Re: More than stereo (4 channels in my case)

[Takashi Iwai <tiwai@suse.de>]

At Sun, 27 Apr 2003 01:02:49 -0700 (PDT),
Tom Watson wrote:
> 
> In a related project I used OSS (even paid for it) and got did a
> program that played 4 channel sound files (of my own making).  On that
> project I had a CMI sound chip (CMI 8738).  To get the thing to work
> properly (the back two playback channels on the "line in" jack, I
> needed to have a special mixer control set, and used ossmix to do the
> job "ossmix misc.rear2lin on".
 
you can toggle this via alsamixer on the fly.
check alsa-kernel/Documentation/CMIPCI.txt for details.

> Fast forward to my current configuration:  VIA SouthBridge chip audio,
> VT8233 (Vendor 1106, Device 3059, Rev 50, from /sbin/lspci).  I'd like
> to do the same thing.  Now I've read quite a few of the examples and my
> attempts to make some sense out of 'amixer' and 'aplay' are frustrating
> me quite a bit.  I've got 0.9.2 alsa, and a couple of problems:
> 1)  The sound in the right channel has a lot of hash.  One time (god
> knows what I did) it seemed to play OK.  I'm using 44.1 kHz sample
> files (if that makes a difference), since the source code seems to want
> 48kHz (or so I surmise).

it looks like a bug of AWARD BIOS.
i'll put a workaround soon to cvs.

> 2)  The rear channels are nowhere to be found.  I suspect that I need
> to turn on some switch in the mixer, but which one is becoming a
> mystery to me.

the multi-channel is supported on the second pcm device.  the first
pcm device is so-called "direct sound" pcm, and supports up to 4
playbacks at the same time but only for two channels.

for 4-channel output, there is no special configuration.
(you need to adjust "Surround" volumes, though.)
depending on the board, you might need to toggle some switches to
configure the line-in as rear output.

> Eventually I'll be moving to a different sound card (a Turtle Beach
> Santa Cruz), then another one. I suspect that some of the same problems
> might continue, so I'd like to solve them here first.  Any/all
> suggestions would be welcome.

is it cs46xx?  then it should work.  just raise the surround volume as
above.

> p.s.  While I will convert to alsa, will the OSS stuff work in
> emulation??  Will I have similar controls available like the
> misc.rear2lin mentioned above??  Is there any way I can put them into
> the OSS emulation stuff??  I'd be willing to do so.

so far, no.  using amixer (or alsamixer) wouldn't suffice?


Takashi


-------------------------------------------------------
This sf.net email is sponsored by:ThinkGeek
Welcome to geek heaven.
http://thinkgeek.com/sf