Video Synchronization Phase Adjustment for Asynchronous Transmission Delay
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Solution Overview
Problem
Existing video transmission systems face challenges in synchronizing video signals over asynchronous transmission lines, particularly due to varying transmission delays, which can result in video distortion and inability to adjust delay times accurately, especially when using low-delay codecs.
Innovation Solution
A receiving device and camera system that include a decoding unit, synchronization output unit, transmission delay information acquisition unit, and synchronization signal transmission unit to measure and adjust transmission delays, ensuring video data is synchronized with a reference synchronization signal by determining and transmitting phase information based on measured delay times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a frame buffer is used to synchronize video output with reference synchronization signal, then synchronization is achieved, but a delay of about one frame is generated which is unacceptable for low-delay transmission
Solution Approach 1:
The transmitting device advances the phase of the synchronization signal by the transmission delay time before transmitting video data. This preliminary phase adjustment ensures that the receiving device can output video synchronized with the reference synchronization signal without introducing additional frame-level delays through buffer waiting mechanisms.
Solution Approach 2:
The system measures the actual transmission delay time and uses this feedback information to dynamically adjust the phase advancement amount. The delay time measurement unit monitors transmission characteristics, and the CPU adjusts the synchronization signal phase accordingly, creating a closed-loop system that maintains synchronization while minimizing delay.
2Device complexity
If transmission delay is not taken into consideration, then simple video transfer is possible, but output video signal will not be correctly synchronized with synchronization signal
Solution Approach 1:
The system performs preliminary measurement of transmission delay time and pre-adjusts the synchronization signal phase before video transmission. This advance preparation enables the receiving device to achieve correct synchronization without complex real-time adjustment mechanisms, maintaining system simplicity while ensuring reliability.
Solution Approach 2:
The system changes the phase parameter of the synchronization signal based on measured transmission delay characteristics. By adjusting this single critical parameter, the system achieves accurate synchronization without introducing complex control logic or additional hardware components.
3Ease of operation
If variations in transmission delay are not taken into consideration, then constant phase adjustment is possible, but video information will not reach appliance B at correct timing causing video distortion
Solution Approach 1:
The system dynamically adjusts the synchronization signal phase based on measured transmission delay variations. The delay time measurement unit continuously monitors transmission characteristics, and the CPU modifies the phase advancement amount in response to changing network conditions, ensuring video quality is maintained despite variable delay conditions.
Solution Approach 2:
The system implements a feedback mechanism where transmission delay measurements are continuously taken and used to adjust the phase advancement parameter. This closed-loop control ensures that video quality is maintained by adapting to real-time transmission conditions while keeping the control mechanism relatively simple.
Data Source
AI summary
A transmitting device in accordance with the present invention includes an encoding unit that converts an input video signal into encoded data and sends out the encoded data to a transmission line, and a synchronization signal generation unit that generates a synchronization signal SYNC for adjusting the phase of an input video signal on the basis of phase information transmitted through the transmission line, wherein the phase information PHS includes information indicating that a timing of a synchronization signal generated by the synchronization signal generation unit is to be advanced by the time necessary for transmission, and the synchronization signal generation unit generates the synchronization signal SYNC so that an input video signal is advanced by the time necessary for transmission.