[alsa-devel] Zoom R16/24 playback slient

[Ricard Wanderlof]

On Wed, 30 Sep 2015, Panu Matilainen wrote:

> >> Another finding from my last round in the spring I do remember clearly,
> >> is that enabling both the input and output interfaces makes things hang
> >> up (timeouts and nothing really works). But if you disable the input
> >> interface and enable the output interface, you get an apparently working
> >> playback stream. Only no sound comes out. If you disable the output and
> >> enable input, capture itself works fine.

I did a small bit of experimenting, and as far as I can tell, playback 
seems to hang the device so it becomes completely unresponsive and needs 
to be restarted.

What I did was change QUICK_IGNORE_INTERFACE to 
QUIRK_AUDIO_STANDARD_INTERFACE for ifnum 1 (playback) in the quirks table.

What happens here is that if I attmempt to aplay a file that is 10.5 
seconds long, it actually plays for about 16 seconds, but no sound comes 
out. If I attempt it again, it takes about 5 seconds, after which I get 
aplay: set_params:1297: Unable to install hw params: <dump of attempted 
parameter settings>. There is no error message the first time.

The problem is the same no matter if I have IGNORE_INTERFACE set for ifnum 
2 (capture) or not. Setting both ifnum 1 and 2 to AUDIO_STANDARD_INTERFACE 
still results in capture to work as expected.

Interestingly enough, if I instrument the call to pcm:set_params(), it 
seems to get called as soon as the device is plugged in, with no ill 
effects. The sample rate display on the R16 also changes from 96.0 kHz to 
44.1 kHz. I don't seem to remember it doing this the first times I plugged 
it in, but the behavior remains after rebooting my computer, so it doesn't 
seem to be anything cached or something like that.

The problem doesn't seem to be in set_params(), as I can tell by adding 
delays that the unit freezes well after calling this function.

/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