On Sun, 30 Nov 2003, Eduard Bloch wrote:
> Moin Jaroslav!
> Jaroslav Kysela schrieb am Sunday, den 30. November 2003:
>
> > > I have some problems with a ac97 based sound card (Notebook built-in)
> > > where the kernel driver works fine (except of not beeing able to
> > > resample on-the-fly).
> > >
> > > When I set the PCM mixer volume to more then 50%, I hear few sound
> > > fragments. If I go over 75% I hear them all the time and on 100% PCM,
> > > the sound is full of scratching fragments. You can get an example
> > > catched with microphone on
> > > http://sites.inka.de/W1752/alsa-distortion.ogg and the original is on
> > > www.vorbis.com/music/Mists_of_Time-4T.ogg . First I suspected a speaker
> > > problem since it sounds very similar to overloud speaker setting, but it
> > > is not!
> >
> > Are you sure that you don't have enable any other analog input? My
> > notebook has very noisy build-in microphone for example.
>
> No, my microphone is not built-in and not attached, the mixer is set to 0.
>
> > Also note that if you have value over 70% with most of AC'97 controls, the
> > analog gain is applied to the signal (thus you can really overdrive the
> > output or input).
>
> After almost an hour playing different stuff with different settings
> with the ALSA, Linux-Kernel and Windows driver, I have the following
> assumption: both, Kernel driver and Windows driver are cheating! They do
> not present the Bass/Treble boost controls and the PCM volume at 75% in
> ALSA is quite comparable with 100% PCM volume with other drivers,
> having quite comparable quality when Bass/Treble boost were set to 0.
>
> So what I wish for the future version of ALSA drivers: a module option
> to set the real mixer scale for PCM (or other sources) between 0 and X
> percent while the visible scale is between 0 and 100 percent and
> recalculated internaly to 0..X%.
Yes, maybe we can do this in highter layers (our library - alsa-lib) in
future, but it's not our goal for the driver where hardware should be
described in most accurate way.
Jaroslav
-----
Jaroslav Kysela <[EMAIL PROTECTED]>
Linux Kernel Sound Maintainer
ALSA Project, SuSE Labs
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