Lip-Sync Correction in Digital Broadcast Recording via Audio Delay
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Solution Overview
Problem
Existing recording and reproducing devices for digital broadcasting face issues with lip-sync errors due to the time lag caused by scaling processing, particularly when converting high-definition (HD) images to standard definition (SD) for display on VTR or DVD recorders, which results in delayed video signals relative to audio signals.
Innovation Solution
A digital broadcasting recording and reproducing device is equipped with a receiver, a video/audio signal generator, an image processing unit, and a delay unit that adjusts the time lag between audio and video signals, ensuring lip-sync by delaying the audio signal to match the processing time of the scaling filter, thereby eliminating lip-sync errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If scaling processing is performed to convert HD images to SD for VTR/DVD recording, then the device can record and reproduce digital broadcasting, but video signals are delayed relative to audio signals causing lip-sync errors
Solution Approach 1:
The delay amount is calculated in advance based on the relationship between input and output image resolutions before video signal processing occurs. This preliminary calculation allows the system to pre-determine the exact delay value that will compensate for the scaling processing time, ensuring lip-sync accuracy without requiring real-time adjustment during signal processing.
Solution Approach 2:
The audio signal is delayed by the predetermined delay amount before video processing occurs. By applying the delay in advance based on pre-calculated values, the system ensures that the audio signal arrives at the output at the same time as the processed video signal, eliminating lip-sync errors caused by scaling processing.
2Reliability
If scaling processing time is reduced to prevent video delay, then lip-sync accuracy improves, but image processing quality may deteriorate
Solution Approach 1:
The system performs preliminary calculation of the delay amount based on the relationship between input and output image resolutions. This allows the full scaling processing to be performed without time constraints, maintaining high image quality, while the delay compensation ensures lip-sync accuracy is achieved through pre-calculated timing adjustment rather than rushed processing.
Data Source
AI summary
The following configuration is preferable for providing a digital broadcast-enabled recording and reproducing device involving no lip-sync error and offering good usability. For example, the recording and reproducing device includes a receiver that receives digital broadcast data, a video/audio signal generator that generates a video signal and an audio signal included in the digital broadcast data received by the receiver, an image processing unit that executes image processing of the video signal input from the video/audio signal generator; and a delay unit that receives the audio signal generated by the video/audio signal generator to adjust time lag between the received audio signal and the video signal processed by the image processing unit.