Sync multiple stream

[pryiz]

Hi there,

I use SRS on 3 differents servers, so 3 IPs. The goal is to have 3 video input from 3 smartphones (using broadcastme mobile app). I have those 3 inputs in my OBS software and then stream it to facebook.

My issue : those 3 inputs are totally desynch, even if allsmartphones are on the same wifi.

Any clue how I can fix it? Is is possible to have multiple devices to the same IPs?

Thanks a for lot for your work and help!

[hy05190134]

what's the mean of sync multiple stream? Do you mean the same delay of different streams as if the 3 different stream coming from the same device?

[pryiz]

Hi, yes you got it!

I have 3 smartphones, each streaming to a different server:
Smartphone1 : rtmp://"IP1"/live/stream
Smartphone2 : rtmp://"IP2"/live/stream
Smartphone3: rtmp://"IP3"/live/stream

and when I add those 3 streams in OBS, videos are not sync...

thanks for your answer

[hy05190134]

@pryiz I wonder how to check the streams whether sync? just by eyes? what's your demand by syncing the 3 streams? for the communicating with 3 people?

[ccMatrix]

This would be an excellent feature which I could also really use.

Maybe inject a timestamp into the stream which is then used to hold back and sync the streams? Smartphone apps could get current time using ntp server and add the current timestamp to meta info of rtmp stream?

[winlinvip]

Won't support, because it's not a common use scenario.

[drunkod]

@winlinvip ,

Please add synchronizing media streams function. This is a unique feature for the project and can attract users like OBS.

This is already implemented in RTP.
SRT?, RTMP? implementation is necessary.

Larix Broadcaster (aka mobile obs) streaming client has added a feature to send NTP timestamps for all supported streams:
Insert SEI time metadata and specify NTP server, this allows synchronizing streams on server side.
https://softvelum.com/timesync/

RTP - Synchronizing media streams:

Implementation of NTP is not required to use RTP... However, if NTP timestamp implemented in RTCP, it can be used to synchronize media streams even from different host... https://gist.github.com/simonkim/a9a3aa4f1ca04448c64212b3b079d107

Synchronizing Streams via SRT:

Some SRT encoders like new JVC-cams , Haivision-encoder and software encoder LarixBroadcaster (iPhone/Android) can do this:
synchronize internal clock by time-server (usually by NTP protocol).
It means all encoders have one clock:if one camera has time 11:59:59 then other cameras have same time.
send this time inside encoded feed (SEI metainfo)

Haivision/srt#2044 (comment)

https://manpages.ubuntu.com/manpages/focal/man1/srt-multiplex.1.html