A Rate-Distortion Optimization Method for Panoramic Video Coding Based on Spherical Weighted Structure Similarity

Abstract

The invention discloses a panoramic video encoding rate distortion optimization method for weighted-spherically-uniform structural similarity, wherein a change factor and a distortion weight are calculated, which are brought by a Lagrange factor in an original rate distortion model of an HEVC encoding platform with each encoding tree unit, in each B frame and each P frame in a planar panoramic video obtained after a spherical panoramic video is subjected to equal rectangular projection, taking structural similarity SSIM as distortion measurement, and a rate distortion optimization model of each encoding tree unit based on spherical weight structure similarity is obtained; according to the distortion weight of each encoding tree unit, a quantization parameter of each encoding tree unit is calculated; and the corresponding encoding tree unit is encoded according to the rate distortion optimization parameter and the quantization parameter of each encoding tree unit based on the sphericalweight structural similarity. The panoramic video coding rate distortion optimization method for weighted-spherically-uniform structural similarity in the invention has the advantages of better distortion performance and optimal encoding effect.

Description

technical field [0001] The present invention relates to a panoramic video coding compression technology, in particular to a spherical weighted structural similarity (Weighted-to-Spherically-uniform Structural Similarity, WS-SSIM) panoramic video coding rate-distortion optimization method. Background technique [0002] The 360-degree spherical panoramic video is a video with a large field of view, high resolution and immersive features, which is shot by a special panoramic camera or spliced ​​after shooting by multiple ordinary cameras. By wearing a Head-Mounted Display (HMD), viewers can move their heads and bodies to freely choose what they watch. The processing system of spherical panoramic video usually includes links such as video imaging, projection, encoding, back projection and interactive display. Due to the limitations of current codecs, usually spherical panoramic video needs to be converted to a 2D plane through different projection methods, encoded and compresse...

AI Technical Summary

Problems solved by technology

For pixel interpolation at the two poles of the equirectangular projection, Ramin et al. proposed an area subsampling method, which divides the equirectangular plane frame into different strips, and performs downsampling and encoding according to the latitude information. However, considering the complexity, this method only divides For 3 strips, the upper and lower strips are 1 / 2 down-sampled, and the middle strip is not sampled. This process does not conform to the pixel interpolation rule of equirectangular projection, and cannot remove the redundancy of two poles well.

Also for equirectangular projections, Hendry et al. proposed an adaptive quantization parameter (Quantization Parameter, QP) encoding based on latitude factors. According to latitude factors, a higher QP value is used for high-latitude regions to remove pixel stretching redundancy. However, this method Only the relationship between QP and latitude factor is considered, but the unreasonable definition of distortion in the rate-distortion model is not considered

[0005] Although the above related studies have achieved good coding results, there is still a lot of room for improvement in improving the efficiency of spherical panoramic video coding.

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