ebiten/audio/writerplayer.go

292 lines
5.5 KiB
Go

// Copyright 2019 The Ebiten Authors
//
// 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
import (
"fmt"
"io"
"sync"
"time"
"github.com/hajimehoshi/ebiten/v2/internal/hooks"
)
// writerDriver represents a driver using io.WriteClosers.
// The actual implementation is otoDriver.
type writerDriver interface {
NewPlayer() io.WriteCloser
io.Closer
}
var writerDriverForTesting writerDriver
func newWriterDriver(sampleRate int) writerDriver {
if writerDriverForTesting != nil {
return writerDriverForTesting
}
ch := make(chan struct{})
var once sync.Once
hooks.AppendHookOnBeforeUpdate(func() error {
once.Do(func() {
close(ch)
})
return nil
})
return newOtoDriver(sampleRate, ch)
}
type writerPlayerFactory struct {
driver writerDriver
}
func newWriterPlayerFactory(sampleRate int) *writerPlayerFactory {
return &writerPlayerFactory{
driver: newWriterDriver(sampleRate),
}
}
type writerPlayer struct {
context *Context
driver writerDriver
src io.Reader
playing bool
closedExplicitly bool
isLoopActive bool
buf []byte
readbuf []byte
pos int64
volume float64
m sync.Mutex
}
func (c *writerPlayerFactory) newPlayerImpl(context *Context, src io.Reader) (playerImpl, error) {
p := &writerPlayer{
context: context,
driver: c.driver,
src: src,
volume: 1,
}
if seeker, ok := p.src.(io.Seeker); ok {
// Get the current position of the source.
pos, err := seeker.Seek(0, io.SeekCurrent)
if err != nil {
return nil, err
}
p.pos = pos
}
return p, nil
}
func (p *writerPlayer) Close() error {
p.m.Lock()
defer p.m.Unlock()
p.playing = false
if p.closedExplicitly {
return fmt.Errorf("audio: the player is already closed")
}
p.closedExplicitly = true
return nil
}
func (p *writerPlayer) Play() {
p.m.Lock()
defer p.m.Unlock()
if p.closedExplicitly {
p.context.setError(fmt.Errorf("audio: the player is already closed"))
return
}
p.playing = true
if p.isLoopActive {
return
}
// Set p.isLoopActive to true here, not in the loop. This prevents duplicated active loops.
p.isLoopActive = true
p.context.addPlayer(p)
go p.loop()
return
}
func (p *writerPlayer) loop() {
p.context.waitUntilInited()
w := p.driver.NewPlayer()
wclosed := make(chan struct{})
defer func() {
<-wclosed
w.Close()
}()
defer func() {
p.m.Lock()
p.playing = false
p.context.removePlayer(p)
p.isLoopActive = false
p.m.Unlock()
}()
ch := make(chan []byte)
defer close(ch)
go func() {
for buf := range ch {
if _, err := w.Write(buf); err != nil {
p.context.setError(err)
break
}
p.context.setReady()
}
close(wclosed)
}()
for {
buf, ok := p.read()
if !ok {
return
}
ch <- buf
}
}
func (p *writerPlayer) read() ([]byte, bool) {
p.m.Lock()
defer p.m.Unlock()
if p.context.hasError() {
return nil, false
}
if p.closedExplicitly {
return nil, false
}
// playing can be false when pausing.
if !p.playing {
return nil, false
}
const bufSize = 2048
p.context.acquireSemaphore()
defer func() {
p.context.releaseSemaphore()
}()
if p.readbuf == nil {
p.readbuf = make([]byte, bufSize)
}
n, err := p.src.Read(p.readbuf[:bufSize-len(p.buf)])
if err != nil {
if err != io.EOF {
p.context.setError(err)
return nil, false
}
if n == 0 {
return nil, false
}
}
buf := append(p.buf, p.readbuf[:n]...)
n2 := len(buf) - len(buf)%bytesPerSample
buf, p.buf = buf[:n2], buf[n2:]
for i := 0; i < len(buf)/2; i++ {
v16 := int16(buf[2*i]) | (int16(buf[2*i+1]) << 8)
v16 = int16(float64(v16) * p.volume)
buf[2*i] = byte(v16)
buf[2*i+1] = byte(v16 >> 8)
}
p.pos += int64(len(buf))
return buf, true
}
func (p *writerPlayer) IsPlaying() bool {
p.m.Lock()
r := p.playing
p.m.Unlock()
return r
}
func (p *writerPlayer) Rewind() error {
if _, ok := p.src.(io.Seeker); !ok {
panic("audio: player to be rewound must be io.Seeker")
}
return p.Seek(0)
}
func (p *writerPlayer) Seek(offset time.Duration) error {
p.m.Lock()
defer p.m.Unlock()
o := int64(offset) * bytesPerSample * int64(p.context.SampleRate()) / int64(time.Second)
o = o - (o % bytesPerSample)
seeker, ok := p.src.(io.Seeker)
if !ok {
panic("audio: the source must be io.Seeker when seeking")
}
pos, err := seeker.Seek(o, io.SeekStart)
if err != nil {
return err
}
p.buf = nil
p.pos = pos
return nil
}
func (p *writerPlayer) Pause() {
p.m.Lock()
p.playing = false
p.m.Unlock()
}
func (p *writerPlayer) Current() time.Duration {
p.m.Lock()
sample := p.pos / bytesPerSample
p.m.Unlock()
return time.Duration(sample) * time.Second / time.Duration(p.context.SampleRate())
}
func (p *writerPlayer) Volume() float64 {
p.m.Lock()
v := p.volume
p.m.Unlock()
return v
}
func (p *writerPlayer) SetVolume(volume float64) {
// 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.m.Lock()
p.volume = volume
p.m.Unlock()
}
func (p *writerPlayer) source() io.Reader {
return p.src
}