Re: S/PDIF on AD1980 patch

[Takashi Iwai <tiwai@suse.de>]

At Thu, 20 Feb 2003 01:01:52 -0800,
Jaroslaw Sobierski wrote:
> 
> Quoting Takashi Iwai <tiwai@suse.de>:
> 
> > At Mon, 17 Feb 2003 08:01:27 -0800,
> > Jaroslaw Sobierski wrote:
> > > 
> > > 
> > > Another question though. I still cannot get the AC3 pass-through to work.
> > > I assume the spdif source must be set to AC-Link (which is hw-reset default
> > 
> > > anyway), and I figure all other stuff should be set by alsa (like
> > Category
> > > Code, etc.). I have no problem with AC3 on emu10k1, so I guess mplayer is
> > > requesting correct stream params from alsa. Yet on AC97 I can't get it to
> > 
> > > work (amp keeps indicating a PCM stream). Any suggestions what to look
> > for?
> > 
> > hmm.. ICH4 has a separate SPDIF channel and it looks like we don't use
> > this properly.  that is, SPDIF is routed via the normal slot 3/4.
> > perhaps we should route the spdif via slot 10/11 (in GLOB_CNT bit
> > 30:31 to 1:1), and set SPSA to the corresponding value.
> > the definition of iec958 in ICH.conf should be rewritten, too...
> The default configuration for ad1980 is to use slots 7/8. 3/4 is not
> the best choice since the DACs are set to this by default. I don't
> think ICH4 has anything to do with this, I downloaded the specs a while
> ago only to realize that it just gives you access to the ac97 regs and
> that's it.

no, as mentioned above, ICH4 has the configuration of SPDIF out slots
via GLOB_CNT bits 30:31.  please check these bits.

> There's practically nothing to configure on the south bridge itself.
> 
> > 
> > anyway,  can you check whether the register 0x3a is set correctly when
> > mplayer tries to play ac3?
> > 
> Yes and no :-). I dumped all ac97 regs from /proc and was going to send
> you teh list, but they did not change at all between PCM and ac3. I later
> discovered, quite by accident, that for some reason ac3 is never routed
> to the ac97 codec - when I choose the hwac3 option the stream always
> goes to emu10k1 (and plays correctly over its spdif), even though I 
> explicitly specify "hw:1". I have to try unloading the modules for emu and 
> see what happens then. But this seems anyway a bug. Unless the ICH driver
> declares no possibilty to create open ac3 stream and alsa falls back on
> the default card? 

can you try ac3dec in alsa-tools (with -C option).
if it works, then it's a bug of mplayer.  mplayer should access
"spdif" or "iec958" as the pcm name.


Takashi


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