MPEG-4 AVC Trick-Play Control via Pre-Stored AU Mapping
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Solution Overview
Problem
MPEG-4 AVC coding methods allow flexible prediction structures, making it difficult to determine which random access units (AUs) to decode or display during trick-play operations like jump-in, variable-speed, and reverse playback without analyzing complex prediction structures.
Innovation Solution
A moving picture stream generation apparatus that includes a supplemental information generation unit to specify pictures for decoding within random access units, allowing instant determination of necessary pictures during playback, and a stream generation unit that adds this information to each random access unit, enabling trick-play functionalities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If flexible prediction structures are used in MPEG-4 AVC coding, then coding efficiency and adaptability are improved, but the complexity of determining AUs for trick-play increases
Solution Approach 1:
The patent applies preliminary action by pre-determining and storing the mapping relationship between AUs and pictures, as well as the prediction structures, during the coding phase. This allows the decoding apparatus to perform trick-play operations by simply referencing the pre-stored information without performing complex analysis during playback, thus resolving the contradiction between coding flexibility and trick-play determination complexity.
2Measurement precision
If complex prediction structures are analyzed to determine AUs for trick-play, then accurate playback control is achieved, but processing time and computational resources increase
Solution Approach 1:
The patent stores the prediction structure information and AU-picture mapping relationships in advance during coding. During trick-play operations, the decoding apparatus only needs to retrieve and reference this pre-stored information to accurately determine which AUs to decode and display, avoiding time-consuming complex analysis during playback while maintaining accurate playback control.
3Reliability
If all AUs in a random access unit are decoded for normal playback, then complete picture quality is maintained, but data transmission and processing volume increase
Solution Approach 1:
The patent enables selective decoding of AUs based on the specific playback mode required. For normal playback, all AUs are decoded to maintain complete picture quality. For trick-play operations like jump-in or variable-speed playback, only the specific AUs needed for the requested operation are decoded, reducing data processing volume while maintaining sufficient picture quality for the specific playback scenario.
Data Source
AI summary
To provide a moving picture stream generation apparatus and the like that generates a moving picture stream that can be played back in trick-play such as variable-speed playback and reverse playback even in a Coding format such as the MPEG-4 AVC in which flexible prediction structures are allowed. A moving picture stream generation apparatus includes: a trick-play information generation unit TricPlay for generating supplemental information on a random access unit basis, the supplemental information being referred to at the time of playback of each random access Unit and each random access unit including one or more pictures; and a variable length coding unit VLC for generating a stream including the generated supplemental information and the one or more pictures by adding the supplemental information to each corresponding random access unit.