[LAD] ALSA FLoat sample format
viceic at net2000.ch
Thu Aug 16 13:32:48 UTC 2007
Le Thursday 16 August 2007 15.04:29 Phil Frost, vous avez écrit :
> I am no alsa programming expert, but could it be that for some reason,
> alsa is attempting to open a hardware device (hw:0, or such) rather than
> a plugin device (such as plughw:0)? Or, perhaps it is opening the
> default interface, which is an alias for hw:0. This default could have
> changed between alsa versions.
I thought this alos but no, it's not the case. In my code i'm forcing the
default openning of plughw:0,0
> Hardware devices will fail if an attempt is made to open them with
> anything other than parameters which are directly supported by the
> hardware. Plug devices however, will happly do things like convert
> sample rates and formats, at the cost of some uncertainty of what
> actually happens, and maybe some performance penalty.
> On Thu, Aug 16, 2007 at 09:39:48AM +0200, Predrag Viceic wrote:
> > Hi,
> > For some unknown reason, I seem to be unable to set SND_PCM_FORMAT_FLOAT
> > format flag when initialising alsa driver. This happens with my both
> > cards (on is the laptops AC'97 Audio Controller and the other a similar
> > onboard cart)
> > This line used to work with alsa 0.9 but return an "Invalid argument"
> > error with alsa 1.0.14a :
> > snd_pcm_hw_params_set_format(alsa_pcm_handle, alsa_hwparams,
> > SND_PCM_FORMAT_FLOAT_LE)
> > If I remove this line, the driver gets initialised but as integer sample
> > format, which, of course, generates noise as I'm sending 32bit floats to
> > the output...
> > Example code at lines 1031-1041 :
> > http://cvs.savannah.nongnu.org/viewvc/freecycle/src/soundplayer.cpp?annot
> > Please, please help !
> > Predrag
> > http://freecycle.redsteamrecords.com
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