Video Encoder Bit-Rate Control via Quantization Scaling
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Solution Overview
Problem
Existing video encoding technologies face challenges in controlling transmission bit-rate effectively, particularly in scenarios requiring constant bit-rate over a short duration, such as low bit-rate bandwidth constrained applications, where maintaining instantaneous bit-rate within strict maximum and minimum limits is crucial.
Innovation Solution
A video encoder system that receives minimum and maximum bit-rates for a segment of image frames and employs a rate control block to determine a base and minimum quantization scale, ensuring the total bits used do not exceed the maximum limit by selecting the maximum of these scales and adding filler bits if necessary, while ensuring the bit-rate remains within the specified constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional video encoding is used without rate control, then encoding simplicity is maintained, but transmission bit-rate cannot be controlled within strict maximum and minimum limits
Solution Approach 1:
The rate control mechanism performs preliminary calculations of base quantization scale and minimum quantization scale before actual encoding. By pre-determining these quantization parameters based on target bit-rate, maximum bits, and segment duration, the encoder can control the output bit-rate without complex real-time adjustments during encoding.
Solution Approach 2:
The invention controls bit-rate by dynamically adjusting quantization parameters (base quantization scale and minimum quantization scale) based on the relationship between target bit-rate, maximum bits, and segment duration. By changing these parameters, the encoder can maintain bit-rate within specified limits while adapting to varying video content complexity.
2Manufacturing precision
If higher bit-rate is used for encoding, then encoding quality is improved, but transmission bandwidth consumption increases
Solution Approach 1:
The rate control mechanism dynamically adjusts quantization parameters to optimize the balance between encoding quality and bit-rate. By calculating appropriate base quantization scale and minimum quantization scale values, the system achieves acceptable encoding quality while maintaining bit-rate within the specified maximum limit, thus reducing unnecessary bandwidth consumption.
Solution Approach 2:
The invention applies partial action by using filler bits to reach the target bit-rate when the encoded segment uses fewer bits than expected. This ensures that the transmission bit-rate meets the minimum requirement without excessively increasing the bit-rate above the maximum limit, achieving a balanced approach to quality and bandwidth usage.
3Reliability
If strict minimum bit-rate is enforced, then transmission reliability is improved, but encoding flexibility is reduced
Solution Approach 1:
The rate control mechanism uses filler bits to partially supplement the encoded data when the bit-count falls short of the target. This partial action ensures that the minimum bit-rate requirement is met for transmission reliability, while allowing the encoder to maintain flexibility in choosing quantization parameters and encoding strategies.
Solution Approach 2:
The invention introduces an intermediary rate control mechanism that sits between the encoder and transmission channel. This intermediary calculates appropriate quantization parameters and adds filler bits as needed, ensuring that the minimum bit-rate is achieved without directly constraining the encoding process, thus preserving encoding flexibility while meeting transmission requirements.
Data Source
AI summary
A video encoder receives a minimum number of bits (MIN) and a maximum number of bits (MAX) to be used to encode a segment of a sequence of image frames, the segment including a set of pictures contained in the sequence of image frames. The video encoder encodes the set of pictures using a total number of bits greater than the minimum number of bits (MIN), and not exceeding the maximum number of bits (MAX). Thus, the transmission bit-rate of the video encoder can be constrained to lie within a maximum and minimum rate. In an embodiment, the constraints are enforced over relatively short time intervals.