Video Encoder Intermediate Buffer for Bit Rate Control
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Solution Overview
Problem
Existing video encoders face challenges in implementing high-precision bit rate control due to processing speed differences between quantizers and CABAC/CAVLC sections, leading to deviations in actual bit rate from target bit rates, regardless of using estimated or actual code amounts for control.
Innovation Solution
An intermediate buffer is coupled between the quantizer and encoding sections to absorb processing speed differences, with a code amount selector adjusting the quantization scale based on buffer data levels to use either estimated or actual code amounts for precise bit rate control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an intermediate buffer is introduced between the quantizer and encoding sections, then bit rate control precision is improved, but device complexity increases
Solution Approach 1:
An intermediate buffer is introduced between the quantizer and encoding sections to mediate the data flow. This buffer stores quantized data temporarily, allowing the system to decouple the processing speeds of different sections and achieve precise bit rate control without requiring complex real-time synchronization mechanisms.
Solution Approach 2:
The quantizer performs quantization processing in advance and stores the results in the intermediate buffer before the encoding section is ready to process. This preliminary action allows the quantizer to operate independently at its optimal speed, while the buffer accumulates data for subsequent encoding, resolving the speed mismatch between sections.
2Productivity
If the quantizer operates at high speed to improve productivity, then processing efficiency is improved, but bit rate control precision deteriorates due to processing speed differences
Solution Approach 1:
The encoding system is segmented into distinct functional sections (quantizer, intermediate buffer, encoding section) that can operate independently at different speeds. The quantizer operates at high speed to maximize productivity, while the intermediate buffer absorbs the speed difference, allowing the encoding section to process at its optimal pace without compromising bit rate control precision.
3Measurement precision
If actual code amount is used for rate control, then control accuracy is improved, but response time increases due to processing delays
Solution Approach 1:
The system implements feedback control by monitoring the actual code amount produced by the encoding section and using this information to adjust the quantizer's operation. The intermediate buffer enables this feedback mechanism to work effectively by storing data while the system calculates and responds to actual bit rate deviations, achieving both accuracy and acceptable response time.
Data Source
AI summary
The present invention provides a video encoder and a method of operating the video encoder to implement high-precision bit rate control by reducing the risk of overflow of an intermediate buffer coupled between a quantizer and an encoding section. The intermediate buffer supplies a selection control signal indicative of whether the amount of stored data is large or small to a selector. If the selection control signal indicates large, the selector outputs an estimated code amount from a code amount estimation section to the rate controller. If the selection control signal indicates small, the selector outputs an actual code amount from the encoding section to the rate controller. The rate controller calculates the quantization scale according to the output of the selector and feedbacks the calculated quantization scale to the quantizer. The quantizer adjusts the quantizer scale.