1/* 2 * Copyright (C) 2008 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17package android.media; 18 19import android.annotation.IntDef; 20import android.annotation.NonNull; 21import android.os.Parcel; 22import android.os.Parcelable; 23 24import java.lang.annotation.Retention; 25import java.lang.annotation.RetentionPolicy; 26import java.util.Arrays; 27import java.util.Objects; 28 29/** 30 * The {@link AudioFormat} class is used to access a number of audio format and 31 * channel configuration constants. They are for instance used 32 * in {@link AudioTrack} and {@link AudioRecord}, as valid values in individual parameters of 33 * constructors like {@link AudioTrack#AudioTrack(int, int, int, int, int, int)}, where the fourth 34 * parameter is one of the <code>AudioFormat.ENCODING_*</code> constants. 35 * The <code>AudioFormat</code> constants are also used in {@link MediaFormat} to specify 36 * audio related values commonly used in media, such as for {@link MediaFormat#KEY_CHANNEL_MASK}. 37 * <p>The {@link AudioFormat.Builder} class can be used to create instances of 38 * the <code>AudioFormat</code> format class. 39 * Refer to 40 * {@link AudioFormat.Builder} for documentation on the mechanics of the configuration and building 41 * of such instances. Here we describe the main concepts that the <code>AudioFormat</code> class 42 * allow you to convey in each instance, they are: 43 * <ol> 44 * <li><a href="#sampleRate">sample rate</a> 45 * <li><a href="#encoding">encoding</a> 46 * <li><a href="#channelMask">channel masks</a> 47 * </ol> 48 * <p>Closely associated with the <code>AudioFormat</code> is the notion of an 49 * <a href="#audioFrame">audio frame</a>, which is used throughout the documentation 50 * to represent the minimum size complete unit of audio data. 51 * 52 * <h4 id="sampleRate">Sample rate</h4> 53 * <p>Expressed in Hz, the sample rate in an <code>AudioFormat</code> instance expresses the number 54 * of audio samples for each channel per second in the content you are playing or recording. It is 55 * not the sample rate 56 * at which content is rendered or produced. For instance a sound at a media sample rate of 8000Hz 57 * can be played on a device operating at a sample rate of 48000Hz; the sample rate conversion is 58 * automatically handled by the platform, it will not play at 6x speed. 59 * 60 * <p>As of API {@link android.os.Build.VERSION_CODES#M}, 61 * sample rates up to 192kHz are supported 62 * for <code>AudioRecord</code> and <code>AudioTrack</code>, with sample rate conversion 63 * performed as needed. 64 * To improve efficiency and avoid lossy conversions, it is recommended to match the sample rate 65 * for <code>AudioRecord</code> and <code>AudioTrack</code> to the endpoint device 66 * sample rate, and limit the sample rate to no more than 48kHz unless there are special 67 * device capabilities that warrant a higher rate. 68 * 69 * <h4 id="encoding">Encoding</h4> 70 * <p>Audio encoding is used to describe the bit representation of audio data, which can be 71 * either linear PCM or compressed audio, such as AC3 or DTS. 72 * <p>For linear PCM, the audio encoding describes the sample size, 8 bits, 16 bits, or 32 bits, 73 * and the sample representation, integer or float. 74 * <ul> 75 * <li> {@link #ENCODING_PCM_8BIT}: The audio sample is a 8 bit unsigned integer in the 76 * range [0, 255], with a 128 offset for zero. This is typically stored as a Java byte in a 77 * byte array or ByteBuffer. Since the Java byte is <em>signed</em>, 78 * be careful with math operations and conversions as the most significant bit is inverted. 79 * </li> 80 * <li> {@link #ENCODING_PCM_16BIT}: The audio sample is a 16 bit signed integer 81 * typically stored as a Java short in a short array, but when the short 82 * is stored in a ByteBuffer, it is native endian (as compared to the default Java big endian). 83 * The short has full range from [-32768, 32767], 84 * and is sometimes interpreted as fixed point Q.15 data. 85 * </li> 86 * <li> {@link #ENCODING_PCM_FLOAT}: Introduced in 87 * API {@link android.os.Build.VERSION_CODES#LOLLIPOP}, this encoding specifies that 88 * the audio sample is a 32 bit IEEE single precision float. The sample can be 89 * manipulated as a Java float in a float array, though within a ByteBuffer 90 * it is stored in native endian byte order. 91 * The nominal range of <code>ENCODING_PCM_FLOAT</code> audio data is [-1.0, 1.0]. 92 * It is implementation dependent whether the positive maximum of 1.0 is included 93 * in the interval. Values outside of the nominal range are clamped before 94 * sending to the endpoint device. Beware that 95 * the handling of NaN is undefined; subnormals may be treated as zero; and 96 * infinities are generally clamped just like other values for <code>AudioTrack</code> 97 * – try to avoid infinities because they can easily generate a NaN. 98 * <br> 99 * To achieve higher audio bit depth than a signed 16 bit integer short, 100 * it is recommended to use <code>ENCODING_PCM_FLOAT</code> for audio capture, processing, 101 * and playback. 102 * Floats are efficiently manipulated by modern CPUs, 103 * have greater precision than 24 bit signed integers, 104 * and have greater dynamic range than 32 bit signed integers. 105 * <code>AudioRecord</code> as of API {@link android.os.Build.VERSION_CODES#M} and 106 * <code>AudioTrack</code> as of API {@link android.os.Build.VERSION_CODES#LOLLIPOP} 107 * support <code>ENCODING_PCM_FLOAT</code>. 108 * </li> 109 * </ul> 110 * <p>For compressed audio, the encoding specifies the method of compression, 111 * for example {@link #ENCODING_AC3} and {@link #ENCODING_DTS}. The compressed 112 * audio data is typically stored as bytes in 113 * a byte array or ByteBuffer. When a compressed audio encoding is specified 114 * for an <code>AudioTrack</code>, it creates a direct (non-mixed) track 115 * for output to an endpoint (such as HDMI) capable of decoding the compressed audio. 116 * For (most) other endpoints, which are not capable of decoding such compressed audio, 117 * you will need to decode the data first, typically by creating a {@link MediaCodec}. 118 * Alternatively, one may use {@link MediaPlayer} for playback of compressed 119 * audio files or streams. 120 * <p>When compressed audio is sent out through a direct <code>AudioTrack</code>, 121 * it need not be written in exact multiples of the audio access unit; 122 * this differs from <code>MediaCodec</code> input buffers. 123 * 124 * <h4 id="channelMask">Channel mask</h4> 125 * <p>Channel masks are used in <code>AudioTrack</code> and <code>AudioRecord</code> to describe 126 * the samples and their arrangement in the audio frame. They are also used in the endpoint (e.g. 127 * a USB audio interface, a DAC connected to headphones) to specify allowable configurations of a 128 * particular device. 129 * <br>As of API {@link android.os.Build.VERSION_CODES#M}, there are two types of channel masks: 130 * channel position masks and channel index masks. 131 * 132 * <h5 id="channelPositionMask">Channel position masks</h5> 133 * Channel position masks are the original Android channel masks, and are used since API 134 * {@link android.os.Build.VERSION_CODES#BASE}. 135 * For input and output, they imply a positional nature - the location of a speaker or a microphone 136 * for recording or playback. 137 * <br>For a channel position mask, each allowed channel position corresponds to a bit in the 138 * channel mask. If that channel position is present in the audio frame, that bit is set, 139 * otherwise it is zero. The order of the bits (from lsb to msb) corresponds to the order of that 140 * position's sample in the audio frame. 141 * <br>The canonical channel position masks by channel count are as follows: 142 * <br><table> 143 * <tr><td>channel count</td><td>channel position mask</td></tr> 144 * <tr><td>1</td><td>{@link #CHANNEL_OUT_MONO}</td></tr> 145 * <tr><td>2</td><td>{@link #CHANNEL_OUT_STEREO}</td></tr> 146 * <tr><td>3</td><td>{@link #CHANNEL_OUT_STEREO} | {@link #CHANNEL_OUT_FRONT_CENTER}</td></tr> 147 * <tr><td>4</td><td>{@link #CHANNEL_OUT_QUAD}</td></tr> 148 * <tr><td>5</td><td>{@link #CHANNEL_OUT_QUAD} | {@link #CHANNEL_OUT_FRONT_CENTER}</td></tr> 149 * <tr><td>6</td><td>{@link #CHANNEL_OUT_5POINT1}</td></tr> 150 * <tr><td>7</td><td>{@link #CHANNEL_OUT_5POINT1} | {@link #CHANNEL_OUT_BACK_CENTER}</td></tr> 151 * <tr><td>8</td><td>{@link #CHANNEL_OUT_7POINT1_SURROUND}</td></tr> 152 * </table> 153 * <br>These masks are an ORed composite of individual channel masks. For example 154 * {@link #CHANNEL_OUT_STEREO} is composed of {@link #CHANNEL_OUT_FRONT_LEFT} and 155 * {@link #CHANNEL_OUT_FRONT_RIGHT}. 156 * 157 * <h5 id="channelIndexMask">Channel index masks</h5> 158 * Channel index masks are introduced in API {@link android.os.Build.VERSION_CODES#M}. They allow 159 * the selection of a particular channel from the source or sink endpoint by number, i.e. the first 160 * channel, the second channel, and so forth. This avoids problems with artificially assigning 161 * positions to channels of an endpoint, or figuring what the i<sup>th</sup> position bit is within 162 * an endpoint's channel position mask etc. 163 * <br>Here's an example where channel index masks address this confusion: dealing with a 4 channel 164 * USB device. Using a position mask, and based on the channel count, this would be a 165 * {@link #CHANNEL_OUT_QUAD} device, but really one is only interested in channel 0 166 * through channel 3. The USB device would then have the following individual bit channel masks: 167 * {@link #CHANNEL_OUT_FRONT_LEFT}, 168 * {@link #CHANNEL_OUT_FRONT_RIGHT}, {@link #CHANNEL_OUT_BACK_LEFT} 169 * and {@link #CHANNEL_OUT_BACK_RIGHT}. But which is channel 0 and which is 170 * channel 3? 171 * <br>For a channel index mask, each channel number is represented as a bit in the mask, from the 172 * lsb (channel 0) upwards to the msb, numerically this bit value is 173 * <code>1 << channelNumber</code>. 174 * A set bit indicates that channel is present in the audio frame, otherwise it is cleared. 175 * The order of the bits also correspond to that channel number's sample order in the audio frame. 176 * <br>For the previous 4 channel USB device example, the device would have a channel index mask 177 * <code>0xF</code>. Suppose we wanted to select only the first and the third channels; this would 178 * correspond to a channel index mask <code>0x5</code> (the first and third bits set). If an 179 * <code>AudioTrack</code> uses this channel index mask, the audio frame would consist of two 180 * samples, the first sample of each frame routed to channel 0, and the second sample of each frame 181 * routed to channel 2. 182 * The canonical channel index masks by channel count are given by the formula 183 * <code>(1 << channelCount) - 1</code>. 184 * 185 * <h5>Use cases</h5> 186 * <ul> 187 * <li><i>Channel position mask for an endpoint:</i> <code>CHANNEL_OUT_FRONT_LEFT</code>, 188 * <code>CHANNEL_OUT_FRONT_CENTER</code>, etc. for HDMI home theater purposes. 189 * <li><i>Channel position mask for an audio stream:</i> Creating an <code>AudioTrack</code> 190 * to output movie content, where 5.1 multichannel output is to be written. 191 * <li><i>Channel index mask for an endpoint:</i> USB devices for which input and output do not 192 * correspond to left or right speaker or microphone. 193 * <li><i>Channel index mask for an audio stream:</i> An <code>AudioRecord</code> may only want the 194 * third and fourth audio channels of the endpoint (i.e. the second channel pair), and not care the 195 * about position it corresponds to, in which case the channel index mask is <code>0xC</code>. 196 * Multichannel <code>AudioRecord</code> sessions should use channel index masks. 197 * </ul> 198 * <h4 id="audioFrame">Audio Frame</h4> 199 * <p>For linear PCM, an audio frame consists of a set of samples captured at the same time, 200 * whose count and 201 * channel association are given by the <a href="#channelMask">channel mask</a>, 202 * and whose sample contents are specified by the <a href="#encoding">encoding</a>. 203 * For example, a stereo 16 bit PCM frame consists of 204 * two 16 bit linear PCM samples, with a frame size of 4 bytes. 205 * For compressed audio, an audio frame may alternately 206 * refer to an access unit of compressed data bytes that is logically grouped together for 207 * decoding and bitstream access (e.g. {@link MediaCodec}), 208 * or a single byte of compressed data (e.g. {@link AudioTrack#getBufferSizeInFrames() 209 * AudioTrack.getBufferSizeInFrames()}), 210 * or the linear PCM frame result from decoding the compressed data 211 * (e.g.{@link AudioTrack#getPlaybackHeadPosition() 212 * AudioTrack.getPlaybackHeadPosition()}), 213 * depending on the context where audio frame is used. 214 */ 215public final class AudioFormat implements Parcelable { 216 217 //--------------------------------------------------------- 218 // Constants 219 //-------------------- 220 /** Invalid audio data format */ 221 public static final int ENCODING_INVALID = 0; 222 /** Default audio data format */ 223 public static final int ENCODING_DEFAULT = 1; 224 225 // These values must be kept in sync with core/jni/android_media_AudioFormat.h 226 // Also sync av/services/audiopolicy/managerdefault/ConfigParsingUtils.h 227 /** Audio data format: PCM 16 bit per sample. Guaranteed to be supported by devices. */ 228 public static final int ENCODING_PCM_16BIT = 2; 229 /** Audio data format: PCM 8 bit per sample. Not guaranteed to be supported by devices. */ 230 public static final int ENCODING_PCM_8BIT = 3; 231 /** Audio data format: single-precision floating-point per sample */ 232 public static final int ENCODING_PCM_FLOAT = 4; 233 /** Audio data format: AC-3 compressed */ 234 public static final int ENCODING_AC3 = 5; 235 /** Audio data format: E-AC-3 compressed */ 236 public static final int ENCODING_E_AC3 = 6; 237 /** Audio data format: DTS compressed */ 238 public static final int ENCODING_DTS = 7; 239 /** Audio data format: DTS HD compressed */ 240 public static final int ENCODING_DTS_HD = 8; 241 /** Audio data format: MP3 compressed 242 * @hide 243 * */ 244 public static final int ENCODING_MP3 = 9; 245 /** Audio data format: AAC LC compressed 246 * @hide 247 * */ 248 public static final int ENCODING_AAC_LC = 10; 249 /** Audio data format: AAC HE V1 compressed 250 * @hide 251 * */ 252 public static final int ENCODING_AAC_HE_V1 = 11; 253 /** Audio data format: AAC HE V2 compressed 254 * @hide 255 * */ 256 public static final int ENCODING_AAC_HE_V2 = 12; 257 /** Audio data format: compressed audio wrapped in PCM for HDMI 258 * or S/PDIF passthrough. 259 * IEC61937 uses a stereo stream of 16-bit samples as the wrapper. 260 * So the channel mask for the track must be {@link #CHANNEL_OUT_STEREO}. 261 * Data should be written to the stream in a short[] array. 262 * If the data is written in a byte[] array then there may be endian problems 263 * on some platforms when converting to short internally. 264 */ 265 public static final int ENCODING_IEC61937 = 13; 266 267 /** Invalid audio channel configuration */ 268 /** @deprecated Use {@link #CHANNEL_INVALID} instead. */ 269 @Deprecated public static final int CHANNEL_CONFIGURATION_INVALID = 0; 270 /** Default audio channel configuration */ 271 /** @deprecated Use {@link #CHANNEL_OUT_DEFAULT} or {@link #CHANNEL_IN_DEFAULT} instead. */ 272 @Deprecated public static final int CHANNEL_CONFIGURATION_DEFAULT = 1; 273 /** Mono audio configuration */ 274 /** @deprecated Use {@link #CHANNEL_OUT_MONO} or {@link #CHANNEL_IN_MONO} instead. */ 275 @Deprecated public static final int CHANNEL_CONFIGURATION_MONO = 2; 276 /** Stereo (2 channel) audio configuration */ 277 /** @deprecated Use {@link #CHANNEL_OUT_STEREO} or {@link #CHANNEL_IN_STEREO} instead. */ 278 @Deprecated public static final int CHANNEL_CONFIGURATION_STEREO = 3; 279 280 /** Invalid audio channel mask */ 281 public static final int CHANNEL_INVALID = 0; 282 /** Default audio channel mask */ 283 public static final int CHANNEL_OUT_DEFAULT = 1; 284 285 // Output channel mask definitions below are translated to the native values defined in 286 // in /system/media/audio/include/system/audio.h in the JNI code of AudioTrack 287 public static final int CHANNEL_OUT_FRONT_LEFT = 0x4; 288 public static final int CHANNEL_OUT_FRONT_RIGHT = 0x8; 289 public static final int CHANNEL_OUT_FRONT_CENTER = 0x10; 290 public static final int CHANNEL_OUT_LOW_FREQUENCY = 0x20; 291 public static final int CHANNEL_OUT_BACK_LEFT = 0x40; 292 public static final int CHANNEL_OUT_BACK_RIGHT = 0x80; 293 public static final int CHANNEL_OUT_FRONT_LEFT_OF_CENTER = 0x100; 294 public static final int CHANNEL_OUT_FRONT_RIGHT_OF_CENTER = 0x200; 295 public static final int CHANNEL_OUT_BACK_CENTER = 0x400; 296 public static final int CHANNEL_OUT_SIDE_LEFT = 0x800; 297 public static final int CHANNEL_OUT_SIDE_RIGHT = 0x1000; 298 /** @hide */ 299 public static final int CHANNEL_OUT_TOP_CENTER = 0x2000; 300 /** @hide */ 301 public static final int CHANNEL_OUT_TOP_FRONT_LEFT = 0x4000; 302 /** @hide */ 303 public static final int CHANNEL_OUT_TOP_FRONT_CENTER = 0x8000; 304 /** @hide */ 305 public static final int CHANNEL_OUT_TOP_FRONT_RIGHT = 0x10000; 306 /** @hide */ 307 public static final int CHANNEL_OUT_TOP_BACK_LEFT = 0x20000; 308 /** @hide */ 309 public static final int CHANNEL_OUT_TOP_BACK_CENTER = 0x40000; 310 /** @hide */ 311 public static final int CHANNEL_OUT_TOP_BACK_RIGHT = 0x80000; 312 313 public static final int CHANNEL_OUT_MONO = CHANNEL_OUT_FRONT_LEFT; 314 public static final int CHANNEL_OUT_STEREO = (CHANNEL_OUT_FRONT_LEFT | CHANNEL_OUT_FRONT_RIGHT); 315 // aka QUAD_BACK 316 public static final int CHANNEL_OUT_QUAD = (CHANNEL_OUT_FRONT_LEFT | CHANNEL_OUT_FRONT_RIGHT | 317 CHANNEL_OUT_BACK_LEFT | CHANNEL_OUT_BACK_RIGHT); 318 /** @hide */ 319 public static final int CHANNEL_OUT_QUAD_SIDE = (CHANNEL_OUT_FRONT_LEFT | CHANNEL_OUT_FRONT_RIGHT | 320 CHANNEL_OUT_SIDE_LEFT | CHANNEL_OUT_SIDE_RIGHT); 321 public static final int CHANNEL_OUT_SURROUND = (CHANNEL_OUT_FRONT_LEFT | CHANNEL_OUT_FRONT_RIGHT | 322 CHANNEL_OUT_FRONT_CENTER | CHANNEL_OUT_BACK_CENTER); 323 // aka 5POINT1_BACK 324 public static final int CHANNEL_OUT_5POINT1 = (CHANNEL_OUT_FRONT_LEFT | CHANNEL_OUT_FRONT_RIGHT | 325 CHANNEL_OUT_FRONT_CENTER | CHANNEL_OUT_LOW_FREQUENCY | CHANNEL_OUT_BACK_LEFT | CHANNEL_OUT_BACK_RIGHT); 326 /** @hide */ 327 public static final int CHANNEL_OUT_5POINT1_SIDE = (CHANNEL_OUT_FRONT_LEFT | CHANNEL_OUT_FRONT_RIGHT | 328 CHANNEL_OUT_FRONT_CENTER | CHANNEL_OUT_LOW_FREQUENCY | 329 CHANNEL_OUT_SIDE_LEFT | CHANNEL_OUT_SIDE_RIGHT); 330 // different from AUDIO_CHANNEL_OUT_7POINT1 used internally, and not accepted by AudioRecord. 331 /** @deprecated Not the typical 7.1 surround configuration. Use {@link #CHANNEL_OUT_7POINT1_SURROUND} instead. */ 332 @Deprecated public static final int CHANNEL_OUT_7POINT1 = (CHANNEL_OUT_FRONT_LEFT | CHANNEL_OUT_FRONT_RIGHT | 333 CHANNEL_OUT_FRONT_CENTER | CHANNEL_OUT_LOW_FREQUENCY | CHANNEL_OUT_BACK_LEFT | CHANNEL_OUT_BACK_RIGHT | 334 CHANNEL_OUT_FRONT_LEFT_OF_CENTER | CHANNEL_OUT_FRONT_RIGHT_OF_CENTER); 335 // matches AUDIO_CHANNEL_OUT_7POINT1 336 public static final int CHANNEL_OUT_7POINT1_SURROUND = ( 337 CHANNEL_OUT_FRONT_LEFT | CHANNEL_OUT_FRONT_CENTER | CHANNEL_OUT_FRONT_RIGHT | 338 CHANNEL_OUT_SIDE_LEFT | CHANNEL_OUT_SIDE_RIGHT | 339 CHANNEL_OUT_BACK_LEFT | CHANNEL_OUT_BACK_RIGHT | 340 CHANNEL_OUT_LOW_FREQUENCY); 341 // CHANNEL_OUT_ALL is not yet defined; if added then it should match AUDIO_CHANNEL_OUT_ALL 342 343 /** Minimum value for sample rate, 344 * assuming AudioTrack and AudioRecord share the same limitations. 345 * @hide 346 */ 347 // never unhide 348 public static final int SAMPLE_RATE_HZ_MIN = 4000; 349 /** Maximum value for sample rate, 350 * assuming AudioTrack and AudioRecord share the same limitations. 351 * @hide 352 */ 353 // never unhide 354 public static final int SAMPLE_RATE_HZ_MAX = 192000; 355 /** Sample rate will be a route-dependent value. 356 * For AudioTrack, it is usually the sink sample rate, 357 * and for AudioRecord it is usually the source sample rate. 358 */ 359 public static final int SAMPLE_RATE_UNSPECIFIED = 0; 360 361 /** 362 * @hide 363 * Return the input channel mask corresponding to an output channel mask. 364 * This can be used for submix rerouting for the mask of the recorder to map to that of the mix. 365 * @param outMask a combination of the CHANNEL_OUT_* definitions, but not CHANNEL_OUT_DEFAULT 366 * @return a combination of CHANNEL_IN_* definitions matching an output channel mask 367 * @throws IllegalArgumentException 368 */ 369 public static int inChannelMaskFromOutChannelMask(int outMask) throws IllegalArgumentException { 370 if (outMask == CHANNEL_OUT_DEFAULT) { 371 throw new IllegalArgumentException( 372 "Illegal CHANNEL_OUT_DEFAULT channel mask for input."); 373 } 374 switch (channelCountFromOutChannelMask(outMask)) { 375 case 1: 376 return CHANNEL_IN_MONO; 377 case 2: 378 return CHANNEL_IN_STEREO; 379 default: 380 throw new IllegalArgumentException("Unsupported channel configuration for input."); 381 } 382 } 383 384 /** 385 * @hide 386 * Return the number of channels from an input channel mask 387 * @param mask a combination of the CHANNEL_IN_* definitions, even CHANNEL_IN_DEFAULT 388 * @return number of channels for the mask 389 */ 390 public static int channelCountFromInChannelMask(int mask) { 391 return Integer.bitCount(mask); 392 } 393 /** 394 * @hide 395 * Return the number of channels from an output channel mask 396 * @param mask a combination of the CHANNEL_OUT_* definitions, but not CHANNEL_OUT_DEFAULT 397 * @return number of channels for the mask 398 */ 399 public static int channelCountFromOutChannelMask(int mask) { 400 return Integer.bitCount(mask); 401 } 402 /** 403 * @hide 404 * Return a channel mask ready to be used by native code 405 * @param mask a combination of the CHANNEL_OUT_* definitions, but not CHANNEL_OUT_DEFAULT 406 * @return a native channel mask 407 */ 408 public static int convertChannelOutMaskToNativeMask(int javaMask) { 409 return (javaMask >> 2); 410 } 411 412 /** 413 * @hide 414 * Return a java output channel mask 415 * @param mask a native channel mask 416 * @return a combination of the CHANNEL_OUT_* definitions 417 */ 418 public static int convertNativeChannelMaskToOutMask(int nativeMask) { 419 return (nativeMask << 2); 420 } 421 422 public static final int CHANNEL_IN_DEFAULT = 1; 423 // These directly match native 424 public static final int CHANNEL_IN_LEFT = 0x4; 425 public static final int CHANNEL_IN_RIGHT = 0x8; 426 public static final int CHANNEL_IN_FRONT = 0x10; 427 public static final int CHANNEL_IN_BACK = 0x20; 428 public static final int CHANNEL_IN_LEFT_PROCESSED = 0x40; 429 public static final int CHANNEL_IN_RIGHT_PROCESSED = 0x80; 430 public static final int CHANNEL_IN_FRONT_PROCESSED = 0x100; 431 public static final int CHANNEL_IN_BACK_PROCESSED = 0x200; 432 public static final int CHANNEL_IN_PRESSURE = 0x400; 433 public static final int CHANNEL_IN_X_AXIS = 0x800; 434 public static final int CHANNEL_IN_Y_AXIS = 0x1000; 435 public static final int CHANNEL_IN_Z_AXIS = 0x2000; 436 public static final int CHANNEL_IN_VOICE_UPLINK = 0x4000; 437 public static final int CHANNEL_IN_VOICE_DNLINK = 0x8000; 438 public static final int CHANNEL_IN_MONO = CHANNEL_IN_FRONT; 439 public static final int CHANNEL_IN_STEREO = (CHANNEL_IN_LEFT | CHANNEL_IN_RIGHT); 440 /** @hide */ 441 public static final int CHANNEL_IN_FRONT_BACK = CHANNEL_IN_FRONT | CHANNEL_IN_BACK; 442 // CHANNEL_IN_ALL is not yet defined; if added then it should match AUDIO_CHANNEL_IN_ALL 443 444 /** @hide */ 445 public static int getBytesPerSample(int audioFormat) 446 { 447 switch (audioFormat) { 448 case ENCODING_PCM_8BIT: 449 return 1; 450 case ENCODING_PCM_16BIT: 451 case ENCODING_IEC61937: 452 case ENCODING_DEFAULT: 453 return 2; 454 case ENCODING_PCM_FLOAT: 455 return 4; 456 case ENCODING_INVALID: 457 default: 458 throw new IllegalArgumentException("Bad audio format " + audioFormat); 459 } 460 } 461 462 /** @hide */ 463 public static boolean isValidEncoding(int audioFormat) 464 { 465 switch (audioFormat) { 466 case ENCODING_PCM_8BIT: 467 case ENCODING_PCM_16BIT: 468 case ENCODING_PCM_FLOAT: 469 case ENCODING_AC3: 470 case ENCODING_E_AC3: 471 case ENCODING_DTS: 472 case ENCODING_DTS_HD: 473 case ENCODING_MP3: 474 case ENCODING_AAC_LC: 475 case ENCODING_AAC_HE_V1: 476 case ENCODING_AAC_HE_V2: 477 case ENCODING_IEC61937: 478 return true; 479 default: 480 return false; 481 } 482 } 483 484 /** @hide */ 485 public static boolean isPublicEncoding(int audioFormat) 486 { 487 switch (audioFormat) { 488 case ENCODING_PCM_8BIT: 489 case ENCODING_PCM_16BIT: 490 case ENCODING_PCM_FLOAT: 491 case ENCODING_AC3: 492 case ENCODING_E_AC3: 493 case ENCODING_DTS: 494 case ENCODING_DTS_HD: 495 case ENCODING_IEC61937: 496 return true; 497 default: 498 return false; 499 } 500 } 501 502 /** @hide */ 503 public static boolean isEncodingLinearPcm(int audioFormat) 504 { 505 switch (audioFormat) { 506 case ENCODING_PCM_8BIT: 507 case ENCODING_PCM_16BIT: 508 case ENCODING_PCM_FLOAT: 509 case ENCODING_DEFAULT: 510 return true; 511 case ENCODING_AC3: 512 case ENCODING_E_AC3: 513 case ENCODING_DTS: 514 case ENCODING_DTS_HD: 515 case ENCODING_MP3: 516 case ENCODING_AAC_LC: 517 case ENCODING_AAC_HE_V1: 518 case ENCODING_AAC_HE_V2: 519 case ENCODING_IEC61937: // wrapped in PCM but compressed 520 return false; 521 case ENCODING_INVALID: 522 default: 523 throw new IllegalArgumentException("Bad audio format " + audioFormat); 524 } 525 } 526 527 /** @hide */ 528 public static boolean isEncodingLinearFrames(int audioFormat) 529 { 530 switch (audioFormat) { 531 case ENCODING_PCM_8BIT: 532 case ENCODING_PCM_16BIT: 533 case ENCODING_PCM_FLOAT: 534 case ENCODING_IEC61937: // same size as stereo PCM 535 case ENCODING_DEFAULT: 536 return true; 537 case ENCODING_AC3: 538 case ENCODING_E_AC3: 539 case ENCODING_DTS: 540 case ENCODING_DTS_HD: 541 case ENCODING_MP3: 542 case ENCODING_AAC_LC: 543 case ENCODING_AAC_HE_V1: 544 case ENCODING_AAC_HE_V2: 545 return false; 546 case ENCODING_INVALID: 547 default: 548 throw new IllegalArgumentException("Bad audio format " + audioFormat); 549 } 550 } 551 /** 552 * Returns an array of public encoding values extracted from an array of 553 * encoding values. 554 * @hide 555 */ 556 public static int[] filterPublicFormats(int[] formats) { 557 if (formats == null) { 558 return null; 559 } 560 int[] myCopy = Arrays.copyOf(formats, formats.length); 561 int size = 0; 562 for (int i = 0; i < myCopy.length; i++) { 563 if (isPublicEncoding(myCopy[i])) { 564 if (size != i) { 565 myCopy[size] = myCopy[i]; 566 } 567 size++; 568 } 569 } 570 return Arrays.copyOf(myCopy, size); 571 } 572 573 /** @removed */ 574 public AudioFormat() 575 { 576 throw new UnsupportedOperationException("There is no valid usage of this constructor"); 577 } 578 579 /** 580 * Private constructor with an ignored argument to differentiate from the removed default ctor 581 * @param ignoredArgument 582 */ 583 private AudioFormat(int ignoredArgument) { 584 } 585 586 /** 587 * Constructor used by the JNI. Parameters are not checked for validity. 588 */ 589 // Update sound trigger JNI in core/jni/android_hardware_SoundTrigger.cpp when modifying this 590 // constructor 591 private AudioFormat(int encoding, int sampleRate, int channelMask, int channelIndexMask) { 592 mEncoding = encoding; 593 mSampleRate = sampleRate; 594 mChannelMask = channelMask; 595 mChannelIndexMask = channelIndexMask; 596 mPropertySetMask = AUDIO_FORMAT_HAS_PROPERTY_ENCODING | 597 AUDIO_FORMAT_HAS_PROPERTY_SAMPLE_RATE | 598 AUDIO_FORMAT_HAS_PROPERTY_CHANNEL_MASK | 599 AUDIO_FORMAT_HAS_PROPERTY_CHANNEL_INDEX_MASK; 600 } 601 602 /** @hide */ 603 public final static int AUDIO_FORMAT_HAS_PROPERTY_NONE = 0x0; 604 /** @hide */ 605 public final static int AUDIO_FORMAT_HAS_PROPERTY_ENCODING = 0x1 << 0; 606 /** @hide */ 607 public final static int AUDIO_FORMAT_HAS_PROPERTY_SAMPLE_RATE = 0x1 << 1; 608 /** @hide */ 609 public final static int AUDIO_FORMAT_HAS_PROPERTY_CHANNEL_MASK = 0x1 << 2; 610 /** @hide */ 611 public final static int AUDIO_FORMAT_HAS_PROPERTY_CHANNEL_INDEX_MASK = 0x1 << 3; 612 613 private int mEncoding; 614 private int mSampleRate; 615 private int mChannelMask; 616 private int mChannelIndexMask; 617 private int mPropertySetMask; 618 619 /** 620 * Return the encoding. 621 * See the section on <a href="#encoding">encodings</a> for more information about the different 622 * types of supported audio encoding. 623 * @return one of the values that can be set in {@link Builder#setEncoding(int)} or 624 * {@link AudioFormat#ENCODING_INVALID} if not set. 625 */ 626 public int getEncoding() { 627 if ((mPropertySetMask & AUDIO_FORMAT_HAS_PROPERTY_ENCODING) == 0) { 628 return ENCODING_INVALID; 629 } 630 return mEncoding; 631 } 632 633 /** 634 * Return the sample rate. 635 * @return one of the values that can be set in {@link Builder#setSampleRate(int)} or 636 * {@link #SAMPLE_RATE_UNSPECIFIED} if not set. 637 */ 638 public int getSampleRate() { 639 return mSampleRate; 640 } 641 642 /** 643 * Return the channel mask. 644 * See the section on <a href="#channelMask">channel masks</a> for more information about 645 * the difference between index-based masks(as returned by {@link #getChannelIndexMask()}) and 646 * the position-based mask returned by this function. 647 * @return one of the values that can be set in {@link Builder#setChannelMask(int)} or 648 * {@link AudioFormat#CHANNEL_INVALID} if not set. 649 */ 650 public int getChannelMask() { 651 if ((mPropertySetMask & AUDIO_FORMAT_HAS_PROPERTY_CHANNEL_MASK) == 0) { 652 return CHANNEL_INVALID; 653 } 654 return mChannelMask; 655 } 656 657 /** 658 * Return the channel index mask. 659 * See the section on <a href="#channelMask">channel masks</a> for more information about 660 * the difference between index-based masks, and position-based masks (as returned 661 * by {@link #getChannelMask()}). 662 * @return one of the values that can be set in {@link Builder#setChannelIndexMask(int)} or 663 * {@link AudioFormat#CHANNEL_INVALID} if not set or an invalid mask was used. 664 */ 665 public int getChannelIndexMask() { 666 if ((mPropertySetMask & AUDIO_FORMAT_HAS_PROPERTY_CHANNEL_INDEX_MASK) == 0) { 667 return CHANNEL_INVALID; 668 } 669 return mChannelIndexMask; 670 } 671 672 /** 673 * Return the channel count. 674 * @return the channel count derived from the channel position mask or the channel index mask. 675 * Zero is returned if both the channel position mask and the channel index mask are not set. 676 */ 677 public int getChannelCount() { 678 final int channelIndexCount = Integer.bitCount(getChannelIndexMask()); 679 int channelCount = channelCountFromOutChannelMask(getChannelMask()); 680 if (channelCount == 0) { 681 channelCount = channelIndexCount; 682 } else if (channelCount != channelIndexCount && channelIndexCount != 0) { 683 channelCount = 0; // position and index channel count mismatch 684 } 685 return channelCount; 686 } 687 688 /** @hide */ 689 public int getPropertySetMask() { 690 return mPropertySetMask; 691 } 692 693 /** 694 * Builder class for {@link AudioFormat} objects. 695 * Use this class to configure and create an AudioFormat instance. By setting format 696 * characteristics such as audio encoding, channel mask or sample rate, you indicate which 697 * of those are to vary from the default behavior on this device wherever this audio format 698 * is used. See {@link AudioFormat} for a complete description of the different parameters that 699 * can be used to configure an <code>AudioFormat</code> instance. 700 * <p>{@link AudioFormat} is for instance used in 701 * {@link AudioTrack#AudioTrack(AudioAttributes, AudioFormat, int, int, int)}. In this 702 * constructor, every format characteristic set on the <code>Builder</code> (e.g. with 703 * {@link #setSampleRate(int)}) will alter the default values used by an 704 * <code>AudioTrack</code>. In this case for audio playback with <code>AudioTrack</code>, the 705 * sample rate set in the <code>Builder</code> would override the platform output sample rate 706 * which would otherwise be selected by default. 707 */ 708 public static class Builder { 709 private int mEncoding = ENCODING_INVALID; 710 private int mSampleRate = SAMPLE_RATE_UNSPECIFIED; 711 private int mChannelMask = CHANNEL_INVALID; 712 private int mChannelIndexMask = 0; 713 private int mPropertySetMask = AUDIO_FORMAT_HAS_PROPERTY_NONE; 714 715 /** 716 * Constructs a new Builder with none of the format characteristics set. 717 */ 718 public Builder() { 719 } 720 721 /** 722 * Constructs a new Builder from a given {@link AudioFormat}. 723 * @param af the {@link AudioFormat} object whose data will be reused in the new Builder. 724 */ 725 public Builder(AudioFormat af) { 726 mEncoding = af.mEncoding; 727 mSampleRate = af.mSampleRate; 728 mChannelMask = af.mChannelMask; 729 mChannelIndexMask = af.mChannelIndexMask; 730 mPropertySetMask = af.mPropertySetMask; 731 } 732 733 /** 734 * Combines all of the format characteristics that have been set and return a new 735 * {@link AudioFormat} object. 736 * @return a new {@link AudioFormat} object 737 */ 738 public AudioFormat build() { 739 AudioFormat af = new AudioFormat(1980/*ignored*/); 740 af.mEncoding = mEncoding; 741 // not calling setSampleRate is equivalent to calling 742 // setSampleRate(SAMPLE_RATE_UNSPECIFIED) 743 af.mSampleRate = mSampleRate; 744 af.mChannelMask = mChannelMask; 745 af.mChannelIndexMask = mChannelIndexMask; 746 af.mPropertySetMask = mPropertySetMask; 747 return af; 748 } 749 750 /** 751 * Sets the data encoding format. 752 * @param encoding one of {@link AudioFormat#ENCODING_DEFAULT}, 753 * {@link AudioFormat#ENCODING_PCM_8BIT}, 754 * {@link AudioFormat#ENCODING_PCM_16BIT}, 755 * {@link AudioFormat#ENCODING_PCM_FLOAT}, 756 * {@link AudioFormat#ENCODING_AC3}, 757 * {@link AudioFormat#ENCODING_E_AC3}. 758 * {@link AudioFormat#ENCODING_DTS}, 759 * {@link AudioFormat#ENCODING_DTS_HD}. 760 * @return the same Builder instance. 761 * @throws java.lang.IllegalArgumentException 762 */ 763 public Builder setEncoding(@Encoding int encoding) throws IllegalArgumentException { 764 switch (encoding) { 765 case ENCODING_DEFAULT: 766 mEncoding = ENCODING_PCM_16BIT; 767 break; 768 case ENCODING_PCM_8BIT: 769 case ENCODING_PCM_16BIT: 770 case ENCODING_PCM_FLOAT: 771 case ENCODING_AC3: 772 case ENCODING_E_AC3: 773 case ENCODING_DTS: 774 case ENCODING_DTS_HD: 775 case ENCODING_IEC61937: 776 mEncoding = encoding; 777 break; 778 case ENCODING_INVALID: 779 default: 780 throw new IllegalArgumentException("Invalid encoding " + encoding); 781 } 782 mPropertySetMask |= AUDIO_FORMAT_HAS_PROPERTY_ENCODING; 783 return this; 784 } 785 786 /** 787 * Sets the channel position mask. 788 * The channel position mask specifies the association between audio samples in a frame 789 * with named endpoint channels. The samples in the frame correspond to the 790 * named set bits in the channel position mask, in ascending bit order. 791 * See {@link #setChannelIndexMask(int)} to specify channels 792 * based on endpoint numbered channels. This <a href="#channelPositionMask>description of 793 * channel position masks</a> covers the concept in more details. 794 * @param channelMask describes the configuration of the audio channels. 795 * <p> For output, the channelMask can be an OR-ed combination of 796 * channel position masks, e.g. 797 * {@link AudioFormat#CHANNEL_OUT_FRONT_LEFT}, 798 * {@link AudioFormat#CHANNEL_OUT_FRONT_RIGHT}, 799 * {@link AudioFormat#CHANNEL_OUT_FRONT_CENTER}, 800 * {@link AudioFormat#CHANNEL_OUT_LOW_FREQUENCY} 801 * {@link AudioFormat#CHANNEL_OUT_BACK_LEFT}, 802 * {@link AudioFormat#CHANNEL_OUT_BACK_RIGHT}, 803 * {@link AudioFormat#CHANNEL_OUT_BACK_CENTER}, 804 * {@link AudioFormat#CHANNEL_OUT_SIDE_LEFT}, 805 * {@link AudioFormat#CHANNEL_OUT_SIDE_RIGHT}. 806 * <p> For a valid {@link AudioTrack} channel position mask, 807 * the following conditions apply: 808 * <br> (1) at most eight channel positions may be used; 809 * <br> (2) right/left pairs should be matched. 810 * <p> For input or {@link AudioRecord}, the mask should be 811 * {@link AudioFormat#CHANNEL_IN_MONO} or 812 * {@link AudioFormat#CHANNEL_IN_STEREO}. {@link AudioFormat#CHANNEL_IN_MONO} is 813 * guaranteed to work on all devices. 814 * @return the same <code>Builder</code> instance. 815 * @throws IllegalArgumentException if the channel mask is invalid or 816 * if both channel index mask and channel position mask 817 * are specified but do not have the same channel count. 818 */ 819 public @NonNull Builder setChannelMask(int channelMask) { 820 if (channelMask == CHANNEL_INVALID) { 821 throw new IllegalArgumentException("Invalid zero channel mask"); 822 } else if (/* channelMask != 0 && */ mChannelIndexMask != 0 && 823 Integer.bitCount(channelMask) != Integer.bitCount(mChannelIndexMask)) { 824 throw new IllegalArgumentException("Mismatched channel count for mask " + 825 Integer.toHexString(channelMask).toUpperCase()); 826 } 827 mChannelMask = channelMask; 828 mPropertySetMask |= AUDIO_FORMAT_HAS_PROPERTY_CHANNEL_MASK; 829 return this; 830 } 831 832 /** 833 * Sets the channel index mask. 834 * A channel index mask specifies the association of audio samples in the frame 835 * with numbered endpoint channels. The i-th bit in the channel index 836 * mask corresponds to the i-th endpoint channel. 837 * For example, an endpoint with four channels is represented 838 * as index mask bits 0 through 3. This <a href="#channelIndexMask>description of channel 839 * index masks</a> covers the concept in more details. 840 * See {@link #setChannelMask(int)} for a positional mask interpretation. 841 * <p> Both {@link AudioTrack} and {@link AudioRecord} support 842 * a channel index mask. 843 * If a channel index mask is specified it is used, 844 * otherwise the channel position mask specified 845 * by <code>setChannelMask</code> is used. 846 * For <code>AudioTrack</code> and <code>AudioRecord</code>, 847 * a channel position mask is not required if a channel index mask is specified. 848 * 849 * @param channelIndexMask describes the configuration of the audio channels. 850 * <p> For output, the <code>channelIndexMask</code> is an OR-ed combination of 851 * bits representing the mapping of <code>AudioTrack</code> write samples 852 * to output sink channels. 853 * For example, a mask of <code>0xa</code>, or binary <code>1010</code>, 854 * means the <code>AudioTrack</code> write frame consists of two samples, 855 * which are routed to the second and the fourth channels of the output sink. 856 * Unmatched output sink channels are zero filled and unmatched 857 * <code>AudioTrack</code> write samples are dropped. 858 * <p> For input, the <code>channelIndexMask</code> is an OR-ed combination of 859 * bits representing the mapping of input source channels to 860 * <code>AudioRecord</code> read samples. 861 * For example, a mask of <code>0x5</code>, or binary 862 * <code>101</code>, will read from the first and third channel of the input 863 * source device and store them in the first and second sample of the 864 * <code>AudioRecord</code> read frame. 865 * Unmatched input source channels are dropped and 866 * unmatched <code>AudioRecord</code> read samples are zero filled. 867 * @return the same <code>Builder</code> instance. 868 * @throws IllegalArgumentException if the channel index mask is invalid or 869 * if both channel index mask and channel position mask 870 * are specified but do not have the same channel count. 871 */ 872 public @NonNull Builder setChannelIndexMask(int channelIndexMask) { 873 if (channelIndexMask == 0) { 874 throw new IllegalArgumentException("Invalid zero channel index mask"); 875 } else if (/* channelIndexMask != 0 && */ mChannelMask != 0 && 876 Integer.bitCount(channelIndexMask) != Integer.bitCount(mChannelMask)) { 877 throw new IllegalArgumentException("Mismatched channel count for index mask " + 878 Integer.toHexString(channelIndexMask).toUpperCase()); 879 } 880 mChannelIndexMask = channelIndexMask; 881 mPropertySetMask |= AUDIO_FORMAT_HAS_PROPERTY_CHANNEL_INDEX_MASK; 882 return this; 883 } 884 885 /** 886 * Sets the sample rate. 887 * @param sampleRate the sample rate expressed in Hz 888 * @return the same Builder instance. 889 * @throws java.lang.IllegalArgumentException 890 */ 891 public Builder setSampleRate(int sampleRate) throws IllegalArgumentException { 892 // TODO Consider whether to keep the MIN and MAX range checks here. 893 // It is not necessary and poses the problem of defining the limits independently from 894 // native implementation or platform capabilities. 895 if (((sampleRate < SAMPLE_RATE_HZ_MIN) || (sampleRate > SAMPLE_RATE_HZ_MAX)) && 896 sampleRate != SAMPLE_RATE_UNSPECIFIED) { 897 throw new IllegalArgumentException("Invalid sample rate " + sampleRate); 898 } 899 mSampleRate = sampleRate; 900 mPropertySetMask |= AUDIO_FORMAT_HAS_PROPERTY_SAMPLE_RATE; 901 return this; 902 } 903 } 904 905 @Override 906 public boolean equals(Object o) { 907 if (this == o) return true; 908 if (o == null || getClass() != o.getClass()) return false; 909 910 AudioFormat that = (AudioFormat) o; 911 912 if (mPropertySetMask != that.mPropertySetMask) return false; 913 914 // return false if any of the properties is set and the values differ 915 return !((((mPropertySetMask & AUDIO_FORMAT_HAS_PROPERTY_ENCODING) != 0) 916 && (mEncoding != that.mEncoding)) 917 || (((mPropertySetMask & AUDIO_FORMAT_HAS_PROPERTY_SAMPLE_RATE) != 0) 918 && (mSampleRate != that.mSampleRate)) 919 || (((mPropertySetMask & AUDIO_FORMAT_HAS_PROPERTY_CHANNEL_MASK) != 0) 920 && (mChannelMask != that.mChannelMask)) 921 || (((mPropertySetMask & AUDIO_FORMAT_HAS_PROPERTY_CHANNEL_INDEX_MASK) != 0) 922 && (mChannelIndexMask != that.mChannelIndexMask))); 923 } 924 925 @Override 926 public int hashCode() { 927 return Objects.hash(mPropertySetMask, mSampleRate, mEncoding, mChannelMask, 928 mChannelIndexMask); 929 } 930 931 @Override 932 public int describeContents() { 933 return 0; 934 } 935 936 @Override 937 public void writeToParcel(Parcel dest, int flags) { 938 dest.writeInt(mPropertySetMask); 939 dest.writeInt(mEncoding); 940 dest.writeInt(mSampleRate); 941 dest.writeInt(mChannelMask); 942 dest.writeInt(mChannelIndexMask); 943 } 944 945 private AudioFormat(Parcel in) { 946 mPropertySetMask = in.readInt(); 947 mEncoding = in.readInt(); 948 mSampleRate = in.readInt(); 949 mChannelMask = in.readInt(); 950 mChannelIndexMask = in.readInt(); 951 } 952 953 public static final Parcelable.Creator<AudioFormat> CREATOR = 954 new Parcelable.Creator<AudioFormat>() { 955 public AudioFormat createFromParcel(Parcel p) { 956 return new AudioFormat(p); 957 } 958 public AudioFormat[] newArray(int size) { 959 return new AudioFormat[size]; 960 } 961 }; 962 963 @Override 964 public String toString () { 965 return new String("AudioFormat:" 966 + " props=" + mPropertySetMask 967 + " enc=" + mEncoding 968 + " chan=0x" + Integer.toHexString(mChannelMask).toUpperCase() 969 + " chan_index=0x" + Integer.toHexString(mChannelIndexMask).toUpperCase() 970 + " rate=" + mSampleRate); 971 } 972 973 /** @hide */ 974 @IntDef({ 975 ENCODING_DEFAULT, 976 ENCODING_PCM_8BIT, 977 ENCODING_PCM_16BIT, 978 ENCODING_PCM_FLOAT, 979 ENCODING_AC3, 980 ENCODING_E_AC3, 981 ENCODING_DTS, 982 ENCODING_DTS_HD, 983 ENCODING_IEC61937 984 }) 985 @Retention(RetentionPolicy.SOURCE) 986 public @interface Encoding {} 987 988} 989