add config option for audio device name and set it on startup

backend/app.go

@@ -56,9 +56,12 @@ func StartupApp(appName, appVersionTag, configFile, latestReleaseURL string) (*A
 	if err := a.initMPV(); err != nil {
 		return nil, err
 	}
+
 	a.Config.LocalPlayback.Volume = clamp(a.Config.LocalPlayback.Volume, 0, 100)
 	a.Player.SetVolume(a.Config.LocalPlayback.Volume)
 
+	a.Player.SetAudioDevice(a.Config.LocalPlayback.AudioDeviceName)
+
 	rgainOpts := []string{ReplayGainNone, ReplayGainAlbum, ReplayGainTrack}
 	if !sharedutil.StringSliceContains(rgainOpts, a.Config.ReplayGain.Mode) {
 		a.Config.ReplayGain.Mode = ReplayGainNone

backend/config.go

@@ -49,6 +49,7 @@ type PlaylistPageConfig struct {
 }
 
 type LocalPlaybackConfig struct {
+	AudioDeviceName     string
 	AudioExclusive      bool
 	InMemoryCacheSizeMB int
 	Volume              int
@@ -108,6 +109,8 @@ func DefaultConfig(appVersionTag string) *Config {
 			TracklistColumns: []string{"Artist", "Album", "Time", "Plays"},
 		},
 		LocalPlayback: LocalPlaybackConfig{
+			// "auto" is the name to pass to MPV for autoselecting the output device
+			AudioDeviceName:     "auto",
 			AudioExclusive:      false,
 			InMemoryCacheSizeMB: 30,
 			Volume:              100,

player/player.go

@@ -406,6 +406,10 @@ func (p *Player) ListAudioDevices() ([]AudioDevice, error) {
 	return devices, nil
 }
 
+func (p *Player) SetAudioDevice(deviceName string) error {
+	return p.mpv.SetPropertyString("audio-device", deviceName)
+}
+
 func (p *Player) getInt64Property(propName string) (int64, error) {
 	playpos, err := p.mpv.GetProperty(propName, mpv.FORMAT_INT64)
 	if err != nil {