Reverse Play Video Decoding Using Re-encoded Anchor Pictures
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Solution Overview
Problem
Existing MPEG decoding systems require large memory buffers to support reverse play mode, as they need to store and decode multiple frames in a specific order, leading to increased memory and processing demands, especially for large groups of pictures (GOPs).
Innovation Solution
Re-encoding a subset of forward predictive encoded pictures as anchor pictures, allowing for independent decoding groups that reduce memory requirements and processing time, with options for re-encoding during forward play or separate from other operating modes, and sub-sampling to further minimize memory needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If all forward predictive encoded pictures are stored and decoded during reverse play, then complete picture quality is maintained, but memory space requirements become extremely large
Solution Approach 1:
The patent divides the sequence of forward predictive encoded pictures into multiple independent groups by inserting anchor pictures at strategic positions. Each group can be decoded independently without requiring all previous pictures to be stored, thus segmenting the memory requirement into smaller, manageable portions while maintaining complete picture quality.
Solution Approach 2:
The patent performs preliminary re-encoding of selected forward predictive encoded pictures as anchor pictures during forward play. These pre-prepared anchor pictures serve as reference points for subsequent reverse play decoding, eliminating the need to store all intermediate pictures and reducing memory requirements while maintaining quality.
2Reliability
If all frames are stored in frame buffer memory for reverse play, then decoding dependency is resolved, but device complexity and processing time increase
Solution Approach 1:
The patent segments the frame buffer memory into multiple smaller buffers, each dedicated to storing a specific group of pictures between anchor pictures. This segmentation allows the system to maintain decoding reliability for reverse play while reducing the complexity of managing a single large buffer and its associated pointer management and memory allocation operations.
3Reliability
If a large frame buffer memory is used for reverse play, then all frames can be stored and decoded, but processing time increases significantly
Solution Approach 1:
By dividing the picture sequence into groups separated by anchor pictures, the patent enables the processor to decode and display only the current group rather than scanning through the entire frame buffer. This segmentation dramatically reduces processing time during reverse play while maintaining the reliability of complete picture decoding.
Solution Approach 2:
The patent performs preliminary re-encoding of selected pictures as anchor pictures during forward play, creating a pre-organized structure that enables faster reverse play decoding. The anchor pictures are prepared in advance with their encoding parameters, allowing the reverse play processor to skip unnecessary decoding steps and reduce overall processing time.
Data Source
AI summary
In the method and apparatus for reverse play, the forward predictive encoded pictures in a compressed video stream are decoded, and selected ones of the decoded, forward predictive encoded pictures are re-encoded as anchor pictures. These anchor pictures are then used to decode portions of the compressed video stream for display in a reverse display order.