Audio Video Playback Rate Synchronization via Frame and Pitch Control
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Solution Overview
Problem
Current digital recording and playback systems, such as DVRs, lack the ability to efficiently play audiovisual content at non-native rates without affecting the viewer's perception of the content's native rate, limiting user navigation and playback features.
Innovation Solution
Implementing a media presentation system with a playback controller that allows audiovisual content to be played at increased or decreased rates while maintaining perception of the content as being played at a native rate, using techniques like frame omission or repetition and pitch correction to synchronize audio and video.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If audiovisual content is played at non-native rates using traditional DVR trick-play features, then playback speed is improved for navigation purposes, but the viewer's perception of the content rate is altered (audio pitch changes, video playback feels unnatural)
Solution Approach 1:
The system separates audio and video processing into independent streams. Video frames are selectively dropped or repeated to achieve non-native playback rates, while audio is processed separately through pitch correction algorithms. This segmentation allows each stream to be optimized independently, maintaining video temporal accuracy while correcting audio pitch perception.
Solution Approach 2:
The system dynamically changes audio sampling rate parameters to compensate for non-native video playback rates. When video is played back at accelerated rates, the audio sampling rate is adjusted proportionally to maintain the original pitch perception. This parameter transformation ensures that audio remains perceptually accurate even when playback speed changes.
2Ease of operation
If traditional trick-play features are used for content navigation, then ease of operation is improved, but loss of time occurs due to inability to efficiently skip or review content
Solution Approach 1:
The system pre-processes video content by creating an index of key frames and scene boundaries during recording or initial playback. This preliminary action enables rapid seeking and navigation through content without requiring frame-by-frame analysis during actual playback, significantly reducing navigation time and improving operational efficiency.
3Productivity
If video playback rate is increased for faster navigation, then productivity is improved, but video temporal accuracy deteriorates causing perceptible frame drops or repetition
Solution Approach 1:
The system applies partial frame dropping or repetition strategies based on the specific playback rate requirement. Rather than uniformly processing all frames, it selectively applies frame omission or duplication only where necessary to achieve the target playback rate while maintaining overall temporal coherence. This partial action approach minimizes perceptible artifacts while achieving the desired speed increase.
Data Source
AI summary
Methods and apparatus to play audio and video content at non-native rates are described. An example method includes playing a video portion of audiovisual content at a non-native rate, playing an audio portion of the audiovisual content at the non-native rate to correspond with the video portion, wherein a presentation of the audiovisual content at the non-native rate and a presentation of the audiovisual content at a native rate are substantially indistinguishable to an audience.