[Gta04-owner] Routing UMTS sound

Neil Jerram neil at ossau.homelinux.net
Fri Nov 30 09:22:02 CET 2012

Gilles Filippini <gilles.filippini at free.fr> writes:

> Neil Jerram a écrit , Le 30/11/2012 01:29:

>> I'm happy to report that I just had this approach working - i.e. using
>> pulseaudio and those 'pactl ...' lines to route the media during a phone
>> call.
> That's really good news!
>> I think the trick is just to change pulseaudio's default resampling
>> method.  Normally it's speex-float-3, but that performs very badly on
>> the ARMEL architecture - meaning that there's basically no sound
>> transfer at all.  Switching to speex-fixed-3 (in /etc/pulse/daemon.conf)
>> gives clear sound.
>> (FWIW, the 'trivial' resampler also gives fairly clear sound, but makes
>> the voice sound tinny or robotic.)
> Could probably be kept as float on GTA04/armhf, then.

Yes, indeed.

FWIW, here's my list so far of reasons to look forward to running on
- gpsd with a hook for automatic GPS power management
- significantly improved Bluetooth stack (as far as I can gather), which
  I hope will facilitate GPS export over Bluetooth
- x11vnc with the extra bits needed to handle input/output when running
  on a framebuffer
- pulseaudio with the webrtc implementation of module-echo-cancel
  (although I think I also now understand why the current use of Speex
  echo cancellation doesn't work particularly well, and it could be that
  we don't really need the webrtc implementation)
- not being caught out by float usage such as speex-float-3 resampling
- X drivers closer to what we need to do X rotation (if I remember the
  discussion correctly).

(And there are probably other specific reasons that I can't remember yet
this morning.)


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