libavutil/channel_layout.h

   1 /*
   2  * Copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
   3  * Copyright (c) 2008 Peter Ross
   4  *
   5  * This file is part of FFmpeg.
   6  *
   7  * FFmpeg is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * FFmpeg is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with FFmpeg; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 #ifndef AVUTIL_CHANNEL_LAYOUT_H
  23 #define AVUTIL_CHANNEL_LAYOUT_H
  24
  25 #include <stdint.h>
  26 #include <stdlib.h>
  27
  28 #include "version.h"
  29 #include "attributes.h"
  30
  31 /**
  32  * @file
  33  * @ingroup lavu_audio_channels
  34  * Public libavutil channel layout APIs header.
  35  */
  36
  37
  38 /**
  39  * @defgroup lavu_audio_channels Audio channels
  40  * @ingroup lavu_audio
  41  *
  42  * Audio channel layout utility functions
  43  *
  44  * @{
  45  */
  46
  47 enum AVChannel {
  48     ///< Invalid channel index
  49     AV_CHAN_NONE = -1,
  50     AV_CHAN_FRONT_LEFT,
  51     AV_CHAN_FRONT_RIGHT,
  52     AV_CHAN_FRONT_CENTER,
  53     AV_CHAN_LOW_FREQUENCY,
  54     AV_CHAN_BACK_LEFT,
  55     AV_CHAN_BACK_RIGHT,
  56     AV_CHAN_FRONT_LEFT_OF_CENTER,
  57     AV_CHAN_FRONT_RIGHT_OF_CENTER,
  58     AV_CHAN_BACK_CENTER,
  59     AV_CHAN_SIDE_LEFT,
  60     AV_CHAN_SIDE_RIGHT,
  61     AV_CHAN_TOP_CENTER,
  62     AV_CHAN_TOP_FRONT_LEFT,
  63     AV_CHAN_TOP_FRONT_CENTER,
  64     AV_CHAN_TOP_FRONT_RIGHT,
  65     AV_CHAN_TOP_BACK_LEFT,
  66     AV_CHAN_TOP_BACK_CENTER,
  67     AV_CHAN_TOP_BACK_RIGHT,
  68     /** Stereo downmix. */
  69     AV_CHAN_STEREO_LEFT = 29,
  70     /** See above. */
  71     AV_CHAN_STEREO_RIGHT,
  72     AV_CHAN_WIDE_LEFT,
  73     AV_CHAN_WIDE_RIGHT,
  74     AV_CHAN_SURROUND_DIRECT_LEFT,
  75     AV_CHAN_SURROUND_DIRECT_RIGHT,
  76     AV_CHAN_LOW_FREQUENCY_2,
  77     AV_CHAN_TOP_SIDE_LEFT,
  78     AV_CHAN_TOP_SIDE_RIGHT,
  79     AV_CHAN_BOTTOM_FRONT_CENTER,
  80     AV_CHAN_BOTTOM_FRONT_LEFT,
  81     AV_CHAN_BOTTOM_FRONT_RIGHT,
  82     AV_CHAN_SIDE_SURROUND_LEFT,     ///<  +90 degrees, Lss, SiL
  83     AV_CHAN_SIDE_SURROUND_RIGHT,    ///<  -90 degrees, Rss, SiR
  84     AV_CHAN_TOP_SURROUND_LEFT,      ///< +110 degrees, Lvs, TpLS
  85     AV_CHAN_TOP_SURROUND_RIGHT,     ///< -110 degrees, Rvs, TpRS
  86
  87     AV_CHAN_BINAURAL_LEFT = 61,
  88     AV_CHAN_BINAURAL_RIGHT,
  89
  90     /** Channel is empty can be safely skipped. */
  91     AV_CHAN_UNUSED = 0x200,
  92
  93     /** Channel contains data, but its position is unknown. */
  94     AV_CHAN_UNKNOWN = 0x300,
  95
  96     /**
  97      * Range of channels between AV_CHAN_AMBISONIC_BASE and
  98      * AV_CHAN_AMBISONIC_END represent Ambisonic components using the ACN system.
  99      *
 100      * Given a channel id `<i>` between AV_CHAN_AMBISONIC_BASE and
 101      * AV_CHAN_AMBISONIC_END (inclusive), the ACN index of the channel `<n>` is
 102      * `<n> = <i> - AV_CHAN_AMBISONIC_BASE`.
 103      *
 104      * @note these values are only used for AV_CHANNEL_ORDER_CUSTOM channel
 105      * orderings, the AV_CHANNEL_ORDER_AMBISONIC ordering orders the channels
 106      * implicitly by their position in the stream.
 107      */
 108     AV_CHAN_AMBISONIC_BASE = 0x400,
 109     // leave space for 1024 ids, which correspond to maximum order-32 harmonics,
 110     // which should be enough for the foreseeable use cases
 111     AV_CHAN_AMBISONIC_END  = 0x7ff,
 112 };
 113
 114 enum AVChannelOrder {
 115     /**
 116      * Only the channel count is specified, without any further information
 117      * about the channel order.
 118      */
 119     AV_CHANNEL_ORDER_UNSPEC,
 120     /**
 121      * The native channel order, i.e. the channels are in the same order in
 122      * which they are defined in the AVChannel enum. This supports up to 63
 123      * different channels.
 124      */
 125     AV_CHANNEL_ORDER_NATIVE,
 126     /**
 127      * The channel order does not correspond to any other predefined order and
 128      * is stored as an explicit map. For example, this could be used to support
 129      * layouts with 64 or more channels, or with empty/skipped (AV_CHAN_UNUSED)
 130      * channels at arbitrary positions.
 131      */
 132     AV_CHANNEL_ORDER_CUSTOM,
 133     /**
 134      * The audio is represented as the decomposition of the sound field into
 135      * spherical harmonics. Each channel corresponds to a single expansion
 136      * component. Channels are ordered according to ACN (Ambisonic Channel
 137      * Number).
 138      *
 139      * The channel with the index n in the stream contains the spherical
 140      * harmonic of degree l and order m given by
 141      * @code{.unparsed}
 142      *   l   = floor(sqrt(n)),
 143      *   m   = n - l * (l + 1).
 144      * @endcode
 145      *
 146      * Conversely given a spherical harmonic of degree l and order m, the
 147      * corresponding channel index n is given by
 148      * @code{.unparsed}
 149      *   n = l * (l + 1) + m.
 150      * @endcode
 151      *
 152      * Normalization is assumed to be SN3D (Schmidt Semi-Normalization)
 153      * as defined in AmbiX format $ 2.1.
 154      */
 155     AV_CHANNEL_ORDER_AMBISONIC,
 156     /**
 157      * Number of channel orders, not part of ABI/API
 158      */
 159     FF_CHANNEL_ORDER_NB
 160 };
 161
 162
 163 /**
 164  * @defgroup channel_masks Audio channel masks
 165  *
 166  * A channel layout is a 64-bits integer with a bit set for every channel.
 167  * The number of bits set must be equal to the number of channels.
 168  * The value 0 means that the channel layout is not known.
 169  * @note this data structure is not powerful enough to handle channels
 170  * combinations that have the same channel multiple times, such as
 171  * dual-mono.
 172  *
 173  * @{
 174  */
 175 #define AV_CH_FRONT_LEFT             (1ULL << AV_CHAN_FRONT_LEFT           )
 176 #define AV_CH_FRONT_RIGHT            (1ULL << AV_CHAN_FRONT_RIGHT          )
 177 #define AV_CH_FRONT_CENTER           (1ULL << AV_CHAN_FRONT_CENTER         )
 178 #define AV_CH_LOW_FREQUENCY          (1ULL << AV_CHAN_LOW_FREQUENCY        )
 179 #define AV_CH_BACK_LEFT              (1ULL << AV_CHAN_BACK_LEFT            )
 180 #define AV_CH_BACK_RIGHT             (1ULL << AV_CHAN_BACK_RIGHT           )
 181 #define AV_CH_FRONT_LEFT_OF_CENTER   (1ULL << AV_CHAN_FRONT_LEFT_OF_CENTER )
 182 #define AV_CH_FRONT_RIGHT_OF_CENTER  (1ULL << AV_CHAN_FRONT_RIGHT_OF_CENTER)
 183 #define AV_CH_BACK_CENTER            (1ULL << AV_CHAN_BACK_CENTER          )
 184 #define AV_CH_SIDE_LEFT              (1ULL << AV_CHAN_SIDE_LEFT            )
 185 #define AV_CH_SIDE_RIGHT             (1ULL << AV_CHAN_SIDE_RIGHT           )
 186 #define AV_CH_TOP_CENTER             (1ULL << AV_CHAN_TOP_CENTER           )
 187 #define AV_CH_TOP_FRONT_LEFT         (1ULL << AV_CHAN_TOP_FRONT_LEFT       )
 188 #define AV_CH_TOP_FRONT_CENTER       (1ULL << AV_CHAN_TOP_FRONT_CENTER     )
 189 #define AV_CH_TOP_FRONT_RIGHT        (1ULL << AV_CHAN_TOP_FRONT_RIGHT      )
 190 #define AV_CH_TOP_BACK_LEFT          (1ULL << AV_CHAN_TOP_BACK_LEFT        )
 191 #define AV_CH_TOP_BACK_CENTER        (1ULL << AV_CHAN_TOP_BACK_CENTER      )
 192 #define AV_CH_TOP_BACK_RIGHT         (1ULL << AV_CHAN_TOP_BACK_RIGHT       )
 193 #define AV_CH_STEREO_LEFT            (1ULL << AV_CHAN_STEREO_LEFT          )
 194 #define AV_CH_STEREO_RIGHT           (1ULL << AV_CHAN_STEREO_RIGHT         )
 195 #define AV_CH_WIDE_LEFT              (1ULL << AV_CHAN_WIDE_LEFT            )
 196 #define AV_CH_WIDE_RIGHT             (1ULL << AV_CHAN_WIDE_RIGHT           )
 197 #define AV_CH_SURROUND_DIRECT_LEFT   (1ULL << AV_CHAN_SURROUND_DIRECT_LEFT )
 198 #define AV_CH_SURROUND_DIRECT_RIGHT  (1ULL << AV_CHAN_SURROUND_DIRECT_RIGHT)
 199 #define AV_CH_LOW_FREQUENCY_2        (1ULL << AV_CHAN_LOW_FREQUENCY_2      )
 200 #define AV_CH_TOP_SIDE_LEFT          (1ULL << AV_CHAN_TOP_SIDE_LEFT        )
 201 #define AV_CH_TOP_SIDE_RIGHT         (1ULL << AV_CHAN_TOP_SIDE_RIGHT       )
 202 #define AV_CH_BOTTOM_FRONT_CENTER    (1ULL << AV_CHAN_BOTTOM_FRONT_CENTER  )
 203 #define AV_CH_BOTTOM_FRONT_LEFT      (1ULL << AV_CHAN_BOTTOM_FRONT_LEFT    )
 204 #define AV_CH_BOTTOM_FRONT_RIGHT     (1ULL << AV_CHAN_BOTTOM_FRONT_RIGHT   )
 205 #define AV_CH_SIDE_SURROUND_LEFT     (1ULL << AV_CHAN_SIDE_SURROUND_LEFT   )
 206 #define AV_CH_SIDE_SURROUND_RIGHT    (1ULL << AV_CHAN_SIDE_SURROUND_RIGHT  )
 207 #define AV_CH_TOP_SURROUND_LEFT      (1ULL << AV_CHAN_TOP_SURROUND_LEFT    )
 208 #define AV_CH_TOP_SURROUND_RIGHT     (1ULL << AV_CHAN_TOP_SURROUND_RIGHT   )
 209 #define AV_CH_BINAURAL_LEFT          (1ULL << AV_CHAN_BINAURAL_LEFT        )
 210 #define AV_CH_BINAURAL_RIGHT         (1ULL << AV_CHAN_BINAURAL_RIGHT       )
 211
 212 /**
 213  * @}
 214  * @defgroup channel_mask_c Audio channel layouts
 215  * @{
 216  * */
 217 #define AV_CH_LAYOUT_MONO              (AV_CH_FRONT_CENTER)
 218 #define AV_CH_LAYOUT_STEREO            (AV_CH_FRONT_LEFT|AV_CH_FRONT_RIGHT)
 219 #define AV_CH_LAYOUT_2POINT1           (AV_CH_LAYOUT_STEREO|AV_CH_LOW_FREQUENCY)
 220 #define AV_CH_LAYOUT_2_1               (AV_CH_LAYOUT_STEREO|AV_CH_BACK_CENTER)
 221 #define AV_CH_LAYOUT_SURROUND          (AV_CH_LAYOUT_STEREO|AV_CH_FRONT_CENTER)
 222 #define AV_CH_LAYOUT_3POINT1           (AV_CH_LAYOUT_SURROUND|AV_CH_LOW_FREQUENCY)
 223 #define AV_CH_LAYOUT_4POINT0           (AV_CH_LAYOUT_SURROUND|AV_CH_BACK_CENTER)
 224 #define AV_CH_LAYOUT_4POINT1           (AV_CH_LAYOUT_4POINT0|AV_CH_LOW_FREQUENCY)
 225 #define AV_CH_LAYOUT_2_2               (AV_CH_LAYOUT_STEREO|AV_CH_SIDE_LEFT|AV_CH_SIDE_RIGHT)
 226 #define AV_CH_LAYOUT_QUAD              (AV_CH_LAYOUT_STEREO|AV_CH_BACK_LEFT|AV_CH_BACK_RIGHT)
 227 #define AV_CH_LAYOUT_5POINT0           (AV_CH_LAYOUT_SURROUND|AV_CH_SIDE_LEFT|AV_CH_SIDE_RIGHT)
 228 #define AV_CH_LAYOUT_5POINT1           (AV_CH_LAYOUT_5POINT0|AV_CH_LOW_FREQUENCY)
 229 #define AV_CH_LAYOUT_5POINT0_BACK      (AV_CH_LAYOUT_SURROUND|AV_CH_BACK_LEFT|AV_CH_BACK_RIGHT)
 230 #define AV_CH_LAYOUT_5POINT1_BACK      (AV_CH_LAYOUT_5POINT0_BACK|AV_CH_LOW_FREQUENCY)
 231 #define AV_CH_LAYOUT_6POINT0           (AV_CH_LAYOUT_5POINT0|AV_CH_BACK_CENTER)
 232 #define AV_CH_LAYOUT_6POINT0_FRONT     (AV_CH_LAYOUT_2_2|AV_CH_FRONT_LEFT_OF_CENTER|AV_CH_FRONT_RIGHT_OF_CENTER)
 233 #define AV_CH_LAYOUT_HEXAGONAL         (AV_CH_LAYOUT_5POINT0_BACK|AV_CH_BACK_CENTER)
 234 #define AV_CH_LAYOUT_3POINT1POINT2     (AV_CH_LAYOUT_3POINT1|AV_CH_TOP_FRONT_LEFT|AV_CH_TOP_FRONT_RIGHT)
 235 #define AV_CH_LAYOUT_6POINT1           (AV_CH_LAYOUT_5POINT1|AV_CH_BACK_CENTER)
 236 #define AV_CH_LAYOUT_6POINT1_BACK      (AV_CH_LAYOUT_5POINT1_BACK|AV_CH_BACK_CENTER)
 237 #define AV_CH_LAYOUT_6POINT1_FRONT     (AV_CH_LAYOUT_6POINT0_FRONT|AV_CH_LOW_FREQUENCY)
 238 #define AV_CH_LAYOUT_7POINT0           (AV_CH_LAYOUT_5POINT0|AV_CH_BACK_LEFT|AV_CH_BACK_RIGHT)
 239 #define AV_CH_LAYOUT_7POINT0_FRONT     (AV_CH_LAYOUT_5POINT0|AV_CH_FRONT_LEFT_OF_CENTER|AV_CH_FRONT_RIGHT_OF_CENTER)
 240 #define AV_CH_LAYOUT_7POINT1           (AV_CH_LAYOUT_5POINT1|AV_CH_BACK_LEFT|AV_CH_BACK_RIGHT)
 241 #define AV_CH_LAYOUT_7POINT1_WIDE      (AV_CH_LAYOUT_5POINT1|AV_CH_FRONT_LEFT_OF_CENTER|AV_CH_FRONT_RIGHT_OF_CENTER)
 242 #define AV_CH_LAYOUT_7POINT1_WIDE_BACK (AV_CH_LAYOUT_5POINT1_BACK|AV_CH_FRONT_LEFT_OF_CENTER|AV_CH_FRONT_RIGHT_OF_CENTER)
 243 #define AV_CH_LAYOUT_5POINT1POINT2     (AV_CH_LAYOUT_5POINT1|AV_CH_TOP_FRONT_LEFT|AV_CH_TOP_FRONT_RIGHT)
 244 #define AV_CH_LAYOUT_5POINT1POINT2_BACK (AV_CH_LAYOUT_5POINT1_BACK|AV_CH_TOP_FRONT_LEFT|AV_CH_TOP_FRONT_RIGHT)
 245 #define AV_CH_LAYOUT_OCTAGONAL         (AV_CH_LAYOUT_5POINT0|AV_CH_BACK_LEFT|AV_CH_BACK_CENTER|AV_CH_BACK_RIGHT)
 246 #define AV_CH_LAYOUT_CUBE              (AV_CH_LAYOUT_QUAD|AV_CH_TOP_FRONT_LEFT|AV_CH_TOP_FRONT_RIGHT|AV_CH_TOP_BACK_LEFT|AV_CH_TOP_BACK_RIGHT)
 247 #define AV_CH_LAYOUT_5POINT1POINT4_BACK (AV_CH_LAYOUT_5POINT1POINT2|AV_CH_TOP_BACK_LEFT|AV_CH_TOP_BACK_RIGHT)
 248 #define AV_CH_LAYOUT_7POINT1POINT2     (AV_CH_LAYOUT_7POINT1|AV_CH_TOP_FRONT_LEFT|AV_CH_TOP_FRONT_RIGHT)
 249 #define AV_CH_LAYOUT_7POINT1POINT4_BACK (AV_CH_LAYOUT_7POINT1POINT2|AV_CH_TOP_BACK_LEFT|AV_CH_TOP_BACK_RIGHT)
 250 #define AV_CH_LAYOUT_7POINT2POINT3     (AV_CH_LAYOUT_7POINT1POINT2|AV_CH_TOP_BACK_CENTER|AV_CH_LOW_FREQUENCY_2)
 251 #define AV_CH_LAYOUT_9POINT1POINT4_BACK (AV_CH_LAYOUT_7POINT1POINT4_BACK|AV_CH_FRONT_LEFT_OF_CENTER|AV_CH_FRONT_RIGHT_OF_CENTER)
 252 #define AV_CH_LAYOUT_9POINT1POINT6     (AV_CH_LAYOUT_9POINT1POINT4_BACK|AV_CH_TOP_SIDE_LEFT|AV_CH_TOP_SIDE_RIGHT)
 253 #define AV_CH_LAYOUT_HEXADECAGONAL     (AV_CH_LAYOUT_OCTAGONAL|AV_CH_WIDE_LEFT|AV_CH_WIDE_RIGHT|AV_CH_TOP_BACK_LEFT|AV_CH_TOP_BACK_RIGHT|AV_CH_TOP_BACK_CENTER|AV_CH_TOP_FRONT_CENTER|AV_CH_TOP_FRONT_LEFT|AV_CH_TOP_FRONT_RIGHT)
 254 #define AV_CH_LAYOUT_BINAURAL          (AV_CH_BINAURAL_LEFT|AV_CH_BINAURAL_RIGHT)
 255 #define AV_CH_LAYOUT_STEREO_DOWNMIX    (AV_CH_STEREO_LEFT|AV_CH_STEREO_RIGHT)
 256 #define AV_CH_LAYOUT_22POINT2          (AV_CH_LAYOUT_9POINT1POINT6|AV_CH_BACK_CENTER|AV_CH_LOW_FREQUENCY_2|AV_CH_TOP_FRONT_CENTER|AV_CH_TOP_CENTER|AV_CH_TOP_BACK_CENTER|AV_CH_BOTTOM_FRONT_CENTER|AV_CH_BOTTOM_FRONT_LEFT|AV_CH_BOTTOM_FRONT_RIGHT)
 257
 258 #define AV_CH_LAYOUT_7POINT1_TOP_BACK AV_CH_LAYOUT_5POINT1POINT2_BACK
 259
 260 enum AVMatrixEncoding {
 261     AV_MATRIX_ENCODING_NONE,
 262     AV_MATRIX_ENCODING_DOLBY,
 263     AV_MATRIX_ENCODING_DPLII,
 264     AV_MATRIX_ENCODING_DPLIIX,
 265     AV_MATRIX_ENCODING_DPLIIZ,
 266     AV_MATRIX_ENCODING_DOLBYEX,
 267     AV_MATRIX_ENCODING_DOLBYHEADPHONE,
 268     AV_MATRIX_ENCODING_NB
 269 };
 270
 271 /**
 272  * @}
 273  */
 274
 275 /**
 276  * An AVChannelCustom defines a single channel within a custom order layout
 277  *
 278  * Unlike most structures in FFmpeg, sizeof(AVChannelCustom) is a part of the
 279  * public ABI.
 280  *
 281  * No new fields may be added to it without a major version bump.
 282  */
 283 typedef struct AVChannelCustom {
 284     enum AVChannel id;
 285     char name[16];
 286     void *opaque;
 287 } AVChannelCustom;
 288
 289 /**
 290  * An AVChannelLayout holds information about the channel layout of audio data.
 291  *
 292  * A channel layout here is defined as a set of channels ordered in a specific
 293  * way (unless the channel order is AV_CHANNEL_ORDER_UNSPEC, in which case an
 294  * AVChannelLayout carries only the channel count).
 295  * All orders may be treated as if they were AV_CHANNEL_ORDER_UNSPEC by
 296  * ignoring everything but the channel count, as long as av_channel_layout_check()
 297  * considers they are valid.
 298  *
 299  * Unlike most structures in FFmpeg, sizeof(AVChannelLayout) is a part of the
 300  * public ABI and may be used by the caller. E.g. it may be allocated on stack
 301  * or embedded in caller-defined structs.
 302  *
 303  * AVChannelLayout can be initialized as follows:
 304  * - default initialization with {0}, followed by setting all used fields
 305  *   correctly;
 306  * - by assigning one of the predefined AV_CHANNEL_LAYOUT_* initializers;
 307  * - with a constructor function, such as av_channel_layout_default(),
 308  *   av_channel_layout_from_mask() or av_channel_layout_from_string().
 309  *
 310  * The channel layout must be unitialized with av_channel_layout_uninit()
 311  *
 312  * Copying an AVChannelLayout via assigning is forbidden,
 313  * av_channel_layout_copy() must be used instead (and its return value should
 314  * be checked)
 315  *
 316  * No new fields may be added to it without a major version bump, except for
 317  * new elements of the union fitting in sizeof(uint64_t).
 318  */
 319 typedef struct AVChannelLayout {
 320     /**
 321      * Channel order used in this layout.
 322      * This is a mandatory field.
 323      */
 324     enum AVChannelOrder order;
 325
 326     /**
 327      * Number of channels in this layout. Mandatory field.
 328      */
 329     int nb_channels;
 330
 331     /**
 332      * Details about which channels are present in this layout.
 333      * For AV_CHANNEL_ORDER_UNSPEC, this field is undefined and must not be
 334      * used.
 335      */
 336     union {
 337         /**
 338          * This member must be used for AV_CHANNEL_ORDER_NATIVE, and may be used
 339          * for AV_CHANNEL_ORDER_AMBISONIC to signal non-diegetic channels.
 340          * It is a bitmask, where the position of each set bit means that the
 341          * AVChannel with the corresponding value is present.
 342          *
 343          * I.e. when (mask & (1 << AV_CHAN_FOO)) is non-zero, then AV_CHAN_FOO
 344          * is present in the layout. Otherwise it is not present.
 345          *
 346          * @note when a channel layout using a bitmask is constructed or
 347          * modified manually (i.e.  not using any of the av_channel_layout_*
 348          * functions), the code doing it must ensure that the number of set bits
 349          * is equal to nb_channels.
 350          */
 351         uint64_t mask;
 352         /**
 353          * This member must be used when the channel order is
 354          * AV_CHANNEL_ORDER_CUSTOM. It is a nb_channels-sized array, with each
 355          * element signalling the presence of the AVChannel with the
 356          * corresponding value in map[i].id.
 357          *
 358          * I.e. when map[i].id is equal to AV_CHAN_FOO, then AV_CH_FOO is the
 359          * i-th channel in the audio data.
 360          *
 361          * When map[i].id is in the range between AV_CHAN_AMBISONIC_BASE and
 362          * AV_CHAN_AMBISONIC_END (inclusive), the channel contains an ambisonic
 363          * component with ACN index (as defined above)
 364          * n = map[i].id - AV_CHAN_AMBISONIC_BASE.
 365          *
 366          * map[i].name may be filled with a 0-terminated string, in which case
 367          * it will be used for the purpose of identifying the channel with the
 368          * convenience functions below. Otherise it must be zeroed.
 369          */
 370         AVChannelCustom *map;
 371     } u;
 372
 373     /**
 374      * For some private data of the user.
 375      */
 376     void *opaque;
 377 } AVChannelLayout;
 378
 379 /**
 380  * Macro to define native channel layouts
 381  *
 382  * @note This doesn't use designated initializers for compatibility with C++ 17 and older.
 383  */
 384 #define AV_CHANNEL_LAYOUT_MASK(nb, m) \
 385     { /* .order */ AV_CHANNEL_ORDER_NATIVE, \
 386       /* .nb_channels */  (nb), \
 387       /* .u.mask */ { m }, \
 388       /* .opaque */ NULL }
 389
 390 /**
 391  * @name Common pre-defined channel layouts
 392  * @{
 393  */
 394 #define AV_CHANNEL_LAYOUT_MONO              AV_CHANNEL_LAYOUT_MASK(1,  AV_CH_LAYOUT_MONO)
 395 #define AV_CHANNEL_LAYOUT_STEREO            AV_CHANNEL_LAYOUT_MASK(2,  AV_CH_LAYOUT_STEREO)
 396 #define AV_CHANNEL_LAYOUT_2POINT1           AV_CHANNEL_LAYOUT_MASK(3,  AV_CH_LAYOUT_2POINT1)
 397 #define AV_CHANNEL_LAYOUT_2_1               AV_CHANNEL_LAYOUT_MASK(3,  AV_CH_LAYOUT_2_1)
 398 #define AV_CHANNEL_LAYOUT_SURROUND          AV_CHANNEL_LAYOUT_MASK(3,  AV_CH_LAYOUT_SURROUND)
 399 #define AV_CHANNEL_LAYOUT_3POINT1           AV_CHANNEL_LAYOUT_MASK(4,  AV_CH_LAYOUT_3POINT1)
 400 #define AV_CHANNEL_LAYOUT_4POINT0           AV_CHANNEL_LAYOUT_MASK(4,  AV_CH_LAYOUT_4POINT0)
 401 #define AV_CHANNEL_LAYOUT_4POINT1           AV_CHANNEL_LAYOUT_MASK(5,  AV_CH_LAYOUT_4POINT1)
 402 #define AV_CHANNEL_LAYOUT_2_2               AV_CHANNEL_LAYOUT_MASK(4,  AV_CH_LAYOUT_2_2)
 403 #define AV_CHANNEL_LAYOUT_QUAD              AV_CHANNEL_LAYOUT_MASK(4,  AV_CH_LAYOUT_QUAD)
 404 #define AV_CHANNEL_LAYOUT_5POINT0           AV_CHANNEL_LAYOUT_MASK(5,  AV_CH_LAYOUT_5POINT0)
 405 #define AV_CHANNEL_LAYOUT_5POINT1           AV_CHANNEL_LAYOUT_MASK(6,  AV_CH_LAYOUT_5POINT1)
 406 #define AV_CHANNEL_LAYOUT_5POINT0_BACK      AV_CHANNEL_LAYOUT_MASK(5,  AV_CH_LAYOUT_5POINT0_BACK)
 407 #define AV_CHANNEL_LAYOUT_5POINT1_BACK      AV_CHANNEL_LAYOUT_MASK(6,  AV_CH_LAYOUT_5POINT1_BACK)
 408 #define AV_CHANNEL_LAYOUT_6POINT0           AV_CHANNEL_LAYOUT_MASK(6,  AV_CH_LAYOUT_6POINT0)
 409 #define AV_CHANNEL_LAYOUT_6POINT0_FRONT     AV_CHANNEL_LAYOUT_MASK(6,  AV_CH_LAYOUT_6POINT0_FRONT)
 410 #define AV_CHANNEL_LAYOUT_3POINT1POINT2     AV_CHANNEL_LAYOUT_MASK(6,  AV_CH_LAYOUT_3POINT1POINT2)
 411 #define AV_CHANNEL_LAYOUT_HEXAGONAL         AV_CHANNEL_LAYOUT_MASK(6,  AV_CH_LAYOUT_HEXAGONAL)
 412 #define AV_CHANNEL_LAYOUT_6POINT1           AV_CHANNEL_LAYOUT_MASK(7,  AV_CH_LAYOUT_6POINT1)
 413 #define AV_CHANNEL_LAYOUT_6POINT1_BACK      AV_CHANNEL_LAYOUT_MASK(7,  AV_CH_LAYOUT_6POINT1_BACK)
 414 #define AV_CHANNEL_LAYOUT_6POINT1_FRONT     AV_CHANNEL_LAYOUT_MASK(7,  AV_CH_LAYOUT_6POINT1_FRONT)
 415 #define AV_CHANNEL_LAYOUT_7POINT0           AV_CHANNEL_LAYOUT_MASK(7,  AV_CH_LAYOUT_7POINT0)
 416 #define AV_CHANNEL_LAYOUT_7POINT0_FRONT     AV_CHANNEL_LAYOUT_MASK(7,  AV_CH_LAYOUT_7POINT0_FRONT)
 417 #define AV_CHANNEL_LAYOUT_7POINT1           AV_CHANNEL_LAYOUT_MASK(8,  AV_CH_LAYOUT_7POINT1)
 418 #define AV_CHANNEL_LAYOUT_7POINT1_WIDE      AV_CHANNEL_LAYOUT_MASK(8,  AV_CH_LAYOUT_7POINT1_WIDE)
 419 #define AV_CHANNEL_LAYOUT_7POINT1_WIDE_BACK AV_CHANNEL_LAYOUT_MASK(8,  AV_CH_LAYOUT_7POINT1_WIDE_BACK)
 420 #define AV_CHANNEL_LAYOUT_5POINT1POINT2     AV_CHANNEL_LAYOUT_MASK(8,  AV_CH_LAYOUT_5POINT1POINT2)
 421 #define AV_CHANNEL_LAYOUT_5POINT1POINT2_BACK AV_CHANNEL_LAYOUT_MASK(8, AV_CH_LAYOUT_5POINT1POINT2_BACK)
 422 #define AV_CHANNEL_LAYOUT_OCTAGONAL         AV_CHANNEL_LAYOUT_MASK(8,  AV_CH_LAYOUT_OCTAGONAL)
 423 #define AV_CHANNEL_LAYOUT_CUBE              AV_CHANNEL_LAYOUT_MASK(8,  AV_CH_LAYOUT_CUBE)
 424 #define AV_CHANNEL_LAYOUT_5POINT1POINT4_BACK AV_CHANNEL_LAYOUT_MASK(10, AV_CH_LAYOUT_5POINT1POINT4_BACK)
 425 #define AV_CHANNEL_LAYOUT_7POINT1POINT2     AV_CHANNEL_LAYOUT_MASK(10, AV_CH_LAYOUT_7POINT1POINT2)
 426 #define AV_CHANNEL_LAYOUT_7POINT1POINT4_BACK AV_CHANNEL_LAYOUT_MASK(12, AV_CH_LAYOUT_7POINT1POINT4_BACK)
 427 #define AV_CHANNEL_LAYOUT_7POINT2POINT3     AV_CHANNEL_LAYOUT_MASK(12, AV_CH_LAYOUT_7POINT2POINT3)
 428 #define AV_CHANNEL_LAYOUT_9POINT1POINT4_BACK AV_CHANNEL_LAYOUT_MASK(14, AV_CH_LAYOUT_9POINT1POINT4_BACK)
 429 #define AV_CHANNEL_LAYOUT_9POINT1POINT6     AV_CHANNEL_LAYOUT_MASK(16, AV_CH_LAYOUT_9POINT1POINT6)
 430 #define AV_CHANNEL_LAYOUT_HEXADECAGONAL     AV_CHANNEL_LAYOUT_MASK(16, AV_CH_LAYOUT_HEXADECAGONAL)
 431 #define AV_CHANNEL_LAYOUT_BINAURAL          AV_CHANNEL_LAYOUT_MASK(2,  AV_CH_LAYOUT_BINAURAL)
 432 #define AV_CHANNEL_LAYOUT_STEREO_DOWNMIX    AV_CHANNEL_LAYOUT_MASK(2,  AV_CH_LAYOUT_STEREO_DOWNMIX)
 433 #define AV_CHANNEL_LAYOUT_22POINT2          AV_CHANNEL_LAYOUT_MASK(24, AV_CH_LAYOUT_22POINT2)
 434
 435 #define AV_CHANNEL_LAYOUT_7POINT1_TOP_BACK  AV_CHANNEL_LAYOUT_5POINT1POINT2_BACK
 436
 437 #define AV_CHANNEL_LAYOUT_AMBISONIC_FIRST_ORDER \
 438     { /* .order */ AV_CHANNEL_ORDER_AMBISONIC, \
 439       /* .nb_channels */ 4, \
 440       /* .u.mask */ { 0 }, \
 441       /* .opaque */ NULL }
 442 /** @} */
 443
 444 struct AVBPrint;
 445
 446 /**
 447  * Get a human readable string in an abbreviated form describing a given channel.
 448  * This is the inverse function of @ref av_channel_from_string().
 449  *
 450  * @param buf pre-allocated buffer where to put the generated string
 451  * @param buf_size size in bytes of the buffer.
 452  * @param channel the AVChannel whose name to get
 453  * @return amount of bytes needed to hold the output string, or a negative AVERROR
 454  *         on failure. If the returned value is bigger than buf_size, then the
 455  *         string was truncated.
 456  */
 457 int av_channel_name(char *buf, size_t buf_size, enum AVChannel channel);
 458
 459 /**
 460  * bprint variant of av_channel_name().
 461  *
 462  * @note the string will be appended to the bprint buffer.
 463  */
 464 void av_channel_name_bprint(struct AVBPrint *bp, enum AVChannel channel_id);
 465
 466 /**
 467  * Get a human readable string describing a given channel.
 468  *
 469  * @param buf pre-allocated buffer where to put the generated string
 470  * @param buf_size size in bytes of the buffer.
 471  * @param channel the AVChannel whose description to get
 472  * @return amount of bytes needed to hold the output string, or a negative AVERROR
 473  *         on failure. If the returned value is bigger than buf_size, then the
 474  *         string was truncated.
 475  */
 476 int av_channel_description(char *buf, size_t buf_size, enum AVChannel channel);
 477
 478 /**
 479  * bprint variant of av_channel_description().
 480  *
 481  * @note the string will be appended to the bprint buffer.
 482  */
 483 void av_channel_description_bprint(struct AVBPrint *bp, enum AVChannel channel_id);
 484
 485 /**
 486  * This is the inverse function of @ref av_channel_name().
 487  *
 488  * @return the channel with the given name
 489  *         AV_CHAN_NONE when name does not identify a known channel
 490  */
 491 enum AVChannel av_channel_from_string(const char *name);
 492
 493 /**
 494  * Initialize a custom channel layout with the specified number of channels.
 495  * The channel map will be allocated and the designation of all channels will
 496  * be set to AV_CHAN_UNKNOWN.
 497  *
 498  * This is only a convenience helper function, a custom channel layout can also
 499  * be constructed without using this.
 500  *
 501  * @param channel_layout the layout structure to be initialized
 502  * @param nb_channels the number of channels
 503  *
 504  * @return 0 on success
 505  *         AVERROR(EINVAL) if the number of channels <= 0
 506  *         AVERROR(ENOMEM) if the channel map could not be allocated
 507  */
 508 int av_channel_layout_custom_init(AVChannelLayout *channel_layout, int nb_channels);
 509
 510 /**
 511  * Initialize a native channel layout from a bitmask indicating which channels
 512  * are present.
 513  *
 514  * @param channel_layout the layout structure to be initialized
 515  * @param mask bitmask describing the channel layout
 516  *
 517  * @return 0 on success
 518  *         AVERROR(EINVAL) for invalid mask values
 519  */
 520 int av_channel_layout_from_mask(AVChannelLayout *channel_layout, uint64_t mask);
 521
 522 /**
 523  * Initialize a channel layout from a given string description.
 524  * The input string can be represented by:
 525  *  - the formal channel layout name (returned by av_channel_layout_describe())
 526  *  - single or multiple channel names (returned by av_channel_name(), eg. "FL",
 527  *    or concatenated with "+", each optionally containing a custom name after
 528  *    a "@", eg. "FL@Left+FR@Right+LFE")
 529  *  - a decimal or hexadecimal value of a native channel layout (eg. "4" or "0x4")
 530  *  - the number of channels with default layout (eg. "4c")
 531  *  - the number of unordered channels (eg. "4C" or "4 channels")
 532  *  - the ambisonic order followed by optional non-diegetic channels (eg.
 533  *    "ambisonic 2+stereo")
 534  * On error, the channel layout will remain uninitialized, but not necessarily
 535  * untouched.
 536  *
 537  * @param channel_layout uninitialized channel layout for the result
 538  * @param str string describing the channel layout
 539  * @return 0 on success parsing the channel layout
 540  *         AVERROR(EINVAL) if an invalid channel layout string was provided
 541  *         AVERROR(ENOMEM) if there was not enough memory
 542  */
 543 int av_channel_layout_from_string(AVChannelLayout *channel_layout,
 544                                   const char *str);
 545
 546 /**
 547  * Get the default channel layout for a given number of channels.
 548  *
 549  * @param ch_layout the layout structure to be initialized
 550  * @param nb_channels number of channels
 551  */
 552 void av_channel_layout_default(AVChannelLayout *ch_layout, int nb_channels);
 553
 554 /**
 555  * Iterate over all standard channel layouts.
 556  *
 557  * @param opaque a pointer where libavutil will store the iteration state. Must
 558  *               point to NULL to start the iteration.
 559  *
 560  * @return the standard channel layout or NULL when the iteration is
 561  *         finished
 562  */
 563 const AVChannelLayout *av_channel_layout_standard(void **opaque);
 564
 565 /**
 566  * Free any allocated data in the channel layout and reset the channel
 567  * count to 0.
 568  *
 569  * @param channel_layout the layout structure to be uninitialized
 570  */
 571 void av_channel_layout_uninit(AVChannelLayout *channel_layout);
 572
 573 /**
 574  * Make a copy of a channel layout. This differs from just assigning src to dst
 575  * in that it allocates and copies the map for AV_CHANNEL_ORDER_CUSTOM.
 576  *
 577  * @note the destination channel_layout will be always uninitialized before copy.
 578  *
 579  * @param dst destination channel layout
 580  * @param src source channel layout
 581  * @return 0 on success, a negative AVERROR on error.
 582  */
 583 int av_channel_layout_copy(AVChannelLayout *dst, const AVChannelLayout *src);
 584
 585 /**
 586  * Get a human-readable string describing the channel layout properties.
 587  * The string will be in the same format that is accepted by
 588  * @ref av_channel_layout_from_string(), allowing to rebuild the same
 589  * channel layout, except for opaque pointers.
 590  *
 591  * @param channel_layout channel layout to be described
 592  * @param buf pre-allocated buffer where to put the generated string
 593  * @param buf_size size in bytes of the buffer.
 594  * @return amount of bytes needed to hold the output string, or a negative AVERROR
 595  *         on failure. If the returned value is bigger than buf_size, then the
 596  *         string was truncated.
 597  */
 598 int av_channel_layout_describe(const AVChannelLayout *channel_layout,
 599                                char *buf, size_t buf_size);
 600
 601 /**
 602  * bprint variant of av_channel_layout_describe().
 603  *
 604  * @note the string will be appended to the bprint buffer.
 605  * @return 0 on success, or a negative AVERROR value on failure.
 606  */
 607 int av_channel_layout_describe_bprint(const AVChannelLayout *channel_layout,
 608                                       struct AVBPrint *bp);
 609
 610 /**
 611  * Get the channel with the given index in a channel layout.
 612  *
 613  * @param channel_layout input channel layout
 614  * @param idx index of the channel
 615  * @return channel with the index idx in channel_layout on success or
 616  *         AV_CHAN_NONE on failure (if idx is not valid or the channel order is
 617  *         unspecified)
 618  */
 619 enum AVChannel
 620 av_channel_layout_channel_from_index(const AVChannelLayout *channel_layout, unsigned int idx);
 621
 622 /**
 623  * Get the index of a given channel in a channel layout. In case multiple
 624  * channels are found, only the first match will be returned.
 625  *
 626  * @param channel_layout input channel layout
 627  * @param channel the channel whose index to obtain
 628  * @return index of channel in channel_layout on success or a negative number if
 629  *         channel is not present in channel_layout.
 630  */
 631 int av_channel_layout_index_from_channel(const AVChannelLayout *channel_layout,
 632                                          enum AVChannel channel);
 633
 634 /**
 635  * Get the index in a channel layout of a channel described by the given string.
 636  * In case multiple channels are found, only the first match will be returned.
 637  *
 638  * This function accepts channel names in the same format as
 639  * @ref av_channel_from_string().
 640  *
 641  * @param channel_layout input channel layout
 642  * @param name string describing the channel whose index to obtain
 643  * @return a channel index described by the given string, or a negative AVERROR
 644  *         value.
 645  */
 646 int av_channel_layout_index_from_string(const AVChannelLayout *channel_layout,
 647                                         const char *name);
 648
 649 /**
 650  * Get a channel described by the given string.
 651  *
 652  * This function accepts channel names in the same format as
 653  * @ref av_channel_from_string().
 654  *
 655  * @param channel_layout input channel layout
 656  * @param name string describing the channel to obtain
 657  * @return a channel described by the given string in channel_layout on success
 658  *         or AV_CHAN_NONE on failure (if the string is not valid or the channel
 659  *         order is unspecified)
 660  */
 661 enum AVChannel
 662 av_channel_layout_channel_from_string(const AVChannelLayout *channel_layout,
 663                                       const char *name);
 664
 665 /**
 666  * Find out what channels from a given set are present in a channel layout,
 667  * without regard for their positions.
 668  *
 669  * @param channel_layout input channel layout
 670  * @param mask a combination of AV_CH_* representing a set of channels
 671  * @return a bitfield representing all the channels from mask that are present
 672  *         in channel_layout
 673  */
 674 uint64_t av_channel_layout_subset(const AVChannelLayout *channel_layout,
 675                                   uint64_t mask);
 676
 677 /**
 678  * Check whether a channel layout is valid, i.e. can possibly describe audio
 679  * data.
 680  *
 681  * @param channel_layout input channel layout
 682  * @return 1 if channel_layout is valid, 0 otherwise.
 683  */
 684 int av_channel_layout_check(const AVChannelLayout *channel_layout);
 685
 686 /**
 687  * Check whether two channel layouts are semantically the same, i.e. the same
 688  * channels are present on the same positions in both.
 689  *
 690  * If one of the channel layouts is AV_CHANNEL_ORDER_UNSPEC, while the other is
 691  * not, they are considered to be unequal. If both are AV_CHANNEL_ORDER_UNSPEC,
 692  * they are considered equal iff the channel counts are the same in both.
 693  *
 694  * @param chl input channel layout
 695  * @param chl1 input channel layout
 696  * @return 0 if chl and chl1 are equal, 1 if they are not equal. A negative
 697  *         AVERROR code if one or both are invalid.
 698  */
 699 int av_channel_layout_compare(const AVChannelLayout *chl, const AVChannelLayout *chl1);
 700
 701 /**
 702  * Return the order if the layout is n-th order standard-order ambisonic.
 703  * The presence of optional extra non-diegetic channels at the end is not taken
 704  * into account.
 705  *
 706  * @param channel_layout input channel layout
 707  * @return the order of the layout, a negative error code otherwise.
 708  */
 709 int av_channel_layout_ambisonic_order(const AVChannelLayout *channel_layout);
 710
 711 /**
 712  * The conversion must be lossless.
 713  */
 714 #define AV_CHANNEL_LAYOUT_RETYPE_FLAG_LOSSLESS (1 << 0)
 715
 716 /**
 717  * The specified retype target order is ignored and the simplest possible
 718  * (canonical) order is used for which the input layout can be losslessy
 719  * represented.
 720  */
 721 #define AV_CHANNEL_LAYOUT_RETYPE_FLAG_CANONICAL (1 << 1)
 722
 723 /**
 724  * Change the AVChannelOrder of a channel layout.
 725  *
 726  * Change of AVChannelOrder can be either lossless or lossy. In case of a
 727  * lossless conversion all the channel designations and the associated channel
 728  * names (if any) are kept. On a lossy conversion the channel names and channel
 729  * designations might be lost depending on the capabilities of the desired
 730  * AVChannelOrder. Note that some conversions are simply not possible in which
 731  * case this function returns AVERROR(ENOSYS).
 732  *
 733  * The following conversions are supported:
 734  *
 735  * Any       -> Custom     : Always possible, always lossless.
 736  * Any       -> Unspecified: Always possible, lossless if channel designations
 737  *   are all unknown and channel names are not used, lossy otherwise.
 738  * Custom    -> Ambisonic  : Possible if it contains ambisonic channels with
 739  *   optional non-diegetic channels in the end. Lossy if the channels have
 740  *   custom names, lossless otherwise.
 741  * Custom    -> Native     : Possible if it contains native channels in native
 742  *     order. Lossy if the channels have custom names, lossless otherwise.
 743  *
 744  * On error this function keeps the original channel layout untouched.
 745  *
 746  * @param channel_layout channel layout which will be changed
 747  * @param order the desired channel layout order
 748  * @param flags a combination of AV_CHANNEL_LAYOUT_RETYPE_FLAG_* constants
 749  * @return 0 if the conversion was successful and lossless or if the channel
 750  *           layout was already in the desired order
 751  *         >0 if the conversion was successful but lossy
 752  *         AVERROR(ENOSYS) if the conversion was not possible (or would be
 753  *           lossy and AV_CHANNEL_LAYOUT_RETYPE_FLAG_LOSSLESS was specified)
 754  *         AVERROR(EINVAL), AVERROR(ENOMEM) on error
 755  */
 756 int av_channel_layout_retype(AVChannelLayout *channel_layout, enum AVChannelOrder order, int flags);
 757
 758 /**
 759  * @}
 760  */
 761
 762 #endif /* AVUTIL_CHANNEL_LAYOUT_H */