. (IEICE Journal B Vol. J7 B No. 1
0 pp. llIO) Encoding can be conceptually divided into three parts.

Stage 1: Variable process to suppress redundancy using correlation of input video (e.g. prediction, orthogonal transformation)...1
701, 1705 Stage 2: Irreversible (m childization) process with distortion
...1702, 1708 Stage 3: Process of assigning codes according to information ffi (entropy) ...1703, ITO'
7 The major difference between conventional fixed rate encoding and variable rate encoding is the puff 1 and its limitations on information generation. That is, in conventional fixed rate encoding, the transmission rate is fixed using the buffer yl704 to absorb rate fluctuations, and the code 'a 1 is used to prevent the buffer from overflowing.
7 0 2 (Stage 2). For this reason, conventional fixed rate encoding often causes a significant drop in quality due to delays caused by puff T and a certain increase in distortion. On the other hand, in variable rate coding that takes advantage of ATM, although the maximum rate from the network is specified, it is thought that the generated information can be transmitted as it is by converting it into cells at 1708, and the rate puffer controls the information generation. Instead, the encoder can be controlled based on quality, and encoding with constant quality can be realized.

As described above, if a video signal is variable rate encoded using ATM transmission, a video signal of constant quality can be transmitted with high efficiency. However, a problem arises here. In an ATM transmission network, flow control is not performed in order to increase switching speed, and the buffer capacity is small. Therefore, there is a high probability that overflow will occur in the switching system and that cells will be discarded.

When cells are discarded on a transmission line or in an exchange, a portion of the highly efficiently encoded information is lost in bursts, resulting in a large deterioration in image quality. Conventional burst encoding of video signals has not taken sufficient measures against cell discard.

Problems to be Solved by the Invention As explained above, in conventional video signal packet transmission devices, when packets (cells) are discarded in the transmission system or the switching system, the image quality of the video signal on the receiving side is greatly affected. The drawback was that it deteriorated.

In view of the above, an object of the present invention is to provide a packet transmission device for video signals that prevents quality deterioration of video signals when packets (cells) are discarded in a transmission system or a switching system.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a first video signal component with a small deterioration in image quality even if packets are lost in the transmission system, etc.
A second group of packets is composed of video signal components that would cause a significant deterioration in image quality if packets 1 and 2 were lost. Then, a high priority is given to the second group of packets, so that the packets of the second group are not discarded.

According to the present invention, when a situation arises in which packets are discarded on a transmission path, the first group of packets are discarded first.

Since the first group of packets is not high-importance image information, even if the first packet is discarded, ii! Li quality deterioration is not so large.

Example A first example of the present invention will be described. FIG. 1 shows the configuration of the transmitter. The analog video signal 1o1 is converted into a digital signal by an analog-digital (A/D) converter 102, the upper e bits are stored in the memory 103, the least significant bit of the lower 2 bits is stored in the memory 105, and the next bit is stored in the memory. 104. When the video data recorded in each memory reaches the amount of information equivalent to one packet, a header is added by a header addition section 107 and output from 108. The header appending section attaches a header that gives a higher priority to the output of the memory 103, and gives the output of the memory 105 the lowest priority. The timing circuit 10B controls memory write timing, read timing, etc. FIG. 2 shows the configuration of the receiving section. A synchronization timing circuit 203 synchronizes packet boundaries from the received signal (packet synchronization). The header of the received packet is analyzed by the analysis unit 202.
The packet is analyzed to determine whether it is a packet made up of high-order bits or a packet made up of low-order bits. According to this determination, the data is distributed in distribution 1204 and recorded in the memories 205, 208, and 207 in order from the most significant bit. If a packet is discarded in the transmission system, all information of that packet is
'' and record it in the memory 207.The output from the memory is digital-analog (D/A) variable tiin20.
It is converted at B and output as analog. In the transmission system, non-priority packets are discarded first. Therefore, when a packet is discarded, the lower bit of the PCM signal becomes "0" in this embodiment. Even if the lower bits of the PCM video signal are lost, the image does not deteriorate much.

A second embodiment of the present invention will be described. FIG. 3 shows the configuration of the transmitter. component video signal Y 301,
CR302, C. 8 3 0 3 itA/DI converter 3
04, 305, and 30B are converted into digital signals.

Each digital video signal is generated by a block generator 307.
, 30B, and 309 into 8×8 blocks. Each block information is recorded in the memory 3/1 under the control of the timing circuit 310. The header adding section 312 includes a luminance signal. The priority of the packet is increased and the packet is converted into a packet and output. FIG. 4 shows the configuration of the receiving section.

A synchronization timing circuit 403 performs packet synchronization with respect to the reception bucket} 401. The analysis unit 402 determines whether the content of the packet is a luminance signal Y, a color signal CR, or CB. At the same time, it is determined whether or not a packet was discarded. Packet information is recorded in buffer 7 memory 404. If a packet is discarded, it is replaced with "0". The output from the puff 1 memory 404 is input to the block decomposition unit 4 for the Y signal.
06, the CR signal is input to 407, and the CB signal is input to 408, and each is returned to the original digital (PC:M) video signal. This digital video signal is D/A converted.
The signal is returned to an analog signal at 9, 410, and 411. In this embodiment, packets made up of color signals are discarded first. Since the human eye is less sensitive to color information than to luminance information, even if packets are discarded, image quality deterioration is relatively small. In this example! A block constituted one packet.

A third embodiment of the present invention will be described. FIG. 5a shows the configuration of the transmitter. The digital video signal 501 is processed by the block generation unit 502 into a size of 41ifj elements×4 lines (18
The discrete cosine transform (DCT) unit 503 converts the (amplitude) coefficients of 16 two-dimensional frequency components COO, Cot, C 10, ...
C32. C33 (see Figure 5b). Among the conversion coefficients, a coefficient CO1 representing a DC component COO and a low-order frequency component is used. C 10, CO2, C ft. c20 stores coefficients CO3 and Cl2 representing high-order frequency components in the memory 504.
．． C21, C30, C13, C22. C31, C23.
C32. C33 is recorded in memory 505. When the coefficient data recorded in each memory reaches the amount of information for one packet, a header is added by the header adding section 50B.
is output as In the header adding section 50B, the memory 5
The packet generated by 04 includes information that has a higher priority than the packet in the memory 505 in the header. A timing circuit 507 controls writing, reading, etc. of the memory. FIG. 6a shows the configuration of the receiving section. A synchronization timing circuit 803 performs packet synchronization with respect to the receiving bucket }601. The analysis unit 602 analyzes the presence or absence of packet discard and the header information of the received packet. In response to instructions from the analysis unit, the distribution unit 604 stores a packet consisting of coefficients representing DC components and low-order frequency components in a memo 17.
At e 0 5, a packet consisting of coefficients representing higher-order frequency components is recorded in the memory 606. Furthermore, if it is found that a packet consisting of coefficients representing high-order frequency components has been discarded in a transmission system, etc., the replacement unit E307 replaces the packet with a packet with all components of "0°" and records it in the memory 606. Inverse discrete cosine transform PA (IDCT) section 608
is the DC and low-order frequency component coefficients from memory 805 and the low-order frequency component coefficients from memory eoe, and I
Apply DCT to obtain a block consisting of 16 pixels (
(See Figure 6b). A block decomposition unit 609 decomposes this pixel block and generates a digital video signal 610.

A fourth embodiment of the present invention will be described. FIG. 7a shows the configuration of the transmitter. The digital video signal 701 is processed by the block generation unit 702 into a size of 4 pixels x 4 lines (16
The DCT unit 703 calculates (amplitude) coefficients COO,C of 16 two-dimensional frequency components.
O1. CIO, ... is converted to C32, C33 (see Figure 7-2). The upper 6 bits of the conversion coefficient, ie, MOO. MO1, MIO,...M32. M33 is recorded in memory 704. On the other hand, the lower two bits, ie, LOG, LOI, LIO, ...L32. L3
3 is recorded in the memory 705. When the coefficient data recorded in each memory reaches the amount of information for one packet, a header is added by the header addition unit 70B and a transmission packet 708 is added.
is output as The header addition unit 70EI adds a header containing information that gives the packet 1 generated from the data in the memory 704 a higher priority than the packet generated from the data in the memory 705.

A timing circuit 708 controls writing, reading, etc. of the memory. FIG. 8a shows the configuration of the receiving section.

A synchronization timing circuit 803 performs packet synchronization with respect to the received packet 801. The analysis unit 802 analyzes the presence or absence of packet discard and the header information of the received packet. Based on this analysis result, the distribution unit 804 stores a packet consisting of the upper bits (MO01MO1...M33) of the DCT transform coefficients in the memory 805, and stores the lower bits of the transform coefficients} (L
Packets consisting of OO, LOI...L33) are recorded in the memory 806, respectively. In addition, in transmission systems, etc., lower bits of conversion coefficients (LOG, LOI...L
33), the replacement unit 807 records this in the replacement memory 808 as a packet with all components "O". IDCT section 808
is the 8-bit conversion coefficient C OO by adding the upper bits from memory 805 and the lower bits from memory 80B.
1C 011C 10...C 33, IDC
Apply T (see Figure 7b). This is block decomposition part 80
9 is decomposed to obtain a digital video signal 810.

A fifth embodiment of the present invention will be described. FIG. 9a shows the configuration of the transmitter. The digital video signal 90l is converted into 4 pixels x 4 lines (1B pixels) by the vector generator 902.
The tree search vector quantization (VQ) section 903 quantizes the vector and outputs a 6-bit index 1t. This index 1t
is obtained using a quantization search tree as shown in Fig. 9b, where the upper 3 bits represent the quantization result at the 8-keyed level (YO-Y7) in layer 3, and the total 5 bits are 32ffi childization level (XO-X
31) represents the quantization results divided into 31).

The upper 3 bits IM of index it is memory 9O4
Then, the remaining lower two bits iL are recorded in the memory 905. When the index data recorded in each memory reaches the amount of information equivalent to one packet, a header is attached by a header adding section 906 and outputted as 908. Header addition section 9
In 0B, the packet generated by the memory 904 includes information in the header that gives it a higher priority than the packet in the memory 905. A timing circuit 907 controls memory writing, reading, etc. FIG. 10 shows the configuration of the receiving section. A synchronization timing circuit 1003 synchronizes packets with respect to the receiving bucket 1001. Analysis section 100
2 analyzes the presence or absence of packet discard and the header information of the received packet. Upon receiving instructions from this analysis section, the distribution section 1
004 stores the packet consisting of the upper 3-bit index III in the memory 1005, and stores the packet consisting of the lower 2-bit index I
A packet consisting of L is recorded in the memory 100B. VQ
The decoding unit 1007 combines the upper 3-bit index 1M from the memory 1005 and the lower 2-bit index iL from the memory 100B to form a total 5-bit index 11, and reproduces the vector from the 32ffi childization level (XO-X31). If it is found that a packet consisting of the lower 2-bit index has been discarded in the transmission system, etc., upon receiving instructions from the analysis unit 1002, the vQ decoding unit 1007 uses only the upper 3-bit index to
Regenerate vectors from the ffi child level (YO to Y7). A vector decomposition unit 1008 decomposes this pixel vector into a digital video signal 1009.

A sixth embodiment of the present invention will be described. FIG. 11 shows the configuration of the transmitter. A digital video signal 1101 is turned into a 16-dimensional vector consisting of 4 pixels x 4 lines (16 pixels) in a vector generation unit 1102, vector quantized by an average value jliVQ unit 1103, and an 8-bit index la and an average value separation for the average value signal. Outputs 6 beats/beat index 1b for the signal. Index ia is recorded in memory 1104 and index lb is recorded in memory 1105. When the index data recorded in each memory reaches the amount of information equivalent to one packet, a header is attached by the header adding section 110B and outputted as 1108. In the header adding section 1106, the memory 11
The packet generated by 04 includes information that has a higher priority than the packet in the memory 1105 in the header, and the packet 1108 is output. timing circuit 11
07 controls memory writing, reading, etc. 1st
Figure 2 shows the configuration of the receiving section. Synchronous timing circuit 120
3 performs packet synchronization with respect to the received packet 1201. The analysis unit 1202 analyzes the presence or absence of packet waste and the header information of the received packet. -This analysis section 1202
In response to the instruction, the distribution unit 1204 stores the packet consisting of the average value signal index Ia in the memory 1205 and the packet consisting of the average value separation signal index tb in the memory 1205.
206. Average value l! ! lvQ decoding unit 120
8 reproduces the vector using index ia from memo IJ 1205 and index 1b from memory 1206. When it is found that a packet consisting of the average value separation signal index 1b has been discarded in the transmission system, etc., the replacement unit 1207 receives an instruction from the analysis unit 1202 and replaces the average value separation signal corresponding to the discarded packet with the average value separation signal index 1b.
O” and record it in the memo IJ 1 2 0 E!.

A vector decomposition unit l209 decomposes this image preference vector into a digital video signal 1210.

Effects of the Invention As described above, according to the present invention, when a situation arises in which packets are discarded on a transmission line or the like, the first group of packets are discarded first. The first group of packets does not contain highly important image information, so even if the first packet is discarded, the image quality will not deteriorate significantly.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a transmitter in a first embodiment of the present invention, FIG. 2 is a block diagram of a receiver in a first embodiment of the present invention, and FIG. 3 is a block diagram of a receiver in a first embodiment of the present invention. FIG. 4 is a configuration diagram of the transmitting section in the third embodiment of the present invention, FIG. 6 is a configuration diagram of the receiving section in the third embodiment of the present invention, and FIG. 7 is a configuration diagram of the transmitting section in the fourth embodiment of the present invention. 8 is a block diagram of the receiving section in the fourth embodiment of the present invention, FIG. 9 is a block diagram of the transmitting section in the fifth embodiment of the present invention, and FIG. 11 is a block diagram of the transmitter in the sixth embodiment of the present invention; FIG. 12 is a block diagram of the receiver in the sixth embodiment of the present invention; FIG. 13 is a block diagram of the receiver in the sixth embodiment of the present invention; The figure is a block diagram of a conventional PCM multiplexing device, Figure 14 is a frame block diagram, Figure 15 is a conceptual diagram of ATM transmission, and Figure 16 is an S
An explanatory diagram of TM and ATM transmission systems, and FIG. 17 is an explanatory diagram of variable encoding. 102...Analog-digital (A/D) converter,
103, 104, 105...Memory, 106...Timing circuit, 107...Header addition unit, 202...
- Analysis section, 203... Synchronous timing circuit, 204.
...Distribution unit, 205, 208, 207...Memory, 2
08...Digital to analog (D/A) converter, 3
04,305.3011...A/D converter, 307,
308.30 Death...Block generation department, 3! O...Timing circuit, 311...Memory, 3I2...Header addition section, 402...Analysis section, 403...Synchronization timing circuit, 404...Memory, 405...Distribution section,
40B. 407.408...Block decomposition section, 409
, 410. Quadruple...D/A converter, 502... Block generator, 503... Discrete cosine transform (DCT
) section, 504, 505...memory, 50...header addition section, 507...timing circuit, 602...analysis section, 603...synchronous timing circuit, 804...
Distribution section, fi05, BOB...Memory, B07...
Replacement unit, 608... inverse discrete cosine transform (IDCT)
part, 609...Block decomposition part, 702...Block decomposition part, 703...DCT part, 704,705...
-Memory, 706...Header addition section, 707...Timing circuit, 802...Analysis section, 803...Synchronization timing circuit, 804...Distribution section, 805, 808
...Memory, 807...Replacement part, 808...I
DCT section, 809...Block decomposition section, 902...
Vector generation unit, 903...Tree search vector quantization (
VQ) section, 904, 905... memory, 90... header addition section, 907... timing circuit, 100
2... Analysis section, 1003... Synchronous timing circuit,
1004...Distribution section, 1005.100[i...
-Memory, 1007...VQ decoding unit, 1008...
Vector decomposition unit, item 02...Vector generation unit, 110
3...Average value 1IiVQ section, 1104.1105"
'Memory, 110L・'''yda addition section, 1107...
・Timing circuit, 1202...Analysis section, 1203・
...Synchronous timing circuit, 1204...Distribution section,! 2
05,1206...Memory, 1207...Replacement part,
1208... Mean value separation VQ decoding unit, 120... Vector decomposition unit.

Claims (16)

[Claims] (1) There is a circuit that configures packets with video signal components that cause little deterioration in image quality even if they are lost in the transmission system, etc., a circuit that configures packets with video signal components that cause major deterioration in image quality if they are lost, and a circuit that configures packets with video signal components that cause significant deterioration in image quality if lost. 1. A packet transmitting device for a video signal, comprising a circuit that gives a high priority in a packet priority display area to packets that have a large degree of deterioration. (2) A circuit that classifies packets according to the priority order of received packets, a circuit that determines whether a packet is lost, and a circuit that detects the contents of a packet when a packet is lost, which consists of a video signal component whose image quality is minimally degraded due to loss. 1. A video signal packet receiving device comprising: a circuit for replacing with a predetermined value. (3) In PCM transmission, there is a circuit that configures a packet with lower bits whose image quality will be degraded only slightly if lost, a circuit that configures a packet with upper bits that will cause a large amount of image quality degradation if lost, and a packet that is configured with higher bits. What is claimed is: 1. A video signal packet transmitting device comprising: a circuit that gives a higher priority; (4) In PCM transmission, there is a circuit that classifies received packets according to their priority, a circuit that determines whether a packet is lost, and a circuit that replaces the contents of the packet with a predetermined value if a packet consisting of lower bits is lost. 1. A video signal packet receiving device comprising: a circuit for receiving a video signal; (5) In component transmission, there is a circuit that configures a packet with the color component of the video signal, which causes a small deterioration in image quality even if it is lost, a circuit that configures a packet with the luminance component of the video signal, which causes a large deterioration in image quality if it is lost, and a circuit that configures the packet with the luminance component of the video signal, which causes a large deterioration in image quality if it is lost, 1. A video signal packet transmitting device comprising: a circuit that gives a high priority to packets composed of luminance components. (6) In component transmission, a circuit that classifies received packets according to their priority order, a circuit that determines whether a packet is lost, and a circuit that determines the contents of a packet when a packet composed of color components of a video signal is lost. 1. A video signal packet receiving device, comprising: a circuit for replacing with a value. (7) In the transmission of orthogonal transform coded signals, there is a circuit that configures a packet with high-order coefficient components of the orthogonal transform coefficients of the video signal, which will cause a small deterioration in image quality even if lost, and a circuit that configures a packet with high-order coefficient components of the orthogonal transform coefficients of the video signal, which will cause a large deterioration in image quality if lost. Packet transmission of a video signal characterized by comprising a circuit that configures a packet with a low-order coefficient component of an orthogonal transform coefficient, and a circuit that gives higher priority to a packet that is configured with a lower-order frequency component. Device. (8) a circuit for classifying received packets according to their priorities in transmitting orthogonal transform encoded signals;
It is characterized by comprising a circuit that determines whether a packet is lost, and a circuit that replaces the contents of the packet with a predetermined value when a packet composed of high-order coefficient components of orthogonal transform coefficients of a video signal is lost. Video signal packet receiving device. (9) In the transmission of orthogonal transform encoded signals, there is a circuit that configures packets using the lower bits of the orthogonal transform coefficients, which cause little deterioration in image quality even if they are lost, and a circuit that configures packets with the upper bits of the orthogonal transform coefficients, which cause large deterioration in image quality if they are lost. The constituent circuits and
1. A video signal packet transmitting device comprising a circuit that gives higher priority to packets made up of higher order bit components. (10) In the transmission of orthogonal transform encoded signals, there is a circuit that classifies the received packets according to their priority order, a circuit that determines whether a packet is lost, and the contents of the packet when a packet consisting of lower bits is lost. What is claimed is: 1. A video signal packet receiving device comprising: a circuit for replacing a predetermined value with a predetermined value; (11) In transmission using a tree search vector quantized signal, there is a circuit that configures a packet with index components close to the tree search root using a tree-structured quantization table, which causes little image quality deterioration even if it is lost, and a circuit that configures a packet with index components that are close to the root of the tree search, and which causes a large image quality deterioration if lost. It is characterized by comprising a circuit that configures a packet from the upper bit components of the remaining index components far from the root of the tree search, and a circuit that gives higher priority to packets that are configured from the higher bit components. Video signal packet transmitter. (12) Tree search In transmission using vector quantized signals, a circuit that classifies packets according to the priority of received packets, a circuit that determines whether a packet is lost, and a circuit that is far from the tree search route using a tree-structured quantization table. A video signal packet receiving device comprising: a circuit for decoding using a tree-structured quantization table using only index components close to the root of tree search when a packet composed of remaining index components is lost. . (13) In transmission using mean-separated vector quantized signals, a circuit that configures a packet with an index for the mean-separated signal of a video signal that causes little image quality deterioration even if it is lost, and a circuit that configures a packet with an index for the mean-separated signal of a video signal that causes a large image quality deterioration if lost. 1. A video signal packet transmitting device comprising: a circuit that configures packets using indexes; and a circuit that gives a high priority to packets that configure packets based on output indices relative to an average value signal of the video signal. (14) In transmission using mean value separation vector quantized signals, a circuit that classifies packets according to the priority of the received packets, a circuit that determines whether a packet is lost, and a packet configured with an index for the mean value separation signal. 1. A video signal packet receiving device comprising a circuit that replaces the average value separation signal with a predetermined value if lost. (15) In multi-stage coding transmission where coding distortion caused by the previous encoder is encoded by the subsequent encoder, the transmission code by the later encoder has less image quality degradation even if it is lost in the transmission system, etc. A circuit that configures a packet with a transmission code from an earlier stage encoder, which would cause a major deterioration in image quality if lost, and a circuit that gives higher priority to packets that are composed of transmission codes from an earlier stage. A video signal packet transmitting device comprising: (16) In transmission using multi-stage encoding, packets are lost, which are composed of a circuit that classifies packets according to the priority of received packets, a circuit that determines whether a packet is lost, and a transmission code by a later-stage encoder. 1. A packet receiving device for a video signal, comprising a circuit for decoding the video signal using only a transmission code from an encoder at a previous stage.