mirror of
https://github.com/hajimehoshi/ebiten.git
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589 lines
13 KiB
Go
589 lines
13 KiB
Go
// Copyright 2015 Hajime Hoshi
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Package audio provides audio players.
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//
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// The stream format must be 16-bit little endian and 2 channels. The format is as follows:
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// [data] = [sample 1] [sample 2] [sample 3] ...
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// [sample *] = [channel 1] ...
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// [channel *] = [byte 1] [byte 2] ...
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//
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// An audio context (audio.Context object) has a sample rate you can specify and all streams you want to play must have the same
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// sample rate. However, decoders in e.g. audio/mp3 package adjust sample rate automatically,
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// and you don't have to care about it as long as you use those decoders.
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//
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// An audio context can generate 'players' (audio.Player objects),
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// and you can play sound by calling Play function of players.
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// When multiple players play, mixing is automatically done.
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// Note that too many players may cause distortion.
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//
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// For the simplest example to play sound, see wav package in the examples.
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package audio
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import (
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"bytes"
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"errors"
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"fmt"
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"io"
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"runtime"
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"sync"
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"time"
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)
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const (
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channelNum = 2
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bytesPerSample = 2 * channelNum
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)
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// A Context represents a current state of audio.
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//
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// At most one Context object can exist in one process.
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// This means only one constant sample rate is valid in your one application.
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//
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// For a typical usage example, see examples/wav/main.go.
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type Context struct {
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c context
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// inited represents whether the audio device is initialized and available or not.
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// On Android, audio loop cannot be started unless JVM is accessible. After updating one frame, JVM should exist.
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inited chan struct{}
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initedOnce sync.Once
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sampleRate int
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err error
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ready bool
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players map[*playerImpl]struct{}
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m sync.Mutex
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semaphore chan struct{}
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}
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var (
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theContext *Context
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theContextLock sync.Mutex
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)
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// NewContext creates a new audio context with the given sample rate.
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//
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// The sample rate is also used for decoding MP3 with audio/mp3 package
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// or other formats as the target sample rate.
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//
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// sampleRate should be 44100 or 48000.
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// Other values might not work.
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// For example, 22050 causes error on Safari when decoding MP3.
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//
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// NewContext panics when an audio context is already created.
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func NewContext(sampleRate int) *Context {
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theContextLock.Lock()
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defer theContextLock.Unlock()
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if theContext != nil {
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panic("audio: context is already created")
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}
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c := &Context{
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sampleRate: sampleRate,
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c: newContext(sampleRate),
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players: map[*playerImpl]struct{}{},
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inited: make(chan struct{}),
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semaphore: make(chan struct{}, 1),
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}
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theContext = c
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h := getHook()
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h.OnSuspendAudio(func() {
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c.semaphore <- struct{}{}
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})
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h.OnResumeAudio(func() {
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<-c.semaphore
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})
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h.AppendHookOnBeforeUpdate(func() error {
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c.initedOnce.Do(func() {
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close(c.inited)
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})
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var err error
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theContextLock.Lock()
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if theContext != nil {
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theContext.m.Lock()
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err = theContext.err
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theContext.m.Unlock()
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}
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theContextLock.Unlock()
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return err
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})
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return c
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}
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// CurrentContext returns the current context or nil if there is no context.
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func CurrentContext() *Context {
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theContextLock.Lock()
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c := theContext
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theContextLock.Unlock()
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return c
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}
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func (c *Context) hasError() bool {
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c.m.Lock()
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r := c.err != nil
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c.m.Unlock()
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return r
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}
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func (c *Context) setError(err error) {
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// TODO: What if c.err already exists?
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c.m.Lock()
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c.err = err
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c.m.Unlock()
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}
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func (c *Context) setReady() {
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c.m.Lock()
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c.ready = true
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c.m.Unlock()
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}
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func (c *Context) addPlayer(p *playerImpl) {
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c.m.Lock()
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defer c.m.Unlock()
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c.players[p] = struct{}{}
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// Check the source duplication
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srcs := map[io.ReadCloser]struct{}{}
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for p := range c.players {
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if _, ok := srcs[p.src]; ok {
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c.err = errors.New("audio: a same source is used by multiple Player")
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return
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}
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srcs[p.src] = struct{}{}
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}
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}
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func (c *Context) removePlayer(p *playerImpl) {
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c.m.Lock()
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delete(c.players, p)
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c.m.Unlock()
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}
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// IsReady returns a boolean value indicating whether the audio is ready or not.
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//
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// On some browsers, user interaction like click or pressing keys is required to start audio.
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func (c *Context) IsReady() bool {
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c.m.Lock()
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defer c.m.Unlock()
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r := c.ready
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if r {
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return r
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}
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if len(c.players) != 0 {
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return r
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}
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// Create another goroutine since (*Player).Play can lock the context's mutex.
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go func() {
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// The audio context is never ready unless there is a player. This is
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// problematic when a user tries to play audio after the context is ready.
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// Play a dummy player to avoid the blocking (#969).
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// Use a long enough buffer so that writing doesn't finish immediately (#970).
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p := NewPlayerFromBytes(c, make([]byte, bufferSize()*2))
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p.Play()
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}()
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return r
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}
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// SampleRate returns the sample rate.
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func (c *Context) SampleRate() int {
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return c.sampleRate
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}
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// ReadSeekCloser is an io.ReadSeeker and io.Closer.
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type ReadSeekCloser interface {
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io.ReadSeeker
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io.Closer
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}
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type bytesReadSeekCloser struct {
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reader *bytes.Reader
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}
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func (b *bytesReadSeekCloser) Read(buf []byte) (int, error) {
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return b.reader.Read(buf)
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}
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func (b *bytesReadSeekCloser) Seek(offset int64, whence int) (int64, error) {
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return b.reader.Seek(offset, whence)
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}
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func (b *bytesReadSeekCloser) Close() error {
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b.reader = nil
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return nil
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}
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// BytesReadSeekCloser creates ReadSeekCloser from bytes.
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func BytesReadSeekCloser(b []byte) ReadSeekCloser {
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return &bytesReadSeekCloser{reader: bytes.NewReader(b)}
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}
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// Player is an audio player which has one stream.
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//
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// Even when all references to a Player object is gone,
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// the object is not GCed until the player finishes playing.
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// This means that if a Player plays an infinite stream,
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// the object is never GCed unless Close is called.
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type Player struct {
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p *playerImpl
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}
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type playerImpl struct {
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context *Context
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src io.ReadCloser
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sampleRate int
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playing bool
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closedExplicitly bool
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isLoopActive bool
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buf []byte
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pos int64
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volume float64
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m sync.Mutex
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}
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// NewPlayer creates a new player with the given stream.
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//
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// src's format must be linear PCM (16bits little endian, 2 channel stereo)
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// without a header (e.g. RIFF header).
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// The sample rate must be same as that of the audio context.
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//
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// The player is seekable when src is io.Seeker.
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// Attempt to seek the player that is not io.Seeker causes panic.
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//
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// Note that the given src can't be shared with other Player objects.
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//
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// NewPlayer tries to call Seek of src to get the current position.
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// NewPlayer returns error when the Seek returns error.
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//
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// NewPlayer takes the ownership of src. Player's Close calls src's Close.
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func NewPlayer(context *Context, src io.ReadCloser) (*Player, error) {
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p := &Player{
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&playerImpl{
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context: context,
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src: src,
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sampleRate: context.sampleRate,
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volume: 1,
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},
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}
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if seeker, ok := p.p.src.(io.Seeker); ok {
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// Get the current position of the source.
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pos, err := seeker.Seek(0, io.SeekCurrent)
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if err != nil {
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return nil, err
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}
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p.p.pos = pos
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}
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runtime.SetFinalizer(p, (*Player).finalize)
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return p, nil
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}
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// NewPlayerFromBytes creates a new player with the given bytes.
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//
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// As opposed to NewPlayer, you don't have to care if src is already used by another player or not.
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// src can be shared by multiple players.
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//
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// The format of src should be same as noted at NewPlayer.
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func NewPlayerFromBytes(context *Context, src []byte) *Player {
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b := BytesReadSeekCloser(src)
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p, err := NewPlayer(context, b)
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if err != nil {
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// Errors should never happen.
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panic(fmt.Sprintf("audio: %v at NewPlayerFromBytes", err))
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}
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return p
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}
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func (p *Player) finalize() {
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runtime.SetFinalizer(p, nil)
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if !p.IsPlaying() {
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p.Close()
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}
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}
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// Close closes the stream.
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//
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// When closing, the stream owned by the player will also be closed by calling its Close.
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// This means that the source stream passed via NewPlayer will also be closed.
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//
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// Close returns error when closing the source returns error.
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func (p *Player) Close() error {
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runtime.SetFinalizer(p, nil)
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return p.p.Close()
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}
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func (p *playerImpl) Close() error {
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p.m.Lock()
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defer p.m.Unlock()
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p.playing = false
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if p.closedExplicitly {
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return fmt.Errorf("audio: the player is already closed")
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}
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p.closedExplicitly = true
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// src.Close is called only when Player's Close is called.
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// TODO: Is it ok not to call src.Close when GCed?
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if err := p.src.Close(); err != nil {
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return err
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}
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return nil
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}
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// Play plays the stream.
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//
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// Play always returns nil.
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func (p *Player) Play() error {
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p.p.Play()
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return nil
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}
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func (p *playerImpl) Play() {
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p.m.Lock()
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defer p.m.Unlock()
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if p.closedExplicitly {
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p.context.setError(fmt.Errorf("audio: the player is already closed"))
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return
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}
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p.playing = true
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if p.isLoopActive {
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return
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}
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// Set p.isLoopActive to true here, not in the loop. This prevents duplicated active loops.
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p.isLoopActive = true
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p.context.addPlayer(p)
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go p.loop()
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return
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}
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func (p *playerImpl) loop() {
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<-p.context.inited
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w := p.context.c.NewPlayer()
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wclosed := make(chan struct{})
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defer func() {
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<-wclosed
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w.Close()
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}()
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defer func() {
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p.m.Lock()
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p.playing = false
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p.context.removePlayer(p)
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p.isLoopActive = false
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p.m.Unlock()
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}()
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ch := make(chan []byte)
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defer close(ch)
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go func() {
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for buf := range ch {
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if _, err := w.Write(buf); err != nil {
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p.context.setError(err)
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break
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}
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p.context.setReady()
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}
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close(wclosed)
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}()
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for {
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buf, ok := p.read()
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if !ok {
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return
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}
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ch <- buf
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}
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}
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func (p *playerImpl) read() ([]byte, bool) {
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p.m.Lock()
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defer p.m.Unlock()
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if p.context.hasError() {
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return nil, false
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}
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if p.closedExplicitly {
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return nil, false
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}
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// playing can be false when pausing.
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if !p.playing {
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return nil, false
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}
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const bufSize = 2048
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p.context.semaphore <- struct{}{}
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defer func() {
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<-p.context.semaphore
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}()
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newBuf := make([]byte, bufSize-len(p.buf))
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n, err := p.src.Read(newBuf)
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if err != nil {
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if err != io.EOF {
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p.context.setError(err)
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return nil, false
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}
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if n == 0 {
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return nil, false
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}
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}
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buf := append(p.buf, newBuf[:n]...)
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n2 := len(buf) - len(buf)%bytesPerSample
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buf, p.buf = buf[:n2], buf[n2:]
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for i := 0; i < len(buf)/2; i++ {
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v16 := int16(buf[2*i]) | (int16(buf[2*i+1]) << 8)
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v16 = int16(float64(v16) * p.volume)
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buf[2*i] = byte(v16)
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buf[2*i+1] = byte(v16 >> 8)
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}
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p.pos += int64(len(buf))
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return buf, true
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}
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// IsPlaying returns boolean indicating whether the player is playing.
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func (p *Player) IsPlaying() bool {
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return p.p.IsPlaying()
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}
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func (p *playerImpl) IsPlaying() bool {
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p.m.Lock()
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r := p.playing
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p.m.Unlock()
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return r
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}
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// Rewind rewinds the current position to the start.
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//
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// The passed source to NewPlayer must be io.Seeker, or Rewind panics.
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//
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// Rewind returns error when seeking the source stream returns error.
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func (p *Player) Rewind() error {
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return p.p.Rewind()
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}
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func (p *playerImpl) Rewind() error {
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if _, ok := p.src.(io.Seeker); !ok {
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panic("audio: player to be rewound must be io.Seeker")
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}
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return p.Seek(0)
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}
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// Seek seeks the position with the given offset.
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//
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// The passed source to NewPlayer must be io.Seeker, or Seek panics.
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//
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// Seek returns error when seeking the source stream returns error.
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func (p *Player) Seek(offset time.Duration) error {
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return p.p.Seek(offset)
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}
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func (p *playerImpl) Seek(offset time.Duration) error {
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p.m.Lock()
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defer p.m.Unlock()
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o := int64(offset) * bytesPerSample * int64(p.sampleRate) / int64(time.Second)
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o = o - (o % bytesPerSample)
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seeker, ok := p.src.(io.Seeker)
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if !ok {
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panic("audio: the source must be io.Seeker when seeking")
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}
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pos, err := seeker.Seek(o, io.SeekStart)
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if err != nil {
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return err
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}
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p.buf = nil
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p.pos = pos
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return nil
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}
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// Pause pauses the playing.
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//
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// Pause always returns nil.
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func (p *Player) Pause() error {
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p.p.Pause()
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return nil
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}
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func (p *playerImpl) Pause() {
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p.m.Lock()
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p.playing = false
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p.m.Unlock()
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}
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// Current returns the current position in time.
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func (p *Player) Current() time.Duration {
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return p.p.Current()
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}
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func (p *playerImpl) Current() time.Duration {
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p.m.Lock()
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sample := p.pos / bytesPerSample
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p.m.Unlock()
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return time.Duration(sample) * time.Second / time.Duration(p.sampleRate)
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}
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// Volume returns the current volume of this player [0-1].
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func (p *Player) Volume() float64 {
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return p.p.Volume()
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}
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func (p *playerImpl) Volume() float64 {
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p.m.Lock()
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v := p.volume
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p.m.Unlock()
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return v
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}
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|
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// SetVolume sets the volume of this player.
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// volume must be in between 0 and 1. SetVolume panics otherwise.
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func (p *Player) SetVolume(volume float64) {
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p.p.SetVolume(volume)
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}
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func (p *playerImpl) SetVolume(volume float64) {
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// 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()
|
|
}
|