Dynamic Quantization for Video Encoding Latency
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Solution Overview
Problem
Video encoders face challenges in maintaining low latency while ensuring high picture quality, as strict latency requirements in applications like video conferencing and gaming are difficult to meet due to the need to skip encoding pictures to avoid buffer overflow, leading to issues like video pulsing and jerkiness.
Innovation Solution
A method and system for encoding video data that dynamically adjusts the quantization scale and determines whether to encode pictures based on a skip assessment and the encoding status of preceding pictures, using a pre-selected maximum encoded picture size ranging from 15 to 45 times the average number of bits, to mitigate video pulsing and jerkiness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the maximum encoded picture size is limited to meet latency requirements, then the latency is reduced, but the picture quality deteriorates when picture prediction is not effective and residual energy is large
Solution Approach 1:
The patent implements dynamic rate control by adjusting the quantization parameter (QP) based on the actual encoding bit consumption and residual energy of each picture. Instead of using a fixed maximum picture size limit, the system dynamically modifies encoding parameters to adapt to varying picture complexity and prediction effectiveness, thereby maintaining picture quality while controlling latency.
Solution Approach 2:
The patent changes the quantization parameter (QP) as a key encoding parameter based on the residual energy and bit consumption characteristics of each picture. By adjusting QP dynamically, the system can allocate more bits to complex pictures with large residual energy and fewer bits to simple pictures, resolving the contradiction between latency control and picture quality maintenance.
2Reliability
If pictures are skipped during encoding to reduce buffer occupancy, then the latency specification is met, but video pulsing and jerkiness occur
Solution Approach 1:
The patent employs feedback mechanisms by continuously monitoring the buffer occupancy, encoding bit consumption, and picture complexity metrics. Based on this feedback, the system adjusts the quantization parameter and encoding decisions in real-time, allowing it to maintain latency specifications while avoiding excessive picture skipping that causes video pulsing and jerkiness.
Solution Approach 2:
The patent performs preliminary assessment of picture complexity and residual energy before encoding decisions are made. By evaluating pictures in advance and pre-adjusting encoding parameters, the system can prevent buffer overflow without resorting to abrupt picture skipping, thereby maintaining smooth video playback while meeting latency requirements.
3Device complexity
If a strict maximum encoded picture size is imposed, then the encoding complexity is reduced, but the picture quality suffers when residual energy is large
Solution Approach 1:
The patent replaces the static maximum encoded picture size limit with dynamic rate control that adjusts encoding parameters based on actual picture characteristics. This dynamic approach maintains manageable encoding complexity while adapting to varying picture complexity and residual energy, preventing quality degradation in difficult-to-compress pictures.
Data Source
AI summary
Several methods and systems for encoding pictures associated with video data are disclosed. In an embodiment, a method includes determining by a processing module, whether a picture is to be encoded based on at least one of a skip assessment associated with the picture and an encoding status of a pre-selected number of pictures preceding the picture in an encoding sequence. The method further includes encoding by the processing module, a plurality of rows of video data associated with the picture upon determining that the picture is to be encoded, wherein the plurality of rows are encoded based on a pre-selected maximum encoded picture size.