AptoVision Adaptive Clock Re-Synchronization (ACR)
Video transmission of HDMI or other video signals are considered synchronous, in that they occur in real time without delay. Consider a lap top computer connected directly to a display or via a HDMI switch, the connecting cables and electronics introduce no delay, so mouse movements re-appear on the extrenal display exactly the same as what is on the lap top’s display with zero latency.
Data transmission in a networking environment is not sent in real time. The packetized data is transmitted and received separately, so to ensure original data is reconstructed correctly at the receiver, various error checking and re-clocking methods are employed.
Networks introduce delays
The timing delays for asynchronous transmission are very small and handled quite well in the data world, however in the video world even the tiniest delay can cause problems. In the example of the lap top computer, if the reproduced mouse movement is only a few frames out, then at best, it’s use will be frustrating and or at worst, just plain un-useable.
Video is synchronous, we expect it’s reproduction to contain no artifacts and have zero latency, there should be no discernable difference between it and the original signal. So it seems the use of networking technology to transmit video material appears to be at odds with the goals of video transmission.
Enter Adaptive Clock Re-Synchronization (ACR)
The technology behind AptoVision ACR essentially allows the transportation of synchronous video across an asynchronous medium, which results in virtually identical timing between original video and transmitted video. There is a very small delay in the order of 15uS (15 microseconds), which is imperceptible to the human eye. This compares favorably to the latency expectation of the Pro AV industry where HDbaseT, the current matrix standard has a latency figure of 10uS. Comparing against compressed technologies, JPEG2000 has latency figures of 30,000uS+, while H.264 100,000uS+.
The ACR engine employed by iMAGsystems Lightning eliminates latency by reconstructing the original clock of a HDMI source, this reconstructed clock is totally genlocked to the original one providing latency free video transmssion. ACR is a patented technology from AptoVision and demonstrates clearly why the future of matrix switching lay with Blue River NT and Lightning.