Image Processor Error Recovery Reference Switching
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Solution Overview
Problem
Low-delay codecs experience increased delay times between error occurrence and recovery due to the need to send I-pictures after error notification, which elongates data transmission time and image degradation.
Innovation Solution
The image processor employs a mechanism where, upon error detection, it switches to using local or previously decoded images as reference images for encoding and decoding, without sending I-pictures, thereby managing errors by changing P-picture references and minimizing data transmission time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If I-pictures are sent after error notification to ensure reliable error recovery, then reliability of error recovery is improved, but delay time between error occurrence and recovery increases
Solution Approach 1:
The patent dynamically switches the reference image selection strategy based on error state. During normal operation, P-pictures use the immediately preceding picture as reference. Upon error detection, the system dynamically changes to use a reference image from before the error occurred, and maintains this dynamic switching capability throughout error recovery, allowing adaptive response to error conditions while minimizing delay.
Solution Approach 2:
The patent changes the parameter of reference image selection timing. Instead of always using the immediately preceding picture, the system changes the reference parameter to select from stored local decoded images based on error notification, thereby controlling the recovery process without requiring full I-picture transmission and reducing the associated delay.
2Manufacturing precision
If I-pictures are transmitted for error recovery, then image quality is improved, but data transmission time is elongated
Solution Approach 1:
The patent extracts the essential error recovery function from the complete I-picture transmission process. By using selectively chosen reference images from local decoded images stored in memory, the system separates the error recovery need from the full I-picture data transmission, thereby maintaining image quality recovery while eliminating the elongated transmission time associated with sending complete I-pictures.
Solution Approach 2:
The patent performs preliminary action by storing multiple local decoded images in memory before error occurrence. This pre-stored reference images are prepared in advance, allowing immediate selection and use upon error detection without requiring new data transmission, thus maintaining image quality while avoiding transmission delay.
3Manufacturing precision
If reference images from before error are used, then image degradation is reduced, but complexity of reference image management increases
Solution Approach 1:
The patent segments the reference image management into distinct functional components: an error notification receiving circuit that detects errors, a first reference image determination circuit that selects appropriate reference images for encoding, and a second reference image determination circuit that selects reference images for decoding. This segmentation manages complexity by distributing the reference image management task across specialized circuits rather than a single complex system.
Solution Approach 2:
The patent introduces intermediary circuits (error notification receiving circuit and reference image determination circuits) that mediate between the error condition and the reference image selection process. These intermediary components simplify management by providing a structured interface for selecting reference images from stored local decoded images, reducing the overall system complexity while maintaining image quality.
Data Source
AI summary
In an earliest vertical synchronization period after sending an encoded image data is restarted, a first reference image determination circuit determines to employ a local decoded image generated in a vertical synchronization period immediately preceding a vertical synchronization period in which an error occurs among multiple local decoded images stored in a first DRAM as a reference image. In an earliest vertical synchronization period after a decoding circuit is reset, a second reference image determination circuit determines to employ a decoded image generated in the vertical synchronization period immediately preceding the vertical synchronization period in which the error occurs among multiple decoded images stored in a second DRAM as a reference image.