Adaptive Quantizer Parameter for Video Encoder Rate Control
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Solution Overview
Problem
Prior rate control methods for video encoders, such as Test Model 5, result in varying picture quality and blocking issues due to inadequate bit allocation, particularly in variable bit-rate scenarios.
Innovation Solution
An adaptive quantizer parameter determination method for video encoders that optimizes picture quality by calculating and adjusting quantizer parameters based on current bit-rate, using a model that assigns bits to different picture types and updates quantizer settings to maintain consistent quality across frames.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If Test Model 5 rate control is used, then bit-rate allocation is simplified, but picture quality varies too much between pictures and blocking occurs
Solution Approach 1:
The patent implements dynamic rate control by adjusting quantizer parameters based on buffer status and picture characteristics. The quantizer parameter is modified dynamically using feedback from the buffer fullness and picture type (I, P, or B pictures), allowing the system to adapt bit allocation to varying scene complexity and motion levels, thereby maintaining consistent picture quality while managing bit-rate effectively.
Solution Approach 2:
The patent employs feedback mechanisms where the buffer fullness is continuously monitored and used to adjust the quantizer parameter for subsequent pictures. The rate control system receives feedback about actual bit consumption and buffer status, then modifies quantizer settings to maintain target bit-rate and prevent buffer overflow or underflow, resolving the quality inconsistency problem.
2Quantity of substance
If variable bit-rate is used for storage optimization, then average bit-rate can be reduced, but maximum bit-rate constraints and buffer management become more complex
Solution Approach 1:
The patent changes the quantizer parameter based on buffer status and picture type to achieve variable bit-rate encoding. By adjusting the quantizer parameter (a key encoding parameter), the system optimizes storage efficiency by using coarser quantization when buffer is full and finer quantization when buffer has space, while automatically adapting to different picture types without requiring complex manual buffer management.
3Manufacturing precision
If adaptive quantizer adjustment is implemented, then picture quality consistency improves, but calculation and control complexity increases
Solution Approach 1:
The patent segments the rate control process into distinct components: buffer status monitoring, picture type identification, quantizer parameter calculation, and bit allocation. By dividing the control logic into manageable segments based on picture type (I, P, B) and buffer status levels, the system achieves sophisticated adaptive control while keeping each segment's complexity manageable and implementable.
Data Source
AI summary
An apparatus and corresponding method are provided for encoding video signal data by applying an adaptive quantizer parameter responsive to bit-rate; where a video encoder for encoding video signal data for an image block relative to at least one reference picture includes an adaptive quantizer for applying an adaptive quantizer parameter responsive to a current bit-rate; and where a corresponding method includes initializing an adaptive quantizer, calculating the bits used by the video signal data with the adaptive quantizer, assigning bits to each of a plurality of picture types, calculating a difference in adaptive quantizer responsive to the assigned bits from the previous number of bits used by the group of pictures and obtaining an updated adaptive quantizer for the video signal data, calculating an adaptive quantizer for a portion of the video signal data, encoding the portion of the video signal data, and obtaining the actual number of bits used for the encoded portion of the video signal data.