Hybrid Video Encoder Rate Control Across Enhancement Layers
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Solution Overview
Problem
Existing video encoding technologies struggle with flexible and efficient rate control, particularly in hybrid video streams, where maintaining desired quality levels across different encoding layers is challenging due to varying complexity and bandwidth constraints.
Innovation Solution
A hybrid video encoding method that generates a base stream and multiple enhancement streams, allowing independent rate control for each layer, using quantization parameters to adapt data rates while maintaining quality, and employing a hierarchical encoding approach to correct for quirks in base codecs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If constant bitrate encoding is used, then bandwidth utilization is efficient, but quality consistency across different scene complexities deteriorates
Solution Approach 1:
The patent implements dynamic bitrate allocation across enhancement layers, allowing the system to adaptively adjust the number of bits assigned to each layer based on scene complexity and buffer status, rather than using a fixed constant bitrate approach. This enables quality consistency to be maintained while efficiently utilizing available bandwidth.
Solution Approach 2:
The patent changes the quantization parameter (QP) dynamically for different enhancement layers based on the desired quality level and available bitrate. By adjusting QP values, the system can control the trade-off between quality and bitrate for each layer, resolving the contradiction between efficient bandwidth utilization and quality consistency.
2Manufacturing precision
If constant quality factor (CRF) encoding is used, then quality consistency is maintained, but bandwidth utilization becomes inefficient
Solution Approach 1:
The patent segments the video stream into multiple enhancement layers, each with its own quantization parameter and bitrate allocation. This allows independent control of quality and bitrate for each layer, enabling the system to maintain quality consistency where needed while reducing overall bitrate through efficient segmentation and selective encoding.
3Adaptability or versatility
If multiple enhancement layers are added to hybrid video streams, then adaptability and quality control improve, but device complexity increases
Solution Approach 1:
The patent implements a nested enhancement layer structure where each layer builds upon the previous one, with inner layers providing base quality and outer layers adding incremental improvements. This nested approach allows adaptability and quality control to improve while managing device complexity through a systematic, hierarchical encoding framework that can be efficiently processed.
4Manufacturing precision
If quantization parameters are adjusted for each enhancement layer, then quality control improves, but computational complexity increases
Solution Approach 1:
The patent applies different quantization parameters to different enhancement layers based on their specific quality requirements and importance. Rather than using a uniform QP across all layers, the system assigns locally optimized QP values to each layer, improving overall quality control while managing computational load through targeted, layer-specific parameter adjustment rather than exhaustive optimization.
Data Source
AI summary
A method of encoding an input video as a hybrid video stream, the method comprising: receiving the input video at a first resolution; obtaining an indication of a desired quality level for the encoding, the desired quality level setting one or more bit rates for the hybrid video stream, said hybrid stream comprising a base encoded stream at a second resolution and a plurality of enhancement streams at each of the first and second resolutions, the first resolution being higher than the second resolution; encoding each of the plurality of enhancement streams by: generating a set of residuals based on a difference between the input video and a reconstructed video at the respective resolution of the enhancement stream; determining quantisation parameters for the set of residuals for based on the desired quality level; quantising the set of residuals based on the quantisation parameters; and creating an encoded stream from the set of quantised residuals.