[pulseaudio-discuss] Pulseaudio raop module plus "songcast"

Colin Guthrie gmane at colin.guthr.ie
Thu Jun 6 08:11:56 PDT 2013

Hi Paul,

I've taken the liberty of sending your mail to the Mailing List itself,
rather than as a mail to the list-request address (normally used for
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'Twas brillig, and Paul Wilkinson at 06/06/13 15:02 did gyre and gimble:
> Hi Lennart, Colin & Arun
> Thank you and your colleagues for all your work on Pulseaudio.
> I have been hoping for a fix for a while now but as it has not arrived I
> thought I should contact you directly so would appreciate your attention
> and advice on how to get this done - I have read much of the
> documentation including how to build modules but fear that I do not have
> enough knowledge to be able to do this myself
> 1) The  RAOP module does not work which I think is because Airtunes has
> switched to UDP per wikipedia <http://en.wikipedia.org/wiki/AirPlay>
> There has been some work done by Christophe Fergeau here
> <http://git.zx2c4.com/pulseaudio-raop2/> (assuming this does fix the
> problem) which is 3 years old and therefore might not integrate as-is
> with Pulseaudio 3.0 & 4.0 currently in use. So I believe this would
> benefit from your consideration. There are other open-source projects
> that I think have information you might find useful as to the changes in
> this format node_airtunes
> <https://github.com/radioline/node_airtunes>node-airplay
> <https://github.com/benvanik/node-airplay> forked-daapd
> <https://github.com/jasonmc/forked-daapd#readme>

Yes, the RAOP module has definitely stagnated. I was hoping my work
would be enough to get people interested, but sadly there has not been
much uptake on the front.

I actually spoke to Christophe while in Paris about a month or two ago
and he mentioned this refactor work. It wasn't completed at the time so
wasn't proposed for merging but it would be great if someone was able to
work with his changes so far and complete them. My memory fails me but I
think Christophe was switching to a newer airtunes protocol tho' I've
not looked for a loooooong time as to whether this was UDP or not.

It would certainly be interesting to complete this work.

It's also worth noting that Bryce Guinta (also CC'ed) was interested in
getting this working as part of GSoC. Unfortunately his application for
this project was unsuccessful this time but he might still be interested
in helping out here.

> 2) Once Pulseaudio can send UDP streams too It would be great if a
> module could be written to "Songcast" to "OpenHome" compatible devices
> specifications here <http://www.openhome.org/wiki/Av:Developer:Songcast:Ohm>

I've not read the docs much but it seems to be related to RTP and/or
UPnP both of which are already supported in PulseAudio (the latter
through integration with Rygel). Perhaps this just needs the right magic

> Due to the complexity of pulseaudio & the current level of its
> documentation I am not able to take the information from the sources
> linked here and amend and test but feel it should be reasonably
> straightforward for you ( unless the UDP streaming is a major problem).

If you would like to get your hands dirty, there does exist developer
documentation here:

It does explain about modules and the various internal APIs, but it's
also useful to work with existing modules and copy+paste certain
elements. You can also ask on the Mailing List for assistance on certain
topics and (ideally) help make the docs better!

Unfortunately I've not really had the time to be too active on
PulseAudio of late. I will happily lend my Airport Express device to
anyone who wants to hack on RAOP stuff however. It does take a lot of
time to test this stuff tho', so it's not a trivial task and will take a
while to complete (I'd guess at least a day or two to review and merge
Christophes work and then a few days more to hack away at the latest

The OpenHome stuff looks well documented so with the right h/w it
shouldn't take more than a week or two to come up with a suitable module.

> I am sure you and your colleagues have tons to do, I hope you don't mind
> me making this request in this way - if there is a better way please let
> me know.  I would appreciate your help in this matter and think
> ,especially 1), that there are any others that would be grateful too.

Perfectly OK by me, but the mailing list is the better place to do this
and where any followup discussion should occur!

Take care.



Colin Guthrie

Day Job:
  Tribalogic Limited http://www.tribalogic.net/
Open Source:
  Mageia Contributor http://www.mageia.org/
  PulseAudio Hacker http://www.pulseaudio.org/
  Trac Hacker http://trac.edgewall.org/

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