Audio Backends

librespot supports various audio backends. Multiple backends can be enabled at compile time by enabling the corresponding cargo feature. By default, only Rodio is enabled.

Building

A specific backend can selected at runtime using the --backend switch.

cargo build --release --features portaudio-backend
target/release/librespot [...] --backend portaudio

The following backends are currently available:

• Rodio (Default)
• ALSA
• PortAudio
• PulseAudio
• JACK
• Pipe

Usage

Most backends don't require specific setup. Some however do.

ALSA

The right alsa device needs to be passed to librespot via the --device flag. The alsa terminology of hw:X,Y is used, where X is the card number, and Y is the device number. This can be determined by:

~/librespot$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: PCH [HDA Intel PCH], device 0: ALC3234 Analog [ALC3234 Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: PCH [HDA Intel PCH], device 3: HDMI 0 [HDMI 0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: PCH [HDA Intel PCH], device 7: HDMI 1 [HDMI 1]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: PCH [HDA Intel PCH], device 8: HDMI 2 [HDMI 2]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: PCH [HDA Intel PCH], device 9: HDMI 3 [HDMI 3]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: PCH [HDA Intel PCH], device 10: HDMI 4 [HDMI 4]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

# To determine the right mixer name for your card, try
~/librespot$  amixer --device "hw:0" --card "0" # Results truncated here 
Simple mixer control 'Master',0
  Capabilities: pvolume pvolume-joined pswitch pswitch-joined
  Playback channels: Mono
  Limits: Playback 0 - 87
  Mono: Playback 64 [74%] [-17.25dB] [on]
Simple mixer control 'Headphone',0
  Capabilities: pswitch
  Playback channels: Front Left - Front Right
  Mono:
  Front Left: Playback [off]
  Front Right: Playback [off]
Simple mixer control 'PCM',0
  Capabilities: pvolume
  Playback channels: Front Left - Front Right
  Limits: Playback 0 - 255
  Mono:
  Front Left: Playback 2 [1%] [-50.60dB]
  Front Right: Playback 2 [1%] [-50.60dB]

Thus, in this example the settings would be:

./target/release/librespot [] --backend alsa  \
        --device="hw:0,0" \
        --mixer="alsa" --mixer-card="hw:0" --mixer-name="Master" \

NOTE: librespot you might want to turn on --linear-volume when utilising a hardware mixer.