Ubuntu 18.10上のmpdでs/pdifを使いたくなったのでメモ。

端末上でaplay -Lを実行する

default
     Playback/recording through the PulseAudio sound server
 null
     Discard all samples (playback) or generate zero samples (capture)
 pulse
     PulseAudio Sound Server
 hdmi:CARD=Generic,DEV=0
     HD-Audio Generic, HDMI 0
     HDMI Audio Output
 hdmi:CARD=Generic,DEV=1
     HD-Audio Generic, HDMI 1
     HDMI Audio Output
 hdmi:CARD=Generic,DEV=2
     HD-Audio Generic, HDMI 2
     HDMI Audio Output
 hdmi:CARD=Generic,DEV=3
     HD-Audio Generic, HDMI 3
     HDMI Audio Output
 hdmi:CARD=Generic,DEV=4
     HD-Audio Generic, HDMI 4
     HDMI Audio Output
 hdmi:CARD=Generic,DEV=5
     HD-Audio Generic, HDMI 5
     HDMI Audio Output
 dmix:CARD=Generic,DEV=3
     HD-Audio Generic, HDMI 0
     Direct sample mixing device
 dmix:CARD=Generic,DEV=7
     HD-Audio Generic, HDMI 1
     Direct sample mixing device
 dmix:CARD=Generic,DEV=8
     HD-Audio Generic, HDMI 2
     Direct sample mixing device
 dmix:CARD=Generic,DEV=9
     HD-Audio Generic, HDMI 3
     Direct sample mixing device
 dmix:CARD=Generic,DEV=10
     HD-Audio Generic, HDMI 4
     Direct sample mixing device
 dmix:CARD=Generic,DEV=11
     HD-Audio Generic, HDMI 5
     Direct sample mixing device
 dsnoop:CARD=Generic,DEV=3
     HD-Audio Generic, HDMI 0
     Direct sample snooping device
 dsnoop:CARD=Generic,DEV=7
     HD-Audio Generic, HDMI 1
     Direct sample snooping device
 dsnoop:CARD=Generic,DEV=8
     HD-Audio Generic, HDMI 2
     Direct sample snooping device
 dsnoop:CARD=Generic,DEV=9
     HD-Audio Generic, HDMI 3
     Direct sample snooping device
 dsnoop:CARD=Generic,DEV=10
     HD-Audio Generic, HDMI 4
     Direct sample snooping device
 dsnoop:CARD=Generic,DEV=11
     HD-Audio Generic, HDMI 5
     Direct sample snooping device
 hw:CARD=Generic,DEV=3
     HD-Audio Generic, HDMI 0
     Direct hardware device without any conversions
 hw:CARD=Generic,DEV=7
     HD-Audio Generic, HDMI 1
     Direct hardware device without any conversions
 hw:CARD=Generic,DEV=8
     HD-Audio Generic, HDMI 2
     Direct hardware device without any conversions
 hw:CARD=Generic,DEV=9
     HD-Audio Generic, HDMI 3
     Direct hardware device without any conversions
 hw:CARD=Generic,DEV=10
     HD-Audio Generic, HDMI 4
     Direct hardware device without any conversions
 hw:CARD=Generic,DEV=11
     HD-Audio Generic, HDMI 5
     Direct hardware device without any conversions
 plughw:CARD=Generic,DEV=3
     HD-Audio Generic, HDMI 0
     Hardware device with all software conversions
 plughw:CARD=Generic,DEV=7
     HD-Audio Generic, HDMI 1
     Hardware device with all software conversions
 plughw:CARD=Generic,DEV=8
     HD-Audio Generic, HDMI 2
     Hardware device with all software conversions
 plughw:CARD=Generic,DEV=9
     HD-Audio Generic, HDMI 3
     Hardware device with all software conversions
 plughw:CARD=Generic,DEV=10
     HD-Audio Generic, HDMI 4
     Hardware device with all software conversions
 plughw:CARD=Generic,DEV=11
     HD-Audio Generic, HDMI 5
     Hardware device with all software conversions
 sysdefault:CARD=Generic_1
     HD-Audio Generic, ALC1220 Analog
     Default Audio Device
 front:CARD=Generic_1,DEV=0
     HD-Audio Generic, ALC1220 Analog
     Front speakers
 surround21:CARD=Generic_1,DEV=0
     HD-Audio Generic, ALC1220 Analog
     2.1 Surround output to Front and Subwoofer speakers
 surround40:CARD=Generic_1,DEV=0
     HD-Audio Generic, ALC1220 Analog
     4.0 Surround output to Front and Rear speakers
 surround41:CARD=Generic_1,DEV=0
     HD-Audio Generic, ALC1220 Analog
     4.1 Surround output to Front, Rear and Subwoofer speakers
 surround50:CARD=Generic_1,DEV=0
     HD-Audio Generic, ALC1220 Analog
     5.0 Surround output to Front, Center and Rear speakers
 surround51:CARD=Generic_1,DEV=0
     HD-Audio Generic, ALC1220 Analog
     5.1 Surround output to Front, Center, Rear and Subwoofer speakers
 surround71:CARD=Generic_1,DEV=0
     HD-Audio Generic, ALC1220 Analog
     7.1 Surround output to Front, Center, Side, Rear and Woofer speakers
 iec958:CARD=Generic_1,DEV=0
     HD-Audio Generic, ALC1220 Digital
     IEC958 (S/PDIF) Digital Audio Output
 dmix:CARD=Generic_1,DEV=0
     HD-Audio Generic, ALC1220 Analog
     Direct sample mixing device
 dmix:CARD=Generic_1,DEV=1
     HD-Audio Generic, ALC1220 Digital
     Direct sample mixing device
 dsnoop:CARD=Generic_1,DEV=0
     HD-Audio Generic, ALC1220 Analog
     Direct sample snooping device
 dsnoop:CARD=Generic_1,DEV=1
     HD-Audio Generic, ALC1220 Digital
     Direct sample snooping device
 hw:CARD=Generic_1,DEV=0
     HD-Audio Generic, ALC1220 Analog
     Direct hardware device without any conversions
 hw:CARD=Generic_1,DEV=1
     HD-Audio Generic, ALC1220 Digital
     Direct hardware device without any conversions
 plughw:CARD=Generic_1,DEV=0
     HD-Audio Generic, ALC1220 Analog
     Hardware device with all software conversions
 plughw:CARD=Generic_1,DEV=1
     HD-Audio Generic, ALC1220 Digital
     Hardware device with all software conversions

上の段落の太字になっているところを参考にして、mpd.confのoutputを編集する。

audio_output {
         type            "alsa"
         name            "ALC1220 Digital"
         device          "iec958:CARD=Generic_1,DEV=0"
         auto_resample   "no"
         auto_channels   "no"
         auto_format     "no"
         use_mmap        "yes"
         mixer_type      "disabled"
}