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| 1 // Copyright 2015 The Go Authors. All rights reserved. | |
| 2 // Use of this source code is governed by a BSD-style | |
| 3 // license that can be found in the LICENSE file. | |
| 4 | |
| 5 // +build darwin | |
| 6 | |
| 7 // Package audio provides a basic audio player. | |
| 8 package audio | |
| 9 | |
| 10 import ( | |
| 11 "fmt" | |
| 12 "io" | |
| 13 "sync" | |
| 14 "time" | |
| 15 | |
| 16 "golang.org/x/mobile/audio/al" | |
| 17 "golang.org/x/mobile/audio/alc" | |
| 18 ) | |
| 19 | |
| 20 // Format represents an audio file format. | |
| 21 type Format string | |
| 22 | |
| 23 const ( | |
| 24 Mono8 = Format("mono8") | |
| 25 Mono16 = Format("mono16") | |
| 26 Stereo8 = Format("stereo8") | |
| 27 Stereo16 = Format("stereo16") | |
| 28 ) | |
| 29 | |
| 30 var formatToCode = map[Format]int32{ | |
| 31 Mono8: 0x1100, | |
| 32 Mono16: 0x1101, | |
| 33 Stereo8: 0x1102, | |
| 34 Stereo16: 0x1103, | |
| 35 } | |
| 36 | |
| 37 // State indicates the current playing state of the player. | |
| 38 type State string | |
| 39 | |
| 40 const ( | |
| 41 Unknown = State("unknown") | |
| 42 Initial = State("initial") | |
| 43 Playing = State("playing") | |
| 44 Paused = State("paused") | |
| 45 Stopped = State("stopped") | |
| 46 ) | |
| 47 | |
| 48 var codeToState = map[int32]State{ | |
| 49 0: Unknown, | |
| 50 0x1011: Initial, | |
| 51 0x1012: Playing, | |
| 52 0x1013: Paused, | |
| 53 0x1014: Stopped, | |
| 54 } | |
| 55 | |
| 56 var device struct { | |
| 57 sync.Mutex | |
| 58 d *alc.Device | |
| 59 } | |
| 60 | |
| 61 type track struct { | |
| 62 format Format | |
| 63 rate int64 // sample rate | |
| 64 src io.ReadSeeker | |
| 65 } | |
| 66 | |
| 67 // Player is a basic audio player that plays PCM data. | |
| 68 // Operations on a nil *Player are no-op, a nil *Player can | |
| 69 // be used for testing purposes. | |
| 70 type Player struct { | |
| 71 t *track | |
| 72 source al.Source | |
| 73 | |
| 74 muPrep sync.Mutex // guards prep and bufs | |
| 75 prep bool | |
| 76 bufs []al.Buffer | |
| 77 size int64 // size of the audio source | |
| 78 } | |
| 79 | |
| 80 // NewPlayer returns a new Player. | |
| 81 // It initializes the underlying audio devices and the related resources. | |
| 82 func NewPlayer(src io.ReadSeeker, format Format, sampleRate int64) (*Player, err
or) { | |
| 83 device.Lock() | |
| 84 defer device.Unlock() | |
| 85 | |
| 86 if device.d == nil { | |
| 87 device.d = alc.Open("") | |
| 88 c := device.d.CreateContext(nil) | |
| 89 if !alc.MakeContextCurrent(c) { | |
| 90 return nil, fmt.Errorf("player: cannot initiate a new pl
ayer") | |
| 91 } | |
| 92 } | |
| 93 s := al.GenSources(1) | |
| 94 if code := al.Error(); code != 0 { | |
| 95 return nil, fmt.Errorf("player: cannot generate an audio source
[err=%x]", code) | |
| 96 } | |
| 97 bufs := al.GenBuffers(2) | |
| 98 if err := lastErr(); err != nil { | |
| 99 return nil, err | |
| 100 } | |
| 101 return &Player{ | |
| 102 t: &track{format: format, src: src, rate: sampleRate}, | |
| 103 source: s[0], | |
| 104 bufs: bufs, | |
| 105 }, nil | |
| 106 } | |
| 107 | |
| 108 func (p *Player) prepare(offset int64, force bool) error { | |
| 109 p.muPrep.Lock() | |
| 110 defer p.muPrep.Unlock() | |
| 111 if !force && p.prep { | |
| 112 return nil | |
| 113 } | |
| 114 if len(p.bufs) > 0 { | |
| 115 p.source.UnqueueBuffers(p.bufs) | |
| 116 al.DeleteBuffers(p.bufs) | |
| 117 } | |
| 118 if _, err := p.t.src.Seek(offset, 0); err != nil { | |
| 119 return err | |
| 120 } | |
| 121 p.bufs = []al.Buffer{} | |
| 122 // TODO(jbd): Limit the number of buffers in use, unqueue and reuse | |
| 123 // the existing buffers as buffers are processed. | |
| 124 buf := make([]byte, 128*1024) | |
| 125 size := offset | |
| 126 for { | |
| 127 n, err := p.t.src.Read(buf) | |
| 128 if n > 0 { | |
| 129 size += int64(n) | |
| 130 b := al.GenBuffers(1) | |
| 131 b[0].BufferData(uint32(formatToCode[p.t.format]), buf[:n
], int32(p.t.rate)) | |
| 132 p.bufs = append(p.bufs, b[0]) | |
| 133 } | |
| 134 if err == io.EOF { | |
| 135 break | |
| 136 } | |
| 137 if err != nil { | |
| 138 return err | |
| 139 } | |
| 140 } | |
| 141 p.size = size | |
| 142 if len(p.bufs) > 0 { | |
| 143 p.source.QueueBuffers(p.bufs) | |
| 144 } | |
| 145 p.prep = true | |
| 146 return nil | |
| 147 } | |
| 148 | |
| 149 // Play buffers the source audio to the audio device and starts | |
| 150 // to play the source. | |
| 151 // If the player paused or stopped, it reuses the previously buffered | |
| 152 // resources to keep playing from the time it has paused or stopped. | |
| 153 func (p *Player) Play() error { | |
| 154 if p == nil { | |
| 155 return nil | |
| 156 } | |
| 157 // Prepares if the track hasn't been buffered before. | |
| 158 if err := p.prepare(0, false); err != nil { | |
| 159 return err | |
| 160 } | |
| 161 al.PlaySources(p.source) | |
| 162 return lastErr() | |
| 163 } | |
| 164 | |
| 165 // Pause pauses the player. | |
| 166 func (p *Player) Pause() error { | |
| 167 if p == nil { | |
| 168 return nil | |
| 169 } | |
| 170 al.PauseSources(p.source) | |
| 171 return lastErr() | |
| 172 } | |
| 173 | |
| 174 // Stop stops the player. | |
| 175 func (p *Player) Stop() error { | |
| 176 if p == nil { | |
| 177 return nil | |
| 178 } | |
| 179 al.StopSources(p.source) | |
| 180 return lastErr() | |
| 181 } | |
| 182 | |
| 183 // Seek moves the play head to the given offset relative to the start of the sou
rce. | |
| 184 func (p *Player) Seek(offset time.Duration) error { | |
| 185 if p == nil { | |
| 186 return nil | |
| 187 } | |
| 188 if err := p.Stop(); err != nil { | |
| 189 return err | |
| 190 } | |
| 191 size := durToByteOffset(p.t, offset) | |
| 192 if err := p.prepare(size, true); err != nil { | |
| 193 return err | |
| 194 } | |
| 195 al.PlaySources(p.source) | |
| 196 return lastErr() | |
| 197 } | |
| 198 | |
| 199 // Current returns the current playback position of the audio that is being play
ed. | |
| 200 func (p *Player) Current() time.Duration { | |
| 201 if p == nil { | |
| 202 return time.Duration(0) | |
| 203 } | |
| 204 // TODO(jbd): Current never returns the Total when the playing is finish
ed. | |
| 205 // OpenAL may be returning the last buffer's start point as an OffsetByt
e. | |
| 206 return byteOffsetToDur(p.t, int64(p.source.OffsetByte())) | |
| 207 } | |
| 208 | |
| 209 // Total returns the total duration of the audio source. | |
| 210 func (p *Player) Total() time.Duration { | |
| 211 if p == nil { | |
| 212 return 0 | |
| 213 } | |
| 214 // Prepare is required to determine the length of the source. | |
| 215 // We need to read the entire source to calculate the length. | |
| 216 p.prepare(0, false) | |
| 217 return byteOffsetToDur(p.t, p.size) | |
| 218 } | |
| 219 | |
| 220 // Volume returns the current player volume. The range of the volume is [0, 1]. | |
| 221 func (p *Player) Volume() float64 { | |
| 222 if p == nil { | |
| 223 return 0 | |
| 224 } | |
| 225 return float64(p.source.Gain()) | |
| 226 } | |
| 227 | |
| 228 // SetVolume sets the volume of the player. The range of the volume is [0, 1]. | |
| 229 func (p *Player) SetVolume(vol float64) { | |
| 230 if p == nil { | |
| 231 return | |
| 232 } | |
| 233 p.source.SetGain(float32(vol)) | |
| 234 } | |
| 235 | |
| 236 // State returns the player's current state. | |
| 237 func (p *Player) State() State { | |
| 238 if p == nil { | |
| 239 return Unknown | |
| 240 } | |
| 241 return codeToState[p.source.State()] | |
| 242 } | |
| 243 | |
| 244 // Destroy frees the underlying resources used by the player. | |
| 245 // It should be called as soon as the player is not in-use anymore. | |
| 246 func (p *Player) Destroy() { | |
| 247 if p == nil { | |
| 248 return | |
| 249 } | |
| 250 if p.source != 0 { | |
| 251 al.DeleteSources(p.source) | |
| 252 } | |
| 253 p.muPrep.Lock() | |
| 254 if len(p.bufs) > 0 { | |
| 255 al.DeleteBuffers(p.bufs) | |
| 256 } | |
| 257 p.muPrep.Unlock() | |
| 258 } | |
| 259 | |
| 260 func byteOffsetToDur(t *track, offset int64) time.Duration { | |
| 261 size := float64(offset) | |
| 262 if t.format == Mono16 || t.format == Stereo16 { | |
| 263 size /= 2 | |
| 264 } | |
| 265 if t.format == Stereo8 || t.format == Stereo16 { | |
| 266 size /= 2 | |
| 267 } | |
| 268 size /= float64(t.rate) | |
| 269 // Casting size back to int64. Work in milliseconds, | |
| 270 // so that size doesn't get rounded excessively. | |
| 271 return time.Duration(size*1000) * time.Duration(time.Millisecond) | |
| 272 } | |
| 273 | |
| 274 func durToByteOffset(t *track, dur time.Duration) int64 { | |
| 275 size := int64(dur/time.Second) * t.rate | |
| 276 // Each sample is represented by 16-bits. Move twice further. | |
| 277 if t.format == Mono16 || t.format == Stereo16 { | |
| 278 size *= 2 | |
| 279 } | |
| 280 if t.format == Stereo8 || t.format == Stereo16 { | |
| 281 size *= 2 | |
| 282 } | |
| 283 return size | |
| 284 } | |
| 285 | |
| 286 // lastErr returns the last error or nil if the last operation | |
| 287 // has been succesful. | |
| 288 func lastErr() error { | |
| 289 if code := al.Error(); code != 0 { | |
| 290 return fmt.Errorf("audio: openal failed with %x", code) | |
| 291 } | |
| 292 return nil | |
| 293 } | |
| 294 | |
| 295 // TODO(jbd): Destroy context, close the device. | |
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Chromium Code Reviews
Issue 1275153002:
Remove third_party/golang.org/x/mobile as it is no longer used with Go 1.5. (Closed)
Base URL: https://github.com/domokit/mojo.git@master