Buffer Storage for Reverse Video Playback Delay
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Solution Overview
Problem
Image devices playing MPEG-formatted video sequences face issues with cutoff and time delays during reverse play, as they often only display I pictures and cut off P pictures, due to the structure of Group of Pictures (GOP) and the need to decode and store previous GOPs for reverse playback.
Innovation Solution
An image device with a buffer capable of storing more than one GOP, including decoded I and P pictures, and a controller to manage the buffer for seamless reverse playback by storing a previous GOP alongside the current one, allowing continuous display without cutoff or delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If one GOP is stored in the buffer for reverse play, then reverse play of that GOP is achieved, but time delay occurs when decoding and storing previous GOPs
Solution Approach 1:
The patent applies preliminary action by pre-decoding and pre-storing multiple GOPs (specifically two GOPs worth of pictures) in the buffer before reverse play is initiated. This allows the system to immediately output pictures in reverse order without waiting to decode previous GOPs during reverse play, thereby eliminating time delay while maintaining continuous reverse playback
Solution Approach 2:
The patent transitions from storing one GOP to storing two GOPs (I-picture GOP and P-picture GOP) in the buffer, adding an additional dimension of storage capacity. This dimensional change allows the system to have both current and previous GOPs available simultaneously, enabling seamless reverse playback without time delay
2Device complexity
If only I pictures are displayed during reverse play, then decoding complexity is reduced, but picture quality and continuity deteriorate due to cutoff of P pictures
Solution Approach 1:
The patent applies preliminary action by pre-decoding both I pictures and P pictures and storing them in the buffer before reverse play begins. This allows the system to output both I and P pictures in reverse order during reverse playback, maintaining picture continuity and quality without increasing decoding complexity during the reverse play operation itself
Solution Approach 2:
The patent creates copies of previous GOPs (I-picture GOP and P-picture GOP) in the buffer, storing multiple versions of picture data. This copying approach allows the system to retrieve and display P pictures during reverse play without needing to re-decode them, maintaining picture continuity while avoiding additional decoding complexity
Data Source
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AI summary
An image device capable of reverse play with minimal time delay, and a method thereof. The image device includes a buffer to store a greater number of pictures than constitute a single group of pictures (GOP), and a controller to operate the buffer to store decoded pictures. Accordingly, problems such as cutoff of pictures or time delays are minimized when performing reverse play.