On Thu, Jun 09, 2011 at 05:01:39PM +0000, Christian Weisgerber wrote:
> Eventually I also picked up a Sweex SC015 card. (These are readily
> available in Europe at the time of writing.)
>
> cmpci0 at pci1 dev 2 function 0 "C-Media Electronics CMI8738/C3DX Audio" rev
> 0x10: ivec 0x7d5
> audio1 at cmpci0
> opl at cmpci0 not configured
> mpu at cmpci0 not configured
>
> Playing stereo audio at 44.1 and 48 kHz over S/PDIF works. The
> relevant mixer knob is this:
>
> playback.mode=dac [ dac spdif ]
>
> Set to "spdif" for S/PDIF output, "dac" (default) for analog output.
>
> This particular card also has a two-pin "CD S/PDIF" header. If you
> have an optical drive with a two-pin "digital audio" output, you
> can connect it to the card, and then enable a by-pass mode where
> audio from the drive is directly output to S/PDIF without the CPU
> having to read any data. The mixer controls involved are these:
>
> spdif.input=spdin1 [ spdin1 spdin2 spdout ]
> spdif.output=playback [ playback spdin ]
>
> Set spdif.input=spdin2 to select the CD input and spdif.output=spdin
> to direct it to the card's S/PDIF output.
>
> Strangely, AC3/DTS pass-through does *not* work. Neither for normal
> playback with MPlayer, nor for a DTS CD using the S/PDIF by-pass.
> My A/V receiver just remains silent or reports a decoding error.
there's this comment in cmpci.c:
/* disable ac3 and 24 and 32 bit s/pdif modes */
and then the relevant register bits are cleared. feel free to play
with making it work ;) I imagine you'll need a mixer control to
select ac3 mode.
--
jake...@sdf.lonestar.org
SDF Public Access UNIX System - http://sdf.lonestar.org
