Video Block Type Prediction Using Pixel Activity Analysis
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Solution Overview
Problem
Video encoders face challenges in maintaining perceptual quality while adhering to a target bitrate, particularly when the complexity and layout of a scene are unknown, leading to inefficient bit allocation across frames.
Innovation Solution
A system comprising a pre-encoder and an encoder that predicts block types based on pixel activities, using gradients or texture analysis to determine quantization strength, allowing for accurate bit allocation and meeting target bitrates by predicting block types as skip, P, or I-blocks, and adjusting quantization parameters accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the encoder performs extensive analysis and encoding without control mechanisms, then the encoding quality may improve, but the encoder strays from the desired target bit size
Solution Approach 1:
The patent applies preliminary action by performing block type prediction before the actual encoding process. The pre-encoder analyzes pixel activities and predicts block types (I-blocks, P-blocks, skip blocks) in advance, allowing the encoder to allocate bits appropriately from the start and avoid straying from the target bit size while maintaining encoding quality.
2Quantity of substance
If the encoder uses a fixed bit allocation strategy, then the target bitrate can be met, but the perceptual quality of frames with varying complexity is not preserved
Solution Approach 1:
The patent applies local quality by allocating bits differently based on the predicted block types and scene complexity in different regions. Instead of uniform bit allocation, the pre-encoder identifies areas with high pixel activity or complexity and allocates more bits to those regions, while using fewer bits for simpler regions, thus preserving perceptual quality while meeting the target bitrate.
3Device complexity
If the encoder processes frames without predicting block types, then the encoding process is simpler, but efficient bit allocation across frames cannot be achieved
Solution Approach 1:
The patent introduces a pre-encoder stage that performs block type prediction based on pixel activity analysis before the main encoding process. This preliminary action enables efficient bit allocation by predicting which blocks will require more bits (I-blocks in complex regions) and which can use fewer bits (skip blocks in simple regions), improving bit allocation efficiency without significantly increasing overall system complexity.
Data Source
AI summary
Systems, apparatuses, and methods for block type prediction leveraging block-based pixel activities are disclosed. A pre-encoder generates predictions of block types for the blocks of a video frame based on associated pixel activities. For each block, the pre-encoder calculates the difference between the pixel activities of the block of a current frame and the pixel activities of a corresponding block of a previous video frame. If the difference is less than a first threshold, the pre-encoder predicts that the block will be a skip block. If the difference is in between the first threshold and a second threshold, the pre-encoder predicts that the block will be a P-block. Otherwise, if the difference is greater than the second threshold, then the pre-encoder predicts that the block will be an I-block. The pre-encoder uses the predictions to select quantization parameter (QP) ranges for encoding the blocks of the video frame.