Latency (or image delay) is an important measure of AV-over-IP systems and a major focus for consumers and technical end users. Simply, latency is the measurement of delay from when a video image leaves its source device to when that image is displayed on screen. The total delay time is the sum of encoding time, transport delay, decoding time, and processing time. Users have been accustomed to the latency of a traditional matrix switch: under 1 millisecond. Many AV-over-IP systems have a latency range of 100 to 1,000 milliseconds. Because the latency is based solely on transport delay (no encoding, decoding, or processing), matrix switches have traditionally been the only solution for ultra-low latency distribution.
Developed to outperform and even replace matrix switches, Semtech’s BlueRiver® technology was innovated with efficiency in mind. Today, BlueRiver delivers exceptionally low latency by delivering the latest 4K content in as little as 0.1 milliseconds – one tenth of a millisecond. But what happens when advanced video processing is added to this world-class low latency transport?
A video scaler is the device responsible for processing video signals and altering their format. A video’s format consists of resolution and frame rate. Today’s popular resolutions vary from 720p, 1080p, to 4k and frame rate can vary from 24 frames per second to 60 frames per second. A typical video scaler includes an integrated frame buffer to enable frame rate conversion, and to simplify the architecture of the scaler itself. Frame buffers, however, add one or more frames of latency (potentially over 80 milliseconds!) simply because each frame must be stored for at least one frame period.
In order to develop ground-breaking technology, the engineers of BlueRiver altered their focus. By concentrating on transforming the existing process, as opposed to working within the confines of what already existed, they were able to achieve minimal latency. The answer to lessening delay times was solved by transforming the part of the process that was causing extra delays. Instead of using a video scaler with a frame buffer and accepting the additional latency, the scaler inside BlueRiver was made so that the scaling function could be deployed independently from the frame buffer. This new architecture completely eliminates the long delays associated with older AV processing technologies. Even with its video scaler enabled, BlueRiver’s end-to-end latency is approximately 3 milliseconds which is notably faster than competitors who claim 30 milliseconds and up.
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