[pulseaudio-discuss] Sound streaming over network using pulseaudio. Newcomer questions.

[Tanu Kaskinen]

On Wed, 2013-03-20 at 12:45 +0200, vitaly.repin at gmail.com wrote:
> Hello,
> 
> I want to setup a sound streaming using pulseaudio from my linux
> computer to JVC boombox over LAN. The schema is shown here:
> http://www.flickr.com/photos/vitalyrepin/8573579969/
> 
> I managed to set it up with Nokia N9 (Harmattan MeeGo, pulseaudio
> 0.9.19) without any issues. But when I take Nokia N900 (less powerful
> device, Maemo, pulseaudio 0.9.15) I hear audio drops every 5 seconds.
> 
> There are can be 2 reasons for this to happen from my PoV:
> 
> - Too many data is coming over network to process by N900
> - Old protocol is used.  protocol-version-limit=15 is set using the
> patches from  Tanu Kaskinen:
> http://lists.freedesktop.org/archives/pulseaudio-discuss/2011-June/010256.html
> 
> I can not upgrade the pulseaudio version used in N900 - it contains
> custom patches made by Nokia and I am a little bit afraid of breaking
> them.
> 
> Can the protocol used be the root cause of the issue?

I don't know for sure, but it doesn't sound very likely.

> How can I limit the stream - say, set its parameters to the lower
> quality than CD audio?  Decrease the sampling rate for the networked
> connections, for example?

That's certainly possible. How do you play the music from the desktop to
the phone? Do you have a tunnel sink on the desktop, or do you use
direct connection from the music application to the remote server? If
you use a tunnel sink, it's possible to set its sample rate to e.g.
22050 with the "rate" module argument. If you use a direct connection,
then this might not be possible, because the application would have to
support specifying the sample rate.

In general, tunnel sinks work less reliably than direct connections
(which is sad, since the tunnel sink setup is better in other ways). So,
if you're currently using a tunnel sink, try a direct connection (just
set the PULSE_SERVER environment variable when starting the music
application).

> Is there any way to stream mp3, not PCM? If not, is it planned and is
> any work already done in this direction (don't want to invent the
> wheel and prefer to base my patches on somebody's else work if
> possible)?

No, MP3 streaming is not supported. Adding Opus compression for network
audio is one of the possible GSoC projects for this summer, but that
will never work with Fremantle's PulseAudio version.

I'm not sure if Fremantle supports receiving audio via Bluetooth A2DP.
If it does, that would be one alternative transport from the desktop to
the phone.

If you don't use the N900 as your primary phone, you could try Nemo[1]
if it works any better (and if we get the Opus compression, that will
eventually land on Nemo). Nemo can be run from an SD card, so
overwriting Fremantle is not necessary.

[1] https://wiki.merproject.org/wiki/Nemo/Installing

-- 
Tanu