PCM Block Deblocking Filter Control via Noise Flags
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Solution Overview
Problem
Existing deblocking filtering techniques struggle to effectively address blocking artifacts in PCM-coded samples, particularly when these samples are adjacent to predicted blocks, as filtering can reduce the quality of noise-free PCM regions and introduce additional noise from adaptive loop filters or sample adaptive offsets.
Innovation Solution
The proposed solution involves individually controlling the application of deblocking filters for PCM-coded blocks based on the amount of noise in the PCM-coded signal, allowing for separate management of filtering for samples modified and not modified by the deblocking filter, and using flags to enable or disable filtering in the bit stream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If deblocking filtering is applied to PCM-coded samples adjacent to predicted blocks, then blocking artifacts are reduced, but quality of noise-free PCM regions deteriorates and additional noise is introduced
Solution Approach 1:
The patent segments the filtering control by introducing separate flags for different block types. PCM-coded blocks use a dedicated 'pcm_loop_filter_disable_flag' while predicted blocks use existing loop filter controls, allowing independent filtering decisions for each block type to avoid degrading noise-free PCM regions while still removing blocking artifacts from predicted blocks
Solution Approach 2:
The patent implements dynamic filtering control where the application of deblocking filters is adaptively determined based on block type characteristics. The encoder and decoder dynamically adjust filtering behavior using the pcm_loop_filter_disable_flag to enable filtering for predicted blocks and disable it for PCM blocks, optimizing quality for each case
2Manufacturing precision
If deblocking filters are selectively applied based on noise amount, then image quality is improved, but device complexity increases due to separate filter management
Solution Approach 1:
The patent extracts the filtering control mechanism from the general loop filter and creates a separate, dedicated control flag 'pcm_loop_filter_disable_flag' specifically for PCM-coded blocks. This extraction simplifies the overall system by providing targeted control without requiring complex analysis of noise amounts in each block
Solution Approach 2:
The patent enables self-service filtering control where the block type itself (PCM-coded vs. predicted) automatically determines the filtering behavior through the pcm_loop_filter_disable_flag. The system serves itself by using the coding mode information already available to make filtering decisions, eliminating the need for additional noise analysis complexity
Data Source
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AI summary
The present invention relates to coding of an image of a video sequence block wisely and, in particular, to coding of a block of samples, which may be chrominace or luminance samples, or samples of any colour space, by a pulse code modulation (PCM). After PCM coding, deblocking filtering may be applied. The deblocking filter may be selected for the present PCM coded block based on its noise and/or the noise of its adjacent block. The noise of the PCM coded block is indicated by a so-called PCM quantization parameter, which is also encoded in the bitstream.