V__matrix C100 processing blade #1
Media Fabric (△ depends on network)
Video Transmitter
Frame Phaser △ 1-2 frames
Video Matrix
SDI Input
Audio Delay
Sample Rate Converter
Audio Matrix
SDI Output
Audio Transmitter
V__matrix C100 processing blade #2
Frame Phaser △ 1-2 frames
Video Matrix
COLOUR SCHEME SDI input to SDI output over an IP network (pink = video; blue = audio; purple = video and embedded audio; yellow = latency)
SDI Output
Audio Receiver
Audio Matrix
ne of the hot topics around the broadcast IP environment is latency. While absolute zero latency is not on the cards, careful planning allows operators to achieve
various stadiums only support up to 10Gbps. VC-2 compression was chosen for its fast algorithm, while also being lossless and inducing minimal delay (a mere 20 lines – much less time than a frame). Processing, however, is only one stage where streams can be delayed, and it does not necessarily generate high latency values. A key variable to pay attention to is synchronisation. BE PREPARED The first point of delay is introduced right after an SDI input, for signals that are not running in sync. If they are concurrent, they can be compressed straight away and passed on to the network. Missing synchronisation needs to be supplied by a PTP clock – for IP-savvy devices – or by a device like Lawo’s V__remote4, which can generate black burst signals. A C100 processing blade inside a V__matrix frame is perfectly able to take care of frame synchronisation. The resulting one-frame latency is not due to the infrastructure – it’s because the signal sources do not run together. Lawo’s customer in Belgium ingests video and audio signals at its football stadiums using a remote IP rack, which contains a V__matrix unit with two C100 processing blades. The V__matrix transmits VC-2-compressed signals to the production facility in Brussels, where they are decompressed using dedicated C100 blades. As these will only convert VC-2-compressed signals to uncompressed ones, they have no SDI rear plates.
end-to-end delays amounting to only a single frame. Let’s look at the key factors – and what a broadcaster must consider to keep it in check. One Lawo customer in Belgium just refurbished its infrastructure, turning an ST 2022-6 operation into an ST 2110 workflow. The set-up incorporates Lawo’s V__matrix platform with gateway functionality and VC-2 compression (up to 6.6:1 and 8:1), each installed at top-league football stadiums. In this case, signal compression is necessary, as fibre links from the client’s headquarters to the
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