[alsa-devel] Bugs on aspire one A150

[Takashi Iwai]

At Mon, 16 Mar 2009 14:30:01 +0100,
Andreas Mohr wrote:
> 
> Hi,
> 
> On Mon, Mar 16, 2009 at 01:09:50PM +0100, Takashi Iwai wrote:
> > At Mon, 16 Mar 2009 13:03:12 +0100,
> > Andreas Mohr wrote:
> > > 
> > > Hi,
> > > 
> > > On Sun, Mar 15, 2009 at 10:21:17AM +0100, Andreas Mohr wrote:
> > > > Hi,
> > > > 
> > > > On Mon, Nov 24, 2008 at 03:35:10PM +0100, Takashi Iwai wrote:
> > > > > At Sat, 22 Nov 2008 21:00:18 +0200,
> > > > > Maxim Levitsky wrote:
> > > > > > Finally, I found how to reproduce that bug,
> > > > > > I mean to get normal volume on internal mic, I have to increase volume
> > > > > > only on left or right channel.
> > > > > > 
> > > > > > So, this happens always, and _only_ when recording _mono_ sound from internal
> > > > > > mic.
> > > > > > 
> > > > > > Since hardware doesn't support hardware mono input, tested with -D hw:0
> > > > > > I suspect this to be alsa-lib bug, any ideas?
> > > > > > Happens with arecord -D plughw:0 -c1 .
> > > > > 
> > > > > What does show with -v option?
> > > > 
> > > > OK, I could fully reproduce this now (sorry for the delay!).
> > > > 
> > > > Currently 2.6.28, u8.10, model acer-aspire, libasound2 1.0.17a-0ubuntu4,
> > > > libasound2-plugins 1.0.17-0ubuntu5.
> > > 
> > > Same microphone behaviour on 2.6.29-rc8 (additionally remembered to enable
> > > CONFIG_SND_HDA_HWDEP for further testing!), u9.04, model acer-aspire,
> > > libasound2 1.0.18-1ubuntu7, libasound2-plugins 1.0.18-1ubuntu4
> > > (yes, I've just done some monster upgrade).
> > > 
> > > Will try to eventually analyze things using your _HWDEP-related tools.
> > 
> > The question in the top priority is whether it's a kernel driver
> > issue or alsa-lib converter issue.  Could you check whether the sounds
> > recorded with -Dhw (and with matching rate, format, etc) have the same
> > noise problem at first?
> 
> OK, tried arecord -v -D hw:0 -c1 test.wav, which ended with
> arecord: set_params:961: Sample format non available
> .
> 
> arecord -v -D hw:0 -c1 -f S16_LE test.wav then ended with
> arecord: set_params:966: Channels count non available
> thus completing it into a
> arecord -v -D hw:0 -c2 -f S16_LE test.wav
> worked.
> 
> Trying this line with plughw then worked (of course, since two channels
> never has any problems).
> 
> Interestingly when using plughw there seems to be some LPF effect, since
> with hw I get lots of white noise whereas with plughw the recorded sound
> is dark (no higher-frequency components at all).
> 
> And audio is always being recorded properly no matter which Capture
> sliders position.
>
> To state it more clearly, both hw and plughw have no issues whatsoever
> with -c2 -f S16_LE, any sliders position.
> If I then switch to plughw:0 -c2 -f U8 (IOW change to U8 format),
> no problems either. Trouble starts if I then change to -c1 and have
> both channel sliders about equal (if they're not equal then I'm getting
> audio returned properly).

So, the following is also problematic

	% arecord -fdat -c1 -Dplughw ng.wav

while the below works?

	% arecord -fdat -Dhw good.wav

> > And, if it's about the alsa-lib conversion problem, we can reproduce
> > without the hardware, e.g. via file plugin...
> 
> So, what to do?

Does the conversion by sox from good.wav to a mono-channel file work?


Takashi