Video Encoding Flicker Reduction via Quantization Control
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Solution Overview
Problem
Existing video encoding techniques often result in flicker, a visual discontinuity that degrades the quality of displayed video streams, due to differences in encoding modes and quantization parameters between frames.
Innovation Solution
The proposed solution involves capping quantization parameters for I-frames to match those of previous P-frames, computing quantization step sizes based on quantization errors of co-located macro-blocks, and using higher quantization values for high-frequency components, as well as replacing flicker-prone macro-blocks with best-match macro-blocks from previous frames through motion estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If different quantization parameters are used for different frames to optimize compression, then compression efficiency is improved, but visual discontinuity (flicker) increases
Solution Approach 1:
The patent dynamically adjusts quantization parameters based on frame type (I-frames vs P-frames) and scene complexity metrics. By changing the quantization parameter values adaptively rather than using fixed values, the system achieves better compression efficiency while maintaining visual consistency through controlled parameter transitions between frames
Solution Approach 2:
The system implements dynamic quantization parameter selection that adapts to changing video content characteristics. The quantization parameters are adjusted in real-time based on frame type and measured scene complexity, allowing the encoding process to respond dynamically to content variations while maintaining visual quality consistency
2Quantity of substance
If higher quantization parameters are used to reduce bit rate, then transmission rate is reduced, but visual quality degrades
Solution Approach 1:
The patent applies different quantization parameter strategies to different frame types (I-frames and P-frames) based on their specific characteristics and roles in the video stream. By tailoring the quantization approach to local frame requirements rather than applying a uniform strategy, the system achieves efficient bit rate control while preserving visual quality where most needed
3Productivity
If quantization parameters vary between I-frames and P-frames to optimize encoding, then encoding efficiency is improved, but frame-to-frame consistency deteriorates
Solution Approach 1:
The system implements dynamic quantization parameter selection that adapts to changing video content characteristics. The quantization parameters are adjusted in real-time based on frame type and measured scene complexity, allowing the encoding process to respond dynamically to content variations while maintaining visual quality consistency
Solution Approach 2:
The patent employs scene complexity metrics as a feedback mechanism to guide quantization parameter selection. By measuring content characteristics and using this information to adjust encoding parameters, the system achieves efficient encoding while maintaining frame-to-frame visual consistency through closed-loop parameter control
Data Source
AI summary
Image frames of a video stream are encoded with the aim of reducing flicker in the video stream when displayed. In one embodiment, the quantization parameter used to quantize an image frame is capped to be not greater than a quantization parameter used to quantize an immediately previous image frame. In another embodiment, the quantization step size used to quantize a macro-block of an image frame is computed based on the value of a quantization error of a co-located macro-block in an immediately previous image frame. In yet another embodiment, macro-block transform coefficients corresponding to high-frequency components are quantized using relatively higher quantization parameter values if the image frame is deemed to contain high activity. In yet another embodiment, flicker-prone macro-blocks of a source frame are replaced by corresponding best-match macro-blocks of a previous reconstructed frame, prior to being encoded.