Stream Generation Apparatus for Trick-Play Buffer Management
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Solution Overview
Problem
The existing technologies face challenges in performing trick-play operations, such as fast forward and jump-in playback, in MPEG-4 AVC streams due to complex memory management in the Decoded Picture Buffer (DPB), which can lead to breakdowns when necessary reference pictures are skipped or deleted, preventing correct decoding of subsequent pictures.
Innovation Solution
A stream generation apparatus that adds a memory management command to coded pictures, allowing repetition of memory management information using Decoded Reference Picture Marking Repetition Supplemental Enhancement Information (DRPMR SEI), ensuring that necessary reference pictures are stored in the buffer during trick-play operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex memory management is performed in the DPB during trick-play operations, then picture decoding accuracy is improved, but system reliability deteriorates due to breakdowns when reference pictures are skipped or deleted
Solution Approach 1:
The patent applies preliminary action by adding memory management commands to I pictures and P pictures in advance before trick-play operations occur. These commands ensure that necessary reference pictures are preserved in the DPB before they might be needed, preventing breakdowns during fast forward or jump-in playback operations.
Solution Approach 2:
The patent implements feedback through the DRPMR SEI mechanism that provides information about which reference pictures should be retained in the DPB. This feedback loop allows the system to adjust memory management dynamically based on trick-play requirements, ensuring reliability while maintaining decoding accuracy.
2Reliability
If all reference pictures are stored in the buffer during trick-play, then system reliability is improved, but memory usage increases
Solution Approach 1:
The patent applies local quality by selectively managing different types of pictures in the DPB based on their specific roles. I pictures and P pictures that serve as reference pictures are preserved with higher priority, while other pictures can be discarded. This selective approach ensures reliability for trick-play operations while optimizing memory usage by not storing all pictures equally.
Solution Approach 2:
The patent changes the parameter of picture retention priority dynamically based on picture type and trick-play requirements. By modifying which pictures are retained in the DPB according to their classification as I or P pictures, the system achieves reliable trick-play functionality while controlling memory consumption through parameter-based differentiation.
3Productivity
If only I and P pictures are decoded during fast forward, then productivity is improved, but picture decoding accuracy deteriorates due to missing reference pictures
Solution Approach 1:
The patent applies preliminary action by pre-identifying and preserving necessary reference pictures (I and P pictures) in the DPB before fast forward operations. This ensures that when only I and P pictures are decoded during productivity-optimized playback, the reference pictures are already available, maintaining decoding accuracy without sacrificing playback speed.
Data Source
AI summary
A stream generation apparatus of the present invention is a stream generation apparatus which generates a stream including coded pictures and a command for managing a buffer which holds a decoded picture, the command being added to one of the coded pictures as a reference picture. It includes a judging unit which judges whether or not the coded picture to which the command is added is skipped at the time of trick-play, an adding unit which adds, in the case where the coded picture is judged to be skipped, repetition information indicating the same contents as the command to another coded picture that follows, in decoding order, the coded picture judged to be skipped and that is not skipped at the time of the trick-play, and a generating unit which generates the stream including the coded pictures, the command and the repetition information.