ebiten/audio/audio.go

537 lines
13 KiB
Go

// Copyright 2015 Hajime Hoshi
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Package audio provides audio players. This can be used with or without ebiten package.
//
// The stream format must be 16-bit little endian and 2 channels.
//
// An audio context has a sample rate you can set and all streams you want to play must have the same
// sample rate. However, decoders like audio/vorbis and audio/wav adjust sample rate,
// and you don't have to care about it as long as you use those decoders.
//
// An audio context can generate 'players' (instances of audio.Player),
// and you can play sound by calling Play function of players.
// When multiple players play, mixing is automatically done.
// Note that too many players may cause distortion.
package audio
import (
"bytes"
"errors"
"io"
"runtime"
"sync"
"time"
"github.com/hajimehoshi/ebiten"
"github.com/hajimehoshi/oto"
)
type players struct {
players map[*Player]struct{}
sync.RWMutex
}
const (
channelNum = 2
bytesPerSample = 2
// TODO: This assumes that channelNum is a power of 2.
mask = ^(channelNum*bytesPerSample - 1)
)
func min(a, b int) int {
if a < b {
return a
}
return b
}
func (p *players) Read(b []uint8) (int, error) {
p.Lock()
defer p.Unlock()
players := []*Player{}
for player := range p.players {
players = append(players, player)
}
if len(players) == 0 {
l := len(b)
l &= mask
copy(b, make([]uint8, l))
return l, nil
}
closed := []*Player{}
l := len(b)
for _, player := range players {
n, err := player.readToBuffer(l)
if err == io.EOF {
closed = append(closed, player)
} else if err != nil {
return 0, err
}
l = min(n, l)
}
l &= mask
b16s := [][]int16{}
for _, player := range players {
b16s = append(b16s, player.bufferToInt16(l))
}
for i := 0; i < l/2; i++ {
x := 0
for _, b16 := range b16s {
x += int(b16[i])
}
if x > (1<<15)-1 {
x = (1 << 15) - 1
}
if x < -(1 << 15) {
x = -(1 << 15)
}
b[2*i] = byte(x)
b[2*i+1] = byte(x >> 8)
}
for _, player := range players {
player.proceed(l)
}
for _, pl := range closed {
delete(p.players, pl)
}
return l, nil
}
func (p *players) addPlayer(player *Player) {
p.Lock()
p.players[player] = struct{}{}
p.Unlock()
}
func (p *players) removePlayer(player *Player) {
p.Lock()
delete(p.players, player)
p.Unlock()
}
func (p *players) hasPlayer(player *Player) bool {
p.RLock()
_, ok := p.players[player]
p.RUnlock()
return ok
}
func (p *players) hasSource(src ReadSeekCloser) bool {
p.RLock()
defer p.RUnlock()
for player := range p.players {
if player.src == src {
return true
}
}
return false
}
// A Context is a current state of audio.
//
// There should be at most one Context object.
// This means only one constant sample rate is valid in your one application.
//
// The typical usage with ebiten package is:
//
// var audioContext *audio.Context
//
// func update(screen *ebiten.Image) error {
// // Update updates the audio stream by 1/60 [sec].
// if err := audioContext.Update(); err != nil {
// return err
// }
// // ...
// }
//
// func main() {
// audioContext, err = audio.NewContext(sampleRate)
// if err != nil {
// panic(err)
// }
// ebiten.Run(run, update, 320, 240, 2, "Audio test")
// }
//
// This is 'sync mode' in that game's (logical) time and audio time are synchronized.
// You can also call Update independently from the game loop as 'async mode'.
// In this case, audio goes on even when the game stops e.g. by diactivating the screen.
type Context struct {
players *players
driver *oto.Player
sampleRate int
frames int64
writtenBytes int64
}
var (
theContext *Context
theContextLock sync.Mutex
)
// NewContext creates a new audio context with the given sample rate (e.g. 44100).
//
// Error returned by NewContext is always nil as of 1.5.0-alpha.
//
// NewContext panics when an audio context is already created.
func NewContext(sampleRate int) (*Context, error) {
theContextLock.Lock()
defer theContextLock.Unlock()
if theContext != nil {
panic("audio: context is already created")
}
c := &Context{
sampleRate: sampleRate,
}
theContext = c
c.players = &players{
players: map[*Player]struct{}{},
}
return c, nil
}
// Update proceeds the inner (logical) time of the context by 1/60 second.
//
// This is expected to be called in the game's updating function (sync mode)
// or an independent goroutine with timers (async mode).
// In sync mode, the game logical time syncs the audio logical time and
// you will find audio stops when the game stops e.g. when the window is deactivated.
// In async mode, the audio never stops even when the game stops.
//
// Update returns error when IO error occurs in the underlying IO object.
func (c *Context) Update() error {
// Initialize c.driver lazily to enable calling NewContext in an 'init' function.
// Accessing driver functions requires the environment to be already initialized,
// but if Ebiten is used for a shared library, the timing when init functions are called
// is unexpectable.
// e.g. a variable for JVM on Android might not be set.
if c.driver == nil {
// The buffer size is 1/15 sec.
// It looks like 1/20 sec is too short for Android.
s := c.sampleRate * channelNum * bytesPerSample / 15
p, err := oto.NewPlayer(c.sampleRate, channelNum, bytesPerSample, s)
c.driver = p
if err != nil {
return err
}
}
c.frames++
bytesPerFrame := c.sampleRate * bytesPerSample * channelNum / ebiten.FPS
l := (c.frames * int64(bytesPerFrame)) - c.writtenBytes
l &= mask
c.writtenBytes += l
buf := make([]uint8, l)
n, err := io.ReadFull(c.players, buf)
if err != nil {
return err
}
if n != len(buf) {
return c.driver.Close()
}
_, err = c.driver.Write(buf)
if err == io.EOF {
return c.driver.Close()
}
if err != nil {
return err
}
return nil
}
// SampleRate returns the sample rate.
func (c *Context) SampleRate() int {
return c.sampleRate
}
// ReadSeekCloser is an io.ReadSeeker and io.Closer.
type ReadSeekCloser interface {
io.ReadSeeker
io.Closer
}
type bytesReadSeekCloser struct {
reader *bytes.Reader
}
func (b *bytesReadSeekCloser) Read(buf []uint8) (int, error) {
return b.reader.Read(buf)
}
func (b *bytesReadSeekCloser) Seek(offset int64, whence int) (int64, error) {
return b.reader.Seek(offset, whence)
}
func (b *bytesReadSeekCloser) Close() error {
b.reader = nil
return nil
}
// BytesReadSeekCloser creates ReadSeekCloser from bytes.
//
// A returned stream is concurrent safe.
func BytesReadSeekCloser(b []uint8) ReadSeekCloser {
return &bytesReadSeekCloser{reader: bytes.NewReader(b)}
}
type readingResult struct {
data []uint8
err error
}
// Player is an audio player which has one stream.
type Player struct {
players *players
src ReadSeekCloser
sampleRate int
readingCh chan readingResult
seekCh chan int64
buf []uint8
pos int64
volume float64
srcM sync.Mutex
m sync.RWMutex
}
// NewPlayer creates a new player with the given stream.
//
// src's format must be linear PCM (16bits little endian, 2 channel stereo)
// without a header (e.g. RIFF header).
// The sample rate must be same as that of the audio context.
//
// Note that the given src can't be shared with other Players.
//
// NewPlayer tries to rewind src by calling Seek to get the current position.
// NewPlayer returns error when the Seek returns error.
func NewPlayer(context *Context, src ReadSeekCloser) (*Player, error) {
if context.players.hasSource(src) {
return nil, errors.New("audio: src cannot be shared with another Player")
}
p := &Player{
players: context.players,
src: src,
sampleRate: context.sampleRate,
seekCh: make(chan int64, 1),
buf: []uint8{},
volume: 1,
}
// Get the current position of the source.
pos, err := p.src.Seek(0, io.SeekCurrent)
if err != nil {
return nil, err
}
p.pos = pos
runtime.SetFinalizer(p, (*Player).Close)
return p, nil
}
// NewPlayerFromBytes creates a new player with the given bytes.
//
// As opposed to NewPlayer, you don't have to care if src is already used by another player or not.
// src can be shared by multiple players.
//
// The format of src should be same as noted at NewPlayer.
//
// NewPlayerFromBytes's error is always nil as of 1.5.0-alpha.
func NewPlayerFromBytes(context *Context, src []uint8) (*Player, error) {
b := BytesReadSeekCloser(src)
p, err := NewPlayer(context, b)
if err != nil {
// Errors should never happen.
panic(err)
}
return p, nil
}
// Close closes the stream. Ths source stream passed by NewPlayer will also be closed.
//
// When closing, the stream owned by the player will also be closed by calling its Close.
//
// Close is concurrent safe.
//
// Close returns error when closing the source returns error.
func (p *Player) Close() error {
p.players.removePlayer(p)
runtime.SetFinalizer(p, nil)
p.srcM.Lock()
err := p.src.Close()
p.srcM.Unlock()
return err
}
func (p *Player) readToBuffer(length int) (int, error) {
if p.readingCh == nil {
p.readingCh = make(chan readingResult)
go func() {
defer close(p.readingCh)
b := make([]uint8, length)
p.srcM.Lock()
n, err := p.src.Read(b)
p.srcM.Unlock()
if err != nil {
p.readingCh <- readingResult{
err: err,
}
return
}
p.readingCh <- readingResult{
data: b[:n],
}
}()
}
select {
case pos := <-p.seekCh:
p.buf = []uint8{}
p.pos = pos
return 0, nil
case r := <-p.readingCh:
if r.err != nil {
return 0, r.err
}
if len(r.data) > 0 {
p.buf = append(p.buf, r.data...)
}
p.readingCh = nil
return len(p.buf), nil
case <-time.After(15 * time.Millisecond):
return length, nil
}
}
func (p *Player) bufferToInt16(lengthInBytes int) []int16 {
r := make([]int16, lengthInBytes/2)
// This function must be called on the same goruotine of readToBuffer.
if p.readingCh != nil {
return r
}
p.m.RLock()
for i := 0; i < lengthInBytes/2; i++ {
r[i] = int16(p.buf[2*i]) | (int16(p.buf[2*i+1]) << 8)
r[i] = int16(float64(r[i]) * p.volume)
}
p.m.RUnlock()
return r
}
func (p *Player) proceed(length int) {
// This function must be called on the same goruotine of readToBuffer.
if p.readingCh != nil {
return
}
p.buf = p.buf[length:]
p.pos += int64(length)
}
// Play plays the stream.
//
// Play always returns nil.
//
// Play is concurrent safe.
func (p *Player) Play() error {
p.players.addPlayer(p)
return nil
}
// IsPlaying returns boolean indicating whether the player is playing.
//
// IsPlaying is concurrent safe.
func (p *Player) IsPlaying() bool {
return p.players.hasPlayer(p)
}
// Rewind rewinds the current position to the start.
//
// Rewind is concurrent safe.
//
// Rewind returns error when seeking the source returns error.
func (p *Player) Rewind() error {
return p.Seek(0)
}
// Seek seeks the position with the given offset.
//
// Seek is concurrent safe.
//
// Seek returns error when seeking the source returns error.
func (p *Player) Seek(offset time.Duration) error {
o := int64(offset) * bytesPerSample * channelNum * int64(p.sampleRate) / int64(time.Second)
o &= mask
p.srcM.Lock()
pos, err := p.src.Seek(o, io.SeekStart)
p.srcM.Unlock()
if err != nil {
return err
}
// When the player p is not playing, as readToBuffer is never called,
// seekCh will never solved.
// Solve the current seeking here if necessary.
select {
case pos := <-p.seekCh:
p.buf = []uint8{}
p.pos = pos
default:
}
p.seekCh <- pos
return nil
}
// Pause pauses the playing.
//
// Pause is concurrent safe.
//
// Pause always returns nil.
func (p *Player) Pause() error {
p.players.removePlayer(p)
return nil
}
// Current returns the current position.
//
// Current is concurrent safe.
func (p *Player) Current() time.Duration {
p.m.RLock()
sample := p.pos / bytesPerSample / channelNum
t := time.Duration(sample) * time.Second / time.Duration(p.sampleRate)
p.m.RUnlock()
return t
}
// Volume returns the current volume of this player [0-1].
//
// Volume is concurrent safe.
func (p *Player) Volume() float64 {
p.m.RLock()
v := p.volume
p.m.RUnlock()
return v
}
// SetVolume sets the volume of this player.
// volume must be in between 0 and 1. This function panics otherwise.
//
// SetVolume is concurrent safe.
func (p *Player) SetVolume(volume float64) {
p.m.Lock()
defer p.m.Unlock()
// The condition must be true when volume is NaN.
if !(0 <= volume && volume <= 1) {
panic("audio: volume must be in between 0 and 1")
}
p.volume = volume
}