A Distortion Measurement Based Parameter Update Algorithm for Hevc Code Rate Control Model

Abstract

The invention discloses a HEVC code rate control model parameter update algorithm based on distortion measurement. This algorithm uses the least mean square error LMS method to iteratively calculate the α parameter and β parameter of the code rate control model. Let D represent the video after compression encoding Distortion; R represents the code rate after compression, C and K are model parameters related to the characteristics of the video sequence; the iteration step size used by the C parameter and the K parameter for an iteration is δC and δK respectively, and the target code rate is R. The R-D rate-distortion model is described by the formula: D(R)=CR-K. In the rate control, the relationship between the rate R and the Lagrange multiplier λ used for encoding is expressed as: the formula used for iteration is: Cnew=Cold×[1-δC×(InDreal-InDold)] Knew=Kold+δK×[(InDreal-InDold)×InRreal] αnew=Cnew×Knew βnew=-Knew-1 The present invention performs iteration according to the video features before and after encoding , by accurately measuring the amount of distortion, to accurately update the parameters of the HEVC code rate control model, so as to obtain a more accurate code rate control effect.

Description

technical field [0001] The present invention relates to the technical field of video coding rate control, in particular to an HEVC rate control model parameter update algorithm based on distortion measurement, which conforms to the H.265 / MPEG-H HEVC (High Efficiency Video Coding) video coding standard. Background technique [0002] In video coding and transmission applications, the new generation of high-performance video coding standard H.265 / MPEG-HHEVC (High Efficiency Video Coding) is jointly developed by video coding established by two international standardization organizations, ISO-IEC / MPEG and ITU-T / VCEG Developed by the JCT-VC group, compared with H.264 / AVC, HEVC can reduce the bit rate by half under the same visual quality. [0003] As a new-generation video coding standard, HEVC still belongs to the hybrid coding framework of prediction and transformation. It also includes coding modules such as intra prediction, inter prediction, orthogonal transformation, quantiz...

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Problems solved by technology

[0025] However, it can be known from formula (5) that λ comp The parameter α of the original model was used in the calculation old and beta old , and its parameters have changed after the video is encoded, so the parameter α of the original video model old and beta old It cannot fully reflect the parameter characteristics of the encoded video, so λ real with lambda comp Between the square error to adjust the α and β values, the resulting update model is only approximately close to the characteristics of the current video sequence

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