[alsa-devel] Roland/Edirol M-16DX

[Ricard Wanderlof]

On Fri, 23 Oct 2015, Clemens Ladisch wrote:

> Ricard Wanderlof wrote:
> > I seem to recall reading posts not to long ago that refer to using an
> > implicit feedback path; my question is, was this in fact implemented,
> 
> Yes, for USB Audio 2.0 devices.
> 
> > meaning that a device like the M-16DX should function as expected also for
> > playback?
> 
> There is some bug in the code that should detect such Roland devices.

I finally got my hands on an M-16DX yesterday, and was preparing myself 
for some initial research into this problem. Connected the device and used 
some DAW software (Ardour 3) to record and playback about half a minute of 
audio. No glitches whatsoever, neither in capture or playback.

So I thought, perhaps a DAW always opens the device for recording and 
playback and hence there's always a feedback channel open. So I tried just 
playing back a 7 minute wav file using aplay instead. Again, no glitches 
in the resulting audio.

More tests are needed - I only used 44.1 kHz sample rate for instance - 
but have I just been extremely lucky with the sample clocks so they match 
up precisely (if that even would work), or could the problem have 
magically fixed itself (ok, more realistically, as a result of something 
else getting fixed)?

/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