Digital Broadcast Receiver Video Audio Synchronization
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Solution Overview
Problem
Digital broadcast receivers face challenges in accurately synchronizing video and audio presentation timing, resulting in a maximum ±½ frame difference, which affects the recognition of synchronized playback.
Innovation Solution
A data processing apparatus that calculates a presentation delay time for video and adjusts the output of audio based on this delay to ensure precise synchronization, using a presentation device for video and a sounding device for audio, ensuring that video presentation timing matches audio output timing with high accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If video is presented using a vertical synchronizing signal generated at the receiver, then video presentation is achieved, but video presentation timing does not match the presentation time stamp, causing synchronization error with audio
Solution Approach 1:
The invention calculates the presentation delay time in advance by comparing the vertical synchronizing signal timing with the presentation time stamp, then applies this pre-calculated delay to the audio output timing to achieve synchronization
Solution Approach 2:
The invention introduces a presentation delay time calculation as an intermediary parameter that bridges the timing difference between video presentation and audio output, enabling precise synchronization
2Measurement precision
If audio is output at the sounding time stamp, then audio timing is achieved, but video presentation timing does not match, resulting in ±½ frame synchronization error
Solution Approach 1:
The invention calculates the presentation delay time before audio output and uses this pre-calculated value to determine the correct audio output timing, ensuring synchronization with video
Solution Approach 2:
The invention uses the comparison between the vertical synchronizing signal and presentation time stamp as feedback to calculate the appropriate delay time for audio output synchronization
Data Source
AI summary
Video presentation timing can match sounding timing with high accuracy. A digital broadcast receiver calculates the presentation delay time dt from the presentation time when video based on the compressed video data is to be presented to the time when the video is presented on the presentation unit, and outputs audio based on the compressed audio data when the calculated presentation delay time dt passes from the sounding time when the audio based on the compressed audio data is to be outputted.