[alsa-devel] Assert in pcm_params.c

[Alan Horstmann]

On Monday 20 April 2015 12:17, Alan Horstmann wrote:
> On Saturday 18 April 2015 09:08, Alan Horstmann wrote:
> > The following assert is being hit in pcm_params.c:
> >
> > "pcm_params.c:2249: snd1_pcm_hw_params_slave: Assertion `err >= 0'
> > failed."
> >
> > This is from a developer using Portaudio in his own application; I have
> > yet to ascertain full details, but it is trying successive sample rates
> > to see which are valid.
>
> Further info: this occurs with an Intel motherboard/soundcard, attempting
> to open and config the stream at 44100 using front, surround or hdmi pcm,
> having previously opened and tried at a lower, not-supported samplerate,
> and closed. AFAIK other pcms work OK.
>
> The assert is hit with all current Debian and Ubuntu distros, for example
>      Debian 8 (jessie) 32 bit:  kernel 3.16.0-4-686-pae (Alsa 1.0.28)
> but is not seen with Fedora 20 or OpenSuse 12.1 (do they have asserts
> off?).
>
> > Does this point to a flaw in the configuration or possibly a bug in
> > Alsa-lib or can it occur just as a result of misuse of the Alsa API?
>
> I will try to conceive some more tests.  How can we debug this further?

A minimal self-contained demo program ('test-format') has been developed and 
is attached, that demonstrates the issue 100% on the reporters machine 
(HDA-Intel, 6-ch I believe).  The output is:

root at Xeon:/home/patest# ./test-format 
Testing device front
Num channels 6
Testing rate: 22050   Result:...Invalid Sample Rate
Testing rate: 32000   Result:...Invalid Sample Rate
test-format: pcm_params.c:2249: snd1_pcm_hw_params_slave: Assertion `err >=
0' failed.
Testing rate: 44100   Aborted

Alsa-info is at:

http://www.alsa-project.org/db/?f=19dfeee29f73007e61a00a8fabe3c958f7cb8e87

This apparently happens with or without Pulseaudio running, with just the 
single 44100 rate, and also with surround devices.  Also, on all current 
Debian and Ubuntu - we have focused on Jessie.

I do not have a machine with similar hardware, so cannot duplicate the 
results.

Any comments, ideas etc would be appreciated.

Regards

Alan
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