JP2000013789A - Method and device for encoding video, recording medium and video communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a video encoding device capable of improving the quantity of information per frame and selecting whether picture quality or motion is given priority on the side of reproduction. SOLUTION: This video encoding device is composed of an output part 300, input part 100 and encoding part 200. The input part 100 is provided with an input video updating part 102 of updating contents in an input video buffer 103. The encoding part 200 is provided with an encoding control part 201, code source selecting part 202 for selecting information, orthogonal transforming part 203 for generating a video stream from the information, quantizing part 204, variable length encoding part 205, structure encoding part 207, inverse quantization part 207 and inverse orthogonal transformation part 208 for decoding the video or differential information, video decoding part 211 for adding the differential information to decoded video, decoded video buffer 209 for storing the decoded video, and video substation part 210 for generating the differential information. The output par 300 is provided with an output circuit 301 for outputting the video stream.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video coding method for compressing and coding a digital video signal, a device therefor, a recording medium storing the program, and a video communication system. The present invention relates to a video encoding method for improving the image quality of a video reproduced with a small code amount by generating video data, an apparatus thereof, a recording medium storing the program, and a video communication system.

[0002]

2. Description of the Related Art Conventionally, there are many video formats related to a video encoding method and apparatus for compressing and encoding a digital video signal. Many of these video encoding methods and apparatuses adopt a compression method that combines intra-frame compression using orthogonal transform and inter-frame compression using motion prediction. In particular, in this compression method, ISO (International Organization for Sta
ndardization), commonly known as MPEG, an image compression standard
(Motion Picture Experts Group) and ITU (Intern
a. Telecommunication Unit) of the image compression standard 261 and the like are currently widely used.

In recent years, MPEG and H.264 have been widely used. Transmission of compressed images encoded in a format such as H.261 via various digital networks is increasing. As this digital network, there are networks of various transfer speeds, from a low transfer speed for transmitting digital moving images such as a data transfer speed of 64 kilobits per second to a high transfer speed exceeding 100 megabits per second. are doing.

Japanese Patent Laid-Open No. 7-95566 discloses a method for efficiently compressing a moving image with a small amount of information of a video signal. According to this method, H. When performing compression encoding in the H.261 format, the resolution of a video can be changed according to the motion of the target video.

[0005]

However, according to the conventional video coding method and the conventional video coding method, the MPEG or H.264 standard, which has already been extended through a network, is used. When transmitting compressed moving image data in a format such as H.261 in real time, there are the following problems.

First, in the case of MPEG, which is widely used, the frame rate is limited to a high frame rate of 24 frames per second or more. When encoding video information having a very low transfer bit rate, the transfer bit rate is limited. Since the frame rate is too high with respect to the rate, there is a problem that the image quality of each frame is extremely deteriorated and is not practical.

Second, MPEG1, MPEG2 main profile main level; 261, and H.264. 26
Standards such as No. 3 do not include a function of selecting and lowering the image quality and frame rate of each frame for one moving image data, thereby reducing the moving image transfer rate. Therefore, for example, it is not possible to prepare moving image data with a high transfer rate in advance, and to perform processing such as selecting image quality priority or motion (frame rate) priority to lower the transfer rate. In addition, there is a problem that the video signal must be compressed each time, and the cost of the video processing increases.

In particular, in the above-mentioned Japanese Patent Application Laid-Open No. 7-95566, since the resolution of the video is determined when the video signal is compressed and coded, the quality of the image cannot be selected on the reproduction side. The second problem cannot be solved.

Further, there is no versatile or compatible compression system capable of transmitting a moving image to an unspecified number of people, and there is no standard which solves the above-mentioned problems.

[0010] Accordingly, the present invention has been made to solve the above-mentioned problems, and its object is to provide MPEG and H.264.
To reduce the substantial frame rate and increase the amount of information per frame for a fixed high frame rate while complying with general-purpose or compatible standard video compression standards such as H.261 It is an object of the present invention to provide a video encoding method, a device therefor, a recording medium, and a video communication system.

Another object of the present invention is to enable a general decoder which does not support scalability to select between giving priority to image quality for each frame or giving priority to motion (frame rate). An encoding method, an apparatus, a recording medium, and a video communication system are provided.

[0012]

According to a first aspect of the present invention, there is provided a video encoding method comprising the steps of: compressing a video signal composed of a plurality of video frames at a predetermined quantization scale; Video encoding method,
Input a plurality of video frames, select a video frame to be encoded from the input plurality of video frames in a predetermined pattern, hold the selected video frame until updated with the next selected video frame, and hold Encoding the video frame to generate video data, decoding the video data to generate a decoded video frame, while holding the video frame, find the difference information between the video frame and the decoded video frame, Encoding difference information to generate difference video data.

The video frame is updated in a predetermined pattern,
Until a video frame is updated to the next video frame, difference information for the same video frame is generated as video data, so that the substantial frame rate can be reduced and the amount of information per frame can be improved.

According to another aspect of the present invention, there is provided a video coding method for compressing a video signal composed of a plurality of video frames by inter-frame compression at a predetermined quantization scale. A plurality of video frames are input, a video frame to be encoded is selected from a plurality of input video frames in a predetermined pattern, and the selected video frame is updated with a next selected video frame. Hold the video frame, generate the video data by encoding the held video frame, decode the video data to generate a decoded video frame, and while holding the video frame,
Video frame, obtain difference information between the decoded video frame, encode the difference information to generate difference video data, when the video frame is updated, determine the motion vector of the updated video frame for the decoded video frame, Differential information is generated based on the motion vector, and either the updated video frame or the differential information is encoded to generate video data or differential video data.

In a video encoding method according to a second aspect, in addition to the features of the video encoding method according to the first aspect, difference information is generated based on a motion vector of an updated video frame for a decoded video frame. Since the frame to be encoded is selected from the updated video frame or its difference information, the content of the video can be changed only when there is a substantial change in the video.

Further, in the video encoding methods of the first and second aspects described above, in the step of generating the differential video data,
When encoding the difference information between the video frame and the decoded video frame, the quantization scale can be made smaller than the previous quantization scale.

By gradually reducing the quantization scale, the quality of the reproduced image can be further improved.

In the above-described video encoding method,
At the stage of selecting video frames in a predetermined pattern, video frames to be encoded may be selected at predetermined intervals from a plurality of input video frames, or one input video of the plurality of input video frames may be selected. For each frame, the displacement between the input video frame and the maintained video frame is measured, and when the measured displacement exceeds a predetermined threshold, the input video frame is updated to update the maintained video frame. You may make it select. Further, at this time, in the step of measuring the displacement, the mean square calculated from the pixel value difference between the input video frame and the maintained video frame for each one of the input video frames. The error may be measured as displacement, and the input video frame and the maintained video frame are divided into predetermined blocks for each input video frame of the plurality of input video frames, and A motion vector may be obtained for each corresponding block, and the total sum of the magnitude of the motion vector may be measured as a displacement.

By arbitrarily selecting a video frame to be encoded, video data can be generated according to a video to be reproduced or according to a data communication speed. As a result, even a general decoder that does not support scalability can easily select between giving priority to image quality for each frame or giving priority to motion (frame rate).

According to another aspect of the present invention, there is provided a video encoding apparatus comprising: an input unit for inputting a signal; an encoding unit for encoding a signal to generate compressed data; and an output unit for outputting compressed data. And a video encoding device having
The input unit includes an input unit for inputting a digital video signal composed of a plurality of video frames, an input video buffer for storing a predetermined video frame from the digital video signal as an input video frame, and a predetermined An input video updating means for selecting a video frame in the pattern and updating the input video frame stored in the input video buffer, comprising: a coding source selecting means for selecting a frame to be coded; Quantizing means for quantizing the frame selected by the code source selecting means at a predetermined quantization scale to generate a quantized coefficient, and coding the quantized coefficient generated by the quantizing means to generate compressed moving image data Encoding means and decoding for generating a decoded video frame or a decoded difference frame based on the quantized coefficients generated by the quantizing means. Stage, a decoded video buffer for storing the decoded video frame, and, if the frame generated by the decoding means is a decoded differential frame, based on the decoded differential frame and the decoded video frame stored in the decoded video buffer. A decoded video generating means for generating a new decoded video frame and updating the content of the decoded video buffer with the new decoded video frame; a decoded video frame stored in the decoded video buffer; and a decoded video frame stored in the input video buffer. Video subtraction means for generating a difference frame from an input video frame which is present, and code source selection means for coding one of the input video frame stored in the input video buffer and the difference frame generated by the video subtraction means. Control means for controlling selection as a frame to be encoded, wherein the output unit outputs the compressed signal generated by the encoding means. An output means for outputting the video data, and wherein the.

In the above-described video encoding apparatus of the present invention, the quantizing means includes means for orthogonally transforming the frame selected by the code source selecting means in predetermined block units to generate orthogonal transform coefficients. Means for generating a quantized coefficient by quantizing the transform coefficient at a predetermined quantization scale, wherein the coding means encodes the quantized coefficient generated by the quantizing means to a variable length to generate a variable length code. A variable-length coding unit for generating the variable-length code generated by the variable-length coding unit, and a structure coding unit for generating compressed moving image data by adding a header or the like to the variable-length code. Means for inversely transforming the quantized coefficients generated in the above to generate transform coefficients, and means for performing inverse orthogonal transform on the transform coefficients, the control means includes an input video buffer and an input video update means of the input unit,
And the encoding unit can be controlled.

The video frame is updated with a predetermined pattern,
Further, by generating a difference frame for the same video frame and selecting the video frame or the difference frame, the substantial frame rate can be reduced to 1
The amount of information per frame can be improved.

Further, in the above-described video encoding apparatus of the present invention, the encoding unit includes quantization control means for determining a quantization scale, and the quantization control means determines whether or not the frame selected by the code source selection means is selected. In the case of a difference frame, the quantization scale can be made smaller than the previous quantization scale.

When the selected frame is a difference frame, the quality of the reproduced image can be further improved by gradually reducing the quantization scale.

In the above-described video encoding apparatus of the present invention, the input video updating means selects video frames at predetermined intervals from the digital video signal input by the input means and stores the input video frames in the input video buffer. Video frames can be updated. The input unit measures a displacement between the video frame and the input video frame stored in the input video buffer for each video frame from the digital video signal input by the input unit, and the displacement exceeds a predetermined threshold. In this case, the input video updating means may include a video analyzing means for controlling the selection of the video frame and updating the input video frame stored in the input video buffer. Further, the video analyzing means includes an error measuring means for measuring a mean square error between a pixel value of the video frame and the input video frame as a displacement, and a mean square error measured by the error measuring means. And a determination unit for determining whether to update the input video frame that has been input. The video frame and the input video frame are divided into predetermined blocks, and a motion vector is set in units of each corresponding block. And a motion measuring means for measuring the sum of the magnitudes of the motion vectors as displacement, and an input video frame stored in the input video buffer based on the sum of the magnitudes of the motion vectors measured by the motion measuring means. And a determination unit for determining whether or not to update.

By arbitrarily selecting a video frame to be encoded from the digital video signal input by the input means, video data can be generated according to a video to be reproduced or a communication speed of data. . As a result, even a general decoder that does not support scalability can easily select between giving priority to image quality for each frame or giving priority to motion (frame rate).

In the above-described video encoding apparatus of the present invention, when the input video frame stored in the input video buffer is updated, the encoding unit performs processing on the decoded video frame stored in the decoded video buffer. A motion vector search unit that obtains a motion vector of the updated input video frame; a video subtraction unit generates a difference frame based on the motion vector obtained by the motion vector search unit; Generating a variable-length code based on the quantization coefficient generated by the quantization means,
The compressed moving image data may be generated based on the variable length code.

A difference frame is generated based on the motion vector of the updated video frame with respect to the decoded video frame, and a frame to be encoded is selected from the updated video frame or the difference frame. The video content can be changed only when there is.

According to another aspect of the present invention, there is provided a computer-readable recording medium comprising: a step of inputting a plurality of video frames; Selecting with a pattern, holding the selected video frame until updated with the next selected video frame, encoding the held video frame to generate video data, Decoding to generate a decoded video frame; and, while holding the video frame, obtaining difference information between the video frame and the decoded video frame, and encoding the difference information to generate difference video data. A program for causing a computer to execute the video encoding method is recorded.

The video frame is updated in a predetermined pattern,
Until a video frame is updated to the next video frame, difference information for the same video frame is generated as video data, so that the substantial frame rate can be reduced and the amount of information per frame can be improved.

According to another aspect of the present invention, there is provided a computer-readable recording medium comprising: a step of inputting a plurality of video frames; Selecting with a pattern, holding the selected video frame until updated with the next selected video frame, encoding the held video frame to generate video data, Decoding and generating a decoded video frame, and while holding the video frame, obtaining difference information between the video frame and the decoded video frame, encoding the difference information to generate differential video data, When the video frame is updated, a motion vector of the updated video frame with respect to the decoded video frame is obtained, Generating difference information based on the reference vector, and coding either the updated video frame or the difference information to generate video data or differential video data. A program for causing the program to be recorded.

In the recording medium according to the second aspect, in addition to the features of the recording medium according to the first aspect, difference information is generated and encoded based on a motion vector of an updated video frame for a decoded video frame. Since the frame is selected from the updated video frame or its difference information, the content of the video can be changed only when there is a substantial change in the video.

In the recording medium according to the first and second aspects, in the step of generating the difference video data, the difference information between the video frame and the decoded video frame is converted to a quantization information smaller than the previous quantization scale. It is also possible to generate differential video data by encoding on a quantization scale.

By gradually reducing the quantization scale, the quality of the reproduced image can be further improved.

In the above-described recording medium, in the step of selecting video frames in a predetermined pattern, video frames to be encoded can be selected from a plurality of video frames at predetermined intervals. Frame 1
Measuring the displacement between the input video frame and the maintained video frame for every two input video frames;
Selecting an input video frame to update a maintained video frame when the measured displacement exceeds a predetermined threshold. Further, the step of measuring the displacement includes, for each input video frame of the plurality of input video frames, a mean square error calculated from a difference in pixel value between the input video frame and the maintained video frame. For each input video frame of the plurality of input video frames, dividing the input video frame and the maintained video frame into predetermined blocks; and for each corresponding block, The method may include a step of obtaining a motion vector and a step of measuring a sum of magnitudes of the motion vectors as a displacement.

By arbitrarily selecting a video frame to be encoded, video data can be generated according to a video to be reproduced or a communication speed of data. As a result, even a general decoder that does not support scalability can easily select between giving priority to image quality for each frame or giving priority to motion (frame rate).

According to another aspect of the present invention, there is provided a video communication system comprising: a video input device for outputting a captured video or a recorded video as a digital video signal; and a digital video signal output from the video input device. A video encoding device that inputs and encodes to generate compressed video data, a video transmission device that transmits the compressed video data generated by the video encoding device over a network, and a compressed video that is transmitted via the network And a video receiving and reproducing device that receives and reproduces data, in a video communication system, the video encoding device is configured with the above-described video encoding device, and the video transmitting device is configured according to a data transfer rate on a network. , Wherein a part of the compressed moving image data is deleted and transmitted.

In the video communication system of the present invention, the video encoding device has the above-described configuration, and the video transmitting device can delete a part of the compressed moving image data according to the data transfer speed. The actual frame rate can be changed in accordance with the data transfer speed of the data to optimize the data transfer speed.

In the above-described video communication system of the present invention, the video receiving and reproducing apparatus includes means for receiving the compressed moving image data, and reproducing means for expanding the received compressed moving image data and reproducing the image. The means can be configured to have an image quality improving means for fixing the video to be reproduced and improving the quality of the video. Further, the image quality improving means may be configured to decode the difference frame related to the video reproduced from the compressed moving image data to improve the image quality of the video.

Since video data can be generated in accordance with the data communication speed, even a general video receiving / reproducing device (such as a decoder) which does not support scalability gives priority to the image quality of each frame or (Frame rate) can be easily selected.

[0041]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a video encoding method and apparatus according to the present invention and a recording medium will be described with reference to the drawings.

< First Embodiment > FIG. 1 is a block diagram showing an overall outline of a video encoding apparatus according to the present invention. This video encoding device has an input unit for inputting a video signal.
100 and an encoding unit 200 for compressing and encoding the video signal
And an output unit 30 for outputting an encoded video format
0, and a control unit 10 that controls each component of the apparatus such as the input unit 100, the encoding unit 200, and the output unit 300.

FIG. 2 shows the input unit 100 and the encoding unit 200 of FIG.
, And a block diagram showing the output unit 300 in detail.
In FIG. 2, an input unit 100 includes an input circuit 101 for inputting an uncompressed digital video signal having a high frame rate such as 30 frames per second, and a digital video signal input from the input circuit 101. An input video update unit 102 for thinning out frames at a fixed interval such as one frame and passing the frames to the input video buffer 103 to update the contents of the input video buffer 103;
An input video buffer 103 for temporarily storing the passed digital video signal is provided.

The encoding section 200 includes an encoding control section 201 for controlling the components in the encoding section 200, the input video updating section 102 and the input video buffer 103 of the input section 100, and an input video buffer 103. A code source selection unit 202 that selects information to be encoded next from the video signal of the video signal and the difference signal from the video subtraction unit 210 and passes it to the orthogonal transformation unit 203;
An orthogonal transform unit 203 for orthogonally transforming the information passed from the block unit, a quantizing unit 204 for quantizing the orthogonal transform coefficient generated by the orthogonal transform unit 203, and a coefficient quantized by the quantizing unit 204. A variable-length encoding unit 205 for encoding into a variable-length code, and necessary information such as a data length are added to the code as a header, and the final video stream (MPEG
Stream, etc.), an inverse quantization unit 207 that inversely quantizes the quantized coefficients generated by the quantization unit 204, and an inverse orthogonal transform coefficient generated by the inverse quantization unit 207. Inverse orthogonal transform unit 208 for transforming and inverse quantization unit 20
A video decoding unit 211 for adding the difference information decoded by the inverse orthogonal transform unit 208 and the previous decoded video stored in the decoded video buffer 209; and a decoded video buffer 209 for temporarily storing the decoded video. And a video subtraction unit 210 that generates difference information from the decoded video stored in the decoded video buffer 209 and the input video.

The output unit 300 includes an output circuit 301 connected to the structure coding unit 206 of the coding unit 200 and outputting the generated video stream. Next, the operation of the video encoding device of the present invention will be described.

FIG. 3 is a flowchart showing the overall operation flow of the video encoding apparatus of the present invention shown in FIG. 1 and FIG. As shown in FIG. 3, the video encoding device of the present invention performs processing according to the following flow.

Step 1100: If there is an unprocessed video to be input, Step 1200: the input circuit 101 inputs one frame of uncompressed video signal, and Step 1300: the input video updating unit 102 It is determined whether or not the input frame has reached the predetermined number of frames to be updated (the number of update frames). Step 2100: If the input frame has reached the number of update frames, the input video update unit 102 , Input circuit 10
The video signal input from 1 is written to the input video buffer 103 to update the stored video signal. Step 2200: The code source selection unit 202 stores the video signal in the input video buffer 103 as video information to be encoded next. The selected video signal is passed to the orthogonal transformation unit 203, and the
Proceed to the process of 00. Step 3100: On the other hand, in step 1300, if the number of input frames has not reached the number of updated frames, the video subtraction unit 210 extracts difference information from the video information stored in the decoded video buffer 209 and the input video buffer 103. Step 3200: The code source selecting unit 202 selects the passed difference information as information to be encoded next, and
Pass to 3. Step 4100: The orthogonal transformer 203 receives the input video information (step 2200) or the difference information (step 3200) from the code source selector 202, and orthogonally transforms the received information in block units to generate transform coefficients. Step 4200: Next, the quantizing section 204 quantizes the transform coefficient generated by the orthogonal transform section 203 to generate a quantized coefficient, which is passed to the variable-length coding section 205 and the inverse quantization section 207. Step 4300: Inverse quantization section 207 and inverse orthogonal transform section 208
Then, the video is decoded using the quantized coefficients generated by the quantization unit 204 and stored in the decoded video buffer 209. Step 4400: On the other hand, the variable length coding unit 205
A variable-length code is generated (variable-length coding) from the transform coefficient generated by step 204. Step 4500: The structure coding unit 206 adds necessary information such as a data length to the variable-length code as a header, A final video stream is generated. Step 4600: The output circuit 301 outputs the video stream generated by the structure coding unit 206, and continues the processing for the next frame again from the beginning (return to step 1100). .

Next, the video decoding processing in step 4300 shown in the flowchart of FIG. 3 will be described in detail.

FIG. 4 is a flowchart showing the video decoding process in step 4300 shown in the flowchart of FIG. As shown in FIG. 4, the content of the video decoding process differs depending on whether the encoded information is input video information or difference information. Hereinafter, the processing will be described.

Step 4301: The inverse quantization unit 207 inversely quantizes the quantized coefficient generated by the quantization unit 204 to generate a transform coefficient. Step 4302: The inverse orthogonal transform unit 208 executes the inverse quantization unit 207 Performs inverse orthogonal transform on the transform coefficient generated by the above to decode information. Step 4303: It is determined whether or not the decoded information is difference information. Step 4304: If the decoded information is difference information, the video adding unit 211 stores the decoded difference information and the decoded video information in the decoded video buffer 209. The new decoded video is generated by adding the decoded video and the decoded video. Step 4305: If the decoded information is not difference information, the decoded video generated by the inverse orthogonal transform 208 is used. If the decoded information is difference information, the video adding unit 21 is used.
1 is transferred to the decoded video buffer 209.
To be stored.

As described above, according to the video encoding apparatus and the video encoding method of the present invention, a video signal is compressed into a video format such as the MPEG format, and a signal format of a high frame rate is substantially retained while maintaining the signal format. It is possible to improve the image quality of video reproduced even at an extremely low transfer rate by lowering the frame rate.

Next, input video information (hereinafter, also simply referred to as "input video"), decoded video, and difference information (hereinafter, also simply referred to as "difference video") will be described.

FIG. 5A shows a part of one frame for each of the input video, FIG. 5B shows the decoded video, and FIG. 5C shows the differential video. Here, in FIG. 5A, Io (x, y) is the luminance of the pixel at the horizontal x and vertical y position,
Or it is a value of the input of the color difference. Also, in FIG. 5B, Ir (x, y) is the luminance of the pixel at the horizontal x and vertical y positions,
Or the decoded value of the color difference. Here, the decoded value of the chrominance is, in the case of a code that is intra-frame coded, a pixel value generated by inversely transforming the quantized value once by orthogonal transformation and inverse orthogonal transformation, In the case of a code that has been subjected to inter-frame coding, it is a pixel value obtained by adding a pixel value generated as described above to a previously decoded pixel value. Also, in FIG. 5C, D (x, y) is a pixel value indicating a luminance difference or a color difference between the input video and the decoded video of the pixel at the horizontal x and vertical y positions.

FIG. 6 is a diagram showing the relationship between the processing of the video encoding apparatus according to the present invention and the input video, decoded video and output video stream used in the apparatus. FIG.
In the video encoding apparatus of the present invention, first, the first frame of the input video O is first stored in the input video buffer 103 (FIG. 2). The first frame of this input video O is O1 in FIG.
Corresponding to In the first encoding process (see FIGS. 3 and 4), the input video frame O1 is directly encoded (intra-encoded) by the orthogonal transformation unit 203 (FIG. 2) and the quantization unit 204 (FIG. 2). An I picture of the video stream is generated. The I picture of the video stream generated in the first encoding process corresponds to I1 in FIG. On the other hand, the quantized coefficients used for I1 are decoded into the decoded video R by the inverse quantization unit 207 (FIG. 2) and the inverse orthogonal transform unit 208 (FIG. 2) as described above, and the decoded video buffer 103 Is stored in The stored decoded video R corresponds to R11 in FIG.

In the next encoding process, the difference between the input video O1 and the decoded video R11 is calculated by the video subtraction unit 210 (FIG. 2).
The resulting difference information (O1-R11) is encoded by the orthogonal transform unit 203 and the quantization unit 204, and a P picture (differential video stream) of the video stream is generated. The difference video stream P generated at this time corresponds to P1 in FIG.
On the other hand, the quantized coefficients used for the difference video stream P1 are decoded by the inverse quantization unit 207 and the inverse orthogonal transform unit 208, and are added to the decoded video R11 to form a new decoded video R12. (The quantized coefficient before decoding the decoded video R11 is I1, and therefore, in FIG. 6, "(I1 + P1) is decoded" for simplicity). Hereinafter, similarly, difference video streams P2 and P3 and a decoded video R13 are generated. When performing the next encoding process that has generated the differential video stream P3, the input video buffer 103
Is updated by the input video updating unit 102. The updated input video O 2 corresponds to O2 in FIG. Thereafter, the encoding of the input video O2 is performed in the same manner as the encoding of the input video O1.

As described above, in the case of the processing in FIG. 6, the input video O does not change for four frames of the video stream.
During this time, inter-frame encoding is performed, but the input video O as a base is all the same video O1. Therefore, when the generated video stream is reproduced, it looks like a quarter frame rate in appearance. That is, in FIG. 6, since the substantial frame rate of the output video stream is one quarter of the actual frame rate, for example, in the case of an MPEG stream having a frame rate of 30 frames per second, The (apparent) frame rate is 7.5 frames per second.

Further, while the input image O is fixed,
In the video stream, difference information between the base input video O and the decoded video R is encoded as P pictures. Since the difference information P is a difference between before and after encoding, it indicates an encoding error, in other words, information lost during encoding. Therefore, when the generated video stream is reproduced, while the P picture is being reproduced, the video (I picture) does not move, but appears to be gradually clearer.

On the other hand, when only the I picture of the video stream is selected and reproduced without the P picture, the video is not sharpened by the P picture as described above. it can. That is, even when the code amount (bit rate) is reduced by the amount excluding the P picture, the video can be reproduced with the image quality reduced while maintaining the predetermined frame rate.

As is clear from the above description, according to the video encoding apparatus and the video encoding method of the first embodiment of the present invention, for example, a format limited to a high frame rate such as MPEG is used. Even if there is, it is possible to arbitrarily lower the apparent frame rate and reduce the amount of code to generate a stream with an extremely low bit rate.

< Second Embodiment > Next, a second embodiment of the video encoding apparatus and the video encoding method of the present invention will be described. The difference between the present embodiment and the first embodiment is that the video encoding device and the video encoding method of the present embodiment gradually reduce the quantization scale when encoding the difference information. By quantizing, it is possible to send more detailed difference information.

FIG. 7 is a block diagram of a video encoding apparatus according to the present invention. The configuration of this video encoding device differs from the configuration of the device shown in the first embodiment in the following points. That is, in addition to the components included in the video encoding device described in the first embodiment, in the video encoding device according to the second embodiment, the video encoding device 200 is connected to the quantization unit 204 in the encoding unit 200. And a quantization control unit 212 for controlling the quantization scale used in the quantization unit 204. Next, the operation of the video encoding device according to the present embodiment will be described.

FIG. 8 is a flowchart showing the overall operation flow of the video encoding apparatus according to the present embodiment. As shown in FIG. 8, the processing flow of the video encoding device according to the present embodiment is the same as that of the flowchart shown in FIG.
The difference is that a step 1210 is added between 00 and 1300. That is, the video encoding method by the video encoding device according to the present embodiment has the following processing flow.

Step 1100: If there is an unprocessed video to be input, Step 1200: the input circuit 101 inputs one frame of uncompressed video signal. Step 1210: The quantization control unit 212 A quantization scale suitable for encoding quantization is set and the quantization scale of the quantization unit 204 is updated. Step 1300: In the input video updating unit 102, the input frame is updated by a predetermined number of frames to be updated. (Step 2100) If the number of input frames has reached the number of updated frames, the input video updating unit 102
The video signal input from 1 is written to the input video buffer 103 to update the stored video signal. Step 2200: The code source selection unit 202 stores the video signal in the input video buffer 103 as video information to be encoded next. The selected video signal is passed to the orthogonal transformation unit 203, and the
Proceed to the process of 00. Step 3100: On the other hand, in step 1300, if the number of input frames has not reached the number of updated frames, the video subtraction unit 210 extracts difference information from the video information stored in the decoded video buffer 209 and the input video buffer 103. Step 3200: The code source selecting unit 202 selects the passed difference information as information to be encoded next, and
Pass to 3. Step 4100: The orthogonal transformer 203 receives the input video information (step 2200) or the difference information (step 3200) from the code source selector 202, and orthogonally transforms the received information in block units to generate transform coefficients. Step 4200: Next, the quantizing section 204 quantizes the transform coefficient generated by the orthogonal transform section 203 with the quantization scale set by the quantization control section 212 to generate a quantized coefficient, and performs variable length coding. This is passed to the section 205 and the inverse quantization section 207. Step 4300: Inverse quantization section 207 and inverse orthogonal transform section 208
Then, the video is decoded using the quantized coefficients generated by the quantization unit 204 and stored in the decoded video buffer 209. Step 4400: On the other hand, the variable length coding unit 205
A variable-length code is generated (variable-length coding) from the transform coefficient generated by step 204. Step 4500: The structure coding unit 206 adds necessary information such as a data length to the variable-length code as a header, A final video stream is generated. Step 4600: The output circuit 301 outputs the video stream generated by the structure coding unit 206, and continues the processing for the next frame again from the beginning (return to step 1100). .

As is clear from the above description, the difference from the processing in the first embodiment is that the quantization scale is updated for each encoding in the video encoding apparatus of the present embodiment (step 1210). is there. In the flowchart shown in FIG. 8, a step of updating the quantization scale for each encoding (step 1210) may be added between steps 4100 and 4200.

This quantization scale is determined by the I picture (FIG. 6).
), The coarsest quantization is performed, and each time a P picture (see FIG. 6) is repeated, the quantization is updated so that fine quantization can be performed. If it returns, the most efficient encoding can be performed at the time of encoding all the pictures. That is, since the P picture is an error (difference) of the previously coded video with respect to the input video O, if the P video which is an error is added and the input video O is repeatedly encoded, the error with respect to the input video O gradually increases. To decrease,
Its value gradually decreases.

In general, when the value of an error to be coded becomes sufficiently small with respect to the quantization scale, all the error values become 0 at the time of quantization, so that it is impossible to further improve the image quality. . On the other hand, in the video encoding device and the video encoding method according to the present embodiment, the quantization scale can be arbitrarily reduced in accordance with the number of pieces of difference information of the picture to be encoded. Can be encoded.

Therefore, in the video encoding device and the video encoding method of the present embodiment, in addition to the features shown in the first embodiment, the quantization scale is gradually increased when encoding the difference information. Since the quantization can be made finer, more detailed difference information can be sent. That is, in the video encoding device and the video encoding method of the present embodiment, the apparent frame rate is extremely low (1/10,
This is particularly effective in the case where it is 1/20.

As is apparent from the above description, according to the video encoding device and the video encoding method of the second embodiment,
Even when the difference between the input video and the decoded video is repeatedly encoded many times, the image quality of the encoded video can be effectively improved.

< Third Embodiment > Next, a description will be given of a third embodiment of the video encoding apparatus and the video encoding method according to the present invention. The difference between the present embodiment and the first embodiment is that, in the video encoding device and the video encoding method of the present embodiment, the frame interval for updating the input video is not a fixed interval, but the input video is updated. The point is that it can be arbitrarily changed according to the magnitude of the change.

FIG. 9 is a block diagram of a video encoding apparatus according to the present embodiment. The configuration of this video encoding device is the first
It differs from the configuration of the device shown in the embodiment in the following points. That is, in addition to the components included in the video encoding device described in the first embodiment, in the video encoding device according to the third embodiment, the input video updating unit 102 and the input video It is connected to the buffer 103 and has a video analyzing unit 104 that determines whether or not to update the input video with reference to the input video. Next, the operation of the video encoding device according to the present embodiment will be described.

FIG. 10 is a flowchart showing the overall operation flow of the video encoding apparatus according to the present embodiment. FIG.
As shown in FIG. 0, the processing flow of the video encoding apparatus according to the present embodiment is different in that step 1300 is replaced by step 1220 and step 1310 in the flowchart shown in FIG. That is, the video encoding method by the video encoding device according to the present embodiment has the following processing flow.

Step 1100: If there is an unprocessed video to be input, Step 1200: the input circuit 101 inputs one frame of uncompressed video signal, and Step 1220: the video analysis unit 104 Measuring the magnitude of the change by comparing the video signal with the video signal currently being used for encoding, step 1310: determining whether the magnitude of the change is greater than a predetermined threshold, Step 2100: If the magnitude of the change in the video signal is larger than a predetermined threshold, the input video update unit 102
Step 2200: The code source selecting unit 202 stores the video signal input from the input video buffer 103 in the input video buffer 103 as video information to be coded next. The selected video signal is passed to the orthogonal transform unit 203, and the
Proceed to the process of 00. Step 3100: On the other hand, if the magnitude of the change is not larger than the predetermined threshold in step 1310, the video subtraction unit 21
0 generates difference information from the video information stored in the decoded video buffer 209 and the input video buffer 103 and passes the difference information to the code source selection unit 202. Step 3200: The code source selection unit 202 The selected difference information is selected as the
Pass to 3. Step 4100: The orthogonal transformer 203 receives the input video information (step 2200) or the difference information (step 3200) from the code source selector 202, and orthogonally transforms the received information in block units to generate transform coefficients. Step 4200: Next, the quantizing section 204 quantizes the transform coefficient generated by the orthogonal transform section 203 to generate a quantized coefficient, which is passed to the variable-length coding section 205 and the inverse quantization section 207. Step 4300: Inverse quantization section 207 and inverse orthogonal transform section 208
Then, the video is decoded using the quantized coefficients generated by the quantization unit 204 and stored in the decoded video buffer 209. Step 4400: On the other hand, the variable length coding unit 205
A variable-length code is generated (variable-length coding) from the transform coefficient generated by step 204. Step 4500: The structure coding unit 206 adds necessary information such as a data length to the variable-length code as a header, A final video stream is generated. Step 4600: The output circuit 301 outputs the video stream generated by the structure coding unit 206, and continues the processing for the next frame again from the beginning (return to step 1100). .

As is apparent from FIG. 10, the difference from the processing in the first embodiment is that the video encoding apparatus of the present embodiment analyzes the video signal every time the video signal is input (step 1220). ), It is determined whether or not to update the video signal used for encoding according to the analysis result (step 1310).

FIGS. 11A and 11B correspond to FIGS.
FIG. 3 is a block diagram showing an example of the configuration of a video analysis unit 104 shown by. In FIG. 11A, the video analysis unit 104 includes an error measurement unit 111 and a determination unit 112. First, the error measuring unit 111 of the video analyzing unit 104 inputs a video signal from the input circuit 101 (FIG. 9) and the input video buffer 103 (FIG. 9), and calculates the pixel value (for example, luminance value) of each of two videos. The difference is calculated and the mean square error is calculated. Next, the determination unit 112 compares the obtained value of the mean square error with a predetermined threshold value. When the mean square error is larger than the threshold, the determination unit 112 transmits an update control signal instructing to update the input video signal to the input video updating unit 102 (FIG. 9). Then, an update control signal instructing not to update the input video signal is transmitted to the input video update unit 102.

In FIG. 11B, a video analyzing unit
104 includes a motion measurement unit 113 and a determination unit 112.
First, the motion measuring unit 113 inputs a video signal from the input circuit 101 (FIG. 9) and the input video buffer 103 (FIG. 9), and calculates a motion vector for a part of the video from the input circuit 101, for example, for each macroblock. Detect and calculate the sum of the magnitudes (distances) of all motion vectors. Next, the judgment unit
112 compares the sum of the determined motion vectors with a predetermined threshold. If the sum of the motion vectors is larger than the threshold, the determination unit 112 transmits an update control signal instructing the input video update unit 102 (FIG. 9) to update the input video signal, and the sum of the motion vectors is smaller than the threshold. In this case, an update control signal instructing not to update the input video signal is transmitted.

Here, when performing video analysis with the configuration shown in FIG. 11A, since the mean square error is used as a variation, there is a useful effect that the amount of calculation required for the analysis can be reduced. However, even when only the luminance changes and there is no apparent movement of the video, such as when the entire video becomes brighter, the input video is updated. Therefore, when the apparent change in the video does not match the update of the input video. May occur. On the other hand, when the video analysis is performed with the configuration shown in FIG. 11B, the apparent change of the video matches the update of the input video because the actual motion vector is used as the change amount. However, in this case, a larger amount of calculation is required for motion vector detection than in FIG.

As described above, in the video encoding apparatus and the video encoding method of the present embodiment, in addition to the features shown in the first embodiment, the frame interval for updating the input video is fixed. It can be changed arbitrarily according to the magnitude of the change of the input image instead of the interval. That is, when the video stream generated by the video encoding device according to the present embodiment is reproduced, the portion where the change of the original video is not large gradually improves the image quality instead of stopping the apparent movement, and In a portion where there is a change, it is possible to suppress an improvement in image quality and smooth an apparent movement or change.

The quantization scale can be changed by adding the quantization control section 212 of the device shown in the second embodiment to the device shown in the third embodiment. As described in the embodiment, the effect of effectively improving the image quality can be obtained even when encoding the difference information many times.

As is apparent from the above description, according to the present embodiment, even when a compressed stream having a fixed and low transfer rate is generated, if the motion is large, the motion is prioritized, and the motion is small. In this case, the quality of the compressed stream video can be improved by giving priority to the image quality.

< Fourth Embodiment > Next, a fourth embodiment of the video coding apparatus and the video coding method of the present invention will be described. The difference between the present embodiment and the first embodiment is that, in the video encoding device and the video encoding method of the present embodiment, the input video itself is encoded not only as I pictures but also as P pictures. In this way, it is possible to reproduce at a plurality of transfer rates similar to the first embodiment, and further improve the video compression efficiency.

FIG. 12 is a block diagram of a video encoding apparatus according to the present embodiment. The configuration of this video encoding device differs from the configuration of the device shown in the first embodiment in the following points. That is, in addition to the components included in the video encoding device shown in the first embodiment, in the video encoding device according to the fourth embodiment, the input video buffer 103, the variable-length encoding unit 205, The encoding unit 200 includes a motion vector search unit 213 that is connected to the video buffer 209 and the video subtraction unit 210 and detects a motion vector from the input video and the decoded video. Next, the operation of the video encoding device according to the present embodiment will be described.

FIG. 13 is a flowchart showing the flow of the entire operation of the video encoding apparatus according to the present embodiment. FIG.
As shown in FIG. 3, the process flow of the video encoding device according to the present embodiment is such that a step 2110 is added between steps 2100 and 2200 in the flowchart shown in FIG.
Also, as the process branched in step 2110, step 2310
The difference is that ~ 2330 has been added. That is,
The video encoding method by the video encoding device according to the present embodiment has the following processing flow.

Step 1100: If there is an unprocessed video to be input, Step 1200: The input circuit 101 inputs the uncompressed video signal for one frame. Step 1300: The input circuit 101 It is determined whether or not the input frame has reached the predetermined number of frames to be updated (the number of update frames). Step 2100: If the input frame has reached the number of update frames, the input video update unit 102 , Input circuit 10
The video signal input from step 1 is written to the input video buffer 103 to update the stored video signal. Step 2110: The encoding control unit 201 determines the encoding format of the updated input video signal. 2200: When encoding an input video signal as an I picture, the code source selection unit 202 selects a video signal stored in the input video buffer 103 as video information to be encoded next, and sends the video signal to the orthogonal transformation unit 203. Hand over, step 4100
Proceed to processing. Step 2310: When encoding the input video signal as a P picture, the motion vector search unit 213 compares the video signal of the input video buffer 103 with the video signal stored in the decoded video buffer 209, and A vector search is performed, and the obtained motion vector is passed to the video subtraction unit 210 and the variable-length coding unit 205. Step 2320: The video subtraction unit 210
The difference between the input video signal of the input video buffer 103 and the decoded video signal of the decoded video buffer 209 is obtained using the motion vector passed from the
Step 2330: The code source selecting unit 202 selects the passed difference information as information to be encoded next, and
Pass to 3. Step 3100: On the other hand, in step 1300, if the number of input frames has not reached the number of updated frames, the video subtraction unit 210 extracts difference information from the video information stored in the decoded video buffer 209 and the input video buffer 103. Step 3200: The code source selecting unit 202 selects the passed difference information as information to be encoded next, and
Pass to 3. Step 4100: The orthogonal transformer 203 receives the input video information (step 2200) or the difference information (step 2330 or step 3200) from the code source selector 202, and orthogonally transforms the received information into blocks to generate transform coefficients. I do. Step 4200: Next, the quantizing section 204 quantizes the transform coefficient generated by the orthogonal transform section 203 to generate a quantized coefficient, which is passed to the variable-length coding section 205 and the inverse quantization section 207. Step 4300: Inverse quantization section 207 and inverse orthogonal transform section 208
Then, the video is decoded using the quantized coefficients generated by the quantization unit 204 and stored in the decoded video buffer 209. Step 4400: On the other hand, the variable length coding unit 205
204 or from the transform coefficients generated by
A variable-length code is generated (variable-length coding) from the transform coefficients generated by the above and the motion vector passed from the motion vector search unit 213. Step 4500: The structure coding unit 206 Step 4600: The output circuit 301 outputs the video stream generated by the structure coding unit 206 and adds the necessary information such as the length as a header to the next frame. On the other hand, the processing is continued from the beginning (return to step 1100).

As is apparent from FIG. 13, the difference from the processing in the first embodiment is that the input video signal of the input video buffer 103 is updated in the video encoding device and the video encoding method of the present embodiment. This is the point where the processing for encoding the updated video as a P picture has been added when the update is performed (steps 2110, 2310, 2320, and 2330). That is, in the video encoding device and the video encoding method of the present embodiment, in addition to the features of the first embodiment, by encoding the input video itself not only as an I picture but also as a P picture, Further, the compression efficiency of the video can be improved.

In the video coding apparatus and the video coding method according to the present embodiment, when the input video signal of the input video buffer 103 is updated, the video subtraction unit 210 A motion-predicted difference image is generated using the vector. On the other hand, the input video buffer 10
If the input video signal of No. 3 is not updated, in a step 3100 for generating difference information, the video subtraction unit 210 determines from the motion vector search unit 213 that there is no motion of the input video.
Is received as a motion vector to generate difference information. Therefore, the difference information generated here is the same as the difference information generated in the first embodiment.

Here, the relationship between the input video signal and the video information to be encoded in the above-described fourth embodiment will be described with reference to the drawings.

FIG. 14 is a diagram showing the relationship between the processing of the video coding apparatus according to the present embodiment, the input video, the decoded video used in the video coding apparatus, and the output video stream. . FIG. 14 corresponds to FIG. 6 shown in the first embodiment. In the video encoding device according to the fourth embodiment, the same processing as in the first embodiment shown in FIG. 6 is performed until the following three pictures are encoded from the first I picture. This embodiment differs from the first embodiment in the processing after the input video signal of the input video buffer 103 (FIG. 12) is updated.

In the video encoding apparatus according to the present embodiment, when the input video O stored in the input video buffer 103 is updated, and the updated input video O is encoded as a P picture (differential video stream), Processing for encoding the P picture PO1 shown in FIG. 14 is performed. That is,
A decoded video R13 obtained by decoding the video information encoded before
And the updated input video O2, P
Encode the picture to generate a new P picture PO1. This P picture PO1 is a video stream I2 of FIG.
When the P-picture PO1 is reproduced, there is a motion in the reproduced video, while the video having the same contents as the above is encoded and there is no apparent movement when the differential video streams P1 to P3 are reproduced. After that, as in the first embodiment, the difference between the input video O2 and the video obtained by decoding the P picture PO1 is coded as the next P picture, and the coding process is continued.

As described above, when the video stream generated by the video encoding apparatus according to the present embodiment is reproduced, similarly to the first embodiment, the apparent frame rate is reduced, but the image quality of each video frame is reduced. It gradually improves.

When only the I picture of the video stream coded by this device and the P picture of the input video coded are selected and reproduced, the image quality is not improved, but the apparent frame rate is Will be maintained. On the other hand, I
If only the picture and the P picture (I1, P1, P2, P3 shown in FIG. 14) for improving the picture quality of the I picture are selected and reproduced, the apparent frame rate is reduced, but the picture quality of each frame is reduced. improves.

As described above, by selecting a frame to be reproduced at the time of reproduction, it is possible to select whether to give priority to motion or image quality for each frame even at a limited transfer rate. Video can be played. Also, if only the I picture is selected and reproduced, the apparent frame rate can be further reduced, and the video stream can be handled as a lower transfer rate video stream. As described above, the video stream encoded by the video encoding device according to the present embodiment can select the characteristics of the video on the reproduction side and can use a generally used encoding standard such as M
Since encoding can be performed in accordance with standards such as PEG, a special reproducing device is not required.

As is clear from the above description, according to the video encoding apparatus and the video encoding method described in the fourth embodiment, the video stream to be reproduced can be set to an extremely low transfer rate. Also, it is possible to generate a compressed video stream in which the frame rate and image quality can be selected on the reproduction side without using a special reproduction device.

The video encoding method has been described as the first to fourth embodiments. However, such a process may be recorded on a computer-readable recording medium as a program for causing a computer to execute such a process.

< Fifth Embodiment > Next, as a fifth embodiment, a video communication system using the video encoding device of the present invention as shown in the first to fourth embodiments will be described. explain.

FIG. 15 is a block diagram showing a configuration of a video communication system according to the present invention. The video communication system includes a video camera 5100 that captures a video and outputs it as a digital video signal, a video encoding device 5200 that compresses a video signal output from the video camera 5100 and encodes the video stream, A video transmission device 5300 for transmitting a video stream generated by the video encoding device 5200 over a network, a high-speed network 5410 such as a LAN (Local Area Network), and a narrow-band integrated services digital network (ISDN).
ervices Digital Network)
20, high speed network 5410 or low speed network 5420
And a video receiving / reproducing device 5500 that receives the video stream transmitted through the device and reproduces the video stream. Here, the video encoding device 5200 may use the video encoding device described in any of the first to fourth embodiments. Next, the operation of the video communication system shown in FIG. 15 will be described.

FIG. 16 is a flowchart showing the operation flow of the video communication system according to the present invention. Hereinafter, FIG.
6, the operation of the video communication system of the present invention will be described. Step 10000: The video camera 5100 captures an image, converts the image into a digital image signal, and converts the image into a digital image signal.
Step 11000: The video encoding device 5200 generates a video stream from the digital video signal and passes it to the video transmission device 5300. Step 12000: The video transmission device 5300 directly transmits this video stream to the high-speed network 5410 as it is. Send,
A part (for example, only I pictures) in the video stream is selected and transmitted to the low-speed network 5420. Step 13000: The video receiving / reproducing device 5500 receives a video stream from the high-speed network 5410 or the low-speed network 5420, and Step 14000: reproduces the received video stream.

As described above, according to the video communication system of the present invention, the video captured by the video camera 5100 is compressed and encoded into the video format by the video encoding device 5200, and the generated video stream is transmitted. The video stream transmitted by the device 5300 via the high-speed and low-speed networks 5410 and 5420, and the transmitted video stream can be received and reproduced by the video reception / reproduction device 5500.

In this processing, the transfer rate of the entire video stream generated by the video encoding device 5200 is set to a transfer rate suitable for transmission on the high-speed network 5410, and this video stream is set to the low-speed network 5420.
When the transmission is performed by the video transmission device 5300, the video transmission device 5300 can selectively thin out the video stream to have a transfer rate suitable for transmission over the low-speed network 5420. By doing so, it is possible to obtain video streams at a plurality of transfer rates in one encoding process, and to improve the processing efficiency of the video communication system.

When the video receiving / reproducing apparatus 5500 connected to the low-speed network 5420 reproduces a video, the image quality cannot be improved during the reproduction because the transfer rate of the video stream is kept low. When stopped, there is no need to advance the video frame.
If the 5300 sends the difference information to improve the image quality for the stopped video frame, and the video receiving and reproducing device 5500 plays the transmitted difference information, the image quality gradually improves while the motion of the video is stopped. Can be done.

The video coding apparatus, the video coding method, the recording medium, and the video communication system according to the present invention have been described above. 261, H .; For example, a general format relating to a moving image such as H.263 can be easily applied.

[0101]

As is clear from the above description, according to the video encoding apparatus, the video encoding method, the recording medium, and the video communication system of the present invention, MPEG and H.264 are used. 261 and the like, while reducing the substantial frame rate for a fixed high frame rate and reducing the amount of information per frame, while complying with the standard video compression standard that combines inter-frame compression and intra-frame compression. Can be improved.

Also, in a general decoder that does not support scalability, the image quality of each frame is given priority.
You can now select whether to give priority to movement (frame rate).

Further, this makes it possible to reproduce a moving picture adapted to various environments and requests at low cost without requiring a special reproducing device or skill on the user side.

[Brief description of the drawings]

FIG. 1 is an overall block diagram of a video encoding device according to the present invention.

FIG. 2 is a block diagram of a video encoding device according to the present invention.

FIG. 3 is a flowchart of the entire processing of the video encoding device of the present invention.

FIG. 4 is a flowchart of a video decoding process.

FIG. 5 is a diagram showing an input video, a decoded video, and a difference video.

FIG. 6 is a diagram showing the relationship between output compressed data and processing.

FIG. 7 is a block diagram of a video encoding device according to the present invention.

FIG. 8 is a flowchart of the entire processing of the video encoding device of the present invention.

FIG. 9 is a block diagram of a video encoding device according to the present invention.

FIG. 10 is a flowchart of the entire processing of the video encoding device of the present invention.

FIG. 11 is a block diagram of a video analysis unit.

FIG. 12 is a block diagram of a video encoding device according to the present invention.

FIG. 13 is a flowchart of the entire processing of the video encoding device of the present invention.

FIG. 14 is a diagram illustrating a relationship between output compressed data and processing.

FIG. 15 is a configuration diagram showing a video communication system of the present invention.

FIG. 16 is a flowchart of the entire processing of the video distribution system of the present invention.

[Explanation of symbols]

 Reference Signs List 10 control unit 100 input unit 101 input circuit 102 input video update unit 103 input video buffer 104 video analysis unit 111 error measurement unit 112 determination unit 113 motion measurement unit 200 coding unit 201 coding control unit 202 code source selection unit 203 orthogonal transform Unit 204 quantization unit 205 variable length encoding unit 206 structure encoding unit 207 inverse quantization unit 208 inverse orthogonal transform unit 209 decoded video buffer 210 video subtraction unit 211 video addition unit 212 quantization control unit 213 motion vector search unit 300 output Unit 301 output circuit 5100 video camera 5200 video encoding device 5300 video transmission device 5410 high-speed network 5420 low-speed network 5500 video reception / reproduction device

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazunori Yamada 1006 Kazuma Kadoma, Kazuma City, Osaka Prefecture F-term (reference) 5C059 KK34 MA01 MA05 MA21 MC18 ME01 NN01 NN27 PP05 PP06 RA01 RC08 RC28 RE20 SS06 TA18 TB04 TC12 TD03 TD12 UA02 UA33 UA39

Claims (25)

[Claims] 1. A video encoding method for compressing a video signal composed of a plurality of video frames by inter-frame compression at a predetermined quantization scale and encoding the plurality of video frames, comprising: A video frame to be encoded is selected from a video frame in a predetermined pattern, the selected video frame is held until it is updated by a next selected video frame, and the held video frame is encoded to generate video data. Generating the decoded video frame by decoding the video data, while holding the video frame, determine the difference information between the video frame and the decoded video frame, encoding the difference information A video encoding method for generating differential video data. 2. A video encoding method for compressing a video signal composed of a plurality of video frames by inter-frame compression at a predetermined quantization scale and coding the plurality of video frames. A video frame to be encoded is selected from a video frame in a predetermined pattern, the selected video frame is held until it is updated by a next selected video frame, and the held video frame is encoded to generate video data. Generating the decoded video frame by decoding the video data, while holding the video frame, obtain the difference information between the video frame and the decoded video frame, encoding the difference information When the video frame is updated, the motion vector of the updated video frame with respect to the decoded video frame is generated. Determined, and generates difference information based on the motion vector,
A video encoding method comprising: encoding one of the updated video frame and the difference information to generate video data or difference video data. 3. The step of generating the difference image data includes:
3. The encoding apparatus according to claim 1, wherein when encoding the difference information between the video frame and the decoded video frame, a quantization scale is made smaller than a previous quantization scale.
The video encoding method as described in the above. 4. The method according to claim 1, wherein the step of selecting the video frames in a predetermined pattern includes selecting video frames to be encoded at predetermined intervals from the plurality of input video frames. Video encoding method. 5. The method according to claim 1, wherein the step of selecting the video frame in a predetermined pattern includes the step of selecting one of the plurality of input video frames.
For each of the input video frames, measure the displacement between the input video frame and the maintained video frame, and update the maintained video frame when the measured displacement exceeds a predetermined threshold. 4. The video encoding method according to claim 1, wherein the input video frame is selected for the purpose. 6. The step of measuring the displacement is performed by calculating, for each input video frame among the plurality of input video frames, a difference between pixel values of the input video frame and a maintained video frame. 6. The video encoding method according to claim 5, wherein a mean square error is measured as a displacement. 7. The step of measuring the displacement includes dividing the input video frame and the maintained video frame into predetermined blocks for each one input video frame of the plurality of input video frames, 6. The video encoding method according to claim 5, wherein a motion vector is obtained for each corresponding block, and a total sum of magnitudes of the motion vectors is measured as a displacement. 8. A video encoding apparatus comprising: an input unit for inputting a signal; an encoding unit for encoding the signal to generate compressed data; and an output unit for outputting the compressed data. Input means for inputting a digital video signal composed of a plurality of video frames; input video buffer for storing a predetermined video frame from the digital video signal as an input video frame; predetermined input from the digital video signal input by the input means; Input image updating means for selecting an image frame in the input image buffer by selecting an image frame according to the pattern described above, wherein the encoding unit selects a frame to be encoded. And quantizing the frame selected by the code source selecting means at a predetermined quantization scale to generate a quantized coefficient. Decoding means; coding means for coding the quantized coefficients generated by the quantizing means to generate compressed moving image data; decoded video based on the quantized coefficients generated by the quantizing means. A decoding unit that generates a frame or a decoded difference frame; a decoded video buffer that stores a decoded video frame; and a frame that is generated by the decoding unit is a decoded difference frame. Decoding video generating means for generating a new decoded video frame based on the stored decoded video frame and updating the content of the decoded video buffer with the new decoded video frame; and storing the decoded video buffer in the decoded video buffer. A difference frame from the decoded video frame that has been input and the input video frame stored in the input video buffer. A video subtraction unit to be generated, and the code source selection unit selects one of the input video frame stored in the input video buffer or the difference frame generated by the video subtraction unit as a frame to be encoded. And a control unit for performing control so as to perform the processing, wherein the output unit includes an output unit that outputs the compressed moving image data generated by the encoding unit. 9. The quantization means includes means for orthogonally transforming the frame selected by the code source selection means in a predetermined block unit to generate an orthogonal transformation coefficient, and a method for quantizing the orthogonal transformation coefficient by a predetermined quantization. Means for quantizing on a scale to generate a quantized coefficient, wherein the encoding means encodes the quantized coefficient generated by the quantizing means to a variable length to generate a variable length code. Encoding means, and a structure encoding means for generating compressed moving image data by adding a header or the like to the variable-length code generated by the variable-length encoding means, wherein the decoding means comprises: Means for generating a transform coefficient by inversely quantizing the quantized coefficient generated in the above, and means for performing an inverse orthogonal transform of the transform coefficient, wherein the control means includes the input video buffer of the input unit and the input. Image update The video encoding device according to claim 8, wherein the video encoding device controls the encoding unit. 10. The encoding unit includes quantization control means for determining the quantization scale. The quantization control means, when the frame selected by the code source selection means is the difference frame, 10. The video encoding apparatus according to claim 8, wherein the quantization scale is smaller than a previous quantization scale. 11. The input video updating unit selects video frames at predetermined intervals from the digital video signal input by the input unit and updates the input video frames stored in the input video buffer. 11. The video encoding device according to claim 8, wherein: 12. The input unit, for each video frame from the digital video signal input by the input unit,
A displacement between the video frame and the input video frame stored in the input video buffer is measured, and when the displacement exceeds a predetermined threshold, the input video updating means selects the video frame and inputs the video frame. 9. The image processing apparatus according to claim 8, further comprising a video analyzing unit that controls the input video frame stored in the video buffer to be updated.
11. The video encoding device according to any one of claims 10 to 10. 13. The image analyzing means includes: an error measuring means for measuring a mean square error between pixel values of the video frame and the input video frame as the displacement; and a mean square error measured by the error measuring means. 13. The video encoding apparatus according to claim 12, further comprising: a determination unit configured to determine whether to update the input video frame stored in the input video buffer. 14. The video analysis unit divides the video frame and the input video frame into predetermined blocks,
A motion measuring unit that searches for a motion vector in units of each corresponding block, and measures a sum of the magnitudes of the motion vectors as the displacement; Based on, determining means for determining whether to update the input video frame stored in the input video buffer,
The video encoding device according to claim 12, further comprising: 15. The encoding unit, when the input video frame stored in the input video buffer is updated, updates the input video frame with respect to the decoded video frame stored in the decoded video buffer. Motion vector searching means for calculating a motion vector of the motion vector, the video subtracting means generates a difference frame based on the motion vector obtained by the motion vector searching means, the encoding means, the motion vector The video code according to any one of claims 8 to 14, wherein a variable length code is generated based on the quantization coefficient generated by the quantization unit, and compressed moving image data is generated based on the variable length code. Device. 16. A step of inputting a plurality of video frames, a step of selecting a video frame to be coded from the plurality of video frames in a predetermined pattern, and a step of replacing the selected video frame with a next selected video frame. Holding until updated, encoding the held video frame to generate video data, decoding the video data to generate a decoded video frame, holding the video frame Calculating difference information between the video frame and the decoded video frame, encoding the difference information to generate differential video data, and causing the computer to execute a video encoding method. A computer-readable recording medium that has been recorded. 17. A method comprising: inputting a plurality of video frames; selecting a video frame to be coded from the plurality of video frames in a predetermined pattern; Holding until updated, encoding the held video frame to generate video data, decoding the video data to generate a decoded video frame, holding the video frame While obtaining the difference information between the video frame and the decoded video frame, encoding the difference information to generate difference video data, and when the video frame is updated, Obtain a motion vector of the updated video frame and generate difference information based on the motion vector And
Encoding one of the updated video frame and the differential information to generate video data or differential video data; and reading a computer-readable recording program for causing the computer to execute the video encoding method. Possible recording medium. 18. The step of generating differential video data includes generating differential video data by encoding differential information between the video frame and the decoded video frame at a quantization scale smaller than a previous quantization scale. 18. The recording medium according to claim 16, wherein: 19. The recording medium according to claim 16, wherein the step of selecting the video frames in a predetermined pattern selects video frames to be encoded from the plurality of video frames at predetermined intervals. . 20. The method according to claim 20, wherein the step of selecting the video frame in a predetermined pattern includes the step of measuring a displacement between the input video frame and a maintained video frame for each one of the plurality of video frames. When,
19. The method of claim 16, further comprising: selecting the input video frame to update the maintained video frame when the measured displacement exceeds a predetermined threshold. Recording medium. 21. The step of measuring the displacement is, for each input video frame of the plurality of input video frames, calculated from a difference between pixel values of the input video frame and a maintained video frame. 21. The recording medium according to claim 20, wherein a mean square error is measured as a displacement. 22. The step of measuring the displacement includes dividing the input video frame and the maintained video frame into predetermined blocks for each one input video frame of the plurality of input video frames. 21. A step of obtaining a motion vector for each corresponding block, and a step of measuring a sum of magnitudes of the motion vectors as displacement.
The recording medium according to the above. 23. A video input device that outputs a captured video or a recorded video as a digital video signal, and inputs and encodes the digital video signal output from the video input device to generate compressed video data. A video encoding device, a video transmission device that transmits the compressed moving image data generated by the video encoding device over a network,
16. A video communication system comprising: a video reception / playback device that receives and plays back the compressed moving image data transmitted via the network. The video coding device is configured by the video coding device according to claim 8 to 15. The video communication system, wherein the video transmission device deletes a part of the compressed moving image data and transmits the compressed moving image data according to a data transfer rate on the network. 24. The video reception / playback apparatus comprises: means for receiving the compressed video data; and playback means for expanding the received compressed video data and playing the video. 24. The video communication system according to claim 23, further comprising: an image quality improving unit that fixes the image quality and improves the image quality of the video. 25. The video communication system according to claim 24, wherein said image quality improving means is configured to decode a difference frame relating to a video being reproduced from said compressed moving image data to improve the image quality of said video.