spdif-trough and snd_ctl_elem_*

spdif-trough and snd_ctl_elem_*

[joy]

hi,

i actually want to set spdif-trough automagically from inside an application
when its needed but it seems there are differences from hardware to
hardware or/and changes in the alsa-lib-api, but im not sure.

i have an old-code fragment which dosn't work for me (ens1371). 
it does not work also on the SB Live Player 5.1.

   ...
   snd_ctl_elem_value_alloca(&ctl);
   snd_ctl_elem_value_set_interface(ctl, SND_CTL_ELEM_IFACE_PCM);
   snd_ctl_elem_value_set_device(ctl, snd_pcm_info_get_device(info));
   snd_ctl_elem_value_set_subdevice(ctl, snd_pcm_info_get_subdevice(info));
   snd_ctl_elem_value_set_name(ctl,SND_CTL_NAME_IEC958("", PLAYBACK, PCM_STREAM));
   snd_ctl_elem_value_set_iec958(ctl, &spdif);
   ...
   snd_ctl_elem_write(ctl_handler, ctl);

i got always "file or directory not found"-error with this and it's no
wonder cause i have no pcm-iface like above.

i changed now iface to SND_CTL_ELEM_IFACE_MIXER and _set_name to:
  snd_ctl_elem_value_set_name(ctl,SND_CTL_NAME_IEC958("", PLAYBACK, SWITCH));
   
it seems to work for me but im not sure if its work on the sbLive. the
switch or whatever on the sblive is called 'IEC958 Optical Raw'.
are the switches different from hadware/mixer to hardware or im wrong?
and if yes is there an 'easy way' to get the default
spdif-through-switch?

any enlightment in this appreciated.

-- 
thanx and regards

____-
joy

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Re: spdif-trough and snd_ctl_elem_*

[Takashi Iwai]

At Sat, 13 Jul 2002 17:19:36 +0200,
joy wrote:
> 
> hi,
> 
> i actually want to set spdif-trough automagically from inside an application
> when its needed but it seems there are differences from hardware to
> hardware or/and changes in the alsa-lib-api, but im not sure.
> 
> i have an old-code fragment which dosn't work for me (ens1371). 
> it does not work also on the SB Live Player 5.1.
> 
>    ...
>    snd_ctl_elem_value_alloca(&ctl);
>    snd_ctl_elem_value_set_interface(ctl, SND_CTL_ELEM_IFACE_PCM);
>    snd_ctl_elem_value_set_device(ctl, snd_pcm_info_get_device(info));
>    snd_ctl_elem_value_set_subdevice(ctl, snd_pcm_info_get_subdevice(info));
>    snd_ctl_elem_value_set_name(ctl,SND_CTL_NAME_IEC958("", PLAYBACK, PCM_STREAM));
>    snd_ctl_elem_value_set_iec958(ctl, &spdif);
>    ...
>    snd_ctl_elem_write(ctl_handler, ctl);
> 
> i got always "file or directory not found"-error with this and it's no
> wonder cause i have no pcm-iface like above.
 
the implementation of controls for iec958 is fairly dependent on each
card.  some card needs more initialization and some not.  it's true
that this might be confusing if you want to access such switches
_directly_.

on alsa, instead of tweaking these lowlevel stuffs, you can use an
abstraction pcm layer.
typically, the pcm "iec958" (or "spdif" equivalently) does all such a
job.  the iec958 pcm accepts arguments which represent status bytes.

	iec958:AES0=0xXXXX,AES1=0xXXXX,AES2=0xXXXX,AES3=0xXXXX

whether it's raw data, on which sample rate, etc. are determined by
these bytes.  (please check the specification document for details.)
you can pass this string as a pcm name of snd_pcm_open(),

	snd_pcm_open(&pcm, "iec958:....", SND_PCM_STREAM_PLAYBACK, 0);

how the iec958 pcm works on each card is defined in the card config
file found under /usr/share/alsa/cards.  for example, emu10k1 toggles
some control switches as you found and passes the status bytes.


well, it seems that ens1371 has still no configuration for iec958.
so, the right way is to add this stuff...


Takashi


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Re: spdif-trough and snd_ctl_elem_*

[joy]

On Wed, Jul 17, 2002 at 02:25:58PM +0200, Takashi Iwai wrote:
> the implementation of controls for iec958 is fairly dependent on each
> card.  some card needs more initialization and some not.  it's true
> that this might be confusing if you want to access such switches
> _directly_.
> 
> on alsa, instead of tweaking these lowlevel stuffs, you can use an
> abstraction pcm layer.
> typically, the pcm "iec958" (or "spdif" equivalently) does all such a
> job.  the iec958 pcm accepts arguments which represent status bytes.
> 
> 	iec958:AES0=0xXXXX,AES1=0xXXXX,AES2=0xXXXX,AES3=0xXXXX
> 
thanx for your reply, i will give it a try, but this kind of init
needs some more rewrite i have expected and i have currently no
iec958-capable-device to do real tests, so users have to wait bit ;)

> well, it seems that ens1371 has still no configuration for iec958.
> so, the right way is to add this stuff...
?
should i add it? will you add it? on which device is the iec958
running on the ens1371? i guess its hw:0,0

-- 
regards

____-
joy

________/\---------%%%___________-----------
webcast every sunday 2000 cest at pingfm.org

pgp key at: x-hkp://wwwkeys.de.pgp.net


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Re: spdif-trough and snd_ctl_elem_*

[Takashi Iwai]

At Thu, 18 Jul 2002 00:31:16 +0200,
joy wrote:
> 
> > well, it seems that ens1371 has still no configuration for iec958.
> > so, the right way is to add this stuff...
> ?
> should i add it? will you add it? on which device is the iec958
> running on the ens1371? i guess its hw:0,0

yes.  there is a switch "IEC958 Playback Switch", and we need to turn
it on in pcm hook.  but i don't see any raw playback switch nor iec958
status configuration, so i have no idea how to turn to the pass-thru
mode.

Jaroslav, do you have any clue?


Takashi


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Re: spdif-trough and snd_ctl_elem_*

[Jaroslav Kysela]

On Fri, 19 Jul 2002, Takashi Iwai wrote:

> At Thu, 18 Jul 2002 00:31:16 +0200,
> joy wrote:
> > 
> > > well, it seems that ens1371 has still no configuration for iec958.
> > > so, the right way is to add this stuff...
> > ?
> > should i add it? will you add it? on which device is the iec958
> > running on the ens1371? i guess its hw:0,0
> 
> yes.  there is a switch "IEC958 Playback Switch", and we need to turn
> it on in pcm hook.  but i don't see any raw playback switch nor iec958
> status configuration, so i have no idea how to turn to the pass-thru
> mode.
> 
> Jaroslav, do you have any clue?

I have no information, if the ES1371 chip can configure bits in the IEC958 
stream. Maybe, all bits are hardcoded.

						Jaroslav

-----
Jaroslav Kysela <perex@suse.cz>
Linux Kernel Sound Maintainer
ALSA Project  http://www.alsa-project.org
SuSE Linux    http://www.suse.com



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