[alsa-devel] Zoom R16/24 playback slient

[Ricard Wanderlof]

Bringing up an old thread from 2014 since I've gotten access to a Zoom R16 
and am keen on getting it to work in full duplex under Linux. Apparently 
(not yet verified here yet, rebuilding a kernel with the patch applied at 
the moment), 8 channel capture works with the quirk, but playback doesn't 
(well, it appears to work, but no sound comes out) and neither does the 
mixer.

> At Sun, 30 Nov 2014 12:08:38 +0200,
> Panu Matilainen wrote:
> > 
> > On 11/29/2014 09:39 PM, Takashi Iwai wrote:
> > > At Sat, 29 Nov 2014 21:35:04 +0200,
> > > Panu Matilainen wrote:
> > >>
> > >> This makes the midi interface and capture work out of the box with
> > >> R16 (and presumably R24 too but untested). Playback stream would also
> > >> seem to function fine except for one caveat: no sound is produced,
> > >> so it is disabled for now.
> >
> > [ ... ]
> > 
> > In the meanwhile I started looking at the mixer - this is just guessing 
> > but maybe its starting with outputs muted which could explain the 
> > playback stream running but without sound.
> > 
> > The descriptors for interface 0 are garbage but what is there would seem 
> > to map to logical elements by subtype and terminaltype, after those the> > data doesn't seem to add up (eg number of input/output channels 
> > missing/wrongly placed etc):
> > 
> > ** UNRECOGNIZED:  0b 24 01 00 01 35 00 03 01 02 03
> >     -> Header?
> > ** UNRECOGNIZED:  0c 24 02 05 01 01 00 02 03 00 00 00
> >     -> USB streaming input terminal?
> > ** UNRECOGNIZED:  09 24 03 08 01 03 00 05 00
> >     -> Speaker output terminal?
> > ** UNRECOGNIZED:  0c 24 02 09 01 02 00 08 00 00 00 00
> >     -> Microphone input terminal?
> > ** UNRECOGNIZED:  09 24 03 0c 01 01 00 09 00
> >     -> USB streaming output terminal?
> > 
> > Anything there that might ring a bell, or other ideas where to start 
> > poking at this thing?
> 
> Yeah, most of these look almost sane, so any off-by-one firmware
> issue?

Searching the archives, I could find no further posts on the subject of 
the R16. Panu, did you do any more work on this?

Where does the above output come from, and where could I find information
on what type of data is expected? I assume what's expected is something 
one would get from an USB mixer device?

In an earlier incarnation of a patch for the R16 (on the 10th of March 
2014), there's a discussion between Jason Mancine and Takashi regarding 
the .format field in the quirks table 
(http://mailman.alsa-project.org/pipermail/alsa-devel/2014-March/074117.html) 
which didn't seem to reach a conclusion; the problem then seemed to be 
that even when setting the .format to SNDRV_PCM_FMTBIT_S24_3LE, ALSA still 
setup up a 32 bit transfer. However, Panu's patch also added a small delay 
in snd_usb_ctl_msg_quirk(), so that perhaps was the real solution to the 
alleged format problem? (The final patch is much smaller than in this 
particular thread, possibly due to the use of QUIRK_ANY_INTERFACE since 
kernel version >3.11 ?)

/Ricard
-- 
Ricard Wolf Wanderlöf                           ricardw(at)axis.com
Axis Communications AB, Lund, Sweden            www.axis.com
Phone +46 46 272 2016                           Fax +46 46 13 61 30