Audio Video Synchronization via Separate Channel Processing
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Solution Overview
Problem
Existing video conferencing systems experience significant audio delays due to differences in transmission times between video and audio signals, leading to undesirable gaps and an unacceptable user experience, particularly in IP-based transmissions where video demands more resources.
Innovation Solution
The method involves timestamping audio and video data packets at the transmitting device, allowing for separate processing and buffering of audio signals to compensate for delays, with the option to output audio packets without corresponding video frames, and providing feedback to adjust video transmission parameters based on detected delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If video and audio signals are transmitted together through the same network channel, then bandwidth utilization is improved, but audio delay increases due to video's higher resource demands
Solution Approach 1:
The patent divides the transmission channel into separate audio channel and video channel, allowing independent transmission paths. Audio packets are transmitted through a dedicated audio channel while video packets use a separate video channel, preventing video's high resource demands from delaying audio transmission.
Solution Approach 2:
The patent changes transmission parameters by allocating different priorities to audio and video channels. Audio channels are given higher priority with lower delay thresholds, while video channels can tolerate higher delays. This parameter differentiation resolves the contradiction by allowing efficient bandwidth utilization without compromising audio timing.
2Stability of the object's composition
If audio packets are buffered waiting for corresponding video frames, then synchronization is improved, but audio output delay increases
Solution Approach 1:
The patent implements dynamic buffering where the buffering behavior adapts based on whether a corresponding video frame is available. If the video frame arrives in time, audio is buffered for synchronization. If the video frame is delayed beyond the threshold, audio is output immediately without buffering, dynamically adjusting to maintain both synchronization and timing.
Solution Approach 2:
Instead of the conventional approach of buffering audio to wait for video, the patent inverts the logic: audio is output immediately unless the video frame arrives in time, in which case it is buffered. This inversion allows audio to generally proceed without delay while still achieving synchronization when possible.
3Manufacturing precision
If video transmission priority is increased to ensure video quality, then video quality is improved, but audio delay becomes unacceptable
Solution Approach 1:
The patent segments the network transmission into separate audio and video channels with independent priority assignments. Video channels can be assigned high priority to ensure video quality, while audio channels maintain separate priority levels to prevent delay, resolving the contradiction through channel separation.
Solution Approach 2:
The patent changes transmission parameters by setting different delay thresholds and priorities for audio versus video. Video transmission can use higher bitrates and tolerate more delay, while audio uses lower delay thresholds, allowing video quality optimization without compromising audio timing.
4Productivity
If separate codecs are used for video and audio compression, then compression efficiency is improved, but system complexity increases
Solution Approach 1:
The patent applies universal processing techniques across both audio and video channels, such as timestamping, priority queuing, and threshold-based output logic. While separate codecs are used for compression, the transmission and synchronization mechanisms are universal, reducing overall system complexity despite specialized compression.
Data Source
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AI summary
The invention relates to a method for synchronization of corresponding audio signals and video signals in a video system for transmission of audio signals (41) and video signals (51) from a transmitting device (2) to a receiving device (3). The method is characterized in that the audio signals (41) and video signals (51) are being processed separately at the receiving device (3) and/or during output of the signals (41, 51). The invention further relates to a receiving and a transmitting device to be used in this method.