Video Bit Rate Adaptation via Sub-band Truncation and Motion Compensation
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Solution Overview
Problem
Existing methods for adapting bit rates of Motion JPEG2000 compressed video streams to constrained transmission channels do not effectively minimize distortion, particularly in radio transmission, as they fail to account for error masking capabilities and temporal correlations between images.
Innovation Solution
A method that selects optimal truncation points and applies motion compensation to minimize distortion, using a key image to reconstruct images at higher resolutions while adhering to bit rate constraints, and optionally employs error-correcting codes to further reduce distortion from transmission errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If sub-bands are deleted to respect constrained bit rate, then bit rate constraint is satisfied, but image resolution and quality deteriorate
Solution Approach 1:
The compressed image is divided into multiple sub-bands representing different spatial resolutions. The method selectively transmits only the necessary sub-bands (e.g., low-frequency components) while omitting higher-frequency sub-bands, thereby segmenting the data to satisfy bit rate constraints while preserving essential image quality information.
Solution Approach 2:
Different sub-bands are treated differently based on their importance. The method applies selective truncation where low-frequency sub-bands are retained for maintaining overall image structure, while high-frequency sub-bands are discarded. This local differentiation optimizes the balance between bit rate and image quality by prioritizing visually important components.
2Reliability
If error-correcting codes are applied to increase total stream rate, then transmission reliability improves, but bit rate consumption increases
Solution Approach 1:
Instead of applying error correction to the entire image stream, the method applies error-correcting codes selectively only to the most important sub-bands (e.g., low-frequency components) that carry essential image information. This partial application provides sufficient protection against transmission errors while minimizing the additional bit rate consumption.
3Manufacturing precision
If temporal correlation is exploited for error masking, then image reconstruction quality improves, but complexity of processing increases
Solution Approach 1:
The method performs motion estimation and motion compensation in advance during the encoding stage, creating motion vectors and predicted blocks that can be used later for error masking. This preliminary preparation enables the decoder to reconstruct damaged blocks using temporal correlation without requiring complex real-time processing, thus improving reconstruction quality while controlling processing complexity.
Data Source
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AI summary
Method and device for adapting the bit rate of a compressed video stream transmitted in a constrained environment. Method for adapting the bit rate of a video stream (300) comprising a plurality N of compressed images (Icn) at a plurality of spatial resolutions and/or a plurality of quality layers, said images being compressed separately from each other.