JPH10304382A - Inter-frame predictive coding system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inter-frame predictive coding system by which image quality of a decoded image is improved by extending a refresh period under normal condition, and a correct decoded image is outputted quickly by reducing the period in case of new connection. SOLUTION: The proposed system includes inter-frame predictive coding sections 102, 103, 104, 105, 106, 107, 108, 112, 113, 114 that receive a moving image signal, apply compression coding to the signal and provide an output of an inter-frame predictive coding signal; a connection signal reception section 110 that receives externally a connection signal to increase a refresh area of an input moving image signal; and, a refresh period control section 111 that reduces the refresh period under the control of the signal from the connection signal reception section. In the case of starting decoding from the inter-frame predictive coding signal on the way of coding, the refresh period is reduced to accelerate generation of the output of a decoded image and in normal case, the refresh period is extended to improve the image quality of the coded image.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video conference system, a LAN for transmitting a moving image, an inter-frame predictive encoding apparatus used for digital television broadcasting, a cable television, etc. TECHNICAL FIELD The present invention relates to an inter-frame prediction encoding system including a device and an inter-frame prediction decoding device.

[0002]

2. Description of the Related Art In recent years, with the development of digital signal processing technology, a LAN, a video conference system, a digital television broadcast, and the like that compress and encode a moving image and transmit the moving image have been put to practical use.
Hereinafter, a conventional inter-frame predictive coding system will be described with reference to FIGS. FIG. 7 is a diagram showing a configuration of a conventional inter-frame prediction coding / decoding system (hereinafter, referred to as an inter-frame prediction coding system) including a conventional inter-frame prediction coding device and an inter-frame prediction decoding device, and FIG. FIG. 10 is a diagram showing a state in which a refresh frame is inserted during the period.

First, a configuration of a conventional inter-frame predictive coding system will be described with reference to FIG. In FIG. 7, reference numeral 700 denotes an inter-frame predictive encoding device that inputs and encodes an input video signal and outputs an inter-frame predictive encoded signal, 701 denotes an input terminal that inputs an input video signal, 7
A subtractor 02 subtracts an inter-frame prediction signal generated based on a previous input video signal from an input video signal to output a prediction error signal, and 703 orthogonally transforms the prediction error signal and outputs an orthogonal transform coefficient. An orthogonal transform unit 704 that quantizes the orthogonal transform coefficient and outputs a quantized coefficient;
Reference numeral 05 denotes a variable-length encoding unit that encodes a quantized coefficient and outputs an inter-frame prediction coded signal. Reference numeral 706 denotes an output terminal that outputs the inter-frame prediction coded signal to a line 731.

[0004] Further, an inverse quantization unit 707 outputs the orthogonal transform coefficient by applying the quantization coefficient from the quantization unit 704.
Reference numeral 8 denotes an inverse orthogonal transform unit that inversely orthogonally transforms the orthogonal transform coefficient and outputs a prediction error signal corresponding to the original error signal. 714 adds the prediction error signal to the previous inter-frame prediction signal stored in the memory 713. The adder 713 stores the input image signal as an inter-frame prediction signal, and 712 subtracts the inter-frame prediction signal from the memory 713 in synchronization with the input moving image signal. Switch for controlling whether or not to output to the adder 702 and the adder 714.

[0005] Further, reference numeral 731 denotes a line for transmitting the inter-frame prediction coded signal to the network 733, and reference numeral 733 denotes a line for transmitting the inter-frame prediction coded signal from the inter-frame prediction coding device 700 to another inter-frame prediction decoding device 720 (a plurality of lines). ) Is a line for transmitting an inter-frame predictive coded signal from the network 733 to the inter-frame predictive decoding device 720.

Reference numeral 720 denotes an inter-frame predictive decoding device that decodes an inter-frame predictive coded signal and outputs a decoded image signal, 721 denotes an input terminal for inputting the inter-frame predictive coded signal from the network 733, and 722 denotes an input terminal. A synchronization detection unit that detects a synchronization code from an input signal and establishes synchronization as an input of an inter-frame prediction coded signal. A variable-length decoding unit 723 performs variable-length decoding of the input inter-frame prediction coded signal and outputs a quantization coefficient. A decoding unit 724 for inversely quantizing the quantized coefficient and outputting an orthogonal transform coefficient;
Reference numeral 25 denotes an inverse orthogonal transform unit for performing an inverse orthogonal transform of the orthogonal transform coefficient to output a prediction error signal, and 726 adds and decodes the prediction error signal from the inverse orthogonal transform unit 725 and the inter-frame prediction signal from the memory 729. Adder for outputting an image signal, 7
29 is a memory for storing the decoded image signal from the adder 726 as an inter-frame prediction signal, and 727 is an output terminal for the decoded image signal.

Next, the operation of the above-described conventional interframe predictive coding system will be described with reference to FIGS. First, a digitized image or moving image signal (hereinafter, also referred to as an input moving image signal or an input image signal) to be compression-coded is input to the input terminal 701. In the input image signal, the inter-frame prediction signal output through the switch 712 is subtracted in the subtracter 702, input to the orthogonal transformation unit 703 as a prediction error signal, and orthogonally transformed by the orthogonal transformation unit 703 to obtain an orthogonal transformation coefficient. Is output. The orthogonally transformed orthogonal transform coefficients are input to the quantization unit 704 and quantized, and the quantized quantized coefficients are input to the variable length encoding unit 705 and the inverse quantization unit 707.

[0008] An inverse quantization unit 707 inversely quantizes the input quantized coefficients and converts them into orthogonal transform coefficients. The transformed orthogonal transform coefficients are subjected to inverse orthogonal transform by the inverse orthogonal transform unit 708 and input to the adder 714. The adder 714 adds the inter-frame prediction signal input from the memory 713 through the switch 712 and the prediction error signal input from the inverse orthogonal transform unit 708, and outputs the original input video signal to the memory 713. The memory 713 records the input moving image signal and outputs it as an inter-frame prediction signal of the next frame. The switch 712 is turned off in synchronization with the input moving image signal input from the input terminal 701 to thereby
02 is periodically inserted into the output of the output No. 02.

Next, a state in which refresh frames are periodically inserted will be described with reference to FIG. In FIG. 8, a hatched portion or region is a refresh region. That is, the frames 801 and 803 are refresh frames. The frame 802 sandwiched between the refresh frames is a non-refresh frame. As can be seen from FIG. 8, the coding of the inter-frame difference is stopped using only a specific frame as a refresh frame, and the coding efficiency of the inter-frame difference is increased for other frames, thereby improving the compression efficiency. I try to improve.

[0010] The inter-frame prediction coded signal which has been subjected to the variable length coding by the variable length coding unit 705 is output from the output terminal 70.
6, through the lines 731 and 732, the network 733, and the input terminal 721, are input to the synchronization detecting unit 722 in the inter-frame predictive decoding device 720. When synchronization is established by the synchronization detection unit 722, the synchronization detection unit 722 outputs the input inter-frame prediction coded signal to the variable length decoding unit 723. The variable length decoding section 723 performs variable length decoding on the result and outputs the result to the inverse quantization section 724 as a quantization coefficient. The quantized coefficients are then dequantized and output as orthogonal transform coefficients.

[0011] The orthogonal transform coefficient output from the inverse quantization unit 724 is input to the inverse orthogonal transform unit 725, subjected to inverse orthogonal transform, and outputs a prediction error signal to the adder 726. Adder 726
Adds the prediction error signal to the inter-frame prediction signal output from the memory 729, and outputs the decoded image signal to the output terminal 727.
And output to the memory 729. The memory 729 records the input decoded image signal and outputs it to the adder 726 as the next inter-frame prediction signal.

In such a conventional inter-frame predictive decoding apparatus 720, when decoding an inter-frame predictive coded signal from the middle of the signal, decoding is performed from a refresh frame. For example, when refreshing is performed from a non-refresh frame, the inter-frame prediction signal becomes 0
Therefore, in order to output the inter-frame prediction signal, the correct value refreshed from the beginning must be recorded in the memory 729.

As described above, the above-mentioned conventional interframe predictive coding apparatus can also compress and encode an input moving image signal and transmit it. It is also possible to decode the inter-frame prediction coded signal from the middle.

[0014]

However, in the above-mentioned conventional inter-frame predictive coding apparatus, inter-frame predictive decoding apparatus, and inter-frame predictive coding system including these devices, a predetermined period (inter-frame period)
In order to perform intra-frame encoding, if another inter-frame predictive decoding device that has been turned off is turned on in the middle to start decoding, a correct decoded image is obtained until a correct decoded image is obtained. At the very least, it will take up to that predetermined period of time. Therefore, if it is desired to shorten the time until a correct decoded image is obtained, this period may be set to be short.However, if this period is shortened, the encoding efficiency is deteriorated, the motion is not smooth, and the compression is not performed. There is a problem that the image quality of the encoded image or the compressed encoded image signal (inter-frame prediction encoded signal) is deteriorated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problem. When a plurality of inter-frame predictive decoding devices are connected to an inter-frame predictive coding device, the inter-frame predictive decoding device is connected later (decoding). The same applies when the encoding device is connected (turned on) after the encoding device). The decoding device can quickly output a correct decoded image signal, and can maintain a normal compressed image or a good image quality of the compressed image signal. A prediction encoding device and an inter-frame prediction decoding device;
It is an object of the present invention to provide an inter-frame prediction encoding system including an inter-frame prediction encoding device and an inter-frame prediction decoding device.

[0016]

According to the present invention, there is provided an inter-frame predictive coding system, comprising: an inter-frame predictive coding device which externally inputs a connection signal designating that the size of a refresh area is changed (larger than usual); A connection signal receiving unit for receiving, and a refresh cycle control unit for changing a refresh cycle (shorter than a normal cycle) by a signal from the connection signal receiving unit. A connection signal transmitting unit or a system control unit for outputting a connection signal to the inter-prediction encoding apparatus, and when the inter-frame prediction encoding apparatus is connected later, decoding is performed by shortening (fastening) the refresh cycle for one frame. The decoding device outputs the correct decoded image signal quickly, and normally increases the refresh period for one frame to make the compressed image signal longer. Is obtained by way may be better to keep the issue of image quality.

According to the present invention, the refresh cycle is lengthened during normal encoding, and the refresh cycle is shortened when a new inter-frame predictive decoding device is connected later. A frame that can output a correct decoded image as soon as possible while maintaining the quality of the decoded image at a good level and maintaining a minimum deterioration of the decoded image when a new inter-frame predictive decoding device is connected later. An inter prediction coding system is obtained.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An inter-frame prediction coding apparatus according to the first aspect of the present invention is an inter-frame prediction coding apparatus which receives a moving image signal, compresses and encodes the moving image signal, and outputs an inter-frame prediction coded signal. An encoding unit, including a connection signal receiving unit that receives a connection signal from the decoder, and a refresh cycle control unit that controls a refresh cycle based on a signal from the connection signal receiving unit and characteristics of an input moving image; Is adaptively changed, and by controlling the connection signal, the refresh area of each frame is normally reduced by extending the refresh period to improve the image quality of the encoded image or improve the compression ratio. When a new inter-frame predictive coding device is newly connected, the refresh area is temporarily increased to increase the refresh cycle. It has an effect of equal refresh cycle to quickly correct image decoding image output from the inter-frame prediction decoding device capable of adaptively changed by Kusuru.

According to a second aspect of the present invention, there is provided an inter-frame predictive encoding unit which receives a moving image signal, compresses and encodes the moving image signal, and outputs an inter-frame predictive encoded signal. A connection signal receiving unit that receives a connection signal from a decoder, and a refresh cycle control unit that controls a refresh cycle by controlling a signal from the connection signal reception unit, wherein the refresh cycle control unit includes A connection signal instructing to temporarily increase the refresh area is received, and the refresh period is temporarily shortened. By controlling the connection signal, the refresh area of each frame is normally reduced. To improve the quality of the coded image or improve the compression ratio by extending the refresh cycle, When the coding device is connected,
By temporarily increasing the refresh area and shortening the refresh cycle, it is possible to quickly and correctly output a decoded image output from the inter-frame predictive decoding device.

According to a third aspect of the present invention, there is provided an inter-frame predictive decoding apparatus which receives and decodes an inter-frame predictive coded signal and outputs a decoded image signal. When starting the decoding from the middle of the received inter-frame predictive coded signal, the inter-frame predictive decoding apparatus includes: a synchronization detecting unit for performing synchronization with the inter-frame predictive coded signal already received; A connection signal transmitting unit that transmits a connection signal that controls a region to be refreshed to the inter-frame predictive encoding device later, the refresh region is temporarily enlarged by the connection signal, and in the inter-frame predictive coding device, The time required for refreshing one frame is shortened. At normal times, the refresh area of each frame is reduced, and When an inter-frame predictive coding device is connected, a connection signal for temporarily increasing the refresh area is output to the inter-frame predictive coding device, and in normal times, the refresh cycle is lengthened to improve the quality of the coded image. Alternatively, when the compression ratio is improved and a new inter-frame predictive encoding device is newly connected, the refresh period is shortened to quickly output a correct image of the decoded image output from the inter-frame predictive decoding device. It has the effect of being able to.

According to a fourth aspect of the present invention, there is provided an inter-frame predictive encoding system which receives a moving image signal and outputs an inter-frame predictive coded signal to a network, and a network. An inter-frame predictive decoding system comprising two or more inter-frame predictive decoding devices for receiving and decoding an inter-frame predictive coded signal through the inter-frame predictive decoding device. Connection for increasing the size of the refresh area of one frame of the inter-frame prediction coded signal when the inter-frame prediction coded signal which is also decoded by the coding apparatus is received and decoded by another inter-frame prediction coded signal A connection signal transmitting unit that outputs a signal, wherein the inter-frame prediction encoding device is transmitted from the inter-frame prediction decoding device. A refresh cycle control unit for temporarily shortening the time for refreshing the entire frame by the connection signal, and temporarily shortening the refresh cycle by temporarily increasing the refresh area of the input moving image by controlling the connection signal. By controlling the connection signal, the refresh area of each frame is normally reduced by controlling the connection signal, thereby increasing the refresh cycle to improve the image quality of the encoded image or improve the compression ratio. When the inter-frame predictive coding device is connected, the decoded image output from the inter-frame predictive decoding device is quickly output as a correct image by temporarily increasing the refresh area and shortening the refresh cycle. It has the effect of being able to.

According to a fifth aspect of the present invention, there is provided an inter-frame predictive encoding system which inputs a moving image signal and outputs an inter-frame predictive coded signal to a network; An inter-frame predictive decoding system comprising two or more inter-frame predictive decoding devices for receiving and decoding an inter-frame predictive coded signal via the inter-frame predictive decoding device. A connection signal for increasing the size of the refresh area of one frame of the inter-frame predictive coded signal when the inter-frame predictive coded signal is received and decoded by another inter-frame predictive decoder. A system control unit is connected, and the inter-frame predictive encoding device uses a connection signal transmitted from the system control unit. A refresh cycle control unit for temporarily reducing the time required to refresh the entire one frame by temporarily increasing the refresh area of the input moving image by controlling the connection signal, thereby temporarily shortening the refresh cycle. By separately providing a system control unit that outputs a connection signal, without providing a connection signal transmission unit in each inter-frame predictive decoding device, by controlling the connection signal, the refresh area of each frame is normally used. , The refresh cycle is lengthened to improve the image quality of the coded image or the compression ratio. When a new inter-frame predictive coding apparatus is newly connected, the refresh area is temporarily increased. Output from the inter-frame predictive decoder by shortening the refresh cycle An effect that can be output quickly correct image decoded image.

Hereinafter, based on the attached drawings and FIGS. 1 to 6,
An embodiment of the present invention will be described in detail. FIG. 1 is a block diagram showing a configuration of an inter-frame predictive coding apparatus according to a first embodiment of the present invention, and FIG. 2 is a diagram showing the relationship between the area of a refresh area of each frame and a refresh cycle according to one method (for each block line). It is a figure which shows the example of a relationship, (A)
FIG. 3B is a diagram showing a refresh period of one frame in a normal state, FIG. 3B is a diagram showing a refresh period of one frame when the decoding device is turned on later (when a connection signal is received), and FIG. (Choose any place)
FIG. 3A is a diagram illustrating an example of a relationship between a refresh region area of each frame and a refresh cycle, and FIG. 4A is a diagram illustrating a refresh cycle of one frame in a normal state;
(B) is a diagram showing a refresh cycle for one frame when the decoding device is turned on later (when a connection signal is received);
FIG. 4 is a block diagram showing a configuration of an inter-frame predictive decoding device according to a second embodiment of the present invention, and FIG. 5 is a block diagram showing a configuration of an inter-frame predictive coding system according to a third embodiment of the present invention. FIG. 6 and FIG. 6 are block diagrams showing a configuration of an inter-frame predictive coding system according to a fourth embodiment of the present invention.

(First Embodiment) First, with reference to FIG. 1, the configuration of an inter-frame predictive coding apparatus according to a first embodiment of the present invention will be described. In FIG. 1, 101 is an input terminal for inputting an input video signal, and 102 is a subtracter for subtracting an inter-frame prediction signal created based on a previous input video signal from the input video signal and outputting a prediction error signal. , 103 is an orthogonal transform unit that orthogonally transforms the prediction error signal and outputs orthogonal transform coefficients, 104 is a quantizer that quantizes the orthogonal transform coefficients and outputs quantized coefficients, and 105 is a frame that encodes the quantized coefficients and A variable-length encoding unit that outputs an inter-frame prediction coded signal; 106, an output terminal that outputs the inter-frame prediction coded signal to an inter-frame prediction decoding device through a network; An inverse quantization unit that quantizes and outputs an orthogonal transform coefficient.

An inverse orthogonal transform unit 108 performs an inverse orthogonal transform of the orthogonal transform coefficient and outputs a prediction error signal corresponding to the original error signal. A reference numeral 114 designates a previous inter-frame prediction signal stored in the memory 113. An adder 113 for adding a prediction error signal to generate a current input image signal; a memory 113 for storing the input image signal as an inter-frame prediction signal;
Reference numeral 2 designates the input video signal as a refresh area without outputting the inter-frame prediction signal from the memory 113 to the subtractor 102 and the adder 114 under the control of the refresh cycle control unit 111 in synchronization with the input of the input video signal. Or
Or a switch for controlling whether to output and output an error signal. Note that the subtractor 103, the orthogonal transformer 103, the quantizer 104, the variable-length encoder 105, and the inverse quantizer 10
7, inverse orthogonal transform unit 108, switch 112, memory 1
13 and the adder 114 constitute an inter-frame predictive coding unit.

Reference numeral 109 denotes a connection signal input terminal for inputting a connection signal for designating or changing a refresh area of a frame (for example, increasing the refresh area when an inter-frame predictive decoding apparatus is connected later) 110. Is a connection signal receiving unit that receives the input connection signal, 111 is synchronized with the input video signal input from the input terminal 101, and controls the connection signal input to the connection signal reception unit 110 to control the refresh area of the frame. The switch 1 changes the refresh cycle by changing the size (for example, shortens the refresh cycle when the inter-frame predictive decoding device is connected later).
12 is a refresh cycle control unit that controls the control unit 12.

Next, the operation of the interframe predictive coding apparatus according to the first embodiment of the present invention will be described with reference to FIG. The input terminal 101 receives a digitized input image or input image signal (hereinafter, also referred to as an input moving image signal) to be compression-coded. Input terminal 101
Is input to the subtractor 102, where the inter-frame prediction signal is subtracted and input to the orthogonal transformer 103 as a prediction error signal. The prediction error signal is orthogonally transformed by the orthogonal transformer 103, input to the quantizer 104 as orthogonal transform coefficients, and quantized. The quantized quantized coefficients are supplied to a variable length coding unit 105 and an inverse quantization unit 107.
Entered as The variable-length-coded quantized coefficients are output from an output terminal 106 to an inter-frame predictive decoding device as inter-frame predictive coded signals.

On the other hand, the quantized coefficient from the quantizer 104 is inversely quantized by the inverse quantizer 107 and returned to an orthogonal transform coefficient, and is input to an inverse orthogonal transformer 108 to be inverse orthogonally transformed to a prediction error signal. Will be returned. This prediction error signal is added to the adder 11
4 is added to the inter-frame prediction signal recorded in the memory 113 and becomes the original input moving image signal, which is recorded in the memory 113 again. Then, it is used to create an inter-frame prediction signal of the subsequent input moving image signal. Here, since the quantization and the orthogonal transformation are irreversible processes, the input video signal recorded in the memory 113 does not completely match the original input video signal.

The refresh cycle control unit 111 controls the refresh position in synchronization with the input moving image signal input from the input terminal 101, and outputs the result to the switch 112.
Output to That is, when the refresh area (also referred to as a refresh portion) of the input moving image is refreshed, the switch 112 is opened, and the inter-frame prediction signal output from the memory 113 is not input to the subtractor 102. Is not performed, and as a result, the prediction error signal to be output from the subtracter 102 and the input video signal match, and the input video signal is output as it is, thereby refreshing the decoded image. Become.

Further, the refresh cycle control section 111 changes the size of the refresh area by the connection signal input to the connection signal receiving section 110 through the connection signal input terminal 109, as can be seen from FIG. Then, the refresh cycle is controlled.

Next, with reference to FIGS. 2A and 2B and FIGS. 3A and 3B, the relationship between the refresh cycle and the area of the refresh region will be described. 2 and 3 are refresh areas (201, 30).
1), and the white part is the non-refresh area (202,
302). In FIG. 2A, refresh is performed for one frame line portion per frame. Therefore, if there are N block lines in one frame, 1
To refresh all the frames, N frame periods are required.

By increasing the number of frames necessary for refreshing one frame, normally,
As shown in FIG. 2A, the transmission efficiency can be improved by increasing the transmission capacity, or if the capacity is the same, the image quality of the compressed image can be improved. FIG. 2B shows a case where a connection signal for increasing the refresh area is input from the connection signal receiving unit 110. In the case of FIG. 2B, the refresh area for one time is tripled to refresh 3N block lines per frame. As a result, the number of frames required to refresh one frame is １ ／ of the case shown in FIG.
The time required until the correct refreshed coded image or coded image signal is output from the inter-frame predictive decoding device is reduced to 1/3. It is possible to output quickly.

The normal refresh area can be selected at an arbitrary place as shown in FIG.
Similarly, the refresh area at the time of receiving the connection signal can be arbitrarily selected as shown in FIG.
Further, the refresh area at the time of receiving the connection signal may be determined in advance for each frame. In this case, the refresh period of each frame to be refreshed when receiving a connection signal is previously provided as a parameter in the encoding device, and refreshing is performed according to the parameter, whereby the refresh cycle can be temporarily shortened.

The size of the refresh area at the time of receiving the connection signal does not need to be equal for each frame, and need not be determined in advance. Therefore, an input image having a high compression efficiency at the time of refresh can have a larger refresh area than an input image having a low compression efficiency. The detection of the compression efficiency at the time of refreshing is possible not only by actually performing compression coding by refreshing but also by, for example, the magnitude of the autocorrelation of the input image. As described above, the refresh area for each frame of the input moving image signal can be adaptively changed according to the properties of the input image signal.

(Second Embodiment) The configuration of an inter-frame predictive decoding apparatus according to a second embodiment of the present invention will be described below with reference to FIG. In FIG. 1, 401
Is, for example, an input terminal for inputting an inter-frame prediction encoded signal from the inter-frame prediction encoding device shown in FIG.
Is a synchronization detection unit for detecting a synchronization code from an input signal and establishing synchronization as an input of an inter-frame prediction coded signal;
Reference numeral 3 denotes a variable-length decoding unit that performs variable-length decoding on the input interframe prediction coded signal and outputs a quantized coefficient, 404 denotes an inverse quantization unit that dequantizes the quantized coefficient and outputs an orthogonal transform coefficient, and 405. Is an inverse orthogonal transform unit that performs an inverse orthogonal transform on the orthogonal transform coefficient and outputs a prediction error signal.

An adder 406 adds the prediction error signal from the inverse orthogonal transform unit 405 and the inter-frame prediction signal from the memory 408 and outputs a decoded image signal.
8 is a memory for storing the decoded image signal from the adder 406 as an inter-frame prediction signal, 407 is an output terminal for the decoded image signal, and 411 is turned on when decoding starts, and outputs a decoding start signal. A switch 409 calculates the product of the decoding start signal from the switch 411 and the synchronization detection signal from the synchronization detection unit 402, and when both are true, the output terminal 4
A connection signal transmitting unit that outputs a connection signal to the device 10.

Next, the operation of the inter-frame predictive decoding apparatus according to the second embodiment of the present invention will be described with reference to FIG. An inter-frame predictive coded signal that has been compression-coded by the inter-frame predictive coding apparatus is input to a synchronization detecting unit 402 through an input terminal 401. Synchronization detector 402
Detects the synchronization code of the input inter-frame prediction coded signal and synchronizes the entire decoding. Further, a detection result of the synchronization code (result of whether synchronization has been achieved or not) is output to connection signal transmitting section 409. In addition, it outputs an inter-frame prediction coded signal to variable length decoding section 403 from the start of the frame after synchronization detection.

The variable-length decoding unit 403 performs variable-length decoding on the input inter-frame predictive coded signal to generate quantized coefficients, and outputs the quantized coefficients to the inverse quantization unit 404. The inverse quantization unit 404 inversely quantizes the quantized coefficients, converts them into orthogonal transform coefficients, and outputs the orthogonal transform coefficients to the inverse orthogonal transform unit 405. The inverse orthogonal transform unit 405 performs an inverse orthogonal transform on the orthogonal transform coefficient into a prediction error signal and outputs the result to the adder 406. The adder 406 is a memory 4
A decoded image signal is created by adding the inter-frame prediction signal output from the decoder 08 to the prediction error signal, and is output to the memory 408 at the same time as being output through the output terminal 407.
The memory 408 records the input decoded image signal,
It is output as the next inter-frame prediction signal (the image signal input after the current frame).

When decoding is to be started halfway, switch 4
11 is closed and a decoding start signal is input to the connection signal transmission unit 409. The connection signal transmission unit 409 includes a switch 411
Of the decoding start signal and the synchronization detection signal from the synchronization detection unit 402, and if both are true, a connection signal is output through the output terminal 410. The inter-frame predictive coding apparatus receives the connection signal, and outputs an inter-frame predictive coded signal having a reduced refresh period according to the control thereof, transmits the signal to the inter-frame predictive decoder, and outputs the inter-frame predictive decoder. By decoding the inter-frame prediction coded signal whose refresh cycle is shortened, a decoded image signal can be output quickly.

(Third Embodiment) The configuration of an inter-frame predictive coding system according to a third embodiment of the present invention will be described below with reference to FIG. In FIG. 5, 51
0 is an input terminal for inputting an input video signal, and 511 is an input terminal for inputting and coding an input video signal and outputting an inter-frame prediction coded signal to an inter-frame prediction decoding device 512, 513, or 514 through a network 509. The predictive coding devices 502, 504, 506 and 508 convert the inter-frame predictive coded signals to the inter-frame predictive decoding device 51.
2, 513, 514.

Reference numeral 509 denotes a network for transmitting an inter-frame prediction coded signal from the inter-frame prediction encoding device 511 to another inter-frame prediction decoding device 512, 513, 514; The inter-frame predictive decoding devices 515, 516, and 517 that decode the encoded signal and output the decoded image signal are output terminals 501, 503, 505, and 50 of the decoded image signal.
7 is an inter-frame predictive decoding device 512, 513, 514
Is a line for transmitting a connection signal to the inter-frame predictive encoding device 511 from the.

Next, the operation of the interframe predictive coding system according to the third embodiment of the present invention will be described with reference to FIG. FIG. 5 shows an embodiment of an interframe prediction encoding system in which the interframe prediction encoding device shown in the first embodiment, the interframe prediction decoding device shown in the second embodiment, and a network are combined. It shows the form. First, an input video signal input from an input terminal 510 is compression-encoded by an inter-frame predictive encoding device 511 and output to a network 509 via a line 502 as an inter-frame predictive encoded signal. At this time (normal state), the inter-frame predictive coding apparatus 511 operates as shown in FIG.
Alternatively, as shown in FIG. 3A, a small area of each frame is refreshed.

The network 509 can take the form of not only a loop type as shown in FIG. 5 but also a soot type. The network 509 converts the input inter-frame predictive coded signals to respective inter-frame predictive decoding devices 512, 513, 514 through lines 504, 506, and 508.
Output to Each inter-frame prediction decoding device 512, 51
3 and 514, the inter-frame prediction coded signals are decoded and output terminals 515 and 51 are output as decoded image signals.
6, 517 are output.

Now, for example, the inter-frame prediction encoding device 5
It is assumed that the inter-frame prediction coded signal output from 11 is being decoded by the inter-frame prediction decoding device 512 and the inter-frame prediction decoding device 513 has not performed decoding. Therefore, the inter-frame prediction decoding device 513
Starts decoding an inter-frame predictive coded signal being output from the inter-frame predictive coder 511, the inter-frame predictive coder 513 first outputs the signal from the inter-frame predictive coder 511 via the line 506. The synchronization code is detected by inputting the inter-frame prediction coded signal.

After detecting the synchronization, the inter-frame predictive decoding device 513 outputs a connection signal to the network 509 via the line 505. The network 509 outputs a connection signal to the inter-frame predictive encoding device 511 through the line 501. The network for transmitting the connection signal may be the same as or different from the one for transmitting the inter-frame predictive coded signal as shown in the present embodiment. The inter-frame predictive coding device 511 receives the connection signal, and performs coding by temporarily shortening the refresh cycle as described in the first embodiment. Thus, the inter-frame predictive decoding device 513 can quickly output the decoded image signal through the output terminal 516.

(Fourth Embodiment) The configuration of an inter-frame predictive coding system according to a fourth embodiment of the present invention will be described below with reference to FIG. In FIG. 6, 61
0 is an input terminal for inputting an input video signal, and 611 is an interframe prediction code for inputting and coding an input video signal and outputting an interframe prediction coded signal to the interframe prediction decoding devices 612 to 614 through the network 609. 602 is a line for transmitting the inter-frame prediction coded signal to the inter-frame prediction decoding devices 612 to 614, and 609 is a line for transmitting the inter-frame prediction coded signal from the inter-frame prediction coding device 611 to the inter-frame prediction decoding device. 612-614
And a connection signal from the system control unit 603 to the inter-frame prediction encoding device 611 and the inter-frame prediction decoding devices 612 to 614.

Reference numerals 612 to 614 denote an inter-frame predictive decoding device for decoding an inter-frame predictive coded signal to output a decoded image signal, reference numerals 615 to 617 denote decoded image signal output terminals, and reference numeral 603 denotes a separate network 609. 605, a system control unit that outputs a connection signal to the inter-frame prediction encoding device 611 and the inter-frame prediction decoding devices 612 to 614; 605, a line that outputs a connection signal;
Is a line for inputting a connection signal, and 604 to 608 are lines for transmitting an inter-frame prediction coded signal and a connection signal to the inter-frame prediction decoding devices 612 to 614.

Next, the operation of the interframe predictive coding system according to the fourth embodiment of the present invention will be described with reference to FIG. FIG. 6 shows still another example of the inter-frame prediction encoding system in which the inter-frame prediction encoding device shown in the first embodiment, the inter-frame prediction decoding device shown in the second embodiment, and the network are combined. 1 shows an embodiment. An input video signal input from an input terminal 610 is compression-coded in an inter-frame predictive coding device 611 and output to a network 609 through a line 602 as an inter-frame predictive coded signal. At this time (normal state), the inter-frame predictive coding apparatus 611 operates as shown in FIG.
Alternatively, as shown in FIG. 3A, a small area of each frame is refreshed.

The network is not limited to the loop type as shown in FIG. 6, but may be a soot type or the like. The network 609 outputs the input inter-frame prediction coded signal to each of the inter-frame prediction decoding devices 612, 613, and 614 through the lines 604, 606, and 608. Each inter-frame prediction decoding device 612, 613, 6
The inter-frame prediction coded signal input to the input terminal 14 is decoded, and each output terminal 615, 616, 6 is decoded as a decoded image signal.
It is output through 17.

Now, the inter-frame predictive coded signal output from the inter-frame predictive coder 611 is being decoded by the inter-frame predictive decoder 612, and the inter-frame predictive decoder 613 performs decoding. Shall not be. An inter-frame predictive coded signal being output from the inter-frame predictive coder 611 is
3, when the decoding is to be started, the system control unit 60
Reference numeral 3 denotes an inter-frame prediction encoding device 611 and an inter-frame prediction decoding device 6
13 is output. At this time, as shown in the present embodiment, there is no problem if the network is the same as or different from the one for transmitting the inter-frame prediction coded signal.

Upon receiving the connection signal, the inter-frame predictive decoding device 613 receives the inter-frame predictive coded signal being output from the inter-frame predictive coding device 611 via the line 606 and performs synchronization detection. On the other hand, after receiving the connection signal, the inter-frame predictive encoding device 611 delays the time required for the inter-frame predictive decoding device 613 to establish synchronization, and temporarily changes the refresh cycle as shown in the first embodiment. And encoding is performed. This allows the inter-frame predictive decoding device 613 to quickly output the decoded image signal through the output terminal 616.

As described above, according to the embodiment of the present invention described above, the refresh area of each frame is reduced during normal encoding except when a new inter-frame predictive encoding apparatus is connected. In addition to increasing the refresh period, the image quality of the encoded image can be improved or the compression ratio can be improved, and when a new inter-frame predictive coding device is newly connected, the refresh area is temporarily increased. And thus shortening the refresh cycle, the decoded image output from the inter-frame predictive decoding device can be quickly changed to a correct image.

[0053]

The interframe predictive coding system according to the present invention is configured as described above, and in particular, by reducing the refresh area having a low compression effect during normal coding, the compression efficiency and the image quality of the decoded image are reduced. In addition to the above, when a new inter-frame prediction encoding device is connected, a connection signal is supplied from the inter-frame prediction decoding device or the network control unit to temporarily increase the refresh area and By shortening the period, a correct decoded image signal can be output immediately from the inter-frame predictive decoding device.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an inter-frame predictive coding apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a relationship between a refresh area of each frame and a refresh cycle according to one method (for each block line), and FIG. 2A is a diagram illustrating a refresh cycle of one frame in a normal state; (B) is a diagram showing a refresh cycle for one frame when the decoding device is turned on later (when a connection signal is received).

FIG. 3 is a diagram illustrating an example of the relationship between the area of the refresh area of each frame and the refresh cycle according to another method (select an arbitrary location), and FIG. (B) is a diagram showing a refresh cycle required for one frame when the decoding device is turned on later (when a connection signal is received).

FIG. 4 is a block diagram showing a configuration of an inter-frame prediction decoding apparatus according to a second embodiment of the present invention.

FIG. 5 is a block diagram illustrating a configuration of an inter-frame predictive coding system according to a third embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration of an inter-frame predictive coding system according to a fourth embodiment of the present invention.

FIG. 7 is a diagram showing a configuration of a conventional inter-frame prediction coding / decoding system including a conventional inter-frame prediction coding device and an inter-frame prediction decoding device.

FIG. 8 is a diagram showing a state in which a refresh frame is inserted between non-refresh frames.

[Explanation of symbols]

101, 401, 510, 610, 701, 721 Input terminal 102, 702 Subtractor 103, 703 Orthogonal transformer 104, 704 Quantizer 105, 705 Variable length encoder 106, 407, 706, 727 Output terminal 107, 404 , 707, 724 Inverse quantization unit 108, 405, 708, 725 Inverse orthogonal transform unit 109 Connection signal input terminal 110 Connection signal reception unit 111 Refresh cycle control unit 112, 411, 712 Switch 113, 408, 713, 729 Memory 114, 406, 714, 726 Adders 201, 301 Refresh area 202, 302 Non-refresh area 402, 722 Synchronization detector 403, 723 Variable length decoder 409 Connection signal transmitter 410 Connection signal output terminal 511, 611 Interframe predictive coding Apparatus 5 9,609 network 512,513,514,612,613,614,7
20 Inter-frame prediction decoding apparatus 501, 502, 503, 504, 505, 506, 5
07, 508, 601, 602, 604, 605, 60
6, 608 lines 515, 516, 517, 615, 616, 617 Output terminal 603 System controller 700 Inter-frame predictive coding device 801 803 Refresh frame 802 Non-refresh frame

Claims (5)

[Claims] An inter-frame prediction encoding unit for inputting a moving image signal, compressing and encoding the same, and outputting an inter-frame prediction encoded signal, a connection signal receiving unit for receiving a connection signal from a decoder, An inter-frame predictive coding apparatus including a refresh cycle control unit that controls a refresh cycle based on a signal from a signal receiving unit and characteristics of an input moving image, wherein a refresh area is adaptively changed. 2. An inter-frame prediction encoding unit for inputting a moving image signal, compressing and encoding the same, and outputting an inter-frame prediction encoded signal, a connection signal receiving unit for receiving a connection signal from a decoder, A refresh cycle control unit that controls a refresh cycle by controlling a signal from a signal receiving unit, wherein the refresh cycle control unit receives a connection signal instructing to temporarily enlarge a refresh area of an input moving image signal. And an inter-frame predictive encoding apparatus, wherein a refresh cycle is temporarily shortened. 3. An inter-frame predictive decoding device for inputting and decoding an inter-frame predictive coded signal and outputting a decoded image signal, wherein the inter-frame predictive decoding device receives a received inter-frame predictive coded signal. When decoding is started in the middle of the process, a synchronization detection unit that synchronizes with the already received interframe prediction coded signal, and a connection signal that controls an area to be refreshed to the interframe prediction coder after synchronization is established And a connection signal transmitting unit for transmitting a frame, and the refresh area is temporarily enlarged by the connection signal so as to reduce the time required for refreshing one frame in the inter-frame predictive coding apparatus. Predictive decoding apparatus. 4. An inter-frame predictive coding device for inputting a moving image signal and outputting an inter-frame predictive coded signal to a network, and two or more receiving and decoding the inter-frame predictive coded signal via a network In the inter-frame predictive decoding system comprising the inter-frame predictive decoding device, the inter-frame predictive decoding device separates the inter-frame predictive coded signal already decoded by another inter-frame predictive decoding device into another. A connection signal transmitting unit that outputs a connection signal for increasing the size of a refresh area of one frame of the inter-frame predictive coded signal when the inter-frame predictive decoding apparatus receives and decodes the inter-frame predictive coded signal; The apparatus temporarily reduces the time required to refresh an entire frame by the connection signal transmitted from the inter-frame predictive decoding apparatus. Wherein the refresh cycle control unit,
An inter-frame predictive coding system wherein a refresh period is temporarily shortened by temporarily increasing a refresh area of an input moving image by controlling a connection signal. 5. An inter-frame predictive coding device for inputting a moving image signal and outputting an inter-frame predictive coded signal to a network, and two or more receiving and decoding the inter-frame predictive coded signal via a network An inter-frame predictive decoding system comprising: an inter-frame predictive decoding apparatus comprising: an inter-frame predictive decoding apparatus for decoding an inter-frame predictive coded signal that has already been decoded by another inter-frame predictive decoding apparatus; A system control unit for outputting a connection signal for increasing the size of the refresh area of one frame of the inter-frame prediction coded signal when receiving and decoding in the coding apparatus, and the inter-frame prediction coding apparatus includes the system control unit. Refreshing that temporarily reduces the time to refresh an entire frame by a connection signal transmitted from the control unit Includes a cycle control unit, by increasing the refresh area of the input moving image temporarily under the control of the connection signal, inter-frame predictive encoding system is characterized in that so as to temporarily shorten the refresh cycle.