[Icecast] Re: [Icecast-dev] Synchronize listeners

Geoff Shang Geoff at QuiteLikely.com
Thu Sep 20 03:48:49 PDT 2007


Ross Levis wrote:

> Is it at all possible to synchronize listeners so they hear the audio at the
> exact same time?  It doesn't matter if the source and listener is a few
> seconds different.

I was thinking about this one.  It occurs to me that ogg bitstreams contain 
timing data (similar to timecode).  You could develop a player that used 
this ogg-based timecode in conjunction with accurate PC clocks to develop 
some kind of sync protocol (matching ogg timestamps to time-of-day).  I 
guess you would have to have a master/slave setup where one system was 
authoritative and others would sync to it.  I guess you could also have 
mechanisms where the master was declared unsound if say it lost the stream, 
and another master would be "elected" or something.

The parallels I see here are the ways that MIDI sequencers and audio 
devices can sync with SMPTE et al.  It's used in video too I think.

Of course, you would have to have accurate time, but NTP is capable of very 
good time-keeping.  YOu'd also have to be able to ensure the same latancy 
for the actual playing of the audio... but that's more complex than I'm 
qualified to speculate on.

Geoff.



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