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jinhualiu-7414 asked XavierPouyat-MSFT answered

The lowest latency of Microsoft Azure when do Live video with OBS

we want to create an Azure Media Services live stream with OBS using below guide, but I found the latency is about 20seconds which is not acceptable in live , Do any guys try this and what is the lowest latency? Is any suggest that could lower this latency. Thanks
https://docs.azure.cn/en-us/media-services/latest/live-event-obs-quickstart

azure-media-services
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XavierPouyat-MSFT answered

Hi,
You can enable low latency on a live event. You may need to use CSF or CMAF with the low latency mode enabled in Azure Media Player.
https://docs.microsoft.com/en-us/azure/media-services/latest/live-event-latency-reference

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JohnDeutscher-4652 answered jinhualiu-7414 edited

In addition, it sounds like you may not be super familiar with how HTTP based streaming works. You should read the site howvideo.works to understand the limitations of client buffers, iOS segment sizes, GOP sizes, etc. to get more of an idea of what controls there are for latency.

Overall, using standard HLS or DASH with 2s GOPs, it is very normal to see 20 seconds of latency. That's actually considered GOOD in the industry for standard HLS.

There is work going on for newer protocols that can get lower latency at scale. LL-HLS and LL-DASH are the two more popular ones being supported.
You will find the specification and a lot of good overview vides on what LL-HLS is here.

https://www.theoplayer.com/blog/how-does-ll-hls-work

LL HLS overview by Roger Pantos (Apple) - https://www.youtube.com/watch?v=Wcc2sInCB1M

LL HLS challenges and difference video from Will Law - https://www.youtube.com/watch?v=DVrPv-8PUm4&t=7s

Apple dev docs - https://developer.apple.com/documentation/http_live_streaming/enabling_low-latency_hls

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Forgot to say - we are building LL-HLS into AMS now, it should be ready in the coming year for production use. We are still testing it.

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Hi JohnDeutscher
Thanks for your comment, I am newer with the Azure media service and now is studying it, we want to see if this solution could used in IP camera for home security, the latency may need less than 2 seconds. do you think current Azure solution could meet this ?

We tried with OBS as the MS's guide and set the GOP size to 1 and play using AMP with Low Latency Heuristics Profile, the latency is about 10 seconds. From the guide ,it seems the lowest latency will be 8 seconds in Pass-through。
By the way, what the latency after applied the LL-HLS into AMS, Is test any information let us reference? Thanks

Thanks

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XavierPouyat-MSFT answered

You may investigate the use of Azure Video Analyzer if you scenario is home security.


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