first commit

2022-12-17 16:52:13 -08:00
parent cd1f795bb4
commit c21d7d03eb
16 changed files with 2069 additions and 0 deletions
@@ -0,0 +1,428 @@
+package player
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	"github.com/yourok/go-mpv/mpv"
+)
+
+// Error returned by many Player functions if called before the player has not been initialized.
+var ErrUnitialized error = errors.New("mpv player uninitialized")
+
+// The playback state (Stopped, Paused, or Playing).
+type State int
+
+const (
+	Stopped State = iota
+	Paused
+	Playing
+)
+
+// The current status of the player.
+// Includes playback state, current time, total track time, and playlist position.
+type Status struct {
+	State       State
+	TimePos     float64
+	Duration    float64
+	PlaylistPos int64
+}
+
+// Argument to Seek function (SeekAbsolute, SeekRelative, SeekAbsolutePercent, SeekRelativePercent).
+type SeekMode int
+
+const (
+	SeekAbsolute SeekMode = iota
+	SeekRelative
+	SeekAbsolutePercent
+	SeekRelativePercent
+)
+
+// Player encapsulates the mpv instance and provides functions
+// to control it and to check its status.
+type Player struct {
+	mpv            *mpv.Mpv
+	vol            int
+	status         Status
+	seeking        bool
+	curPlaylistPos int64
+	prePausedState State
+	clientName     string
+
+	bgCancel context.CancelFunc
+
+	// callbacks
+	onPaused      []func()
+	onStopped     []func()
+	onPlaying     []func()
+	onSeek        []func()
+	onTrackChange []func(int64)
+}
+
+// Returns a new player.
+// Must call Init on the player before it is ready for playback.
+func New() *Player {
+	return NewWithClientName("")
+}
+
+// Same as New, but sets the application name that mpv
+// reports to the system audio API.
+func NewWithClientName(c string) *Player {
+	return &Player{
+		vol:        -1, // use 100 in Init
+		clientName: c,
+	}
+}
+
+// Initializes the Player and makes it ready for playback.
+// Most Player functions will return ErrUnitialized if called before Init.
+func (p *Player) Init() error {
+	if p.mpv == nil {
+		m := mpv.Create()
+		m.SetOptionString("idle", "yes")
+		m.SetOptionString("video", "no")
+		m.SetOptionString("audio-display", "no")
+		m.SetOptionString("gapless-audio", "weak")
+		m.SetOptionString("prefetch-playlist", "yes")
+		m.SetOptionString("force-seekable", "yes")
+		m.SetOptionString("terminal", "no")
+
+		if p.vol < 0 {
+			p.vol = 100
+		}
+		m.SetOption("volume", mpv.FORMAT_INT64, p.vol)
+
+		if p.clientName != "" {
+			m.SetOptionString("audio-client-name", p.clientName)
+		}
+
+		if err := m.Initialize(); err != nil {
+			return fmt.Errorf("error initializing mpv: %s", err.Error())
+		}
+		p.mpv = m
+	}
+	ctx, cancel := context.WithCancel(context.Background())
+	go p.eventHandler(ctx)
+	p.bgCancel = cancel
+	return nil
+}
+
+// Appends the given file to the play queue.
+// Note that the Player API does not provide methods to read
+// the play queue. Clients are expected to maintain their own play queue model.
+func (p *Player) AppendFile(url string) error {
+	if p.mpv == nil {
+		return ErrUnitialized
+	}
+	return p.mpv.Command([]string{"loadfile", url, "append"})
+}
+
+// Plays the specified file, clearing the previous play queue, if any.
+func (p *Player) PlayFile(url string) error {
+	if p.mpv == nil {
+		return ErrUnitialized
+	}
+	err := p.mpv.Command([]string{"loadfile", url, "replace"})
+	if err == nil {
+		p.setState(Playing)
+	}
+	return err
+}
+
+// Stops playback and clears the play queue.
+func (p *Player) Stop() error {
+	if p.mpv == nil {
+		return ErrUnitialized
+	}
+	var err error
+	if p.status.State == Stopped {
+		err = p.mpv.Command([]string{"playlist-clear"})
+	} else {
+		if err = p.mpv.Command([]string{"stop"}); err == nil {
+			// if player was paused, stop command actually doesn't clear pause state
+			err = p.setPaused(false)
+		}
+	}
+	if err == nil {
+		p.setState(Stopped)
+	}
+	return err
+}
+
+// Seeks within the currently playing track.
+// See MPV seek command documentation for more details.
+func (p *Player) Seek(target string, mode SeekMode) error {
+	if p.mpv == nil {
+		return ErrUnitialized
+	}
+	p.seeking = true
+	err := p.mpv.Command([]string{"seek", target, mode.String()})
+	return err
+}
+
+// Seeks to the beginning of the current track if:
+//   - The current track is the first track in the play queue, or
+//   - The current time is more than 3 seconds past the beginning of the track.
+//
+// Else seeks to the beginning of the previous track.
+func (p *Player) SeekBackOrPrevious() error {
+	if p.mpv == nil {
+		return ErrUnitialized
+	}
+
+	if pos, err := p.getInt64Property("time-pos"); err == nil && pos > 3 {
+		return p.Seek("0", SeekAbsolutePercent)
+	}
+	if pos, err := p.getInt64Property("playlist-pos"); err == nil && pos == 0 {
+		return p.Seek("0", SeekAbsolutePercent)
+	}
+	return p.mpv.Command([]string{"playlist-prev"})
+}
+
+// Seeks to the next track in the play queue, if any.
+func (p *Player) SeekNext() error {
+	if p.mpv == nil {
+		return ErrUnitialized
+	}
+	return p.mpv.Command([]string{"playlist-next"})
+}
+
+// Sets the volume of the player (0-100).
+// Unlike most Player functions, SetVolume can be called before Init,
+// to set the initial volume of the player on startup.
+func (p *Player) SetVolume(vol int) error {
+	if vol > 100 {
+		vol = 100
+	} else if vol < 0 {
+		vol = 0
+	}
+	if p.mpv != nil {
+		err := p.mpv.SetProperty("volume", mpv.FORMAT_INT64, vol)
+		if err == nil {
+			p.vol = vol
+		}
+		return err
+	}
+	p.vol = vol
+	return nil
+}
+
+// Gets the current volume of the player.
+func (p *Player) GetVolume() int {
+	return p.vol
+}
+
+func (p *Player) setPaused(paused bool) error {
+	return p.mpv.SetProperty("pause", mpv.FORMAT_FLAG, paused)
+}
+
+// Start playback from the first track in the play queue.
+func (p *Player) PlayFromBeginning() error {
+	err := p.mpv.Command([]string{"playlist-play-index", "0"})
+	if err == nil {
+		p.setState(Playing)
+	}
+	return err
+}
+
+// Begins playback if there is anything in the play queue and player is stopped or paused.
+// If player is playing, pauses playback.
+func (p *Player) PlayPause() error {
+	if p.mpv == nil {
+		return ErrUnitialized
+	}
+
+	switch p.status.State {
+	case Stopped:
+		// check if we have anything to play
+		if c, err := p.getInt64Property("playlist-count"); err == nil && c > 0 {
+			err := p.mpv.Command([]string{"playlist-play-index", "0"})
+			if err == nil {
+				p.setState(Playing)
+			}
+			return err
+		}
+		return nil
+	case Playing:
+		err := p.setPaused(true)
+		if err == nil {
+			p.prePausedState = p.status.State
+			p.setState(Paused)
+		}
+		return err
+	case Paused:
+		err := p.setPaused(false)
+		if err == nil {
+			p.setState(p.prePausedState)
+		}
+		return err
+	default:
+		return errors.New("Unknown player state")
+	}
+}
+
+// Get the current status of the player.
+func (p *Player) GetStatus() Status {
+	if p.mpv == nil {
+		return p.status
+	}
+
+	pos, _ := p.mpv.GetProperty("playback-time", mpv.FORMAT_DOUBLE)
+	dur, _ := p.mpv.GetProperty("duration", mpv.FORMAT_DOUBLE)
+	if pos != nil {
+		p.status.TimePos = pos.(float64)
+	}
+	if dur != nil {
+		p.status.Duration = dur.(float64)
+	}
+	if playpos, err := p.getInt64Property("playlist-pos"); err == nil {
+		p.status.PlaylistPos = playpos
+	}
+	return p.status
+}
+
+func (p *Player) getInt64Property(propName string) (int64, error) {
+	playpos, err := p.mpv.GetProperty(propName, mpv.FORMAT_INT64)
+	if err != nil {
+		return -1, err
+	}
+	if playpos != nil {
+		return playpos.(int64), nil
+	}
+	return -1, errors.New("mpv did not report playlist pos")
+}
+
+// Returns true if a seek is currently in progress.
+func (p *Player) IsSeeking() bool {
+	return p.seeking && p.status.State == Playing
+}
+
+// Registers a callback which is invoked when the player transitions to the Paused state.
+func (p *Player) OnPaused(cb func()) {
+	p.onPaused = append(p.onPaused, cb)
+}
+
+// Registers a callback which is invoked when the player transitions to the Stopped state.
+func (p *Player) OnStopped(cb func()) {
+	p.onStopped = append(p.onStopped, cb)
+}
+
+// Registers a callback which is invoked when the player transitions to the Playing state.
+func (p *Player) OnPlaying(cb func()) {
+	p.onPlaying = append(p.onPlaying, cb)
+}
+
+// Registers a callback which is invoked whenever a seek event occurs.
+func (p *Player) OnSeek(cb func()) {
+	p.onSeek = append(p.onSeek, cb)
+}
+
+// Registers a callback which is invoked when the currently playing track changes,
+// or when playback begins at any time from the Stopped state.
+// Callback is invoked with the index of the currently playing track (zero-based).
+func (p *Player) OnTrackChange(cb func(int64)) {
+	p.onTrackChange = append(p.onTrackChange, cb)
+}
+
+// Destroy the player.
+func (p *Player) Destroy() {
+	if p.bgCancel != nil {
+		p.bgCancel()
+	}
+	if p.mpv != nil {
+		p.mpv.Command([]string{"stop"})
+		p.mpv.DetachDestroy()
+		p.mpv = nil
+	}
+}
+
+// sets the state and invokes callbacks, if triggered
+func (p *Player) setState(s State) {
+	switch {
+	case s == Playing && p.status.State != Playing:
+		defer func() {
+			for _, cb := range p.onPlaying {
+				cb()
+			}
+		}()
+		if p.status.State == Stopped {
+			defer func() {
+				for _, cb := range p.onTrackChange {
+					cb(p.curPlaylistPos)
+				}
+			}()
+		}
+	case s == Paused && p.status.State != Paused:
+		defer func() {
+			for _, cb := range p.onPaused {
+				cb()
+			}
+		}()
+	case s == Stopped && p.status.State != Stopped:
+		defer func() {
+			for _, cb := range p.onStopped {
+				cb()
+			}
+		}()
+	}
+	p.status.State = s
+}
+
+func (p *Player) eventHandler(ctx context.Context) {
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		default:
+			e := p.mpv.WaitEvent(0.2 /*timeout seconds*/)
+			if e.Event_Id != mpv.EVENT_NONE {
+				//log.Printf("mpv event: %+v\n", e)
+			}
+			switch e.Event_Id {
+			case mpv.EVENT_PLAYBACK_RESTART:
+				if p.seeking {
+					p.seeking = false
+				}
+			case mpv.EVENT_SEEK:
+				for _, cb := range p.onSeek {
+					cb()
+				}
+			case mpv.EVENT_FILE_LOADED:
+				if p.status.State == Paused {
+					// seek while paused switches to a new file
+					// mpv does not fire seek event in this case
+					for _, cb := range p.onSeek {
+						cb()
+					}
+				}
+				if pos, err := p.getInt64Property("playlist-pos"); err == nil {
+					if p.curPlaylistPos != pos {
+						p.curPlaylistPos = pos
+						for _, cb := range p.onTrackChange {
+							cb(pos)
+						}
+					}
+				}
+			case mpv.EVENT_IDLE:
+				p.status.Duration = 0
+				p.status.TimePos = 0
+				p.setState(Stopped)
+			}
+		}
+	}
+}
+
+func (s SeekMode) String() string {
+	switch s {
+	case SeekAbsolute:
+		return "absolute"
+	case SeekRelative:
+		return "relative"
+	case SeekAbsolutePercent:
+		return "absolute-percent"
+	case SeekRelativePercent:
+		return "relative-percent"
+	}
+	return "UNKNOWN_SEEK_MODE"
+}