On Mon, 10 Apr 2017 14:19:18 +0200
Takashi Iwai <tiwai@xxxxxxx> wrote:
> On Mon, 10 Apr 2017 14:09:11 +0200,
> Boris Brezillon wrote:
> >
> > Eric, Takashi,
> >
> > On Fri, 07 Apr 2017 10:20:20 -0700
> > Eric Anholt <eric@xxxxxxxxxx> wrote:
> >
> > > Takashi Iwai <tiwai@xxxxxxx> writes:
> > >
> > > > On Thu, 06 Apr 2017 21:46:29 +0200,
> > > > Eric Anholt wrote:
> > > >>
> > > >> Takashi Iwai <tiwai@xxxxxxx> writes:
> > > >>
> > > >> > On Thu, 02 Mar 2017 11:49:33 +0100,
> > > >> > Boris Brezillon wrote:
> > > >> >>
> > > >> >> Add a conf file for the VC4-HDMI sound card.
> > > >> >>
> > > >> >> Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxxxxxxx>
> > > >> >> ---
> > > >> >> Hi,
> > > >> >>
> > > >> >> Sorry for the noise, but I didn't send this patch to the alsa-lib
> > > >> >> maintainer on my first attempt.
> > > >> >>
> > > >> >> This patch is adding a card config file for the audio sound card whose
> > > >> >> driver has been submitted here [1] (not accepted yet).
> > > >> >>
> > > >> >> Since I am a total newbie to the alsa world, I'd like to get some
> > > >> >> feedback on this patch.
> > > >> >>
> > > >> >> Also, the card only supports 2 to 8 channels, and I wonder if we should
> > > >> >> add a plug element to support mono streams, and where this element
> > > >> >> should be added (after or before the iec958 element).
> > > >> >
> > > >> > Applied, thanks.
> > > >>
> > > >> Thanks!
> > > >>
> > > >> Any recommendations on how to restructure this so that things like
> > > >> 'aplay' from the console also work by default?
> > > >
> > > > Well, once after you have your card config in
> > > > /usr/share/alsa/cards/vc4-hdmi.conf, aplay should work as is.
> > > >
> > > > If not, check /proc/asounds output. The entry looks like
> > > > 0 [ID ]: DRIVER - SHORTNAME
> > > > LONGNAME
> > > >
> > > > and in your case, "DRIVER" must be "vc4-hdmi", as same as the config
> > > > file name.
> > >
> > > It doesn't work as is -- the default ends up not having iec958
> > > conversion, so nothing will play. You can do aplay -D iec958, which
> > > works but only as long as you've got stereo input (it seems plug can't
> > > do mono-to-stereo on iec958 data)
> >
> > Sorry for being so silent during the past weeks, but I've been busy
> > with other things and was on vacation last week.
>
> Thanks for joining. I was also slow just because I've been sick and
> off in the last week :-< Now getting recovered, and resuming the
> task...
>
> > As Eric explained, we're looking for advices on how to best expose
> > the sound card so that it can be easily used by end-users without
> > requiring advanced options (like -D iec958) or conf tweaking (like
> > declaring an extra plug element before the iec958 one to convert from
> > mono to stereo and then using -D iec958-mono).
> >
> > Takashi, what do you suggest? Is it possible/acceptable to make iec958
> > the default for this card? What about implicit/automatic mono-to-stereo
> > conversion, is it achievable?
>
> Now I looked at your config again, and one likely problem is that you
> wrap plug *before* iec958 plugin.
>
> vc4-hdmi.pcm.iec958.0 {
> .....
> type iec958
> slave {
> format IEC958_SUBFRAME_LE
> pcm {
> type plug
> slave.pcm {
> type hw
> card $CARD
> }
> }
> }
> status [ $AES0 $AES1 $AES2 $AES3 ]
> }
>
> Why do you need to wrap with plug there?
I honestly don't know. As said in my initila submission I'm a total
newbie hence the request for help ;-).
> Instead, it should be
> accessing directly to hw, i.e.
>
> vc4-hdmi.pcm.iec958.0 {
> @args [ CARD AES0 AES1 AES2 AES3 ]
> @args.CARD {
> type string
> }
> @args.AES0 {
> type integer
> }
> @args.AES1 {
> type integer
> }
> @args.AES2 {
> type integer
> }
> @args.AES3 {
> type integer
> }
> type iec958
> slave {
> format IEC958_SUBFRAME_LE
> pcm {
> type hw
> card $CARD
> }
> }
> status [ $AES0 $AES1 $AES2 $AES3 ]
> }
>
> Then the plug above this plugin should work.
>
> % aplay -D plug:hdmi foo.wav
Oh, I didn't know you could dynamically build the pipeline from the
command line.
Note that I'm not including pcm/hdmi.conf, which is probably wrong.
>
>
> (Note that plug over plug doesn't work -- that's the likely reason it
> failed before.)
>
>
> Then, about the default PCM: I wonder whether the dmix is feasible at
> all with this kind of setup. What format does work with this device?
Only IEC958_SUBFRAME_LE
Thanks for your help.
Boris
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