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 /** Audio data format: DOLBY TRUEHD compressed 267 **/ 268 public static final int ENCODING_DOLBY_TRUEHD = 14; 269 270 /** Invalid audio channel configuration */ 271 /** @deprecated Use {@link #CHANNEL_INVALID} instead. */ 272 @Deprecated public static final int CHANNEL_CONFIGURATION_INVALID = 0; 273 /** Default audio channel configuration */ 274 /** @deprecated Use {@link #CHANNEL_OUT_DEFAULT} or {@link #CHANNEL_IN_DEFAULT} instead. */ 275 @Deprecated public static final int CHANNEL_CONFIGURATION_DEFAULT = 1; 276 /** Mono audio configuration */ 277 /** @deprecated Use {@link #CHANNEL_OUT_MONO} or {@link #CHANNEL_IN_MONO} instead. */ 278 @Deprecated public static final int CHANNEL_CONFIGURATION_MONO = 2; 279 /** Stereo (2 channel) audio configuration */ 280 /** @deprecated Use {@link #CHANNEL_OUT_STEREO} or {@link #CHANNEL_IN_STEREO} instead. */ 281 @Deprecated public static final int CHANNEL_CONFIGURATION_STEREO = 3; 282 283 /** Invalid audio channel mask */ 284 public static final int CHANNEL_INVALID = 0; 285 /** Default audio channel mask */ 286 public static final int CHANNEL_OUT_DEFAULT = 1; 287 288 // Output channel mask definitions below are translated to the native values defined in 289 // in /system/media/audio/include/system/audio.h in the JNI code of AudioTrack 290 public static final int CHANNEL_OUT_FRONT_LEFT = 0x4; 291 public static final int CHANNEL_OUT_FRONT_RIGHT = 0x8; 292 public static final int CHANNEL_OUT_FRONT_CENTER = 0x10; 293 public static final int CHANNEL_OUT_LOW_FREQUENCY = 0x20; 294 public static final int CHANNEL_OUT_BACK_LEFT = 0x40; 295 public static final int CHANNEL_OUT_BACK_RIGHT = 0x80; 296 public static final int CHANNEL_OUT_FRONT_LEFT_OF_CENTER = 0x100; 297 public static final int CHANNEL_OUT_FRONT_RIGHT_OF_CENTER = 0x200; 298 public static final int CHANNEL_OUT_BACK_CENTER = 0x400; 299 public static final int CHANNEL_OUT_SIDE_LEFT = 0x800; 300 public static final int CHANNEL_OUT_SIDE_RIGHT = 0x1000; 301 /** @hide */ 302 public static final int CHANNEL_OUT_TOP_CENTER = 0x2000; 303 /** @hide */ 304 public static final int CHANNEL_OUT_TOP_FRONT_LEFT = 0x4000; 305 /** @hide */ 306 public static final int CHANNEL_OUT_TOP_FRONT_CENTER = 0x8000; 307 /** @hide */ 308 public static final int CHANNEL_OUT_TOP_FRONT_RIGHT = 0x10000; 309 /** @hide */ 310 public static final int CHANNEL_OUT_TOP_BACK_LEFT = 0x20000; 311 /** @hide */ 312 public static final int CHANNEL_OUT_TOP_BACK_CENTER = 0x40000; 313 /** @hide */ 314 public static final int CHANNEL_OUT_TOP_BACK_RIGHT = 0x80000; 315 316 public static final int CHANNEL_OUT_MONO = CHANNEL_OUT_FRONT_LEFT; 317 public static final int CHANNEL_OUT_STEREO = (CHANNEL_OUT_FRONT_LEFT | CHANNEL_OUT_FRONT_RIGHT); 318 // aka QUAD_BACK 319 public static final int CHANNEL_OUT_QUAD = (CHANNEL_OUT_FRONT_LEFT | CHANNEL_OUT_FRONT_RIGHT | 320 CHANNEL_OUT_BACK_LEFT | CHANNEL_OUT_BACK_RIGHT); 321 /** @hide */ 322 public static final int CHANNEL_OUT_QUAD_SIDE = (CHANNEL_OUT_FRONT_LEFT | CHANNEL_OUT_FRONT_RIGHT | 323 CHANNEL_OUT_SIDE_LEFT | CHANNEL_OUT_SIDE_RIGHT); 324 public static final int CHANNEL_OUT_SURROUND = (CHANNEL_OUT_FRONT_LEFT | CHANNEL_OUT_FRONT_RIGHT | 325 CHANNEL_OUT_FRONT_CENTER | CHANNEL_OUT_BACK_CENTER); 326 // aka 5POINT1_BACK 327 public static final int CHANNEL_OUT_5POINT1 = (CHANNEL_OUT_FRONT_LEFT | CHANNEL_OUT_FRONT_RIGHT | 328 CHANNEL_OUT_FRONT_CENTER | CHANNEL_OUT_LOW_FREQUENCY | CHANNEL_OUT_BACK_LEFT | CHANNEL_OUT_BACK_RIGHT); 329 /** @hide */ 330 public static final int CHANNEL_OUT_5POINT1_SIDE = (CHANNEL_OUT_FRONT_LEFT | CHANNEL_OUT_FRONT_RIGHT | 331 CHANNEL_OUT_FRONT_CENTER | CHANNEL_OUT_LOW_FREQUENCY | 332 CHANNEL_OUT_SIDE_LEFT | CHANNEL_OUT_SIDE_RIGHT); 333 // different from AUDIO_CHANNEL_OUT_7POINT1 used internally, and not accepted by AudioRecord. 334 /** @deprecated Not the typical 7.1 surround configuration. Use {@link #CHANNEL_OUT_7POINT1_SURROUND} instead. */ 335 @Deprecated public static final int CHANNEL_OUT_7POINT1 = (CHANNEL_OUT_FRONT_LEFT | CHANNEL_OUT_FRONT_RIGHT | 336 CHANNEL_OUT_FRONT_CENTER | CHANNEL_OUT_LOW_FREQUENCY | CHANNEL_OUT_BACK_LEFT | CHANNEL_OUT_BACK_RIGHT | 337 CHANNEL_OUT_FRONT_LEFT_OF_CENTER | CHANNEL_OUT_FRONT_RIGHT_OF_CENTER); 338 // matches AUDIO_CHANNEL_OUT_7POINT1 339 public static final int CHANNEL_OUT_7POINT1_SURROUND = ( 340 CHANNEL_OUT_FRONT_LEFT | CHANNEL_OUT_FRONT_CENTER | CHANNEL_OUT_FRONT_RIGHT | 341 CHANNEL_OUT_SIDE_LEFT | CHANNEL_OUT_SIDE_RIGHT | 342 CHANNEL_OUT_BACK_LEFT | CHANNEL_OUT_BACK_RIGHT | 343 CHANNEL_OUT_LOW_FREQUENCY); 344 // CHANNEL_OUT_ALL is not yet defined; if added then it should match AUDIO_CHANNEL_OUT_ALL 345 346 /** Minimum value for sample rate, 347 * assuming AudioTrack and AudioRecord share the same limitations. 348 * @hide 349 */ 350 // never unhide 351 public static final int SAMPLE_RATE_HZ_MIN = 4000; 352 /** Maximum value for sample rate, 353 * assuming AudioTrack and AudioRecord share the same limitations. 354 * @hide 355 */ 356 // never unhide 357 public static final int SAMPLE_RATE_HZ_MAX = 192000; 358 /** Sample rate will be a route-dependent value. 359 * For AudioTrack, it is usually the sink sample rate, 360 * and for AudioRecord it is usually the source sample rate. 361 */ 362 public static final int SAMPLE_RATE_UNSPECIFIED = 0; 363 364 /** 365 * @hide 366 * Return the input channel mask corresponding to an output channel mask. 367 * This can be used for submix rerouting for the mask of the recorder to map to that of the mix. 368 * @param outMask a combination of the CHANNEL_OUT_* definitions, but not CHANNEL_OUT_DEFAULT 369 * @return a combination of CHANNEL_IN_* definitions matching an output channel mask 370 * @throws IllegalArgumentException 371 */ 372 public static int inChannelMaskFromOutChannelMask(int outMask) throws IllegalArgumentException { 373 if (outMask == CHANNEL_OUT_DEFAULT) { 374 throw new IllegalArgumentException( 375 "Illegal CHANNEL_OUT_DEFAULT channel mask for input."); 376 } 377 switch (channelCountFromOutChannelMask(outMask)) { 378 case 1: 379 return CHANNEL_IN_MONO; 380 case 2: 381 return CHANNEL_IN_STEREO; 382 default: 383 throw new IllegalArgumentException("Unsupported channel configuration for input."); 384 } 385 } 386 387 /** 388 * @hide 389 * Return the number of channels from an input channel mask 390 * @param mask a combination of the CHANNEL_IN_* definitions, even CHANNEL_IN_DEFAULT 391 * @return number of channels for the mask 392 */ 393 public static int channelCountFromInChannelMask(int mask) { 394 return Integer.bitCount(mask); 395 } 396 /** 397 * @hide 398 * Return the number of channels from an output channel mask 399 * @param mask a combination of the CHANNEL_OUT_* definitions, but not CHANNEL_OUT_DEFAULT 400 * @return number of channels for the mask 401 */ 402 public static int channelCountFromOutChannelMask(int mask) { 403 return Integer.bitCount(mask); 404 } 405 /** 406 * @hide 407 * Return a channel mask ready to be used by native code 408 * @param mask a combination of the CHANNEL_OUT_* definitions, but not CHANNEL_OUT_DEFAULT 409 * @return a native channel mask 410 */ 411 public static int convertChannelOutMaskToNativeMask(int javaMask) { 412 return (javaMask >> 2); 413 } 414 415 /** 416 * @hide 417 * Return a java output channel mask 418 * @param mask a native channel mask 419 * @return a combination of the CHANNEL_OUT_* definitions 420 */ 421 public static int convertNativeChannelMaskToOutMask(int nativeMask) { 422 return (nativeMask << 2); 423 } 424 425 public static final int CHANNEL_IN_DEFAULT = 1; 426 // These directly match native 427 public static final int CHANNEL_IN_LEFT = 0x4; 428 public static final int CHANNEL_IN_RIGHT = 0x8; 429 public static final int CHANNEL_IN_FRONT = 0x10; 430 public static final int CHANNEL_IN_BACK = 0x20; 431 public static final int CHANNEL_IN_LEFT_PROCESSED = 0x40; 432 public static final int CHANNEL_IN_RIGHT_PROCESSED = 0x80; 433 public static final int CHANNEL_IN_FRONT_PROCESSED = 0x100; 434 public static final int CHANNEL_IN_BACK_PROCESSED = 0x200; 435 public static final int CHANNEL_IN_PRESSURE = 0x400; 436 public static final int CHANNEL_IN_X_AXIS = 0x800; 437 public static final int CHANNEL_IN_Y_AXIS = 0x1000; 438 public static final int CHANNEL_IN_Z_AXIS = 0x2000; 439 public static final int CHANNEL_IN_VOICE_UPLINK = 0x4000; 440 public static final int CHANNEL_IN_VOICE_DNLINK = 0x8000; 441 public static final int CHANNEL_IN_MONO = CHANNEL_IN_FRONT; 442 public static final int CHANNEL_IN_STEREO = (CHANNEL_IN_LEFT | CHANNEL_IN_RIGHT); 443 /** @hide */ 444 public static final int CHANNEL_IN_FRONT_BACK = CHANNEL_IN_FRONT | CHANNEL_IN_BACK; 445 // CHANNEL_IN_ALL is not yet defined; if added then it should match AUDIO_CHANNEL_IN_ALL 446 447 /** @hide */ 448 public static int getBytesPerSample(int audioFormat) 449 { 450 switch (audioFormat) { 451 case ENCODING_PCM_8BIT: 452 return 1; 453 case ENCODING_PCM_16BIT: 454 case ENCODING_IEC61937: 455 case ENCODING_DEFAULT: 456 return 2; 457 case ENCODING_PCM_FLOAT: 458 return 4; 459 case ENCODING_INVALID: 460 default: 461 throw new IllegalArgumentException("Bad audio format " + audioFormat); 462 } 463 } 464 465 /** @hide */ 466 public static boolean isValidEncoding(int audioFormat) 467 { 468 switch (audioFormat) { 469 case ENCODING_PCM_8BIT: 470 case ENCODING_PCM_16BIT: 471 case ENCODING_PCM_FLOAT: 472 case ENCODING_AC3: 473 case ENCODING_E_AC3: 474 case ENCODING_DTS: 475 case ENCODING_DTS_HD: 476 case ENCODING_MP3: 477 case ENCODING_AAC_LC: 478 case ENCODING_AAC_HE_V1: 479 case ENCODING_AAC_HE_V2: 480 case ENCODING_IEC61937: 481 return true; 482 default: 483 return false; 484 } 485 } 486 487 /** @hide */ 488 public static boolean isPublicEncoding(int audioFormat) 489 { 490 switch (audioFormat) { 491 case ENCODING_PCM_8BIT: 492 case ENCODING_PCM_16BIT: 493 case ENCODING_PCM_FLOAT: 494 case ENCODING_AC3: 495 case ENCODING_E_AC3: 496 case ENCODING_DTS: 497 case ENCODING_DTS_HD: 498 case ENCODING_IEC61937: 499 return true; 500 default: 501 return false; 502 } 503 } 504 505 /** @hide */ 506 public static boolean isEncodingLinearPcm(int audioFormat) 507 { 508 switch (audioFormat) { 509 case ENCODING_PCM_8BIT: 510 case ENCODING_PCM_16BIT: 511 case ENCODING_PCM_FLOAT: 512 case ENCODING_DEFAULT: 513 return true; 514 case ENCODING_AC3: 515 case ENCODING_E_AC3: 516 case ENCODING_DTS: 517 case ENCODING_DTS_HD: 518 case ENCODING_MP3: 519 case ENCODING_AAC_LC: 520 case ENCODING_AAC_HE_V1: 521 case ENCODING_AAC_HE_V2: 522 case ENCODING_IEC61937: // wrapped in PCM but compressed 523 return false; 524 case ENCODING_INVALID: 525 default: 526 throw new IllegalArgumentException("Bad audio format " + audioFormat); 527 } 528 } 529 530 /** @hide */ 531 public static boolean isEncodingLinearFrames(int audioFormat) 532 { 533 switch (audioFormat) { 534 case ENCODING_PCM_8BIT: 535 case ENCODING_PCM_16BIT: 536 case ENCODING_PCM_FLOAT: 537 case ENCODING_IEC61937: // same size as stereo PCM 538 case ENCODING_DEFAULT: 539 return true; 540 case ENCODING_AC3: 541 case ENCODING_E_AC3: 542 case ENCODING_DTS: 543 case ENCODING_DTS_HD: 544 case ENCODING_MP3: 545 case ENCODING_AAC_LC: 546 case ENCODING_AAC_HE_V1: 547 case ENCODING_AAC_HE_V2: 548 return false; 549 case ENCODING_INVALID: 550 default: 551 throw new IllegalArgumentException("Bad audio format " + audioFormat); 552 } 553 } 554 /** 555 * Returns an array of public encoding values extracted from an array of 556 * encoding values. 557 * @hide 558 */ 559 public static int[] filterPublicFormats(int[] formats) { 560 if (formats == null) { 561 return null; 562 } 563 int[] myCopy = Arrays.copyOf(formats, formats.length); 564 int size = 0; 565 for (int i = 0; i < myCopy.length; i++) { 566 if (isPublicEncoding(myCopy[i])) { 567 if (size != i) { 568 myCopy[size] = myCopy[i]; 569 } 570 size++; 571 } 572 } 573 return Arrays.copyOf(myCopy, size); 574 } 575 576 /** @removed */ 577 public AudioFormat() 578 { 579 throw new UnsupportedOperationException("There is no valid usage of this constructor"); 580 } 581 582 /** 583 * Private constructor with an ignored argument to differentiate from the removed default ctor 584 * @param ignoredArgument 585 */ 586 private AudioFormat(int ignoredArgument) { 587 } 588 589 /** 590 * Constructor used by the JNI. Parameters are not checked for validity. 591 */ 592 // Update sound trigger JNI in core/jni/android_hardware_SoundTrigger.cpp when modifying this 593 // constructor 594 private AudioFormat(int encoding, int sampleRate, int channelMask, int channelIndexMask) { 595 mEncoding = encoding; 596 mSampleRate = sampleRate; 597 mChannelMask = channelMask; 598 mChannelIndexMask = channelIndexMask; 599 mPropertySetMask = AUDIO_FORMAT_HAS_PROPERTY_ENCODING | 600 AUDIO_FORMAT_HAS_PROPERTY_SAMPLE_RATE | 601 AUDIO_FORMAT_HAS_PROPERTY_CHANNEL_MASK | 602 AUDIO_FORMAT_HAS_PROPERTY_CHANNEL_INDEX_MASK; 603 } 604 605 /** @hide */ 606 public final static int AUDIO_FORMAT_HAS_PROPERTY_NONE = 0x0; 607 /** @hide */ 608 public final static int AUDIO_FORMAT_HAS_PROPERTY_ENCODING = 0x1 << 0; 609 /** @hide */ 610 public final static int AUDIO_FORMAT_HAS_PROPERTY_SAMPLE_RATE = 0x1 << 1; 611 /** @hide */ 612 public final static int AUDIO_FORMAT_HAS_PROPERTY_CHANNEL_MASK = 0x1 << 2; 613 /** @hide */ 614 public final static int AUDIO_FORMAT_HAS_PROPERTY_CHANNEL_INDEX_MASK = 0x1 << 3; 615 616 private int mEncoding; 617 private int mSampleRate; 618 private int mChannelMask; 619 private int mChannelIndexMask; 620 private int mPropertySetMask; 621 622 /** 623 * Return the encoding. 624 * See the section on <a href="#encoding">encodings</a> for more information about the different 625 * types of supported audio encoding. 626 * @return one of the values that can be set in {@link Builder#setEncoding(int)} or 627 * {@link AudioFormat#ENCODING_INVALID} if not set. 628 */ 629 public int getEncoding() { 630 if ((mPropertySetMask & AUDIO_FORMAT_HAS_PROPERTY_ENCODING) == 0) { 631 return ENCODING_INVALID; 632 } 633 return mEncoding; 634 } 635 636 /** 637 * Return the sample rate. 638 * @return one of the values that can be set in {@link Builder#setSampleRate(int)} or 639 * {@link #SAMPLE_RATE_UNSPECIFIED} if not set. 640 */ 641 public int getSampleRate() { 642 return mSampleRate; 643 } 644 645 /** 646 * Return the channel mask. 647 * See the section on <a href="#channelMask">channel masks</a> for more information about 648 * the difference between index-based masks(as returned by {@link #getChannelIndexMask()}) and 649 * the position-based mask returned by this function. 650 * @return one of the values that can be set in {@link Builder#setChannelMask(int)} or 651 * {@link AudioFormat#CHANNEL_INVALID} if not set. 652 */ 653 public int getChannelMask() { 654 if ((mPropertySetMask & AUDIO_FORMAT_HAS_PROPERTY_CHANNEL_MASK) == 0) { 655 return CHANNEL_INVALID; 656 } 657 return mChannelMask; 658 } 659 660 /** 661 * Return the channel index mask. 662 * See the section on <a href="#channelMask">channel masks</a> for more information about 663 * the difference between index-based masks, and position-based masks (as returned 664 * by {@link #getChannelMask()}). 665 * @return one of the values that can be set in {@link Builder#setChannelIndexMask(int)} or 666 * {@link AudioFormat#CHANNEL_INVALID} if not set or an invalid mask was used. 667 */ 668 public int getChannelIndexMask() { 669 if ((mPropertySetMask & AUDIO_FORMAT_HAS_PROPERTY_CHANNEL_INDEX_MASK) == 0) { 670 return CHANNEL_INVALID; 671 } 672 return mChannelIndexMask; 673 } 674 675 /** 676 * Return the channel count. 677 * @return the channel count derived from the channel position mask or the channel index mask. 678 * Zero is returned if both the channel position mask and the channel index mask are not set. 679 */ 680 public int getChannelCount() { 681 final int channelIndexCount = Integer.bitCount(getChannelIndexMask()); 682 int channelCount = channelCountFromOutChannelMask(getChannelMask()); 683 if (channelCount == 0) { 684 channelCount = channelIndexCount; 685 } else if (channelCount != channelIndexCount && channelIndexCount != 0) { 686 channelCount = 0; // position and index channel count mismatch 687 } 688 return channelCount; 689 } 690 691 /** @hide */ 692 public int getPropertySetMask() { 693 return mPropertySetMask; 694 } 695 696 /** 697 * Builder class for {@link AudioFormat} objects. 698 * Use this class to configure and create an AudioFormat instance. By setting format 699 * characteristics such as audio encoding, channel mask or sample rate, you indicate which 700 * of those are to vary from the default behavior on this device wherever this audio format 701 * is used. See {@link AudioFormat} for a complete description of the different parameters that 702 * can be used to configure an <code>AudioFormat</code> instance. 703 * <p>{@link AudioFormat} is for instance used in 704 * {@link AudioTrack#AudioTrack(AudioAttributes, AudioFormat, int, int, int)}. In this 705 * constructor, every format characteristic set on the <code>Builder</code> (e.g. with 706 * {@link #setSampleRate(int)}) will alter the default values used by an 707 * <code>AudioTrack</code>. In this case for audio playback with <code>AudioTrack</code>, the 708 * sample rate set in the <code>Builder</code> would override the platform output sample rate 709 * which would otherwise be selected by default. 710 */ 711 public static class Builder { 712 private int mEncoding = ENCODING_INVALID; 713 private int mSampleRate = SAMPLE_RATE_UNSPECIFIED; 714 private int mChannelMask = CHANNEL_INVALID; 715 private int mChannelIndexMask = 0; 716 private int mPropertySetMask = AUDIO_FORMAT_HAS_PROPERTY_NONE; 717 718 /** 719 * Constructs a new Builder with none of the format characteristics set. 720 */ 721 public Builder() { 722 } 723 724 /** 725 * Constructs a new Builder from a given {@link AudioFormat}. 726 * @param af the {@link AudioFormat} object whose data will be reused in the new Builder. 727 */ 728 public Builder(AudioFormat af) { 729 mEncoding = af.mEncoding; 730 mSampleRate = af.mSampleRate; 731 mChannelMask = af.mChannelMask; 732 mChannelIndexMask = af.mChannelIndexMask; 733 mPropertySetMask = af.mPropertySetMask; 734 } 735 736 /** 737 * Combines all of the format characteristics that have been set and return a new 738 * {@link AudioFormat} object. 739 * @return a new {@link AudioFormat} object 740 */ 741 public AudioFormat build() { 742 AudioFormat af = new AudioFormat(1980/*ignored*/); 743 af.mEncoding = mEncoding; 744 // not calling setSampleRate is equivalent to calling 745 // setSampleRate(SAMPLE_RATE_UNSPECIFIED) 746 af.mSampleRate = mSampleRate; 747 af.mChannelMask = mChannelMask; 748 af.mChannelIndexMask = mChannelIndexMask; 749 af.mPropertySetMask = mPropertySetMask; 750 return af; 751 } 752 753 /** 754 * Sets the data encoding format. 755 * @param encoding one of {@link AudioFormat#ENCODING_DEFAULT}, 756 * {@link AudioFormat#ENCODING_PCM_8BIT}, 757 * {@link AudioFormat#ENCODING_PCM_16BIT}, 758 * {@link AudioFormat#ENCODING_PCM_FLOAT}, 759 * {@link AudioFormat#ENCODING_AC3}, 760 * {@link AudioFormat#ENCODING_E_AC3}. 761 * {@link AudioFormat#ENCODING_DTS}, 762 * {@link AudioFormat#ENCODING_DTS_HD}. 763 * @return the same Builder instance. 764 * @throws java.lang.IllegalArgumentException 765 */ 766 public Builder setEncoding(@Encoding int encoding) throws IllegalArgumentException { 767 switch (encoding) { 768 case ENCODING_DEFAULT: 769 mEncoding = ENCODING_PCM_16BIT; 770 break; 771 case ENCODING_PCM_8BIT: 772 case ENCODING_PCM_16BIT: 773 case ENCODING_PCM_FLOAT: 774 case ENCODING_AC3: 775 case ENCODING_E_AC3: 776 case ENCODING_DTS: 777 case ENCODING_DTS_HD: 778 case ENCODING_IEC61937: 779 mEncoding = encoding; 780 break; 781 case ENCODING_INVALID: 782 default: 783 throw new IllegalArgumentException("Invalid encoding " + encoding); 784 } 785 mPropertySetMask |= AUDIO_FORMAT_HAS_PROPERTY_ENCODING; 786 return this; 787 } 788 789 /** 790 * Sets the channel position mask. 791 * The channel position mask specifies the association between audio samples in a frame 792 * with named endpoint channels. The samples in the frame correspond to the 793 * named set bits in the channel position mask, in ascending bit order. 794 * See {@link #setChannelIndexMask(int)} to specify channels 795 * based on endpoint numbered channels. This <a href="#channelPositionMask>description of 796 * channel position masks</a> covers the concept in more details. 797 * @param channelMask describes the configuration of the audio channels. 798 * <p> For output, the channelMask can be an OR-ed combination of 799 * channel position masks, e.g. 800 * {@link AudioFormat#CHANNEL_OUT_FRONT_LEFT}, 801 * {@link AudioFormat#CHANNEL_OUT_FRONT_RIGHT}, 802 * {@link AudioFormat#CHANNEL_OUT_FRONT_CENTER}, 803 * {@link AudioFormat#CHANNEL_OUT_LOW_FREQUENCY} 804 * {@link AudioFormat#CHANNEL_OUT_BACK_LEFT}, 805 * {@link AudioFormat#CHANNEL_OUT_BACK_RIGHT}, 806 * {@link AudioFormat#CHANNEL_OUT_BACK_CENTER}, 807 * {@link AudioFormat#CHANNEL_OUT_SIDE_LEFT}, 808 * {@link AudioFormat#CHANNEL_OUT_SIDE_RIGHT}. 809 * <p> For a valid {@link AudioTrack} channel position mask, 810 * the following conditions apply: 811 * <br> (1) at most eight channel positions may be used; 812 * <br> (2) right/left pairs should be matched. 813 * <p> For input or {@link AudioRecord}, the mask should be 814 * {@link AudioFormat#CHANNEL_IN_MONO} or 815 * {@link AudioFormat#CHANNEL_IN_STEREO}. {@link AudioFormat#CHANNEL_IN_MONO} is 816 * guaranteed to work on all devices. 817 * @return the same <code>Builder</code> instance. 818 * @throws IllegalArgumentException if the channel mask is invalid or 819 * if both channel index mask and channel position mask 820 * are specified but do not have the same channel count. 821 */ 822 public @NonNull Builder setChannelMask(int channelMask) { 823 if (channelMask == CHANNEL_INVALID) { 824 throw new IllegalArgumentException("Invalid zero channel mask"); 825 } else if (/* channelMask != 0 && */ mChannelIndexMask != 0 && 826 Integer.bitCount(channelMask) != Integer.bitCount(mChannelIndexMask)) { 827 throw new IllegalArgumentException("Mismatched channel count for mask " + 828 Integer.toHexString(channelMask).toUpperCase()); 829 } 830 mChannelMask = channelMask; 831 mPropertySetMask |= AUDIO_FORMAT_HAS_PROPERTY_CHANNEL_MASK; 832 return this; 833 } 834 835 /** 836 * Sets the channel index mask. 837 * A channel index mask specifies the association of audio samples in the frame 838 * with numbered endpoint channels. The i-th bit in the channel index 839 * mask corresponds to the i-th endpoint channel. 840 * For example, an endpoint with four channels is represented 841 * as index mask bits 0 through 3. This <a href="#channelIndexMask>description of channel 842 * index masks</a> covers the concept in more details. 843 * See {@link #setChannelMask(int)} for a positional mask interpretation. 844 * <p> Both {@link AudioTrack} and {@link AudioRecord} support 845 * a channel index mask. 846 * If a channel index mask is specified it is used, 847 * otherwise the channel position mask specified 848 * by <code>setChannelMask</code> is used. 849 * For <code>AudioTrack</code> and <code>AudioRecord</code>, 850 * a channel position mask is not required if a channel index mask is specified. 851 * 852 * @param channelIndexMask describes the configuration of the audio channels. 853 * <p> For output, the <code>channelIndexMask</code> is an OR-ed combination of 854 * bits representing the mapping of <code>AudioTrack</code> write samples 855 * to output sink channels. 856 * For example, a mask of <code>0xa</code>, or binary <code>1010</code>, 857 * means the <code>AudioTrack</code> write frame consists of two samples, 858 * which are routed to the second and the fourth channels of the output sink. 859 * Unmatched output sink channels are zero filled and unmatched 860 * <code>AudioTrack</code> write samples are dropped. 861 * <p> For input, the <code>channelIndexMask</code> is an OR-ed combination of 862 * bits representing the mapping of input source channels to 863 * <code>AudioRecord</code> read samples. 864 * For example, a mask of <code>0x5</code>, or binary 865 * <code>101</code>, will read from the first and third channel of the input 866 * source device and store them in the first and second sample of the 867 * <code>AudioRecord</code> read frame. 868 * Unmatched input source channels are dropped and 869 * unmatched <code>AudioRecord</code> read samples are zero filled. 870 * @return the same <code>Builder</code> instance. 871 * @throws IllegalArgumentException if the channel index mask is invalid or 872 * if both channel index mask and channel position mask 873 * are specified but do not have the same channel count. 874 */ 875 public @NonNull Builder setChannelIndexMask(int channelIndexMask) { 876 if (channelIndexMask == 0) { 877 throw new IllegalArgumentException("Invalid zero channel index mask"); 878 } else if (/* channelIndexMask != 0 && */ mChannelMask != 0 && 879 Integer.bitCount(channelIndexMask) != Integer.bitCount(mChannelMask)) { 880 throw new IllegalArgumentException("Mismatched channel count for index mask " + 881 Integer.toHexString(channelIndexMask).toUpperCase()); 882 } 883 mChannelIndexMask = channelIndexMask; 884 mPropertySetMask |= AUDIO_FORMAT_HAS_PROPERTY_CHANNEL_INDEX_MASK; 885 return this; 886 } 887 888 /** 889 * Sets the sample rate. 890 * @param sampleRate the sample rate expressed in Hz 891 * @return the same Builder instance. 892 * @throws java.lang.IllegalArgumentException 893 */ 894 public Builder setSampleRate(int sampleRate) throws IllegalArgumentException { 895 // TODO Consider whether to keep the MIN and MAX range checks here. 896 // It is not necessary and poses the problem of defining the limits independently from 897 // native implementation or platform capabilities. 898 if (((sampleRate < SAMPLE_RATE_HZ_MIN) || (sampleRate > SAMPLE_RATE_HZ_MAX)) && 899 sampleRate != SAMPLE_RATE_UNSPECIFIED) { 900 throw new IllegalArgumentException("Invalid sample rate " + sampleRate); 901 } 902 mSampleRate = sampleRate; 903 mPropertySetMask |= AUDIO_FORMAT_HAS_PROPERTY_SAMPLE_RATE; 904 return this; 905 } 906 } 907 908 @Override 909 public boolean equals(Object o) { 910 if (this == o) return true; 911 if (o == null || getClass() != o.getClass()) return false; 912 913 AudioFormat that = (AudioFormat) o; 914 915 if (mPropertySetMask != that.mPropertySetMask) return false; 916 917 // return false if any of the properties is set and the values differ 918 return !((((mPropertySetMask & AUDIO_FORMAT_HAS_PROPERTY_ENCODING) != 0) 919 && (mEncoding != that.mEncoding)) 920 || (((mPropertySetMask & AUDIO_FORMAT_HAS_PROPERTY_SAMPLE_RATE) != 0) 921 && (mSampleRate != that.mSampleRate)) 922 || (((mPropertySetMask & AUDIO_FORMAT_HAS_PROPERTY_CHANNEL_MASK) != 0) 923 && (mChannelMask != that.mChannelMask)) 924 || (((mPropertySetMask & AUDIO_FORMAT_HAS_PROPERTY_CHANNEL_INDEX_MASK) != 0) 925 && (mChannelIndexMask != that.mChannelIndexMask))); 926 } 927 928 @Override 929 public int hashCode() { 930 return Objects.hash(mPropertySetMask, mSampleRate, mEncoding, mChannelMask, 931 mChannelIndexMask); 932 } 933 934 @Override 935 public int describeContents() { 936 return 0; 937 } 938 939 @Override 940 public void writeToParcel(Parcel dest, int flags) { 941 dest.writeInt(mPropertySetMask); 942 dest.writeInt(mEncoding); 943 dest.writeInt(mSampleRate); 944 dest.writeInt(mChannelMask); 945 dest.writeInt(mChannelIndexMask); 946 } 947 948 private AudioFormat(Parcel in) { 949 mPropertySetMask = in.readInt(); 950 mEncoding = in.readInt(); 951 mSampleRate = in.readInt(); 952 mChannelMask = in.readInt(); 953 mChannelIndexMask = in.readInt(); 954 } 955 956 public static final Parcelable.Creator<AudioFormat> CREATOR = 957 new Parcelable.Creator<AudioFormat>() { 958 public AudioFormat createFromParcel(Parcel p) { 959 return new AudioFormat(p); 960 } 961 public AudioFormat[] newArray(int size) { 962 return new AudioFormat[size]; 963 } 964 }; 965 966 @Override 967 public String toString () { 968 return new String("AudioFormat:" 969 + " props=" + mPropertySetMask 970 + " enc=" + mEncoding 971 + " chan=0x" + Integer.toHexString(mChannelMask).toUpperCase() 972 + " chan_index=0x" + Integer.toHexString(mChannelIndexMask).toUpperCase() 973 + " rate=" + mSampleRate); 974 } 975 976 /** @hide */ 977 @IntDef({ 978 ENCODING_DEFAULT, 979 ENCODING_PCM_8BIT, 980 ENCODING_PCM_16BIT, 981 ENCODING_PCM_FLOAT, 982 ENCODING_AC3, 983 ENCODING_E_AC3, 984 ENCODING_DTS, 985 ENCODING_DTS_HD, 986 ENCODING_IEC61937 987 }) 988 @Retention(RetentionPolicy.SOURCE) 989 public @interface Encoding {} 990 991} 992