Video Encoder Dynamic GOP Length Adjustment
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Solution Overview
Problem
Digital video encoding systems face challenges in balancing bit rate and image quality, particularly in network camera monitoring systems where applying bit rate limits can result in low image quality due to excessive compression, and longer GOP lengths increase encoding artifacts.
Innovation Solution
A method that calculates a global change value based on accumulations of group values from short-term and long-term image frames to dynamically adjust GOP length, allowing more frequent intra-frames during motion and less frequent intra-frames during static scenes, thereby reducing bit rate while maintaining high-quality video.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a bit rate limit is applied to reduce transmission bandwidth consumption, then the output bit rate is reduced, but image quality deteriorates due to severe compression
Solution Approach 1:
The GOP length is dynamically adjusted based on scene motion activity. During static scenes, longer GOP lengths reduce bit rate, while during motion scenes, shorter GOP lengths maintain image quality. This dynamic adaptation resolves the contradiction between bandwidth efficiency and image quality by making the compression strategy context-dependent.
Solution Approach 2:
The encoding parameter GOP length is changed based on the global change value calculated from accumulated group values. By modifying this parameter according to scene characteristics, the system achieves optimal balance between bit rate reduction and image quality preservation for different types of content.
2Loss of energy
If the GOP length is increased to reduce output bit rate, then the bit rate is reduced, but encoding artifacts increase due to error propagation
Solution Approach 1:
The GOP length is made dynamic rather than fixed, adjusting based on scene motion. During static scenes where error propagation is less noticeable, longer GOP lengths reduce bit rate. During motion scenes, shorter GOP lengths prevent excessive artifact accumulation, thus resolving the contradiction between bit rate reduction and artifact minimization.
Solution Approach 2:
The system uses feedback from the calculated global change value to adjust GOP length. This closed-loop control ensures that GOP length is optimized based on actual scene characteristics, preventing encoding artifacts while maintaining low bit rate where possible.
3Device complexity
If a fixed GOP length is used to simplify encoding, then device complexity is reduced, but image quality consistency deteriorates across different scene types
Solution Approach 1:
The GOP length parameter is adapted based on the global change value derived from accumulated group values of pixel groups. This parameter change strategy maintains simple encoding operations while achieving consistent image quality across static and motion scenes by selecting appropriate GOP lengths for each scene type.
Data Source
AI summary
A method for encoding video is disclosed. The method comprises the steps of receiving information representative of pixels in a current digital image frame of a video to be encoded, calculating a group value for each group of neighboring pixels based on the received information, accumulating group values of corresponding groups of pixels in a first sequence of frames to form a first accumulation of accumulated group values, accumulating group values of corresponding groups of pixels in a second sequence of frames to form a second accumulation of accumulated group values, wherein the second sequence includes frames captured over a longer period of time than the first sequence, comparing accumulated group values of the first accumulation with accumulated group values of the second accumulation, calculating a global change value based on the comparison, setting a GOP length based on the global change value; and encoding the current image frame as an intra-frame or inter-frame based on the GOP length. An encoder system for encoding video is also disclosed.