tor-browser

channel_layout.h (32067B)

---

/*
* Copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
* Copyright (c) 2008 Peter Ross
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/

#ifndef AVUTIL_CHANNEL_LAYOUT_H
#define AVUTIL_CHANNEL_LAYOUT_H

#include <stdint.h>
#include <stdlib.h>

#include "version.h"
#include "attributes.h"

/**
* @file
* @ingroup lavu_audio_channels
* Public libavutil channel layout APIs header.
*/

/**
* @defgroup lavu_audio_channels Audio channels
* @ingroup lavu_audio
*
* Audio channel layout utility functions
*
* @{
*/

enum AVChannel {
 ///< Invalid channel index
 AV_CHAN_NONE = -1,
 AV_CHAN_FRONT_LEFT,
 AV_CHAN_FRONT_RIGHT,
 AV_CHAN_FRONT_CENTER,
 AV_CHAN_LOW_FREQUENCY,
 AV_CHAN_BACK_LEFT,
 AV_CHAN_BACK_RIGHT,
 AV_CHAN_FRONT_LEFT_OF_CENTER,
 AV_CHAN_FRONT_RIGHT_OF_CENTER,
 AV_CHAN_BACK_CENTER,
 AV_CHAN_SIDE_LEFT,
 AV_CHAN_SIDE_RIGHT,
 AV_CHAN_TOP_CENTER,
 AV_CHAN_TOP_FRONT_LEFT,
 AV_CHAN_TOP_FRONT_CENTER,
 AV_CHAN_TOP_FRONT_RIGHT,
 AV_CHAN_TOP_BACK_LEFT,
 AV_CHAN_TOP_BACK_CENTER,
 AV_CHAN_TOP_BACK_RIGHT,
 /** Stereo downmix. */
 AV_CHAN_STEREO_LEFT = 29,
 /** See above. */
 AV_CHAN_STEREO_RIGHT,
 AV_CHAN_WIDE_LEFT,
 AV_CHAN_WIDE_RIGHT,
 AV_CHAN_SURROUND_DIRECT_LEFT,
 AV_CHAN_SURROUND_DIRECT_RIGHT,
 AV_CHAN_LOW_FREQUENCY_2,
 AV_CHAN_TOP_SIDE_LEFT,
 AV_CHAN_TOP_SIDE_RIGHT,
 AV_CHAN_BOTTOM_FRONT_CENTER,
 AV_CHAN_BOTTOM_FRONT_LEFT,
 AV_CHAN_BOTTOM_FRONT_RIGHT,

 /** Channel is empty can be safely skipped. */
 AV_CHAN_UNUSED = 0x200,

 /** Channel contains data, but its position is unknown. */
 AV_CHAN_UNKNOWN = 0x300,

 /**
  * Range of channels between AV_CHAN_AMBISONIC_BASE and
  * AV_CHAN_AMBISONIC_END represent Ambisonic components using the ACN system.
  *
  * Given a channel id `<i>` between AV_CHAN_AMBISONIC_BASE and
  * AV_CHAN_AMBISONIC_END (inclusive), the ACN index of the channel `<n>` is
  * `<n> = <i> - AV_CHAN_AMBISONIC_BASE`.
  *
  * @note these values are only used for AV_CHANNEL_ORDER_CUSTOM channel
  * orderings, the AV_CHANNEL_ORDER_AMBISONIC ordering orders the channels
  * implicitly by their position in the stream.
  */
 AV_CHAN_AMBISONIC_BASE = 0x400,
 // leave space for 1024 ids, which correspond to maximum order-32 harmonics,
 // which should be enough for the foreseeable use cases
 AV_CHAN_AMBISONIC_END = 0x7ff,
};

enum AVChannelOrder {
 /**
  * Only the channel count is specified, without any further information
  * about the channel order.
  */
 AV_CHANNEL_ORDER_UNSPEC,
 /**
  * The native channel order, i.e. the channels are in the same order in
  * which they are defined in the AVChannel enum. This supports up to 63
  * different channels.
  */
 AV_CHANNEL_ORDER_NATIVE,
 /**
  * The channel order does not correspond to any other predefined order and
  * is stored as an explicit map. For example, this could be used to support
  * layouts with 64 or more channels, or with empty/skipped (AV_CHAN_UNUSED)
  * channels at arbitrary positions.
  */
 AV_CHANNEL_ORDER_CUSTOM,
 /**
  * The audio is represented as the decomposition of the sound field into
  * spherical harmonics. Each channel corresponds to a single expansion
  * component. Channels are ordered according to ACN (Ambisonic Channel
  * Number).
  *
  * The channel with the index n in the stream contains the spherical
  * harmonic of degree l and order m given by
  * @code{.unparsed}
  *   l   = floor(sqrt(n)),
  *   m   = n - l * (l + 1).
  * @endcode
  *
  * Conversely given a spherical harmonic of degree l and order m, the
  * corresponding channel index n is given by
  * @code{.unparsed}
  *   n = l * (l + 1) + m.
  * @endcode
  *
  * Normalization is assumed to be SN3D (Schmidt Semi-Normalization)
  * as defined in AmbiX format $ 2.1.
  */
 AV_CHANNEL_ORDER_AMBISONIC,
 /**
  * Number of channel orders, not part of ABI/API
  */
 FF_CHANNEL_ORDER_NB
};

/**
* @defgroup channel_masks Audio channel masks
*
* A channel layout is a 64-bits integer with a bit set for every channel.
* The number of bits set must be equal to the number of channels.
* The value 0 means that the channel layout is not known.
* @note this data structure is not powerful enough to handle channels
* combinations that have the same channel multiple times, such as
* dual-mono.
*
* @{
*/
#define AV_CH_FRONT_LEFT (1ULL << AV_CHAN_FRONT_LEFT)
#define AV_CH_FRONT_RIGHT (1ULL << AV_CHAN_FRONT_RIGHT)
#define AV_CH_FRONT_CENTER (1ULL << AV_CHAN_FRONT_CENTER)
#define AV_CH_LOW_FREQUENCY (1ULL << AV_CHAN_LOW_FREQUENCY)
#define AV_CH_BACK_LEFT (1ULL << AV_CHAN_BACK_LEFT)
#define AV_CH_BACK_RIGHT (1ULL << AV_CHAN_BACK_RIGHT)
#define AV_CH_FRONT_LEFT_OF_CENTER (1ULL << AV_CHAN_FRONT_LEFT_OF_CENTER)
#define AV_CH_FRONT_RIGHT_OF_CENTER (1ULL << AV_CHAN_FRONT_RIGHT_OF_CENTER)
#define AV_CH_BACK_CENTER (1ULL << AV_CHAN_BACK_CENTER)
#define AV_CH_SIDE_LEFT (1ULL << AV_CHAN_SIDE_LEFT)
#define AV_CH_SIDE_RIGHT (1ULL << AV_CHAN_SIDE_RIGHT)
#define AV_CH_TOP_CENTER (1ULL << AV_CHAN_TOP_CENTER)
#define AV_CH_TOP_FRONT_LEFT (1ULL << AV_CHAN_TOP_FRONT_LEFT)
#define AV_CH_TOP_FRONT_CENTER (1ULL << AV_CHAN_TOP_FRONT_CENTER)
#define AV_CH_TOP_FRONT_RIGHT (1ULL << AV_CHAN_TOP_FRONT_RIGHT)
#define AV_CH_TOP_BACK_LEFT (1ULL << AV_CHAN_TOP_BACK_LEFT)
#define AV_CH_TOP_BACK_CENTER (1ULL << AV_CHAN_TOP_BACK_CENTER)
#define AV_CH_TOP_BACK_RIGHT (1ULL << AV_CHAN_TOP_BACK_RIGHT)
#define AV_CH_STEREO_LEFT (1ULL << AV_CHAN_STEREO_LEFT)
#define AV_CH_STEREO_RIGHT (1ULL << AV_CHAN_STEREO_RIGHT)
#define AV_CH_WIDE_LEFT (1ULL << AV_CHAN_WIDE_LEFT)
#define AV_CH_WIDE_RIGHT (1ULL << AV_CHAN_WIDE_RIGHT)
#define AV_CH_SURROUND_DIRECT_LEFT (1ULL << AV_CHAN_SURROUND_DIRECT_LEFT)
#define AV_CH_SURROUND_DIRECT_RIGHT (1ULL << AV_CHAN_SURROUND_DIRECT_RIGHT)
#define AV_CH_LOW_FREQUENCY_2 (1ULL << AV_CHAN_LOW_FREQUENCY_2)
#define AV_CH_TOP_SIDE_LEFT (1ULL << AV_CHAN_TOP_SIDE_LEFT)
#define AV_CH_TOP_SIDE_RIGHT (1ULL << AV_CHAN_TOP_SIDE_RIGHT)
#define AV_CH_BOTTOM_FRONT_CENTER (1ULL << AV_CHAN_BOTTOM_FRONT_CENTER)
#define AV_CH_BOTTOM_FRONT_LEFT (1ULL << AV_CHAN_BOTTOM_FRONT_LEFT)
#define AV_CH_BOTTOM_FRONT_RIGHT (1ULL << AV_CHAN_BOTTOM_FRONT_RIGHT)

/**
* @}
* @defgroup channel_mask_c Audio channel layouts
* @{
* */
#define AV_CH_LAYOUT_MONO (AV_CH_FRONT_CENTER)
#define AV_CH_LAYOUT_STEREO (AV_CH_FRONT_LEFT | AV_CH_FRONT_RIGHT)
#define AV_CH_LAYOUT_2POINT1 (AV_CH_LAYOUT_STEREO | AV_CH_LOW_FREQUENCY)
#define AV_CH_LAYOUT_2_1 (AV_CH_LAYOUT_STEREO | AV_CH_BACK_CENTER)
#define AV_CH_LAYOUT_SURROUND (AV_CH_LAYOUT_STEREO | AV_CH_FRONT_CENTER)
#define AV_CH_LAYOUT_3POINT1 (AV_CH_LAYOUT_SURROUND | AV_CH_LOW_FREQUENCY)
#define AV_CH_LAYOUT_4POINT0 (AV_CH_LAYOUT_SURROUND | AV_CH_BACK_CENTER)
#define AV_CH_LAYOUT_4POINT1 (AV_CH_LAYOUT_4POINT0 | AV_CH_LOW_FREQUENCY)
#define AV_CH_LAYOUT_2_2 \
 (AV_CH_LAYOUT_STEREO | AV_CH_SIDE_LEFT | AV_CH_SIDE_RIGHT)
#define AV_CH_LAYOUT_QUAD \
 (AV_CH_LAYOUT_STEREO | AV_CH_BACK_LEFT | AV_CH_BACK_RIGHT)
#define AV_CH_LAYOUT_5POINT0 \
 (AV_CH_LAYOUT_SURROUND | AV_CH_SIDE_LEFT | AV_CH_SIDE_RIGHT)
#define AV_CH_LAYOUT_5POINT1 (AV_CH_LAYOUT_5POINT0 | AV_CH_LOW_FREQUENCY)
#define AV_CH_LAYOUT_5POINT0_BACK \
 (AV_CH_LAYOUT_SURROUND | AV_CH_BACK_LEFT | AV_CH_BACK_RIGHT)
#define AV_CH_LAYOUT_5POINT1_BACK \
 (AV_CH_LAYOUT_5POINT0_BACK | AV_CH_LOW_FREQUENCY)
#define AV_CH_LAYOUT_6POINT0 (AV_CH_LAYOUT_5POINT0 | AV_CH_BACK_CENTER)
#define AV_CH_LAYOUT_6POINT0_FRONT \
 (AV_CH_LAYOUT_2_2 | AV_CH_FRONT_LEFT_OF_CENTER | AV_CH_FRONT_RIGHT_OF_CENTER)
#define AV_CH_LAYOUT_HEXAGONAL (AV_CH_LAYOUT_5POINT0_BACK | AV_CH_BACK_CENTER)
#define AV_CH_LAYOUT_3POINT1POINT2 \
 (AV_CH_LAYOUT_3POINT1 | AV_CH_TOP_FRONT_LEFT | AV_CH_TOP_FRONT_RIGHT)
#define AV_CH_LAYOUT_6POINT1 (AV_CH_LAYOUT_5POINT1 | AV_CH_BACK_CENTER)
#define AV_CH_LAYOUT_6POINT1_BACK \
 (AV_CH_LAYOUT_5POINT1_BACK | AV_CH_BACK_CENTER)
#define AV_CH_LAYOUT_6POINT1_FRONT \
 (AV_CH_LAYOUT_6POINT0_FRONT | AV_CH_LOW_FREQUENCY)
#define AV_CH_LAYOUT_7POINT0 \
 (AV_CH_LAYOUT_5POINT0 | AV_CH_BACK_LEFT | AV_CH_BACK_RIGHT)
#define AV_CH_LAYOUT_7POINT0_FRONT                     \
 (AV_CH_LAYOUT_5POINT0 | AV_CH_FRONT_LEFT_OF_CENTER | \
  AV_CH_FRONT_RIGHT_OF_CENTER)
#define AV_CH_LAYOUT_7POINT1 \
 (AV_CH_LAYOUT_5POINT1 | AV_CH_BACK_LEFT | AV_CH_BACK_RIGHT)
#define AV_CH_LAYOUT_7POINT1_WIDE                      \
 (AV_CH_LAYOUT_5POINT1 | AV_CH_FRONT_LEFT_OF_CENTER | \
  AV_CH_FRONT_RIGHT_OF_CENTER)
#define AV_CH_LAYOUT_7POINT1_WIDE_BACK                      \
 (AV_CH_LAYOUT_5POINT1_BACK | AV_CH_FRONT_LEFT_OF_CENTER | \
  AV_CH_FRONT_RIGHT_OF_CENTER)
#define AV_CH_LAYOUT_5POINT1POINT2_BACK \
 (AV_CH_LAYOUT_5POINT1_BACK | AV_CH_TOP_FRONT_LEFT | AV_CH_TOP_FRONT_RIGHT)
#define AV_CH_LAYOUT_OCTAGONAL                                  \
 (AV_CH_LAYOUT_5POINT0 | AV_CH_BACK_LEFT | AV_CH_BACK_CENTER | \
  AV_CH_BACK_RIGHT)
#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)
#define AV_CH_LAYOUT_5POINT1POINT4_BACK \
 (AV_CH_LAYOUT_5POINT1POINT2_BACK | AV_CH_TOP_BACK_LEFT | AV_CH_TOP_BACK_RIGHT)
#define AV_CH_LAYOUT_7POINT1POINT2 \
 (AV_CH_LAYOUT_7POINT1 | AV_CH_TOP_FRONT_LEFT | AV_CH_TOP_FRONT_RIGHT)
#define AV_CH_LAYOUT_7POINT1POINT4_BACK \
 (AV_CH_LAYOUT_7POINT1POINT2 | AV_CH_TOP_BACK_LEFT | AV_CH_TOP_BACK_RIGHT)
#define AV_CH_LAYOUT_7POINT2POINT3 \
 (AV_CH_LAYOUT_7POINT1POINT2 | AV_CH_TOP_BACK_CENTER | AV_CH_LOW_FREQUENCY_2)
#define AV_CH_LAYOUT_9POINT1POINT4_BACK                           \
 (AV_CH_LAYOUT_7POINT1POINT4_BACK | AV_CH_FRONT_LEFT_OF_CENTER | \
  AV_CH_FRONT_RIGHT_OF_CENTER)
#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)
#define AV_CH_LAYOUT_STEREO_DOWNMIX (AV_CH_STEREO_LEFT | AV_CH_STEREO_RIGHT)
#define AV_CH_LAYOUT_22POINT2                                                 \
 (AV_CH_LAYOUT_7POINT1POINT4_BACK | AV_CH_FRONT_LEFT_OF_CENTER |             \
  AV_CH_FRONT_RIGHT_OF_CENTER | AV_CH_BACK_CENTER | AV_CH_LOW_FREQUENCY_2 |  \
  AV_CH_TOP_FRONT_CENTER | AV_CH_TOP_CENTER | AV_CH_TOP_SIDE_LEFT |          \
  AV_CH_TOP_SIDE_RIGHT | AV_CH_TOP_BACK_CENTER | AV_CH_BOTTOM_FRONT_CENTER | \
  AV_CH_BOTTOM_FRONT_LEFT | AV_CH_BOTTOM_FRONT_RIGHT)

#define AV_CH_LAYOUT_7POINT1_TOP_BACK AV_CH_LAYOUT_5POINT1POINT2_BACK

enum AVMatrixEncoding {
 AV_MATRIX_ENCODING_NONE,
 AV_MATRIX_ENCODING_DOLBY,
 AV_MATRIX_ENCODING_DPLII,
 AV_MATRIX_ENCODING_DPLIIX,
 AV_MATRIX_ENCODING_DPLIIZ,
 AV_MATRIX_ENCODING_DOLBYEX,
 AV_MATRIX_ENCODING_DOLBYHEADPHONE,
 AV_MATRIX_ENCODING_NB
};

/**
* @}
*/

/**
* An AVChannelCustom defines a single channel within a custom order layout
*
* Unlike most structures in FFmpeg, sizeof(AVChannelCustom) is a part of the
* public ABI.
*
* No new fields may be added to it without a major version bump.
*/
typedef struct AVChannelCustom {
 enum AVChannel id;
 char name[16];
 void* opaque;
} AVChannelCustom;

/**
* An AVChannelLayout holds information about the channel layout of audio data.
*
* A channel layout here is defined as a set of channels ordered in a specific
* way (unless the channel order is AV_CHANNEL_ORDER_UNSPEC, in which case an
* AVChannelLayout carries only the channel count).
* All orders may be treated as if they were AV_CHANNEL_ORDER_UNSPEC by
* ignoring everything but the channel count, as long as
* av_channel_layout_check() considers they are valid.
*
* Unlike most structures in FFmpeg, sizeof(AVChannelLayout) is a part of the
* public ABI and may be used by the caller. E.g. it may be allocated on stack
* or embedded in caller-defined structs.
*
* AVChannelLayout can be initialized as follows:
* - default initialization with {0}, followed by setting all used fields
*   correctly;
* - by assigning one of the predefined AV_CHANNEL_LAYOUT_* initializers;
* - with a constructor function, such as av_channel_layout_default(),
*   av_channel_layout_from_mask() or av_channel_layout_from_string().
*
* The channel layout must be unitialized with av_channel_layout_uninit()
*
* Copying an AVChannelLayout via assigning is forbidden,
* av_channel_layout_copy() must be used instead (and its return value should
* be checked)
*
* No new fields may be added to it without a major version bump, except for
* new elements of the union fitting in sizeof(uint64_t).
*/
typedef struct AVChannelLayout {
 /**
  * Channel order used in this layout.
  * This is a mandatory field.
  */
 enum AVChannelOrder order;

 /**
  * Number of channels in this layout. Mandatory field.
  */
 int nb_channels;

 /**
  * Details about which channels are present in this layout.
  * For AV_CHANNEL_ORDER_UNSPEC, this field is undefined and must not be
  * used.
  */
 union {
   /**
    * This member must be used for AV_CHANNEL_ORDER_NATIVE, and may be used
    * for AV_CHANNEL_ORDER_AMBISONIC to signal non-diegetic channels.
    * It is a bitmask, where the position of each set bit means that the
    * AVChannel with the corresponding value is present.
    *
    * I.e. when (mask & (1 << AV_CHAN_FOO)) is non-zero, then AV_CHAN_FOO
    * is present in the layout. Otherwise it is not present.
    *
    * @note when a channel layout using a bitmask is constructed or
    * modified manually (i.e.  not using any of the av_channel_layout_*
    * functions), the code doing it must ensure that the number of set bits
    * is equal to nb_channels.
    */
   uint64_t mask;
   /**
    * This member must be used when the channel order is
    * AV_CHANNEL_ORDER_CUSTOM. It is a nb_channels-sized array, with each
    * element signalling the presence of the AVChannel with the
    * corresponding value in map[i].id.
    *
    * I.e. when map[i].id is equal to AV_CHAN_FOO, then AV_CH_FOO is the
    * i-th channel in the audio data.
    *
    * When map[i].id is in the range between AV_CHAN_AMBISONIC_BASE and
    * AV_CHAN_AMBISONIC_END (inclusive), the channel contains an ambisonic
    * component with ACN index (as defined above)
    * n = map[i].id - AV_CHAN_AMBISONIC_BASE.
    *
    * map[i].name may be filled with a 0-terminated string, in which case
    * it will be used for the purpose of identifying the channel with the
    * convenience functions below. Otherise it must be zeroed.
    */
   AVChannelCustom* map;
 } u;

 /**
  * For some private data of the user.
  */
 void* opaque;
} AVChannelLayout;

/**
* Macro to define native channel layouts
*
* @note This doesn't use designated initializers for compatibility with C++ 17
* and older.
*/
#define AV_CHANNEL_LAYOUT_MASK(nb, m)                                    \
 { /* .order */                                                         \
   AV_CHANNEL_ORDER_NATIVE, /* .nb_channels */ (nb), /* .u.mask */ {m}, \
       /* .opaque */ NULL                                               \
 }

/**
* @name Common pre-defined channel layouts
* @{
*/
#define AV_CHANNEL_LAYOUT_MONO AV_CHANNEL_LAYOUT_MASK(1, AV_CH_LAYOUT_MONO)
#define AV_CHANNEL_LAYOUT_STEREO AV_CHANNEL_LAYOUT_MASK(2, AV_CH_LAYOUT_STEREO)
#define AV_CHANNEL_LAYOUT_2POINT1 \
 AV_CHANNEL_LAYOUT_MASK(3, AV_CH_LAYOUT_2POINT1)
#define AV_CHANNEL_LAYOUT_2_1 AV_CHANNEL_LAYOUT_MASK(3, AV_CH_LAYOUT_2_1)
#define AV_CHANNEL_LAYOUT_SURROUND \
 AV_CHANNEL_LAYOUT_MASK(3, AV_CH_LAYOUT_SURROUND)
#define AV_CHANNEL_LAYOUT_3POINT1 \
 AV_CHANNEL_LAYOUT_MASK(4, AV_CH_LAYOUT_3POINT1)
#define AV_CHANNEL_LAYOUT_4POINT0 \
 AV_CHANNEL_LAYOUT_MASK(4, AV_CH_LAYOUT_4POINT0)
#define AV_CHANNEL_LAYOUT_4POINT1 \
 AV_CHANNEL_LAYOUT_MASK(5, AV_CH_LAYOUT_4POINT1)
#define AV_CHANNEL_LAYOUT_2_2 AV_CHANNEL_LAYOUT_MASK(4, AV_CH_LAYOUT_2_2)
#define AV_CHANNEL_LAYOUT_QUAD AV_CHANNEL_LAYOUT_MASK(4, AV_CH_LAYOUT_QUAD)
#define AV_CHANNEL_LAYOUT_5POINT0 \
 AV_CHANNEL_LAYOUT_MASK(5, AV_CH_LAYOUT_5POINT0)
#define AV_CHANNEL_LAYOUT_5POINT1 \
 AV_CHANNEL_LAYOUT_MASK(6, AV_CH_LAYOUT_5POINT1)
#define AV_CHANNEL_LAYOUT_5POINT0_BACK \
 AV_CHANNEL_LAYOUT_MASK(5, AV_CH_LAYOUT_5POINT0_BACK)
#define AV_CHANNEL_LAYOUT_5POINT1_BACK \
 AV_CHANNEL_LAYOUT_MASK(6, AV_CH_LAYOUT_5POINT1_BACK)
#define AV_CHANNEL_LAYOUT_6POINT0 \
 AV_CHANNEL_LAYOUT_MASK(6, AV_CH_LAYOUT_6POINT0)
#define AV_CHANNEL_LAYOUT_6POINT0_FRONT \
 AV_CHANNEL_LAYOUT_MASK(6, AV_CH_LAYOUT_6POINT0_FRONT)
#define AV_CHANNEL_LAYOUT_3POINT1POINT2 \
 AV_CHANNEL_LAYOUT_MASK(6, AV_CH_LAYOUT_3POINT1POINT2)
#define AV_CHANNEL_LAYOUT_HEXAGONAL \
 AV_CHANNEL_LAYOUT_MASK(6, AV_CH_LAYOUT_HEXAGONAL)
#define AV_CHANNEL_LAYOUT_6POINT1 \
 AV_CHANNEL_LAYOUT_MASK(7, AV_CH_LAYOUT_6POINT1)
#define AV_CHANNEL_LAYOUT_6POINT1_BACK \
 AV_CHANNEL_LAYOUT_MASK(7, AV_CH_LAYOUT_6POINT1_BACK)
#define AV_CHANNEL_LAYOUT_6POINT1_FRONT \
 AV_CHANNEL_LAYOUT_MASK(7, AV_CH_LAYOUT_6POINT1_FRONT)
#define AV_CHANNEL_LAYOUT_7POINT0 \
 AV_CHANNEL_LAYOUT_MASK(7, AV_CH_LAYOUT_7POINT0)
#define AV_CHANNEL_LAYOUT_7POINT0_FRONT \
 AV_CHANNEL_LAYOUT_MASK(7, AV_CH_LAYOUT_7POINT0_FRONT)
#define AV_CHANNEL_LAYOUT_7POINT1 \
 AV_CHANNEL_LAYOUT_MASK(8, AV_CH_LAYOUT_7POINT1)
#define AV_CHANNEL_LAYOUT_7POINT1_WIDE \
 AV_CHANNEL_LAYOUT_MASK(8, AV_CH_LAYOUT_7POINT1_WIDE)
#define AV_CHANNEL_LAYOUT_7POINT1_WIDE_BACK \
 AV_CHANNEL_LAYOUT_MASK(8, AV_CH_LAYOUT_7POINT1_WIDE_BACK)
#define AV_CHANNEL_LAYOUT_5POINT1POINT2_BACK \
 AV_CHANNEL_LAYOUT_MASK(8, AV_CH_LAYOUT_5POINT1POINT2_BACK)
#define AV_CHANNEL_LAYOUT_OCTAGONAL \
 AV_CHANNEL_LAYOUT_MASK(8, AV_CH_LAYOUT_OCTAGONAL)
#define AV_CHANNEL_LAYOUT_CUBE AV_CHANNEL_LAYOUT_MASK(8, AV_CH_LAYOUT_CUBE)
#define AV_CHANNEL_LAYOUT_5POINT1POINT4_BACK \
 AV_CHANNEL_LAYOUT_MASK(10, AV_CH_LAYOUT_5POINT1POINT4_BACK)
#define AV_CHANNEL_LAYOUT_7POINT1POINT2 \
 AV_CHANNEL_LAYOUT_MASK(10, AV_CH_LAYOUT_7POINT1POINT2)
#define AV_CHANNEL_LAYOUT_7POINT1POINT4_BACK \
 AV_CHANNEL_LAYOUT_MASK(12, AV_CH_LAYOUT_7POINT1POINT4_BACK)
#define AV_CHANNEL_LAYOUT_7POINT2POINT3 \
 AV_CHANNEL_LAYOUT_MASK(12, AV_CH_LAYOUT_7POINT2POINT3)
#define AV_CHANNEL_LAYOUT_9POINT1POINT4_BACK \
 AV_CHANNEL_LAYOUT_MASK(14, AV_CH_LAYOUT_9POINT1POINT4_BACK)
#define AV_CHANNEL_LAYOUT_HEXADECAGONAL \
 AV_CHANNEL_LAYOUT_MASK(16, AV_CH_LAYOUT_HEXADECAGONAL)
#define AV_CHANNEL_LAYOUT_STEREO_DOWNMIX \
 AV_CHANNEL_LAYOUT_MASK(2, AV_CH_LAYOUT_STEREO_DOWNMIX)
#define AV_CHANNEL_LAYOUT_22POINT2 \
 AV_CHANNEL_LAYOUT_MASK(24, AV_CH_LAYOUT_22POINT2)

#define AV_CHANNEL_LAYOUT_7POINT1_TOP_BACK AV_CHANNEL_LAYOUT_5POINT1POINT2_BACK

#define AV_CHANNEL_LAYOUT_AMBISONIC_FIRST_ORDER                          \
 { /* .order */                                                         \
   AV_CHANNEL_ORDER_AMBISONIC, /* .nb_channels */ 4, /* .u.mask */ {0}, \
       /* .opaque */ NULL                                               \
 }
/** @} */

struct AVBPrint;

/**
* Get a human readable string in an abbreviated form describing a given
* channel. This is the inverse function of @ref av_channel_from_string().
*
* @param buf pre-allocated buffer where to put the generated string
* @param buf_size size in bytes of the buffer.
* @param channel the AVChannel whose name to get
* @return amount of bytes needed to hold the output string, or a negative
* AVERROR on failure. If the returned value is bigger than buf_size, then the
*         string was truncated.
*/
int av_channel_name(char* buf, size_t buf_size, enum AVChannel channel);

/**
* bprint variant of av_channel_name().
*
* @note the string will be appended to the bprint buffer.
*/
void av_channel_name_bprint(struct AVBPrint* bp, enum AVChannel channel_id);

/**
* Get a human readable string describing a given channel.
*
* @param buf pre-allocated buffer where to put the generated string
* @param buf_size size in bytes of the buffer.
* @param channel the AVChannel whose description to get
* @return amount of bytes needed to hold the output string, or a negative
* AVERROR on failure. If the returned value is bigger than buf_size, then the
*         string was truncated.
*/
int av_channel_description(char* buf, size_t buf_size, enum AVChannel channel);

/**
* bprint variant of av_channel_description().
*
* @note the string will be appended to the bprint buffer.
*/
void av_channel_description_bprint(struct AVBPrint* bp,
                                  enum AVChannel channel_id);

/**
* This is the inverse function of @ref av_channel_name().
*
* @return the channel with the given name
*         AV_CHAN_NONE when name does not identify a known channel
*/
enum AVChannel av_channel_from_string(const char* name);

/**
* Initialize a custom channel layout with the specified number of channels.
* The channel map will be allocated and the designation of all channels will
* be set to AV_CHAN_UNKNOWN.
*
* This is only a convenience helper function, a custom channel layout can also
* be constructed without using this.
*
* @param channel_layout the layout structure to be initialized
* @param nb_channels the number of channels
*
* @return 0 on success
*         AVERROR(EINVAL) if the number of channels <= 0
*         AVERROR(ENOMEM) if the channel map could not be allocated
*/
int av_channel_layout_custom_init(AVChannelLayout* channel_layout,
                                 int nb_channels);

/**
* Initialize a native channel layout from a bitmask indicating which channels
* are present.
*
* @param channel_layout the layout structure to be initialized
* @param mask bitmask describing the channel layout
*
* @return 0 on success
*         AVERROR(EINVAL) for invalid mask values
*/
int av_channel_layout_from_mask(AVChannelLayout* channel_layout, uint64_t mask);

/**
* Initialize a channel layout from a given string description.
* The input string can be represented by:
*  - the formal channel layout name (returned by av_channel_layout_describe())
*  - single or multiple channel names (returned by av_channel_name(), eg. "FL",
*    or concatenated with "+", each optionally containing a custom name after
*    a "@", eg. "FL@Left+FR@Right+LFE")
*  - a decimal or hexadecimal value of a native channel layout (eg. "4" or
* "0x4")
*  - the number of channels with default layout (eg. "4c")
*  - the number of unordered channels (eg. "4C" or "4 channels")
*  - the ambisonic order followed by optional non-diegetic channels (eg.
*    "ambisonic 2+stereo")
* On error, the channel layout will remain uninitialized, but not necessarily
* untouched.
*
* @param channel_layout uninitialized channel layout for the result
* @param str string describing the channel layout
* @return 0 on success parsing the channel layout
*         AVERROR(EINVAL) if an invalid channel layout string was provided
*         AVERROR(ENOMEM) if there was not enough memory
*/
int av_channel_layout_from_string(AVChannelLayout* channel_layout,
                                 const char* str);

/**
* Get the default channel layout for a given number of channels.
*
* @param ch_layout the layout structure to be initialized
* @param nb_channels number of channels
*/
void av_channel_layout_default(AVChannelLayout* ch_layout, int nb_channels);

/**
* Iterate over all standard channel layouts.
*
* @param opaque a pointer where libavutil will store the iteration state. Must
*               point to NULL to start the iteration.
*
* @return the standard channel layout or NULL when the iteration is
*         finished
*/
const AVChannelLayout* av_channel_layout_standard(void** opaque);

/**
* Free any allocated data in the channel layout and reset the channel
* count to 0.
*
* @param channel_layout the layout structure to be uninitialized
*/
void av_channel_layout_uninit(AVChannelLayout* channel_layout);

/**
* Make a copy of a channel layout. This differs from just assigning src to dst
* in that it allocates and copies the map for AV_CHANNEL_ORDER_CUSTOM.
*
* @note the destination channel_layout will be always uninitialized before
* copy.
*
* @param dst destination channel layout
* @param src source channel layout
* @return 0 on success, a negative AVERROR on error.
*/
int av_channel_layout_copy(AVChannelLayout* dst, const AVChannelLayout* src);

/**
* Get a human-readable string describing the channel layout properties.
* The string will be in the same format that is accepted by
* @ref av_channel_layout_from_string(), allowing to rebuild the same
* channel layout, except for opaque pointers.
*
* @param channel_layout channel layout to be described
* @param buf pre-allocated buffer where to put the generated string
* @param buf_size size in bytes of the buffer.
* @return amount of bytes needed to hold the output string, or a negative
* AVERROR on failure. If the returned value is bigger than buf_size, then the
*         string was truncated.
*/
int av_channel_layout_describe(const AVChannelLayout* channel_layout, char* buf,
                              size_t buf_size);

/**
* bprint variant of av_channel_layout_describe().
*
* @note the string will be appended to the bprint buffer.
* @return 0 on success, or a negative AVERROR value on failure.
*/
int av_channel_layout_describe_bprint(const AVChannelLayout* channel_layout,
                                     struct AVBPrint* bp);

/**
* Get the channel with the given index in a channel layout.
*
* @param channel_layout input channel layout
* @param idx index of the channel
* @return channel with the index idx in channel_layout on success or
*         AV_CHAN_NONE on failure (if idx is not valid or the channel order is
*         unspecified)
*/
enum AVChannel av_channel_layout_channel_from_index(
   const AVChannelLayout* channel_layout, unsigned int idx);

/**
* Get the index of a given channel in a channel layout. In case multiple
* channels are found, only the first match will be returned.
*
* @param channel_layout input channel layout
* @param channel the channel whose index to obtain
* @return index of channel in channel_layout on success or a negative number if
*         channel is not present in channel_layout.
*/
int av_channel_layout_index_from_channel(const AVChannelLayout* channel_layout,
                                        enum AVChannel channel);

/**
* Get the index in a channel layout of a channel described by the given string.
* In case multiple channels are found, only the first match will be returned.
*
* This function accepts channel names in the same format as
* @ref av_channel_from_string().
*
* @param channel_layout input channel layout
* @param name string describing the channel whose index to obtain
* @return a channel index described by the given string, or a negative AVERROR
*         value.
*/
int av_channel_layout_index_from_string(const AVChannelLayout* channel_layout,
                                       const char* name);

/**
* Get a channel described by the given string.
*
* This function accepts channel names in the same format as
* @ref av_channel_from_string().
*
* @param channel_layout input channel layout
* @param name string describing the channel to obtain
* @return a channel described by the given string in channel_layout on success
*         or AV_CHAN_NONE on failure (if the string is not valid or the channel
*         order is unspecified)
*/
enum AVChannel av_channel_layout_channel_from_string(
   const AVChannelLayout* channel_layout, const char* name);

/**
* Find out what channels from a given set are present in a channel layout,
* without regard for their positions.
*
* @param channel_layout input channel layout
* @param mask a combination of AV_CH_* representing a set of channels
* @return a bitfield representing all the channels from mask that are present
*         in channel_layout
*/
uint64_t av_channel_layout_subset(const AVChannelLayout* channel_layout,
                                 uint64_t mask);

/**
* Check whether a channel layout is valid, i.e. can possibly describe audio
* data.
*
* @param channel_layout input channel layout
* @return 1 if channel_layout is valid, 0 otherwise.
*/
int av_channel_layout_check(const AVChannelLayout* channel_layout);

/**
* Check whether two channel layouts are semantically the same, i.e. the same
* channels are present on the same positions in both.
*
* If one of the channel layouts is AV_CHANNEL_ORDER_UNSPEC, while the other is
* not, they are considered to be unequal. If both are AV_CHANNEL_ORDER_UNSPEC,
* they are considered equal iff the channel counts are the same in both.
*
* @param chl input channel layout
* @param chl1 input channel layout
* @return 0 if chl and chl1 are equal, 1 if they are not equal. A negative
*         AVERROR code if one or both are invalid.
*/
int av_channel_layout_compare(const AVChannelLayout* chl,
                             const AVChannelLayout* chl1);

/**
* The conversion must be lossless.
*/
#define AV_CHANNEL_LAYOUT_RETYPE_FLAG_LOSSLESS (1 << 0)

/**
* The specified retype target order is ignored and the simplest possible
* (canonical) order is used for which the input layout can be losslessy
* represented.
*/
#define AV_CHANNEL_LAYOUT_RETYPE_FLAG_CANONICAL (1 << 1)

/**
* Change the AVChannelOrder of a channel layout.
*
* Change of AVChannelOrder can be either lossless or lossy. In case of a
* lossless conversion all the channel designations and the associated channel
* names (if any) are kept. On a lossy conversion the channel names and channel
* designations might be lost depending on the capabilities of the desired
* AVChannelOrder. Note that some conversions are simply not possible in which
* case this function returns AVERROR(ENOSYS).
*
* The following conversions are supported:
*
* Any       -> Custom     : Always possible, always lossless.
* Any       -> Unspecified: Always possible, lossless if channel designations
*   are all unknown and channel names are not used, lossy otherwise.
* Custom    -> Ambisonic  : Possible if it contains ambisonic channels with
*   optional non-diegetic channels in the end. Lossy if the channels have
*   custom names, lossless otherwise.
* Custom    -> Native     : Possible if it contains native channels in native
*     order. Lossy if the channels have custom names, lossless otherwise.
*
* On error this function keeps the original channel layout untouched.
*
* @param channel_layout channel layout which will be changed
* @param order the desired channel layout order
* @param flags a combination of AV_CHANNEL_LAYOUT_RETYPE_FLAG_* constants
* @return 0 if the conversion was successful and lossless or if the channel
*           layout was already in the desired order
*         >0 if the conversion was successful but lossy
*         AVERROR(ENOSYS) if the conversion was not possible (or would be
*           lossy and AV_CHANNEL_LAYOUT_RETYPE_FLAG_LOSSLESS was specified)
*         AVERROR(EINVAL), AVERROR(ENOMEM) on error
*/
int av_channel_layout_retype(AVChannelLayout* channel_layout,
                            enum AVChannelOrder order, int flags);

/**
* @}
*/

#endif /* AVUTIL_CHANNEL_LAYOUT_H */