Scalable Bitstream Syntax for Color Bit Depth
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Solution Overview
Problem
Existing video coding solutions, such as H.264/AVC, lack support for color bit depth scalability, requiring multiple bitstreams to be delivered for clients with different color bit depth requirements, leading to inefficiencies in compression ratio and operational complexity.
Innovation Solution
A scalable solution is introduced where a single bitstream is generated containing an H.264/AVC compatible base layer and an enhancement layer, allowing for decoding to 8-bit or 12-bit video based on client capabilities, with two new syntax elements: bit_depth_scalability_flag and bit_depth_pred_idc, enabling color bit depth scalability by utilizing inter-layer prediction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple bitstreams are generated for different color bit depths, then client compatibility is improved, but operational complexity and compression efficiency deteriorate
Solution Approach 1:
The patent combines multiple bitstreams for different color bit depths (8-bit and 12-bit) into a single scalable bitstream. The encoder generates one unified bitstream containing base layer (8-bit) and enhancement layer (12-bit) data, eliminating the need to manage separate bitstreams for different clients. This merging approach maintains client compatibility while significantly reducing operational complexity.
Solution Approach 2:
The single scalable bitstream serves multiple functions: it can be decoded by H.264/AVC decoders for 8-bit output, by color bit depth scalable decoders for 12-bit output, and supports both conventional and high-quality display devices. This universal bitstream design allows one encoding to serve multiple client types without requiring separate encoding operations.
2Adaptability or versatility
If multiple bitstreams are generated for different color bit depths, then client compatibility is improved, but compression ratio deteriorates
Solution Approach 1:
The encoder performs preliminary encoding of the high-bit-depth (12-bit) video content once, generating a scalable bitstream that contains both base layer (8-bit equivalent) and enhancement layer (additional 4 bits) data. This preliminary action eliminates the need for separate encoding operations for different bit depths, improving compression efficiency by avoiding redundant encoding of the same source material multiple times.
Solution Approach 2:
The patent implements a nested structure where the 8-bit base layer is embedded within the 12-bit scalable bitstream. The base layer contains the essential video information at 8-bit precision, while the enhancement layer adds the additional 4 bits of precision. This nesting allows clients to extract only the necessary layer, improving compression efficiency by avoiding transmission of unnecessary data to 8-bit capable clients.
3Productivity
If a single bitstream is generated for color bit depth scalability, then coding efficiency is improved, but decoder complexity increases
Solution Approach 1:
The scalable bitstream is segmented into distinct layers: base layer (8-bit compatible) and enhancement layer (additional 4 bits for 12-bit precision). H.264/AVC decoders can process only the base layer without needing to understand the enhancement layer structure, while color bit depth scalable decoders can process both layers. This segmentation allows simple decoders to maintain low complexity while more advanced decoders can utilize the full capability.
Solution Approach 2:
Different parts of the decoding system are designed with different levels of complexity: H.264/AVC decoders implement only base layer decoding (simpler), while color bit depth scalable decoders implement both base layer and enhancement layer decoding (more complex). This local quality approach ensures that each decoder type has the appropriate complexity for its intended function, with simple decoders handling conventional displays and advanced decoders handling high-quality displays.
Data Source
AI summary
This invention presents a scalable solution to encode the whole 12-bit raw video once to generate one bitstream that contains an H.264/AVC compatible base layer and a scalable enhancement layer. If an H.264/AVC decoder is available at the client end, only the base layer sub-bitstream is decoded and the decoded 8-bit video can be viewed on a conventional 8-bit display device; if the color bit depth scalable decoder is available at the client end, both the base layer and the enhancement layer sub-bitstreams will be decoded to obtain the 12-bit video and it can be viewed on a high quality display device that supports more than eight bit.