Video Encoder Quantization Step Selection
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Solution Overview
Problem
Existing digital video encoding methods face challenges in reducing output bitrate without compromising image quality, particularly in scenarios with motion, where high compression values can lead to increased bandwidth requirements and low image quality, and vice versa.
Innovation Solution
A method and system for optimizing the quantization step in video encoding by selecting from a set of available quantization steps, including larger and smaller steps than the predetermined step, to minimize output bitrate while maintaining acceptable image quality, by choosing the step that results in the smallest remainder after division of group value differences, thereby reducing information loss and improving encoding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If high compression values (large quantization steps) are used to reduce output bitrate, then bandwidth usage is reduced, but image quality deteriorates
Solution Approach 1:
The patent implements dynamic quantization step adjustment where the encoder selects from multiple available quantization steps (including smaller steps than the predetermined step) based on scene characteristics. This dynamic adaptation allows the system to use smaller quantization steps in static scenes to maintain quality while using larger steps in motion scenes to reduce bitrate, resolving the contradiction between bandwidth efficiency and image quality
Solution Approach 2:
The patent changes the quantization parameter (quantization step size) based on the analysis of group value differences between current and reference frames. By calculating remainders after division and selecting steps that minimize these remainders, the system optimizes the balance between compression efficiency and reconstruction quality, addressing the trade-off between bitrate reduction and quality preservation
2Manufacturing precision
If variable bitrate encoding is used to maintain constant quality, then image quality is preserved, but output bitrate increases unnecessarily for static scenes
Solution Approach 1:
The patent applies different quantization steps to different blocks or regions based on their specific characteristics (motion activity, complexity). By analyzing group value differences locally and selecting quantization steps that minimize remainders for each region, the system achieves constant quality where needed while reducing bitrate in less critical areas, resolving the contradiction between quality preservation and bitrate efficiency
Solution Approach 2:
Instead of applying uniform high-quality encoding across all frames, the patent applies enhanced encoding (smaller quantization steps) only when necessary - specifically when group value differences indicate static or low-complexity scenes. This partial application of high-quality encoding reduces unnecessary bitrate consumption while maintaining quality where it matters, addressing the VBR inefficiency
3Loss of energy
If constant bitrate encoding is used to limit bandwidth, then bandwidth usage is controlled, but image quality varies significantly with scene motion
Solution Approach 1:
The patent dynamically adjusts quantization steps within the constant bitrate framework by selecting from multiple available steps based on scene analysis. When motion is detected (large group value differences), larger quantization steps are used to maintain bitrate compliance. When scenes are static (small group value differences), smaller quantization steps are used to maintain quality, thus resolving the contradiction between bandwidth control and quality consistency
Data Source
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AI summary
A method for encoding video is disclosed. Information (S101) representative of pixels in an image frame is received, and a spatial statistical measure of said information is calculated for groups of neighbouring pixels to form a group value (S102) for each group of pixels. A set of available quantization steps is determined (S105) comprising a first predetermined quantization step. For a first group of neighbouring pixels, the method comprises: for each available quantization step calculating a remainder (S106) after division of the group value of the first group of pixels by the respective available quantization step. The quantization step of the set that results in the smallest remainder is selected as selected quantization step (S107). The first group of pixels is encoded (S108) using the selected quantization step. A method of encoding differences between image frames is also disclosed, as well as encoding systems.