Scalable Video Decoding Phase Shift Compensation
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Solution Overview
Problem
Existing video compression technologies face challenges in maintaining high image quality when bitrate is reduced, particularly in mobile devices with limited bandwidth, due to phase shifts between base and enhanced layers during downsampling and upsampling, which reduce coding efficiency.
Innovation Solution
A scalable video signal encoding and decoding method that accounts for phase shifts between layers by recording and compensating for global and local phase shifts during the encoding process, ensuring the base layer is in phase with the enhanced layer, thereby maintaining image quality and increasing coding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If transcoding is performed to adapt video to different mobile device capabilities, then video compatibility is improved, but processing time and system complexity increase
Solution Approach 1:
The video signal is segmented into multiple layers with different resolutions and quality levels. The encoding process creates a base layer and enhancement layers that can be selectively decoded based on device capabilities, eliminating the need for full transcoding while maintaining compatibility across different devices.
Solution Approach 2:
All possible video quality versions are pre-encoded into the scalable video structure during the initial encoding process. This preliminary action stores multiple resolution and quality variants within a single bitstream, so that when video is delivered to mobile devices, no additional transcoding is needed—only selective decoding of the appropriate layer.
2Adaptability or versatility
If transcoding is performed to adapt video to different mobile device capabilities, then video compatibility is improved, but time delay increases
Solution Approach 1:
The scalable video encoding performs all necessary adaptations in advance by creating a multi-layer structure during initial encoding. When video is delivered to mobile devices, the appropriate layers are already prepared and can be decoded immediately without waiting for transcoding operations, thus eliminating time delay.
3Loss of energy
If bitrate is reduced for mobile transmission, then bandwidth consumption is decreased, but image quality deteriorates
Solution Approach 1:
The scalable video structure enables dynamic adaptation of bitrate and quality based on transmission conditions and device capabilities. The encoder can adjust which layers are transmitted and at what quality levels, allowing optimal balance between bandwidth consumption and image quality for mobile devices with limited bandwidth.
Data Source
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AI summary
In one embodiment, decoding of a video signal includes predicting at least a portion of a current image in a current layer based on at least an intra-coded portion of a base image in a base layer and shift information for samples in the predicted current image.