Method for controlling balanced code rate and picture quality code rate

A technology of image quality and bit rate control, applied in the field of audio and video codec, can solve problems such as valley value of bit rate, uncontrollable bit rate of buffer zone, affecting the stability of transmission stream, etc., so as to achieve the effect of improving compression quality

Inactive Publication Date: 2008-06-18
CENT ACADEME OF SVA GROUP
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Problems solved by technology

But in fact, when the image quality changes greatly, it is easy to generate a bit rate peak, and the buffer cannot control the bit rate, thus affecting the stability of the transmission stream; in addition, the image may also achieve very good quality when the bit rate is very low , so it is also easy to produce bit rate valleys

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  • Method for controlling balanced code rate and picture quality code rate

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Embodiment Construction

[0044] A code rate control method for balancing code rate and image quality of the present invention will be further described in detail below.

[0045] The present invention will be described in detail below in conjunction with the code rate control flow chart of FIG. 1 and the coding example of the commonly used image foreman.yuv. The target code rate of this image is 1000kbps. In the image of this embodiment, the 31st frame is coded as an I frame, the 32nd frame and the 33rd frame are coded as a B frame, and the 34th frame is coded as a P frame. The code rate control method is implemented in the following steps:

[0046] Initialize the coding quantization parameters and scale factors of each frame of I, P and B, and initialize the number of times of cyclic coding n=0:

[0047] a) Initialize the first round of quantization parameter QP to 25; initialize the scale factor IP_factor value of I frame and P frame to 1.5; initialize the scale factor PB_factor value of P frame and...

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Abstract

The invention provides a code rate control method for balancing a code rate and image quality; wherein, the method firstly initializes coding parameters and then makes comparison of the peak signal noise ratios and the deviation values of bit uses of I frame, P frame and B frame with the respective value ranges thereof, so as to judge whether the rations and the deviation values meet relative balance conditions in a balancing way; the method then adjusts the coding parameters (such as quantization parameters, etc.) according to the judging result for a plurality of times and returns the adjusted parameters to recode; the method can use as much code rate bandwidths as possible in the condition of ensuring little changes of image quality, and that is to say, the method better improves the compression quality of videos with the same coding rate. The code rate control method can be successfully applied in an AVS coding algorithm.

Description

technical field [0001] The invention relates to the technical field of audio and video encoding and decoding, in particular to a code rate control method for video encoding. Background technique [0002] A number of digital audio and video codec standards that have emerged in recent years are representative of the international standard H.264 / MPEG-4 AVC and the standard AVS independently formulated by my country. These standards all involve bit rate control. Because the code rate (Constant BitRate, CBR for short) of the code stream in the actual transmission application is constant, the stability of the transmission stream can be guaranteed. Since the bit rate generated by most video compression technologies or standards itself is variable, in order to be able to transmit in a communication channel and network with a constant bit rate, the traditional bit rate control algorithm needs to introduce a buffer mechanism into the bit rate control. That is, the variable code rate ...

Claims

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Application Information

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IPC IPC(8): H04N7/26H04N19/146
Inventor 陈勇李国平
Owner CENT ACADEME OF SVA GROUP
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