I recently wrote about it and here comes a very clear explanation by someone who is a bit more techie than me on streaming tech 😎: Jan Ozer
My previous article is here:
What he is basically saying is: 1️⃣
The core issue, track glass-to-glass latency from the pitch to the screen, and track whether every viewer sees the same play at the same moment.
2️⃣ Instrument drift and viewer spread.
Drift is how far one viewer has slipped from the target and viewer spread is the gap between your earliest and your latest viewer. That spread is the number to put on the dashboard.
3️⃣ Test the spoiler path.
Compare your stream against a live feed on a second device. If the feed announces the goal first, you have a synchronization defect.
4️⃣ Match the protocol to the use case.
WebRTC at 0.2 to 1 second for betting and co-watch.
HESP at 1 to 9 seconds for interactive sports.
HLS at 9 seconds and above for broadcast-style OTT with maximum device reach. Run more than one where the audience needs it.
5️⃣ Set targetOffset deliberately.
Configure the default in the dashboard or API, then override per source or per viewer in the player where you need finer control.
6️⃣ Define the drift window.
Set minimumOffset and maximumOffset around the target.
Inside the window the player runs at normal speed, while outside it the player adjusts playback speed by around 8% to bring the viewer back.
7️⃣ Set forceSeekOffset as the hard limit.
Past that line the player performs a hard seek to the target. This is also the mechanism that holds sync on older devices with no support for fine speed adjustment.
8️⃣ Keep the window asymmetric.
Defaults sit at 0.66x targetOffset behind and 1.5x ahead. Allow more room behind the target than in front of it.
9️⃣ Verify on real devices.
Check the same match on phone, tablet, smart TV, and legacy player, on different networks, and record the spread across all of them.
I do not have a 10… maybe… have fun doing it?
Here is the full article: -----
https://optiview.dolby.com/resources/blog/streaming/how-to-ensure-viewer-synchronization-for-live-sports/
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