limit MPV in-memory cache size and make it configurable

backend/app.go

@@ -80,7 +80,9 @@ func (a *App) readConfig() {
 
 func (a *App) initMPV() error {
 	p := player.NewWithClientName(AppName)
-	if err := p.Init(a.Config.LocalPlayback.AudioExclusive); err != nil {
+	c := a.Config.LocalPlayback
+	c.InMemoryCacheSizeMB = clamp(c.InMemoryCacheSizeMB, 10, 500)
+	if err := p.Init(c.AudioExclusive, c.InMemoryCacheSizeMB); err != nil {
 		return fmt.Errorf("failed to initialize mpv player: %s", err.Error())
 	}
 	a.Player = p

backend/config.go

@@ -48,8 +48,9 @@ type PlaylistPageConfig struct {
 }
 
 type LocalPlaybackConfig struct {
-	AudioExclusive bool
-	Volume         int
+	AudioExclusive      bool
+	InMemoryCacheSizeMB int
+	Volume              int
 }
 
 type ScrobbleConfig struct {
@@ -98,8 +99,9 @@ func DefaultConfig() *Config {
 			TracklistColumns: []string{"Artist", "Album", "Time", "Plays"},
 		},
 		LocalPlayback: LocalPlaybackConfig{
-			AudioExclusive: false,
-			Volume:         100,
+			AudioExclusive:      false,
+			InMemoryCacheSizeMB: 30,
+			Volume:              100,
 		},
 		Scrobbling: ScrobbleConfig{
 			Enabled:              true,

player/player.go

@@ -77,7 +77,7 @@ func NewWithClientName(c string) *Player {
 
 // Initializes the Player and makes it ready for playback.
 // Most Player functions will return ErrUnitialized if called before Init.
-func (p *Player) Init(audioExclusive bool) error {
+func (p *Player) Init(audioExclusive bool, maxCacheMB int) error {
 	if !p.initialized {
 		m, err := CreateMPV()
 		if err != nil {
@@ -91,6 +91,9 @@ func (p *Player) Init(audioExclusive bool) error {
 		m.SetOptionString("force-seekable", "yes")
 		m.SetOptionString("terminal", "no")
 
+		// limit in-memory cache size
+		m.SetOptionString("demuxer-max-bytes", fmt.Sprintf("%dMiB", maxCacheMB))
+
 		if p.vol < 0 {
 			p.vol = 100
 		}