H.264 code rate control frame skipping optimization method

A bit rate control and optimization method technology, applied in the field of video coding and decoding, can solve problems such as seldom considering the influence of uncoded frames, low image quality, and less special processing of the first three frames, so as to achieve the effect of good subjective video quality

Inactive Publication Date: 2019-08-09
XIDIAN UNIV
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  • Description
  • Claims
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Problems solved by technology

When the buffer occupancy rate is 50%, if a scene switch occurs, the bits generated by the current frame are very large, which can easily cause buffer overflow
The second point is that although some algorithms consider the complexity of the image, there are certain limitations in using the mean absolute error (MAD) as an index to measure the complexity of the image. The similarity between the frame and the reference frame, so it is necessary to use other indicators to measure the complexity of the image
Third, most of the existing algorithms only consider the impact of encoded frames, and rarely consider the impact of unencoded frames
When the average prediction bit allocated to an unencoded image is lower than the target bit, if the frame is not skipped, the quality of the encoded image will be very low, affecting the overall quality of the sequence
The fourth point, because the I frame and the first few P frames are very important for decoding, skipping one of them will have a great impact on the video quality, so the first three frames should be treated specially, but the existing algorithm Rarely do special processing for the first three frames

Method used

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  • H.264 code rate control frame skipping optimization method

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Embodiment 1

[0029] In video encoding and decoding, when the captured object undergoes violent movement or the scene is switched, the actual bit rate generated by the encoding increases sharply, causing the buffer to overflow, resulting in the loss of encoded data and affecting the image quality. In order to solve this problem, relevant researchers at home and abroad have proposed many algorithms and methods, but these methods still have some shortcomings: the set threshold is too simple, the complexity algorithm cannot reflect the degree of violent motion of the image well, and does not take into account the unforeseen The case of encoded frames and so on. The present invention has launched research and innovation for these present situations, and proposes a kind of H.264 code rate control frame skip optimization method, see figure 1 , including the following steps:

[0030] (1) Set initialization related parameters: set the target code rate T=targetBitRate; set the initial buffer occupa...

Embodiment 2

[0048] A kind of H.264 code rate control frame skip optimization method is the same as embodiment 1, step (3) described setting frame skip related threshold, including setting buffer occupancy rate buf i 4 thresholds, motion complexity C i The 4 thresholds of and the bit factor a of the uncoded frame i thresholds, including:

[0049] (3a) Set the buffer occupancy buf i The 4 thresholds are B 1 = 25%, B 2 = 50%, B 3 = 60%, B 4 = 80%.

[0050] (3b) Set motion complexity C i 4 thresholds, the experiment shows that the 4 thresholds are c 1 = 30%, c 2 = 50%, c 3 = 60%, c 4 = 80%.

[0051] (3c) Set the bit factor threshold β of uncoded frames to 60%.

[0052] The present invention firstly sets the thresholds of 4 buffer occupancy ratios corresponding to the 4 buffer occupancy ratios, which not only avoids the waste of bandwidth when the buffer occupancy ratio is too low, but also prevents the buffer occupancy ratio from being too high to cause overflow and data loss . ...

Embodiment 3

[0054] A kind of H.264 code rate control optimization method is the same as embodiment 1-2, and from the 4th frame described in the step (7) of the present invention, carries out normative frame skip processing, comprises the following steps:

[0055] (7.1) Compare buffer occupancy buf i and buffer occupancy threshold B j The size of j=1, 2, 3, 4, if buf i >B j , then continue to compare buf i and B j+1 the size of up to buf i and B 4 the size of buf if i >B 4 , the frame is skipped, and step (9) is performed after the frame skips.

[0056] (7.2) Judging whether to skip frames according to the motion complexity: if the buffer occupancy rate buf i j , j=1, 2, 3, 4, then further judge whether to skip frame according to motion complexity, if motion complexity is greater than motion complexity threshold value, then skip frame, execute step (9) after frame skipping, otherwise, execute step ( 7.3).

[0057] (7.3) Judging whether frame skipping according to the bit factor of...

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Abstract

The invention discloses an H.264 code rate control frame skipping optimization method, and solves the technical problem of buffer overflow or continuous frame skipping under the condition of scene switching or complex object motion. The method comprises the following implementation steps: setting initialization related parameters; calculating a target bit and a quantization parameter of the current frame; setting a frame skipping related threshold value; calculating the motion complexity of the current frame; calculating a bit factor of the current frame; performing special frame skipping processing on the first three frames; performing normative frame skipping processing from the fourth frame; encoding the current frame; and updating the relevant parameters after frame skipping, and performing frame skipping optimization on the next frame. According to the method, firstly, MAD is replaced with motion complexity, secondly, different buffer occupancy rates are set for different motion complexity, and finally, whether frame skipping occurs or not is judged by integrating the motion complexity, the buffer occupancy rates and bit factors of uncoded frames. The subjective quality of thevideo is effectively improved, and the method is mainly used for code rate control frame skipping optimization.

Description

technical field [0001] The invention belongs to the technical field of video coding and decoding, and mainly relates to code rate control, in particular to an H.264 code rate control frame skip optimization method, which is used to effectively control frame skip and improve subjective video quality. Background technique [0002] Because the H.264 video coding standard has a high compression ratio, good network affinity and strong anti-error ability, it has been widely used in the field of video coding. [0003] Generally speaking, according to the change of the complexity of the image content, the code stream generated by encoding will also change, but the channel bandwidth is generally fixed, which will cause a phenomenon: when the motion complexity of the current frame is high, The output code stream bit is relatively high, which often exceeds the output capability of the channel bandwidth; however, when the motion complexity of the current frame is low, the code stream bi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04N19/103H04N19/154H04N19/177H04N19/184
CPCH04N19/103H04N19/154H04N19/177H04N19/184
Inventor 武斌董泽芳李鹏
Owner XIDIAN UNIV
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