Trick Mode Playback Speed Control via Dynamic GOP Monitoring
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Solution Overview
Problem
Conventional I-frame trick play modes in digital video recorders cannot maintain selected playback speeds when Group-of-Pictures (GOP) size varies during MPEG-2 video stream playback, leading to unpredictable quality of service and user experience issues.
Innovation Solution
The system dynamically controls trick mode playback speeds by monitoring frame indices and determining GOP size to calculate frame-skip count (FSC) and frame-repeat count (FRC) parameters, ensuring consistent playback speeds even when GOP size changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If I-frame trick mode playback is used to enable high-speed playback functions, then playback speed is improved, but playback speed stability deteriorates when GOP size varies
Solution Approach 1:
The system dynamically adjusts the frame repeat count parameter based on the actual GOP size detected during playback. Instead of using a fixed parameter set from the first GOP, the system continuously monitors GOP size changes and recalculates the frame repeat count to maintain the selected trick mode playback speed, making the playback system adaptive to varying content characteristics.
Solution Approach 2:
The invention changes the playback parameters (frame repeat count) based on the detected GOP size. When GOP size varies due to content transitions or commercial insertions, the system recalculates and updates the frame repeat count parameter to compensate for the change, thereby maintaining stable playback speed throughout the playback session.
2Productivity
If playback parameters are set based on the first GOP size, then initial playback speed is established, but speed consistency deteriorates when GOP size changes during playback
Solution Approach 1:
The system implements a feedback mechanism where the actual GOP size during playback is continuously monitored and fed back to the playback control logic. Based on this feedback, the frame repeat count parameter is dynamically adjusted to maintain the selected trick mode playback speed, ensuring consistent playback experience throughout the content.
Solution Approach 2:
The system performs preliminary calculation of the frame repeat count based on the first GOP size to establish initial playback parameters. This preliminary action enables high-speed playback to start immediately, while subsequent dynamic adjustments ensure continued speed consistency as playback progresses through content with varying GOP sizes.
3Speed
If only I-frames are processed for trick mode playback, then high-speed playback is enabled, but playback quality control becomes difficult when GOP size varies
Solution Approach 1:
The system dynamically adjusts the frame repeat count parameter based on the detected GOP size to maintain both high playback speed and consistent quality. By recalculating the parameter in response to GOP size changes, the system ensures that I-frame trick mode playback remains smooth and predictable throughout the entire playback session.
Data Source
AI summary
In one of many possible embodiments, a method is provided for controlling trick mode playback speed. Frame indices associated with video frames of a digital video stream are monitored and a Group-of-Pictures (GOP) size is determined from the frame indices. One or more trick mode play speed parameters are calculated based on the determined GOP size. Presentation of the video frames is controlled based on the calculated trick mode play speed parameters. In one embodiment, the trick mode play speed parameters include a frame-skip count (FSC) and a frame-repeat count (FRC).