Hardware Encoder Rate Control via Software Feedback Loop
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Solution Overview
Problem
Hardware video encoders often struggle to accurately control bit-rate, leading to inaccuracies and difficulties in maintaining desired bit-rate levels, especially when access to tuning parameters is limited, resulting in suboptimal performance.
Innovation Solution
An outer software rate adjustment loop is implemented, utilizing a VBV buffer model to drop frames when full and periodically adjusting the hardware encoder bit-rate based on leaky bucket analysis to ensure accurate bit-rate control, with frame dropping for short-term correction and bit-rate adjustments for long-term stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If hardware encoder is used to reduce cost, then manufacturing cost decreases, but bit-rate control accuracy deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the software monitors the actual bit-rate output from the hardware encoder and compares it against the target bit-rate. Based on this comparison, the software dynamically adjusts the hardware encoder's bit-rate control parameters to minimize the difference between actual and target bit-rates, thereby compensating for the hardware encoder's inherent imprecision while maintaining cost-effectiveness.
Solution Approach 2:
The patent introduces a software intermediary layer that sits between the user and the hardware encoder. This software layer acts as a mediator that translates user bit-rate requirements into adjusted control parameters for the hardware encoder, accounting for the hardware's imprecise response. The software intermediary processes the control signals and compensates for hardware limitations, achieving accurate bit-rate control without requiring a more expensive hardware solution.
2Ease of operation
If hardware encoder parameters are limited for simplicity, then ease of operation improves, but adaptability deteriorates
Solution Approach 1:
The patent enables the system to self-adjust by implementing an automatic bit-rate control algorithm in software. The system continuously monitors encoding performance and automatically modifies hardware encoder parameters without requiring manual intervention or complex user configuration. This self-service approach maintains ease of operation while achieving adaptability, as the software autonomously handles the complexity of parameter tuning based on real-time feedback.
Solution Approach 2:
The patent dynamically changes hardware encoder parameters through software control based on monitored performance metrics. The software adjusts key parameters such as quantization step size, frame skip rate, and bit-rate allocation to adapt to varying content characteristics and network conditions, thereby achieving versatility without exposing complex parameter interfaces to users.
3Manufacturing precision
If frame dropping is used for short-term correction, then bit-rate accuracy improves quickly, but video quality deteriorates
Solution Approach 1:
The patent implements a dynamic bit-rate control strategy that adapts frame dropping decisions based on video content characteristics, scene complexity, and current buffer conditions. Rather than applying fixed frame dropping rules, the system dynamically adjusts the aggressiveness of frame dropping to achieve bit-rate accuracy while minimizing quality impact. Important frames are preserved while less critical frames are dropped, maintaining a balance between bit-rate control and video quality.
Solution Approach 2:
The patent employs periodic rate adjustment analysis where the system periodically evaluates whether frame dropping should be applied based on accumulated bit-rate errors and current video content characteristics. This periodic action allows the system to make informed decisions about when to drop frames versus when to adjust encoder parameters, thereby achieving bit-rate accuracy while minimizing unnecessary frame drops that would degrade video quality.
Data Source
AI summary
Correcting encode bit rate errors developed by a hardware encoder with an outer software rate adjustment loop. The rate adjustment loop maintains a VBV (video buffering verifier) buffer model. When VBV buffer fullness is over a threshold, the rate adjustment loop drops frames. If below the threshold, periodically a rate adjustment analysis performed. If a number of frames above a threshold have been dropped, the hardware encoder bit rate is decreased. A leaky bucket is checked to determine in bits and out bits. If the number of in bits exceeds the number of out bits times a multiplier, the hardware encoder bit rate is decreased. If the number of in bits times a multiplier is less than the number of out bits, the hardware encoder bit rate is increased. Dropping frames on buffer condition provides shorter term correction and adjustment of the hardware encoder bit rate provides longer term correction.