MPD appears to play, but there's no sound

Question

After solving this problem, I have a second one. It appears to play now, according to Gnome Music Player Client (gmpc), but there's no sound. My /etc/mpd.conf so far has this in it:

audio_output {
       type            "alsa"
       name            "XR18"
       device          "plughw:CARD=X18XR18,DEV=0"
       format          "48000:32:2"
       auto_resample   "no"            # make MPD resample, instead of ALSA's libasound
       auto_channels   "no"            # play a multi-track audio file on its specified channels, no remapping
       always_on       "yes"           # keep the output device open, even when not playing
       mixer_type      "software"      # don't look for a hardware mixer because this card doesn't have one (at least not from the PC side)
#       mixer_device    "default"       # optional
#       mixer_control   "PCM"           # optional
#       mixer_index     "0"             # optional
}

With the default mixer_type "hardware", gmpc appeared to be muted, and wouldn't allow me to unmute. The mute command (Ctrl+space, then type mute) did this:

Changing to mixer_type "software" got me a GUI volume control, but still no sound. If I call it like this in my startup script, which itself gets called from rc.local:

mpd >> "$REC_PATH/Debug.log" 2>&1 &

then I get this in Debug.log:

socket: Failed to bind to '[::]:6600': Address already in use

I'm not sure what else would use that though. gmpc connects anyway. aplay with the first level of verbosity does this:

audiohub@DYM-Portable-AudioHub:~$ aplay -v -D plughw:X18XR18 "/home/audiohub/Music/Waterlines/05 - Take Your Time.wav"
Playing WAVE '/home/audiohub/Music/Waterlines/05 - Take Your Time.wav' : Float 32 bit Little Endian, Rate 44100 Hz, Stereo
Plug PCM: Linear Integer <-> Linear Float conversion PCM (S32_LE)
Its setup is:
  stream       : PLAYBACK
  access       : RW_INTERLEAVED
  format       : FLOAT_LE
  subformat    : STD
  channels     : 2
  rate         : 44100
  exact rate   : 44100 (44100/1)
  msbits       : 32
  buffer_size  : 13379
  period_size  : 3345
  period_time  : 75854
  tstamp_mode  : NONE
  period_step  : 1
  avail_min    : 3345
  period_event : 0
  start_threshold  : 13379
  stop_threshold   : 13379
  silence_threshold: 0
  silence_size : 0
  boundary     : 1753612288
Slave: Rate conversion PCM (48000, sformat=S32_LE)
Converter: linear-interpolation
Protocol version: 10002
Its setup is:
  stream       : PLAYBACK
  access       : MMAP_INTERLEAVED
  format       : S32_LE
  subformat    : STD
  channels     : 2
  rate         : 44100
  exact rate   : 44100 (44100/1)
  msbits       : 32
  buffer_size  : 13379
  period_size  : 3345
  period_time  : 75854
  tstamp_mode  : NONE
  period_step  : 1
  avail_min    : 3345
  period_event : 0
  start_threshold  : 13379
  stop_threshold   : 13379
  silence_threshold: 0
  silence_size : 0
  boundary     : 1753612288
Slave: Route conversion PCM (sformat=S32_LE)
  Transformation table:
    0 <- 0
    1 <- 1
    2 <- none
    3 <- none
    4 <- none
    5 <- none
    6 <- none
    7 <- none
    8 <- none
    9 <- none
    10 <- none
    11 <- none
    12 <- none
    13 <- none
    14 <- none
    15 <- none
    16 <- none
    17 <- none
Its setup is:
  stream       : PLAYBACK
  access       : MMAP_INTERLEAVED
  format       : S32_LE
  subformat    : STD
  channels     : 2
  rate         : 48000
  exact rate   : 48000 (48000/1)
  msbits       : 32
  buffer_size  : 14563
  period_size  : 3641
  period_time  : 75854
  tstamp_mode  : NONE
  period_step  : 1
  avail_min    : 3641
  period_event : 0
  start_threshold  : 10923
  stop_threshold   : 14563
  silence_threshold: 0
  silence_size : 0
  boundary     : 1908801536
Slave: Hardware PCM card 2 'X18/XR18' device 0 subdevice 0
Its setup is:
  stream       : PLAYBACK
  access       : MMAP_INTERLEAVED
  format       : S32_LE
  subformat    : STD
  channels     : 18
  rate         : 48000
  exact rate   : 48000 (48000/1)
  msbits       : 32
  buffer_size  : 14563
  period_size  : 3641
  period_time  : 75854
  tstamp_mode  : NONE
  period_step  : 1
  avail_min    : 3641
  period_event : 0
  start_threshold  : 10923
  stop_threshold   : 14563
  silence_threshold: 0
  silence_size : 0
  boundary     : 1908801536
  appl_ptr     : 0
  hw_ptr       : 0

audiohub@DYM-Portable-AudioHub:~$ 

And I see the meters dance in the X18XR18's control app. According to alsamixer, it has no controls at all, which is fine with me because it's actually this: https://www.music-group.com/Categories/Behringer/Mixers/Digital-Mixers/XR18/p/P0BI8 So the mute, volume, and a ton of other stuff is handled on that side through the app, which is available for free in the downloads section of that site. I just want to throw audio at it.

Is there still something missing?

Solution

Assumptions: You are using Ubuntu 16.04, and MPD V0.19.20.

I just found at https://www.musicpd.org/ there is a new version V0.19.21 that may fix your issue, also some issues I am having.

Good luck to both of us.

Mark.

Comments

[CL.]

So aplay is able to generate sounds? What's the output of aplay -v -D plughw:X18XR18 something.wav?

[AaronD]

@CL. It makes the meters dance today, and I heard it yesterday. I have it home now, listening to other music, so I don't have speakers hooked up to it. Updated the question.

[CL.]

The "Slave: Route conversion" shows that the two stereo channels end up at the first two of the eighteen channels of the device. Which channels do you actually want to use?

[AaronD]

@CL. It doesn't really matter. I can remap anything once it gets there. But when I play something with mpd and look at all 18 meters, nothing lights up. If all I wanted was playback, I could set it for 2/2 instead of 18/18 (another binary option in the control app). But I really want the 18-track recording as well, using different software, the details of which are probably outside the scope of this question.

[CL.]

I don't know how mpd behaves for such a device (ask them), but that auto_channels setting looks suspicious.

[AaronD]

It does indeed, now that I finally got back around to this project. It needs to be compiled from source, though. It's not in the repository so apt-get install mpd still gives the old one.