Re: Re: CMI8738-MC6 surround40 plugin on 4 SP systems]

[Marcel <shizuma@magma.ca>]

* Takashi Iwai (tiwai@suse.de) wrote:
> At Fri, 31 Oct 2003 12:39:18 -0500,
> Marcel wrote:
> > 
> > * Takashi Iwai (tiwai@suse.de) wrote:
> > > At Thu, 30 Oct 2003 12:42:39 -0500,
> > > Marcel wrote:
> > > > 
> > > > 
> > > > I've been trying to finetune my cmipci for several weeks now.   And this is
> > > > the best way I've been able to get transparent operation with various audio
> > > > material: stereo, mono, 4.0, 5.1.  The main problem being no surround sound
> > > > iif "Exchange DAC" setting was not set, and sound on the rear speakers only
> > > > if it was.
> > > 
> > > ah, this might be true.
> > > does it happen both on 4.0 and 5.1 outputs?
> > > i don't remember that it's necessary for 5.1 at the last time i
> > > tested.
> > 
> > With surround40 plugin, 4 speakers, yes it's needed for both 4.0 and 5.1
> > material.  Applications such as mplayer or xine will remix 5.1 material to
> > 4 channels.  For 6 speakers systems, I really don't know.
> 
> could you try surround51 and check whether it somehow works?

I tried.  It's ok with stereo material.  With 5.1 material, xine refuses to
use it because I have 4 speakers only.  Mplayer will use it but 2 channels
only.  Seems there is no way to force applications to use 6 channels when I
got only 4 speakers.  "Mplayer -ao alsa9:surround51 -channels 6" gives an
error.  And I don't have any 5.1 sound file in wav or mp3 format for aplay
or alsaplayer to try.  Never been able to locate some.  But I suspect it
will fail too.  I think you'll need someone with 6 physical speakers to have
this verified.

> 
> > > perhaps we should simply remove this control from user and handle
> > > internally for the MC6 chip.
> > > 
> > 
> > I agree.  Its usage is confusing and may results in improper operation
> 
> how about the attached patch?

Great job!  If I understand how it works, the mixer setting is gone for the
8738-MC[46] chipsets, and still there for plain 8[37]38.  Works very well
here, no more confusion.  Multi-channel sound is enabled automatically. 
Front material is always in front, and surround material always in rear.

Adjustment is unconventional, but straightforward for surround material:

1 - Master at 0.
2 - Adjust rear volume with PCM near maximum required.
3 - Increase front volume with Master to obtain rear-front balance.
4 - Decrease PCM to lower volume on all 4 speakers.

Unusual, but that's the way its operates.

Don't forget to remove the following block in alsa/cards/CMI8738-MC6.conf if
you added it in the CVS, otherwise you'll get errors when using surround40
as "Exchange DAC" is no more:

#                       {
#                               name "Exchange DAC"
#                               lock true
#                               preserve true
#                               value true
#                       }

May I suggest adding this patch to the CVS?

One more control that deserves to go in mixer: "3D Control Switch".  It
doesn't work, never did, does nothing at all.


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