BD-ROM Entry Map Excludes Mixed-Format Pictures
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Solution Overview
Problem
Conventional random access technologies for video streams with a high percentage of intra frame coding format pictures result in unstable image resolution due to extended intervals between entry positions, leading to inefficient random access and potential playback issues.
Innovation Solution
A recording medium with an entry map that excludes entry information for pictures with inter frame predictive and intra frame coding formats, ensuring that only intra frame coded pictures are used as entry points, thereby maintaining consistent image resolution during random access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional entry maps include all picture types as entry positions, then the number of entry positions increases, but the intervals between continuous entry positions are extended and image resolution becomes unstable
Solution Approach 1:
The patent applies local quality by differentiating between types of pictures and assigning different roles to them. Only I pictures (intra frame coded pictures) are designated as entry positions, while P pictures (inter frame predictive coded pictures) are excluded. This local differentiation ensures that entry positions are located at pictures that can be decoded independently, maintaining stable full-resolution playback, while still providing sufficient entry points for random access.
2Adaptability or versatility
If entry positions are extended to include P pictures with mixed field formats, then random access coverage improves, but stream analysis frequency increases and response time lengthens
Solution Approach 1:
The patent extracts only the essential entry positions (I pictures) from the set of all possible picture types, excluding P pictures even though they might provide additional access points. This extraction approach ensures that entry positions are located at pictures that can be decoded independently without requiring stream analysis, thereby reducing the frequency of stream analysis operations and shortening response time while still providing adequate random access coverage.
3Quantity of substance
If all picture types are used as entry positions, then entry map density increases, but the number of stream analyses required increases and access efficiency decreases
Solution Approach 1:
The patent changes the selection criterion for entry positions from including all picture types to including only I pictures (intra frame coded pictures). This parameter change in the selection criteria ensures that entry positions are located at pictures that can be decoded independently, eliminating the need for frequent stream analysis operations and thereby improving random access efficiency while maintaining adequate entry map density.
Data Source
AI summary
A BD-ROM on which a VC-1 video stream and an entry map (EP_map) are recorded. The VC-1 video stream includes: (a) picture data (I/P picture) whose first fields are the intra frame coding format and whose second fields are the inter frame predictive coding format; and (b) picture data (P/I picture) whose first fields are the inter frame predictive coding format and whose second fields are the intra frame coding format. The entry map indicates entry positions (SPN) of the I/P pictures, in correspondence with playback times (PTS), but does not indicate entry positions of the P/I pictures.