Graphics Decoder Memory Management for Seamless BD-ROM Playback
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Solution Overview
Problem
Conventional DVD reproduction devices experience momentary interruptions in the display of subtitles and menus when switching between digital streams due to the clearing of graphics stream data, limiting the flexibility in placing digital stream boundaries and making it difficult to achieve seamless playback that follows a desired storyline in multi-story movies.
Innovation Solution
A recording medium that includes digital streams multiplexed with a video stream and a graphics stream containing status information, which instructs the reproduction device to maintain continuous memory management during playback, preventing the reset of the graphics decoder and allowing for seamless transitions between streams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the graphics decoder memory is cleared when switching between digital streams, then the system ensures data independence between streams, but momentary interruptions occur in the display of subtitles and menus
Solution Approach 1:
The patent applies local quality by differentiating the treatment of graphics data based on its type and context. Independent graphics data (such as menu structures) is preserved across stream boundaries, while dependent graphics data (such as subtitles that may change between streams) is selectively updated. This allows the system to maintain display continuity for elements that should persist while ensuring proper updates for elements that should change, resolving the contradiction between data independence and display continuity.
Solution Approach 2:
The patent implements dynamics by introducing a mechanism that dynamically determines whether to clear graphics decoder memory based on the specific stream transition context. The system evaluates the relationship between preceding and following streams, identifying whether graphics data should be maintained or reset. This dynamic approach allows the graphics decoder to adapt its behavior to maintain seamless playback while ensuring data independence where required.
2Manufacturing precision
If digital stream boundaries are placed to avoid speech sections, then momentary interruptions are minimized, but the flexibility in placing boundaries is reduced and desired storyline playback cannot be achieved
Solution Approach 1:
The patent enables precise control over graphics data handling at different locations within the stream structure. By identifying specific graphics elements that should maintain continuity (such as persistent menu items) versus those that should update (such as scene-specific subtitles), the system allows boundary placement to occur at any desired location without compromising display continuity. This local quality approach grants authors complete flexibility in boundary placement while maintaining seamless playback.
Solution Approach 2:
The patent applies preliminary action by pre-identifying and preserving graphics data that should maintain continuity across stream boundaries. Before the actual stream transition occurs, the system determines which graphics elements should be maintained and prepares them for seamless continuation. This preliminary preparation eliminates the need to avoid speech sections when placing boundaries, as the graphics continuity is already established in advance.
3Stability of the object's composition
If the graphics decoder is reset at each stream switch, then data consistency within each stream is ensured, but seamless playback cannot be achieved
Solution Approach 1:
The patent resolves this contradiction by applying local quality to the graphics decoder reset operation. Instead of uniformly resetting the decoder at every stream boundary, the system selectively maintains graphics data for elements that should persist (such as menu structures and persistent graphics) while allowing updates for elements that should change. This localized differentiation ensures data consistency within each stream while maintaining playback seamlessness across boundaries.
Solution Approach 2:
The patent implements dynamics by making the graphics decoder reset behavior adaptive rather than static. The system dynamically evaluates each stream transition to determine whether a reset is appropriate, based on the relationship between preceding and following streams. This dynamic control allows the decoder to maintain data consistency where required while preserving seamlessness where appropriate, eliminating the need for uniform resetting at all boundaries.
Data Source
AI summary
An AV Clip formed by multiplexing a video stream and a graphics stream and recorded on a BD-ROM as a recording medium. The video stream constitutes a moving picture while the graphics stream enables graphics to be overlaid on the moving picture, and includes pieces of control information called a PCS and an ICS. When the AV Clip is played back immediately following playback of another digital stream, the control information indicates to the reproduction device that the presence of data already in memory of a graphics decoder is to be continuous.