[pulseaudio-discuss] PulseAudio gives an assertion error when attempting to load with a USB sound card connected.

Colin Guthrie gmane at colin.guthr.ie
Mon Sep 15 01:14:56 PDT 2008

Luke Yelavich wrote:
> Hi all. Through more 0.9.12 testing of pulseaudio, I have come
> accross a problem when attempting to load pulseaudio with a USB sound
> card detected. The model is in the attached log. I am running alsa
> driver/lib 1.0.18rc3. In addition to this, when using pulseaudio
> normally, i.e loading it with no USB card connected, and then
> connecting the card, pulseaudio crashes with a similar assertion.
> Due to the nature of the error, I am not sure whether this needs to
> be fixed in alsa, or pulseaudio. Pulseaudio 0.9.10 works fine with
> this card.

I had a user accidentally use some packages he didn't intend to earlier 
and ended up with this error:
: module-alsa-source.c: Assertion 'u->hw_dB_supported' failed at 
modules/module-alsa-source.c:742, function source_get_volume_cb(). 

I'm not sure if it's related.

In your case it seems the driver is not returning decibel volume range 
after reporting that it supports it.

This call:
  snd_mixer_selem_get_playback_dB_range(u->mixer_elem, &u->hw_dB_min, 

is returning >= 0 which is success but it is filling both the db volumes 
with zero.

I'd guess this is an alsa error, but someone more familiar with all this 
stuff will be able to answer more authoritatively.

(also I do not know what the valgind macros do, but I would assume they 
do not zero out the values in some cases (e.g. with older valgrind.h or 




Colin Guthrie

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