[MPlayer-users] What output driver for USB DAC?

[John Long]

Hallo Alexander!

On Mon, 2018-02-19 at 00:51 +0100, Alexander Strasser wrote:
> Hi John!
> 
> On 2018-02-04 13:31 +0100, Erik Auerswald wrote:
> > On 02/04/2018 01:21 PM, John Long wrote:
> > > On Sun, 2018-02-04 at 12:56 +0100, Erik Auerswald wrote:
> > > > On 02/04/2018 12:41 PM, John Long wrote:
> > > > > On Sun, 2018-02-04 at 11:59 +0100, Erik Auerswald wrote:
> > > > > > On 02/04/2018 09:32 AM, John Long wrote:
> > > > > > > Does anybody know how to get mplayer to send the correct
> > > > > > > signal
> > > > > > > to
> > > > > > > a
> > > > > > > USB DAC?
> > > > > > 
> > > > > > I've never done this and don't have that kind of device, so
> > > > > > I
> > > > > > cannot
> > > > > > give you a definitive answer.
> > > > > 
> > > > > Thank you for the suggestions! I feel I am on the right
> > > > > track.
> > > > > 
> > > > 
> > > > [...]
> > > > Please note that you may have PulseAudio interfering by
> > > > hijacking
> > > > calls
> > > > to ALSA. I used to use the Hi-Fi DAC via ALSA back before
> > > > PulseAudio
> > > > was
> > > > a thing...
> > > 
> > > Pulse audio is definitely running. I don't know how to send
> > > anything to
> > > it from mplayer (seems to be using alsa) or how it interacts with
> > > anything else. I am pretty lost...
> > 
> > I never looked into this, but using PulseAudio directly from
> > MPlayer (-ao
> > pulse instead of -ao alsa) seems to work better than outputting to
> > ALSA
> > since PulseAudio crept onto my system in 2012. Before, -ao alsa was
> > the way
> > to go for me. AFAIK PulseAudio "emulates" ALSA (partly and not very
> > well) to
> > automatically add PulseAudio greatness to every ALSA using
> > application. Of
> > course this does not include all unusual use cases.
> 
> 
> Might be worth a shot to deactivate pulse audio (just shut it down
> manually) and try with alsa directly.

After building deadbeef from source I have some evidence alsa is
interfering. I have 3 USB DACs. One of them refuses to work with Linux.
Of the other two, one is supposed to light various LEDs to show the
sampling rate and mode (PCM vs. DSD). The one with the lights still
shows no signs of cooperating.

The other DAC which is recognized by my Linux distro and kernel now at
least displays the correct sampling rate, but the bit depth is wrong
and this may be a firmware bug- and I am not sure if it is only a
display bug or that some resampling is going on.

deadbeef has options to control upsampling. I turned them off and the
DAC sees the correct sampling rate. I have more testing to do and not
enough time to do it. I suspect mplayer and other players I have tried
are victimized by some alsa setting and therefore alsa resamples
(downsamples) and ruins the playback experience.

At this point I am so annoyed by lack of clarity and info in Linux (not
suprising, considering the price paid) that I am considering buying a
dedicated box to run Windows on just so I can use foobar, official DAC
drivers, etc. Windows is also terribly annoying, of course, which is
why I use *NIX in the first place.

I will update if I have any more info. Thank you all.

/jl