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

[John Long]

On Sun, 2018-02-04 at 17:41 +0000, Andy Furniss wrote:
> John Long wrote:
> 
> > > You shouldn't need to do anything, if mplayer decodes, what I
> > > called
> > > PCM/raw audio will be sent to alsa/pulse/jack as per setup which
> > > should
> > > then go to the device.
> > 
> > That's what I want but it seems from mplayers output messages it is
> > decoding the audio.
> 
> My use of "raw audio" may have been a bit misleading here - I didn't
> mean
> the compressed bitstream, I meant the PCM that mplayer outputs after
> it
> has decoded something.

Understood. I have not found the magic words to get mplayer to send the
undecoded stream out the USB port. From the messages, it recognizes the
file and chooses the appropriate decoder and decodes it. Using pulse or
alsa alone is not enough, and I am sure the default device is being
used because I hear music via amp & speakers the DAC is connected to,
not the PC.

I used pacat to "cat" the stream to what should be the right /dev/snd
device but I just hear white noise. paplay plays it, but again, it
seems to be decoded before leaving the PC and the DAC just passes it
through to the amp and I hear it, but the DAC is not decoding.

There are happy LEDs to indicate the bit rate and type of stream (PCM
or DSD) but they never light up and even when the music is playing via
mplayer or paplay the display says "USB DAC not connected"

I sent an email to the manufacturer last week but I got an email that
that department doesn't handle it and they gave me a few other places
to try. I'll keep on emailing them.. if it works from MacOS without a
driver I cannot believe there is no way to get it to work from Linux.

Thanks guys

/jl