[RDD] OpenOB 2.3 release

James Harrison james at talkunafraid.co.uk
Thu Nov 29 15:22:24 EST 2012


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Couple of things can affect delay. Sound cards is one thing - the
jitter buffer in OpenOB is the other. By default this is 150ms,
suitable for decent Internet links, and is tweaked with the -j option
on the transmitter. -j 5 should be fine on fast ethernet for 5ms
latency internal to OpenOB. There's nowhere else inside OpenOB itself
that can add latency.

Sound cards will almost certainly make up the rest of the latency, and
that's down to system config like using a low-latency kernel and small
period sizes. See http://www.alsa-project.org/main/index.php/Asoundrc
and http://www.alsa-project.org/main/index.php/FramesPeriods for more
info there - basically, tweak period_size and periods. You may find
you need a non-onboard sound card, but some onboard drivers can be
fine. There's loads of info out there for low-latency Linux operation
and I should really write up some of it into the OpenOB docs or a
supporting site, and I will once I get some spare time.

Hope that helps!

Cheers,
James Harrison

On 29/11/2012 16:03, Fernando Della Torre wrote:
> Hello James,
> 
> This is my very first time experience with OpenOB.
> 
> I have set up 2 old IBM P4 HT 3Ghz desktops running Wheezy and
> installed OpenOB on both. They are running OpenOB on the onboard
> sound cards through ALSA over a 100Mbit fast ethernet.
> 
> Using 96kbps Opus I get 390ms of delay, and using PCM 360ms, far
> above the mentioned 50ms, what am I doing wrong?
> 
> Thanks for building such usefull software! Congratulations,
> 
> 
> Regards,
> 
> 
> 
> Atenciosamente,____
> 
> __ __
> 
> *Fernando Della Torre__*
> 
> Tecnologia da Informação____
> 
> (: +55 16 8137-1240
> 
> (: +55 16 9137-2886
> 
> *: _fdts at vdit.com.br <mailto:fdts at vdit.com.br>_____
> 
> V.D.I.T. Soluções em Virtualização____
> 
> __ __
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> __ __
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> 
> 
> 
> 2012/10/22 James Harrison <james at talkunafraid.co.uk 
> <mailto:james at talkunafraid.co.uk>>
> 
> 
> I know a few Rivendellers have used the earlier (beta) versions of 
> OpenOB in the past so here's a quick notice to all that OpenOB 2.3
> is out, with stable support for the Opus codec recently standarized
> by the IETF, which supports bitrates as low as 16kbps or up to
> 384kbps with a variety of audio bandwidths.
> 
> OpenOB is the open outside broadcast tool, an audio over IP link
> tool which makes moving audio over a network in realtime with very
> low latencies (<10ms in PCM mode, <50ms in Opus mode) fairly
> trivial.
> 
> Other improvements include proper Python packaging for easy 
> installation, reliability improvements, visual feedback changes and
> an improved command line interface.
> 
> Support for the Raspberry Pi single-board computer has now been
> tested, confirmed and verified. It works out of the box with no
> issues using USB sound cards. This means you can put a link
> together (both ends) for under £200.
> 
> You can nab yourself a copy here: 
> http://jamesharrison.github.com/openob/ - all you need is two
> computers running Linux.
> 
> </list-hijack - sorry!>
> 
> _______________________________________________ Rivendell-dev
> mailing list Rivendell-dev at lists.rivendellaudio.org 
> <mailto:Rivendell-dev at lists.rivendellaudio.org> 
> http://lists.rivendellaudio.org/mailman/listinfo/rivendell-dev
> 
> 
> 
> 
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