JP2010213187A - Video coding transmission apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a video coding transmission apparatus capable of suppressing an information generation rate, that is the code information quantity of variable length coded data per fixed period of time so as not to exceed a designated transmission rate even if a video signal with a high coding difficulty is input successively. <P>SOLUTION: If a data occupancy rate of variable length coded data in a buffer 10 is less than a threshold Th, a latest video signal, in which the number of pixels is converted by a pixel number converter 5, is output to a coder 9 and if the data occupancy rate of the variable length coded data in the buffer 10 is equal to or more than the threshold Th, a repeat video signal is output to the coder 9. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  This invention encodes and transmits video so that the information generation rate, which is the amount of encoded code information after compression, does not exceed a specified transmission rate by adaptively processing the input video signal and performing compression encoding It relates to the device.

In recent years, various video compression methods have been proposed as methods for reducing the amount of video and audio information, and a representative method is called MPEG-2 (Moving Picture Experts Group Phase 2).
A digital broadcasting system has been started in which video and audio broadcast data is compressed and encoded using the MPEG-2 system and broadcast using terrestrial or satellite waves.

FIG. 4 is a block diagram showing a video encoding / transmission apparatus disclosed in the following Patent Document 1. The video encoding / transmission apparatus in FIG. 4 compresses and encodes a video signal using the MPEG-2 system. The video encoding transmission device.
Hereinafter, the processing content of the video encoding transmission apparatus of FIG. 4 is demonstrated.

For example, when the video input terminal 101 inputs a video signal output from a video signal supply device such as a video tape recorder, the prefilter 102 has a band corresponding to the frequency characteristic control signal output from the quantization rate control unit 106. By performing the limiting process, the high frequency component of the video signal is reduced, and the video signal after the high frequency component reduction is output to the pixel number conversion unit 103 as a band limited video signal.
Here, the high frequency component of the video signal represents a fine portion of the video.
Therefore, by reducing the high frequency component of the video signal, fine details of the video are omitted, but even if the high frequency component is reduced, there is little influence on the entire video and the bandwidth of the video signal is reduced. .

The pixel number conversion determination unit 107 generates a pixel number control signal according to the frequency characteristic control signal output from the quantization rate control unit 106.
When receiving the band limited video signal from the pre-filter 102, the pixel number conversion unit 103 performs a process of converting the number of pixels of the band limited video signal.
That is, the pixel number conversion unit 103 sets the reduced horizontal pixel number N, which is the number of converted pixels, according to the pixel number control signal output from the pixel number conversion determination unit 107.
Then, when the number of pixels in the horizontal direction (the number of horizontal pixels) of the video signal input from the video input terminal 101 is M, the number-of-pixels conversion unit 103 has the following formula: The number of pixels of the band limited video signal output from the pre-filter 102 is reduced to the reduced number of horizontal pixels N.
Here, the reduced number of horizontal pixels N is determined according to the program content of the video signal, and is set to a large number if the program requires high image quality, and if the program does not require high image quality. Set to a small number.

When the encoding unit 104 receives the pixel number converted video signal which is the video signal after the pixel number conversion from the pixel number conversion unit 103, the encoding unit 104 performs a motion compensation process, a discrete cosine as an inter-frame encoding process on the pixel number converted video signal. By performing conversion processing (DCT: Discrete Cosine Transform), quantization processing and variable length coding processing (VLC: Variable Length Coding), the pixel number conversion video signal is compressed, and the pixel number conversion video signal Variable length encoded data is stored in the buffer 105.
At this time, the encoding unit 104 adjusts the quantization rate in the quantization process according to the quantization control signal output from the quantization rate control unit 106. Also, the encoding timing and the motion vector search range in the motion compensation process are set according to the encoding control information output from the encoding unit control circuit 108.

Here, when the amount of motion of the video in the video signal is large or when the video is complicated, the amount of code information of the variable-length encoded data output from the encoding unit 104 increases.
When a video signal having a large amount of code information of variable-length encoded data is expressed as “high compression difficulty”, the compression difficulty varies depending on the program content and scene of the video signal.
For this reason, by controlling the quantization value of the quantization process in the encoding unit 104 and the band limiting process in the prefilter 102 based on the data occupation amount of the variable-length encoded data in the buffer 105, a predetermined period ( For example, the amount of code information per GOP (Group Of Pictures) is controlled to be constant.

That is, the quantization rate control unit 106 constantly monitors the accumulation state of the variable-length encoded data in the buffer 105, and outputs the accumulation state as the data occupation rate of the variable-length encoded data.
Then, the quantization rate control unit 106 generates a quantization control signal and a frequency characteristic control signal based on the data occupation rate of the variable length encoded data, and outputs the quantization control signal to the encoding unit 104. By outputting the frequency characteristic control signal to the pre-filter 102, the amount of code information per fixed period of the variable length encoded data is controlled to be constant.

However, in the video encoding transmission apparatus, the band reduction width by the prefilter 102 varies depending on the degree of compression difficulty of the video signal, whereas the reduced horizontal pixel number N by the pixel number conversion unit 103 depends on the program content of the video signal. Determined.
For this reason, there may be a case where the reduced horizontal pixel number N of the pixel number-reduced video signal exceeds the number of horizontal pixels necessary for expressing the video of the band limited video signal.
In this case, pixels exceeding the number of pixels necessary for expressing the video of the band limited video signal are encoded, and the quantization value in the quantization process increases to the upper limit.
If such a video signal with a high degree of compression difficulty continues, the amount of code information per fixed period cannot be controlled to be constant, and the data occupancy rate of the variable length encoded data in the buffer 105 is MPEG-2 standard. A situation occurs that exceeds the upper limit defined in.

Japanese Patent Laid-Open No. 11-234668 (paragraph number [0012], FIG. 1)

  Since the conventional video encoding transmission apparatus is configured as described above, the amount of code information of the variable length encoded data output from the encoding unit 104 is the encoding of the video signal input from the video input terminal 101. When video signals (for example, video signals that contain a lot of high-frequency components and have a lot of motion) that are influenced by the difficulty level and that have a high coding difficulty level are input continuously, the variable-length encoded data is constant. The amount of code information per period may exceed the amount of code determined by the transmission rate. At this time, since the output rate of the buffer 105 is constant, the time for sending the variable length encoded data of one screen increases, and as a result, the decoding of the variable length encoded data on the video receiving side is performed at the video display time. There was a problem that a video anomaly sometimes occurred in time.

  The present invention has been made in order to solve the above-described problems, and is the amount of code information of variable-length encoded data per fixed period even when video signals with high encoding difficulty are continuously input. It is an object of the present invention to obtain a video encoding transmission apparatus capable of suppressing an information generation rate so as not to exceed a specified transmission rate.

  According to the video encoding / transmission apparatus of the present invention, the latest video signal in which the number of pixels is converted by the pixel number conversion unit according to the data occupancy rate of the encoded data in the data storage unit, or the video output last time Video selecting means for selecting any one of the same video signals as the signal and outputting the selected video signal to the encoding means is provided.

  According to the present invention, the latest video signal in which the number of pixels is converted by the pixel number conversion unit or the same video signal as the previous output video signal in accordance with the data occupancy rate of the encoded data in the data storage unit Since the video selection means for selecting any one of these and outputting to the encoding means is provided, even if video signals with high encoding difficulty are continuously input, variable length encoding per fixed period There is an effect that it is possible to suppress the information generation rate, which is the amount of code information of data, from exceeding the specified transmission rate.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows the video coding transmission apparatus by Embodiment 1 of this invention. It is a block diagram which shows the repeat video conversion part 8 of the video coding transmission apparatus by Embodiment 1 of this invention. It is a block diagram which shows the video coding transmission apparatus by Embodiment 2 of this invention. 1 is a configuration diagram illustrating a video encoding / transmission apparatus disclosed in Patent Document 1. FIG.

Embodiment 1 FIG.
1 is a block diagram showing a video encoding / transmission apparatus according to Embodiment 1 of the present invention.
In FIG. 1, a video input terminal 1 is a terminal for inputting a video signal output from a video signal supply device such as a video tape recorder.
The quantization rate control unit 2 monitors the accumulation state of the variable-length encoded data in the buffer 10, measures the data occupation rate of the variable-length encoded data in the buffer 10, and the data occupation rate of the variable-length encoded data The process of generating the quantization control signal and the frequency characteristic control signal is performed based on the above.

The pre-filter 3 performs a band limiting process according to the frequency characteristic control signal output from the quantization rate control unit 2, so that the signal band of the video signal input from the video input terminal 1 (for example, the high frequency of the video signal). (Band component) is reduced, and the video signal after the band reduction is output to the pixel number conversion unit 5 as a band limited video signal. Note that the prefilter 3 constitutes a signal band reduction means.
The pixel number conversion determination unit 4 performs a process of generating a pixel number control signal according to the frequency characteristic control signal output from the quantization rate control unit 2.

The pixel number conversion unit 5 sets the reduced horizontal pixel number N, which is the number of converted pixels, according to the pixel number control signal output from the pixel number conversion determination unit 4, and the band limited video output from the pre-filter 3. The number of pixels of the signal is converted into a reduced number of horizontal pixels N, and a process of outputting the video signal after the pixel number conversion to the repeat video converting unit 8 as a pixel number converted video signal is performed. The pixel number conversion determination unit 4 and the pixel number conversion unit 5 constitute a pixel number conversion unit.
In accordance with the pixel number control signal output from the pixel number conversion determination unit 4, the encoding unit control circuit 6 encodes encoding control information indicating encoding timing and a motion vector search range in motion compensation processing. Execute the process to output to.

The repeat video conversion determination unit 7 monitors the accumulation state of the variable length encoded data in the buffer 10 and measures the data occupancy rate of the variable length encoded data in the buffer 10, and if the data occupancy rate is less than the threshold Th. For example, if the video selection signal instructing selection of the latest pixel number conversion video signal output from the pixel number conversion unit 5 is output to the repeat video conversion unit 8 and the data occupancy is equal to or greater than the threshold Th, the repeat video is output. A process of outputting a video selection signal for instructing selection of a signal (the same pixel number converted video signal as the pixel number converted video signal output to the encoding unit 9 the previous time) to the repeat video converting unit 8 is performed.
When the video selection signal for instructing the selection of the latest pixel number converted video signal is output from the repeat video conversion determination unit 7, the repeat video conversion unit 8 outputs the latest pixel number converted video signal output from the pixel number conversion unit 5. Is output to the encoding unit 9, and when a video selection signal instructing selection of a repeat video signal is output from the repeat video conversion determination unit 7, a process of outputting the repeat video signal to the encoding unit 9 is performed.
The repeat video conversion determination unit 7 and the repeat video conversion unit 8 constitute video selection means.

The encoding unit 9 encodes the latest pixel number converted video signal or repeat video signal output from the repeat video converting unit 8 between frames, and generates variable length encoded data of the pixel number converted video signal or repeat video signal. Perform the process. Note that the encoding unit 9 constitutes an encoding means.
The buffer 10 temporarily stores the variable length encoded data generated by the encoding unit 9, and then performs a process of sending the variable length encoded data at a constant output rate. The buffer 10 constitutes data storage means.

The inter-frame differentiator 9a of the encoding unit 9 obtains the difference between the latest pixel number converted video signal or repeat video signal output from the repeat video conversion unit 8 and the predicted image signal output from the motion compensation unit 9i. Then, a process of outputting a difference video signal indicating the difference is performed.
The DCT unit 9b performs a process of performing a DCT on the difference video signal output from the interframe difference unit 9a and outputting a DCT coefficient to the quantization unit 9c.

The quantization unit 9c performs a process of calculating a quantization index by quantizing the DCT coefficient output from the DCT unit 9b with a quantization value corresponding to the quantization control signal output from the quantization rate control unit 2. carry out.
The inverse quantization unit 9d is a quantization value corresponding to the quantization control signal output from the quantization rate control unit 2, and inversely quantizes the quantization index calculated by the quantization unit 9c to obtain the DCT coefficient. Perform the calculation process.
The inverse DCT unit 9e performs a process of decoding the difference video signal by performing inverse DCT on the DCT coefficient calculated by the inverse quantization unit 9d.

The adder 9f calculates the sum of the difference video signal decoded by the inverse DCT unit 9e and the image signal of the predicted image output from the motion compensation unit 9i, and outputs the image reference signal indicating the sum.
The frame memory 9g is a memory for storing the image reference signal output from the adder 9f.
The motion vector detection unit 9h performs processing for detecting a motion vector between the latest pixel number converted video signal or repeat video signal output from the repeat video conversion unit 8 and the image reference signal stored in the frame memory 9g. To do.

The motion compensation unit 9i performs a process of generating an image signal of the predicted image by performing motion compensation of the image reference signal stored in the frame memory 9g using the motion vector detected by the motion vector detection unit 9h. To do.
The VLC unit 9j performs variable length encoding on the quantization index calculated by the quantization unit 9c, the motion vector detected by the motion vector detection unit 9h, and the like, and executes processing for outputting the variable length encoded data to the buffer 10 .

FIG. 2 is a block diagram showing the repeat video conversion unit 8 of the video encoding / transmission apparatus according to Embodiment 1 of the present invention.
In FIG. 2, the frame memory 21 converts the latest pixel number output from the pixel number conversion unit 5 when a video selection signal instructing selection of the latest pixel number conversion video signal is output from the repeat video conversion determination unit 7. It is a memory that stores video signals as repeat video signals in units of frames.
Further, the frame memory 21 does not store the latest pixel number converted video signal output from the pixel number conversion unit 5 when the video selection signal instructing selection of the repeat video signal is output from the repeat video conversion determination unit 7. In addition, the previously stored repeat video signal is continuously held.

  When the video selection signal instructing selection of the latest pixel number conversion video signal is output from the repeat video conversion determination unit 7, the selector 22 selects the latest pixel number conversion video signal output from the pixel number conversion unit 5. When the video selection signal for instructing selection of the repeat video signal is output from the repeat video conversion determination unit 7, the repeat stored in the frame memory 21 is output. Processing for selecting a video signal and outputting the repeated video signal to the encoding unit 9 is performed.

Next, the operation will be described.
The quantization rate control unit 2 measures the data occupation rate of the variable length encoded data in the buffer 10 by constantly monitoring the accumulation state of the variable length encoded data in the buffer 10.
The quantization rate control unit 2 controls the quantization control signal and the frequency based on the data occupancy of the variable length encoded data in order to control the amount of code information per fixed period of the variable length encoded data in the buffer 10 to be constant. A characteristic control signal is generated.
Note that the generation process of the quantization control signal and the frequency characteristic control signal may be performed using, for example, the method disclosed in Patent Document 1 described above, and thus detailed description thereof is omitted.

When the prefilter 3 receives the frequency characteristic control signal from the quantization rate control unit 2, the prefilter 3 performs a band limiting process in accordance with the frequency characteristic control signal, so that the signal band of the video signal input from the video input terminal 1 And the video signal after the band reduction is output to the pixel number conversion unit 5 as a band limited video signal.
For example, when the frequency characteristic control signal instructs to reduce the high frequency component of the video signal, the high frequency component of the video signal input from the video input terminal 1 is reduced.
As described above, the high frequency component of the video signal represents a fine part of the video.
Therefore, by reducing the high frequency component of the video signal, fine details of the video are omitted, but even if the high frequency component is reduced, there is little influence on the entire video and the bandwidth of the video signal is reduced. .

Similar to the quantization rate control unit 2, the repeat video conversion determination unit 7 monitors the accumulation state of the variable length encoded data in the buffer 10 and measures the data occupation rate of the variable length encoded data in the buffer 10. .
When video signals with high encoding difficulty are continuously input, as described above, the amount of code information per fixed period of the variable-length encoded data increases, so the data of the variable-length encoded data in the buffer 10 Occupancy is high.
On the other hand, when video signals with high encoding difficulty are not continuously input, the amount of code information per fixed period of variable-length encoded data decreases, so the data occupancy rate of variable-length encoded data in the buffer 10 Becomes lower.

The repeat video conversion determination unit 7 compares the data occupancy rate of the variable length encoded data in the buffer 10 with a predetermined threshold Th, and if the data occupancy rate is less than the threshold Th, the variable length for one screen from the buffer 10 is determined. Since the time required for sending the encoded data is short and the variable-length encoded data is expected to reach the video receiving side in time for the video display time, the latest pixel output from the pixel number conversion unit 5 A video selection signal for instructing selection of the number conversion video signal is output to the repeat video conversion unit 8.
On the other hand, if the data occupancy is equal to or greater than the threshold value Th, it takes a long time to send the variable length encoded data for one screen from the buffer 10, and the variable length encoded data is in time for the video display time. Is not likely to reach the video receiving side, so the video selection signal instructing the selection of the repeat video signal is sent to the repeat video conversion unit 8 instead of the latest pixel number conversion video signal output from the pixel number conversion unit 5. Output.

When the video selection signal for instructing selection of the latest pixel number conversion video signal is output from the repeat video conversion determination unit 7, the repeat video conversion unit 8 outputs the latest pixel number conversion video output from the pixel number conversion unit 5. The signal is output to the encoding unit 9, and when the video selection signal instructing selection of the repeat video signal is output from the repeat video conversion determination unit 7, the repeat video signal is output to the encoding unit 9.
That is, the frame memory 21 of the repeat video conversion unit 8 is output from the pixel number conversion unit 5 when a video selection signal instructing selection of the latest pixel number conversion video signal is output from the repeat video conversion determination unit 7. The latest pixel number converted video signal is stored as a repeat video signal, and the repeat video signal is delayed by one frame before being output to the selector 22.
On the other hand, when a video selection signal instructing selection of a repeat video signal is output from the repeat video conversion determination unit 7, the latest pixel number conversion video signal output from the pixel number conversion unit 5 is not stored, but is stored last time. The repeated video signal is continuously held, and the repeated video signal is output to the selector 22.

The selector 22 selects the latest pixel number conversion video signal output from the pixel number conversion unit 5 when the video selection signal instructing selection of the latest pixel number conversion video signal is output from the repeat video conversion determination unit 7. Then, the pixel number converted video signal is output to the encoding unit 9.
On the other hand, when a video selection signal instructing selection of a repeat video signal is output from the repeat video conversion determination unit 7, the repeat video signal stored in the frame memory 21 is selected and the repeat video signal is encoded. Output to 9.

When receiving the latest pixel number converted video signal or repeat video signal from the repeat video converting unit 8, the encoding unit 9 performs inter-frame coding on the latest pixel number converted video signal or repeat video signal, thereby obtaining the pixel. Variable length encoded data of the number conversion video signal or the repeat video signal is generated.
At this time, the encoding unit 9 is equipped with an inter-frame differentiator 9a, and if the video signal output from the repeat video converting unit 8 is the same repeat video signal as the previous video signal, the inter-frame differentiator. Since the difference video signal output from 9a becomes zero, the amount of code information of the variable length encoded data related to the difference video signal becomes zero.
In this case, the VLC unit 9j does not encode the difference video signal, but only encodes flag information indicating the repeat of the previous frame, so that the amount of code information of the variable-length encoded data is minimized. Can be suppressed.
For this reason, the data occupation rate of the variable-length encoded data in the buffer 10 is reduced, and the information generation rate that is the amount of code information of the variable-length encoded data per fixed period is controlled so as not to exceed the designated transmission rate. be able to.

  As is apparent from the above, according to the first embodiment, if the data occupancy rate of the variable-length encoded data in the buffer 10 is less than the threshold Th, the latest pixel number converted by the pixel number conversion unit 5 is converted. Since the video signal is output to the encoding unit 9 and the data occupancy rate of the variable length encoded data in the buffer 10 is equal to or greater than the threshold Th, the repeat video signal is output to the encoding unit 9. Even if video signals with high difficulty are continuously input, the information generation rate, which is the amount of code information of variable-length encoded data per fixed period, can be suppressed so as not to exceed a specified transmission rate. As a result, there is an effect that it is possible to prevent the occurrence of video abnormality due to the fact that the decoding of the variable length encoded data on the video receiving side is not in time for the video display time.

  In the first embodiment, when the data occupancy rate of the variable length encoded data in the buffer 10 is equal to or greater than the threshold value Th, the repeat video converting unit 8 repeats the same video signal as the video signal output last time. However, a video signal of a still image prepared in advance may be output to the encoding unit 9.

Embodiment 2. FIG.
3 is a block diagram showing a video encoding / transmission apparatus according to Embodiment 2 of the present invention. In the figure, the same reference numerals as those in FIG.
The adaptive pixel number conversion determination unit 11 monitors the accumulation state of the variable-length encoded data in the buffer 10, measures the data occupation rate of the variable-length encoded data in the buffer 10, and adapts the adaptive pixel according to the data occupation rate. The number conversion unit 12 determines a reduced horizontal pixel number N that is the number of pixels after conversion, and performs a process of outputting a pixel number control signal indicating the reduced horizontal pixel number N.
The adaptive pixel number conversion unit 12 converts the number of pixels of the band limited video signal output from the pre-filter 3 into the reduced horizontal pixel number N indicated by the pixel number control signal output from the adaptive pixel number conversion determination unit 11, and the number of pixels A process of outputting the converted video signal to the repeat video converting unit 8 as a pixel number converted video signal is performed.
The adaptive pixel number conversion determination unit 11 and the adaptive pixel number conversion unit 12 constitute a pixel number conversion unit.

Next, the operation will be described.
The adaptive pixel number conversion determination unit 11 measures the data occupation rate of the variable length encoded data in the buffer 10 by constantly monitoring the accumulation state of the variable length encoded data in the buffer 10.
The adaptive pixel number conversion determination unit 11 increases the difficulty of encoding the video signal as the data occupancy rate of the variable-length encoded data in the buffer 10 increases. Therefore, as the data occupancy rate increases, the reduced horizontal pixel number N Is determined to be a small number, and a pixel number control signal indicating the reduced horizontal pixel number N is output.

When the adaptive pixel number conversion unit 12 receives the band limited video signal having the number of horizontal pixels M (M> N) from the pre-filter 3, the adaptive pixel number conversion determination unit 11 outputs the number of pixels of the band limited video signal. The number of pixels is reduced by converting into the reduced horizontal pixel number N indicated by the pixel number control signal.
The adaptive pixel number conversion unit 12 outputs the video signal after the pixel number conversion to the repeat video conversion unit 8 as a pixel number conversion video signal.

  When the encoding unit 9 is performing the encoding process, the encoding unit control circuit 6 changes the number of pixels in the horizontal direction of the video signal, so that a shock appears in the video received on the video receiving side. In order to avoid this, encoding is performed so that the timing at which the encoding unit 9 changes the encoding parameter matches the timing at which the number of pixels in the horizontal direction of the video signal output to the encoding unit 9 is changed. The number of pixels in the horizontal direction is set in the unit 9.

Here, an example in which the number of pixels is changed from “1920” to “1440” by converting the number of horizontal pixels M of the band limited video signal into the reduced number of horizontal pixels N in HDTV broadcasting in digital broadcasting will be described.
In the encoding unit 9 configured in accordance with the MPEG-2 standard, the DCT unit 9b performs DCT processing in units of MB (Macro Block) in units of horizontal 16 pixels / vertical 16 lines.
The reduction in the number of horizontal pixels directly leads to a reduction in the amount of data encoded per screen, and in this example, 1/4 is reduced.
For this reason, the data occupancy rate of the variable length encoded data in the buffer 10 decreases, and the information generation rate that is the amount of code information of the variable length encoded data per fixed period can be controlled so as not to exceed the transmission rate. .

Note that the reduced horizontal pixel number N determined by the adaptive pixel number conversion determination unit 11 is determined to be a value that can be determined by the application used.
For example, since the number of horizontal pixels of HDTV broadcasting in digital broadcasting has only two values “1920” and “1440”, it cannot be applied when operating with the initial parameter “1440”.

  1 video input terminal, 2 quantization rate control unit, 3 pre-filter (signal band reduction unit), 4 pixel number conversion determination unit (pixel number conversion unit), 5 pixel number conversion unit (pixel number conversion unit), 6 encoding Part control circuit, 7 repeat video conversion determination part (video selection means), 8 repeat video conversion part (video selection means), 9 encoding part (encoding means), 9a inter-frame differentiator, 9b DCT part, 9c quantization Unit, 9d inverse quantization unit, 9e inverse DCT unit, 9f adder, 9g frame memory, 9h motion vector detection unit, 9i motion compensation unit, 9j VLC unit, 10 buffer (data storage means), 11 adaptive pixel number conversion determination Part (pixel number conversion means), 12 adaptive pixel number conversion part (pixel number conversion means), 21 frame memory, 22 selector, 101 video input terminal, 102 prefilter, 1 03 pixel number conversion unit, 104 encoding unit, 105 buffer, 106 quantization rate control unit, 107 pixel number conversion determination unit, 108 encoding unit control circuit.

Claims (4)

  A signal band reduction means for inputting a video signal to reduce the signal band of the video signal, a pixel number conversion means for converting the number of pixels of the video signal whose signal band has been reduced by the signal band reduction means, and the pixel The video signal whose number of pixels has been converted by the number conversion unit is inter-frame encoded to generate encoded data of the video signal, and the encoded data output from the encoding unit is temporarily stored Then, in a video encoding / transmission apparatus comprising data storage means for sending out the encoded data, the pixel number conversion means determines the number of pixels according to the data occupancy of the encoded data in the data storage means. Video selection means for selecting either the latest converted video signal or the same video signal as the video signal output last time and outputting it to the encoding means is provided. Video encoding transmission apparatus characterized.   If the data occupancy rate of the encoded data in the data storage unit is less than the threshold, the video selection unit stores the latest frame video signal in which the number of pixels has been converted by the pixel number conversion unit in the frame memory, and When the video signal of the frame is output to the encoding means, and the data occupancy rate of the encoded data in the data storage means is equal to or greater than the threshold value, the video signal of the previous frame stored in the frame memory is sent to the encoding means. The video encoding transmission apparatus according to claim 1, wherein the video encoding transmission apparatus outputs the video encoding transmission apparatus.   3. The video encoding / transmission apparatus according to claim 1, wherein the pixel number conversion means determines the number of converted pixels according to the data occupancy ratio of the encoded data in the data storage means.   4. The video encoding / transmission apparatus according to claim 3, wherein the pixel number conversion means determines the number of converted pixels to be smaller as the data occupancy of the encoded data in the data storage means is higher.

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