Dependent Random Access Point Pictures for Video Bitstream Efficiency
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Solution Overview
Problem
Current video coding technologies face challenges in balancing the number of random access points and bit cost, particularly with the high bit cost of intra random access points (IRAPs) in video bitstreams, which limits efficient channel switching and seeking in video content.
Innovation Solution
The introduction of dependent random access points (DRAPs) that use previous IRAP or DRAP pictures as sole references, allowing for reduced bit cost while maintaining random access functionality, by encoding DRAPs as trailing pictures that can reference only the preceding IRAP or DRAP pictures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If intra random access points (IRAPs) are used to enable random access in video bitstreams, then random access functionality is improved, but bit cost increases significantly
Solution Approach 1:
The patent segments random access points into two distinct types: IRAP pictures that provide complete independence for random access, and DRAP pictures that provide random access functionality with dependency on previous pictures. This segmentation allows the system to use DRAP pictures for frequent random access operations (reducing bit cost) while relying on occasional IRAP pictures for complete refresh, thereby resolving the contradiction between random access functionality and bit cost.
Solution Approach 2:
The patent changes the parameter of reference picture dependency for random access points. Instead of all random access points being completely independent (IRAP), the system allows some random access points (DRAP) to depend on previous pictures for decoding. This parameter change enables random access functionality while significantly reducing bit cost, as DRAP pictures can reuse reference data from previous pictures rather than encoding complete independent information.
2Productivity
If the number of random access points is increased to improve channel switching and seeking, then access efficiency is improved, but bit cost increases
Solution Approach 1:
The patent segments random access points into IRAP and DRAP types with different frequencies and purposes. DRAP pictures can be inserted more frequently than IRAP pictures because they have lower bit cost requirements. This segmentation enables the system to achieve high access efficiency through frequent DRAP pictures while maintaining overall bit cost efficiency by using the less frequent, more expensive IRAP pictures only when necessary for complete refresh.
3Reliability
If intra coding is used for random access pictures to ensure independence, then decoding independence is improved, but coding efficiency deteriorates
Solution Approach 1:
The patent segments the requirement for decoding independence into two levels: full independence provided by IRAP pictures (used occasionally for complete refresh) and partial independence provided by DRAP pictures (used frequently for efficient access). DRAP pictures achieve sufficient independence for random access operations by depending only on previous IRAP or DRAP pictures, allowing inter coding to be used and thereby improving coding efficiency while maintaining adequate decoding independence.
Solution Approach 2:
The patent changes the parameter of independence requirement for random access pictures. Instead of requiring complete independence (intra coding) for all random access pictures, the system allows DRAP pictures to have dependency on previous pictures. This parameter change enables the use of more efficient inter coding for DRAP pictures while still providing sufficient independence for random access functionality, thereby resolving the contradiction between decoding independence and coding efficiency.
Data Source
AI summary
The present embodiments introduce a new type of random access point in video bitstreams that can be used for random access operations but can be represented in encoded form at a lower bit-cost as compared to IRAP pictures. The random access point is a dependent random access point (DRAP) picture that is encoded and decoded using an IRAP picture and/or a previous, according to a decoding order, DRAP picture as sole reference picture(s) for the DRAP picture. The DRAP picture is encoded as a trailing picture that may be used for reference and constitutes a random access point in a video bitstream.