/*

 * Copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>

 *

 * 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

 */

/**

 * @file

 * audio channel layout utility functions

 */

#include <stdint.h>

#include <stdlib.h>

#include <string.h>

#include "avassert.h"

#include "channel_layout.h"

#include "bprint.h"

#include "common.h"

#include "error.h"

#include "attributes.h"

#include "macros.h"

#include "mem.h"

#include "opt.h"

#define CHAN_IS_AMBI(x) ((x) >= AV_CHAN_AMBISONIC_BASE &&\

                         (x) <= AV_CHAN_AMBISONIC_END)

struct channel_name {

    const char *name;

    const char *description;

};

static const struct channel_name channel_names[] = {

    [AV_CHAN_FRONT_LEFT           ] = { "FL",        "front left"            },

    [AV_CHAN_FRONT_RIGHT          ] = { "FR",        "front right"           },

    [AV_CHAN_FRONT_CENTER         ] = { "FC",        "front center"          },

    [AV_CHAN_LOW_FREQUENCY        ] = { "LFE",       "low frequency"         },

    [AV_CHAN_BACK_LEFT            ] = { "BL",        "back left"             },

    [AV_CHAN_BACK_RIGHT           ] = { "BR",        "back right"            },

    [AV_CHAN_FRONT_LEFT_OF_CENTER ] = { "FLC",       "front left-of-center"  },

    [AV_CHAN_FRONT_RIGHT_OF_CENTER] = { "FRC",       "front right-of-center" },

    [AV_CHAN_BACK_CENTER          ] = { "BC",        "back center"           },

    [AV_CHAN_SIDE_LEFT            ] = { "SL",        "side left"             },

    [AV_CHAN_SIDE_RIGHT           ] = { "SR",        "side right"            },

    [AV_CHAN_TOP_CENTER           ] = { "TC",        "top center"            },

    [AV_CHAN_TOP_FRONT_LEFT       ] = { "TFL",       "top front left"        },

    [AV_CHAN_TOP_FRONT_CENTER     ] = { "TFC",       "top front center"      },

    [AV_CHAN_TOP_FRONT_RIGHT      ] = { "TFR",       "top front right"       },

    [AV_CHAN_TOP_BACK_LEFT        ] = { "TBL",       "top back left"         },

    [AV_CHAN_TOP_BACK_CENTER      ] = { "TBC",       "top back center"       },

    [AV_CHAN_TOP_BACK_RIGHT       ] = { "TBR",       "top back right"        },

    [AV_CHAN_STEREO_LEFT          ] = { "DL",        "downmix left"          },

    [AV_CHAN_STEREO_RIGHT         ] = { "DR",        "downmix right"         },

    [AV_CHAN_WIDE_LEFT            ] = { "WL",        "wide left"             },

    [AV_CHAN_WIDE_RIGHT           ] = { "WR",        "wide right"            },

    [AV_CHAN_SURROUND_DIRECT_LEFT ] = { "SDL",       "surround direct left"  },

    [AV_CHAN_SURROUND_DIRECT_RIGHT] = { "SDR",       "surround direct right" },

    [AV_CHAN_LOW_FREQUENCY_2      ] = { "LFE2",      "low frequency 2"       },

    [AV_CHAN_TOP_SIDE_LEFT        ] = { "TSL",       "top side left"         },

    [AV_CHAN_TOP_SIDE_RIGHT       ] = { "TSR",       "top side right"        },

    [AV_CHAN_BOTTOM_FRONT_CENTER  ] = { "BFC",       "bottom front center"   },

    [AV_CHAN_BOTTOM_FRONT_LEFT    ] = { "BFL",       "bottom front left"     },

    [AV_CHAN_BOTTOM_FRONT_RIGHT   ] = { "BFR",       "bottom front right"    },

    [AV_CHAN_SIDE_SURROUND_LEFT   ] = { "SSL",       "side surround left"    },

    [AV_CHAN_SIDE_SURROUND_RIGHT  ] = { "SSR",       "side surround right"   },

    [AV_CHAN_TOP_SURROUND_LEFT    ] = { "TTL",       "top surround left"     },

    [AV_CHAN_TOP_SURROUND_RIGHT   ] = { "TTR",       "top surround right"    },

    [AV_CHAN_BINAURAL_LEFT        ] = { "BIL",       "binaural left"         },

    [AV_CHAN_BINAURAL_RIGHT       ] = { "BIR",       "binaural right"        },

};

void av_channel_name_bprint(AVBPrint *bp, enum AVChannel channel_id)

{

    if (channel_id >= AV_CHAN_AMBISONIC_BASE &&

        channel_id <= AV_CHAN_AMBISONIC_END)

        av_bprintf(bp, "AMBI%d", channel_id - AV_CHAN_AMBISONIC_BASE);

    else if ((unsigned)channel_id < FF_ARRAY_ELEMS(channel_names) &&

             channel_names[channel_id].name)

        av_bprintf(bp, "%s", channel_names[channel_id].name);

    else if (channel_id == AV_CHAN_NONE)

        av_bprintf(bp, "NONE");

    else if (channel_id == AV_CHAN_UNKNOWN)

        av_bprintf(bp, "UNK");

    else if (channel_id == AV_CHAN_UNUSED)

        av_bprintf(bp, "UNSD");

    else

        av_bprintf(bp, "USR%d", channel_id);

}

int av_channel_name(char *buf, size_t buf_size, enum AVChannel channel_id)

{

    AVBPrint bp;

    if (!buf && buf_size)

        return AVERROR(EINVAL);

    av_bprint_init_for_buffer(&bp, buf, buf_size);

    av_channel_name_bprint(&bp, channel_id);

    if (bp.len >= INT_MAX)

        return AVERROR(ERANGE);

    return bp.len + 1;

}

void av_channel_description_bprint(AVBPrint *bp, enum AVChannel channel_id)

{

    if (channel_id >= AV_CHAN_AMBISONIC_BASE &&

        channel_id <= AV_CHAN_AMBISONIC_END)

        av_bprintf(bp, "ambisonic ACN %d", channel_id - AV_CHAN_AMBISONIC_BASE);

    else if ((unsigned)channel_id < FF_ARRAY_ELEMS(channel_names) &&

             channel_names[channel_id].description)

        av_bprintf(bp, "%s", channel_names[channel_id].description);

    else if (channel_id == AV_CHAN_NONE)

        av_bprintf(bp, "none");

    else if (channel_id == AV_CHAN_UNKNOWN)

        av_bprintf(bp, "unknown");

    else if (channel_id == AV_CHAN_UNUSED)

        av_bprintf(bp, "unused");

    else

        av_bprintf(bp, "user %d", channel_id);

}

int av_channel_description(char *buf, size_t buf_size, enum AVChannel channel_id)

{

    AVBPrint bp;

    if (!buf && buf_size)

        return AVERROR(EINVAL);

    av_bprint_init_for_buffer(&bp, buf, buf_size);

    av_channel_description_bprint(&bp, channel_id);

    if (bp.len >= INT_MAX)

        return AVERROR(ERANGE);

    return bp.len + 1;

}

enum AVChannel av_channel_from_string(const char *str)

{

    int i;

    char *endptr = (char *)str;

    enum AVChannel id = AV_CHAN_NONE;

    if (!strncmp(str, "AMBI", 4)) {

        i = strtol(str + 4, NULL, 0);

        if (i < 0 || i > AV_CHAN_AMBISONIC_END - AV_CHAN_AMBISONIC_BASE)

            return AV_CHAN_NONE;

        return AV_CHAN_AMBISONIC_BASE + i;

    }

    for (i = 0; i < FF_ARRAY_ELEMS(channel_names); i++) {

        if (channel_names[i].name && !strcmp(str, channel_names[i].name))

            return i;

    }

    if (!strcmp(str, "UNK"))

        return AV_CHAN_UNKNOWN;

    if (!strcmp(str, "UNSD"))

        return AV_CHAN_UNUSED;

    if (!strncmp(str, "USR", 3)) {

        const char *p = str + 3;

        id = strtol(p, &endptr, 0);

    }

    if (id >= 0 && !*endptr)

        return id;

    return AV_CHAN_NONE;

}

struct channel_layout_name {

    const char *name;

    AVChannelLayout layout;

};

static const struct channel_layout_name channel_layout_map[] = {

    { "mono",           AV_CHANNEL_LAYOUT_MONO                },

    { "stereo",         AV_CHANNEL_LAYOUT_STEREO              },

    { "2.1",            AV_CHANNEL_LAYOUT_2POINT1             },

    { "3.0",            AV_CHANNEL_LAYOUT_SURROUND            },

    { "3.0(back)",      AV_CHANNEL_LAYOUT_2_1                 },

    { "4.0",            AV_CHANNEL_LAYOUT_4POINT0             },

    { "quad",           AV_CHANNEL_LAYOUT_QUAD                },

    { "quad(side)",     AV_CHANNEL_LAYOUT_2_2                 },

    { "3.1",            AV_CHANNEL_LAYOUT_3POINT1             },

    { "5.0",            AV_CHANNEL_LAYOUT_5POINT0_BACK        },

    { "5.0(side)",      AV_CHANNEL_LAYOUT_5POINT0             },

    { "4.1",            AV_CHANNEL_LAYOUT_4POINT1             },

    { "5.1",            AV_CHANNEL_LAYOUT_5POINT1_BACK        },

    { "5.1(side)",      AV_CHANNEL_LAYOUT_5POINT1             },

    { "6.0",            AV_CHANNEL_LAYOUT_6POINT0             },

    { "6.0(front)",     AV_CHANNEL_LAYOUT_6POINT0_FRONT       },

    { "3.1.2",          AV_CHANNEL_LAYOUT_3POINT1POINT2       },

    { "hexagonal",      AV_CHANNEL_LAYOUT_HEXAGONAL           },

    { "6.1",            AV_CHANNEL_LAYOUT_6POINT1             },

    { "6.1(back)",      AV_CHANNEL_LAYOUT_6POINT1_BACK        },

    { "6.1(front)",     AV_CHANNEL_LAYOUT_6POINT1_FRONT       },

    { "7.0",            AV_CHANNEL_LAYOUT_7POINT0             },

    { "7.0(front)",     AV_CHANNEL_LAYOUT_7POINT0_FRONT       },

    { "7.1",            AV_CHANNEL_LAYOUT_7POINT1             },

    { "7.1(wide)",      AV_CHANNEL_LAYOUT_7POINT1_WIDE_BACK   },

    { "7.1(wide-side)", AV_CHANNEL_LAYOUT_7POINT1_WIDE        },

    { "5.1.2",          AV_CHANNEL_LAYOUT_5POINT1POINT2       },

    { "5.1.2(back)",    AV_CHANNEL_LAYOUT_5POINT1POINT2_BACK  },

    { "octagonal",      AV_CHANNEL_LAYOUT_OCTAGONAL           },

    { "cube",           AV_CHANNEL_LAYOUT_CUBE                },

    { "5.1.4",          AV_CHANNEL_LAYOUT_5POINT1POINT4       },

    { "5.1.6",          AV_CHANNEL_LAYOUT_5POINT1POINT6       },

    { "7.1.2",          AV_CHANNEL_LAYOUT_7POINT1POINT2       },

    { "7.1.4",          AV_CHANNEL_LAYOUT_7POINT1POINT4       },

    { "7.1.6",          AV_CHANNEL_LAYOUT_7POINT1POINT6       },

    { "7.2.3",          AV_CHANNEL_LAYOUT_7POINT2POINT3       },

    { "9.1.4",          AV_CHANNEL_LAYOUT_9POINT1POINT4       },

    { "9.1.6",          AV_CHANNEL_LAYOUT_9POINT1POINT6       },

    { "hexadecagonal",  AV_CHANNEL_LAYOUT_HEXADECAGONAL       },

    { "binaural",       AV_CHANNEL_LAYOUT_BINAURAL            },

    { "downmix",        AV_CHANNEL_LAYOUT_STEREO_DOWNMIX,     },

    { "22.2",           AV_CHANNEL_LAYOUT_22POINT2,           },

};

int av_channel_layout_custom_init(AVChannelLayout *channel_layout, int nb_channels)

{

    AVChannelCustom *map;

    if (nb_channels <= 0)

        return AVERROR(EINVAL);

    map = av_calloc(nb_channels, sizeof(*channel_layout->u.map));

    if (!map)

        return AVERROR(ENOMEM);

    for (int i = 0; i < nb_channels; i++)

        map[i].id = AV_CHAN_UNKNOWN;

    channel_layout->order       = AV_CHANNEL_ORDER_CUSTOM;

    channel_layout->nb_channels = nb_channels;

    channel_layout->u.map       = map;

    return 0;

}

int av_channel_layout_from_mask(AVChannelLayout *channel_layout,

                                uint64_t mask)

{

    if (!mask)

        return AVERROR(EINVAL);

    channel_layout->order       = AV_CHANNEL_ORDER_NATIVE;

    channel_layout->nb_channels = av_popcount64(mask);

    channel_layout->u.mask      = mask;

    return 0;

}

static int parse_channel_list(AVChannelLayout *ch_layout, const char *str)

{

    int ret;

    int nb_channels = 0;

    AVChannelCustom *map = NULL;

    AVChannelCustom custom = {0};

    while (*str) {

        char *channel, *chname;

        ret = av_opt_get_key_value(&str, "@", "+", AV_OPT_FLAG_IMPLICIT_KEY, &channel, &chname);

        if (ret < 0) {

            av_freep(&map);

            return ret;

        }

        if (*str)

            str++; // skip separator

        if (!channel) {

            channel = chname;

            chname = NULL;

        }

        av_strlcpy(custom.name, chname ? chname : "", sizeof(custom.name));

        custom.id = av_channel_from_string(channel);

        av_free(channel);

        av_free(chname);

        if (custom.id == AV_CHAN_NONE) {

            av_freep(&map);

            return AVERROR(EINVAL);

        }

        av_dynarray2_add((void **)&map, &nb_channels, sizeof(custom), (void *)&custom);

        if (!map)

            return AVERROR(ENOMEM);

    }

    if (!nb_channels)

        return AVERROR(EINVAL);

    ch_layout->order = AV_CHANNEL_ORDER_CUSTOM;

    ch_layout->u.map = map;

    ch_layout->nb_channels = nb_channels;

    ret = av_channel_layout_retype(ch_layout, 0, AV_CHANNEL_LAYOUT_RETYPE_FLAG_CANONICAL);

    av_assert0(ret == 0);

    return 0;

}

int av_channel_layout_from_string(AVChannelLayout *channel_layout,

                                  const char *str)

{

    int i, matches, ret;

    int channels = 0, nb_channels = 0;

    char *chlist, *end;

    uint64_t mask = 0;

    /* channel layout names */

    for (i = 0; i < FF_ARRAY_ELEMS(channel_layout_map); i++) {

        if (channel_layout_map[i].name && !strcmp(str, channel_layout_map[i].name)) {

            *channel_layout = channel_layout_map[i].layout;

            return 0;

        }

    }

    /* This function is a channel layout initializer, so we have to

     * zero-initialize before we start setting fields individually. */

    memset(channel_layout, 0, sizeof(*channel_layout));

    /* ambisonic */

    if (!strncmp(str, "ambisonic ", 10)) {

        const char *p = str + 10;

        char *endptr;

        AVChannelLayout extra = {0};

        int order;

        order = strtol(p, &endptr, 0);

        if (order < 0 || order + 1  > INT_MAX / (order + 1) ||

            (*endptr && *endptr != '+'))

            return AVERROR(EINVAL);

        channel_layout->order       = AV_CHANNEL_ORDER_AMBISONIC;

        channel_layout->nb_channels = (order + 1) * (order + 1);

        if (*endptr) {

            ret = av_channel_layout_from_string(&extra, endptr + 1);

            if (ret < 0)

                return ret;

            if (extra.nb_channels >= INT_MAX - channel_layout->nb_channels) {

                av_channel_layout_uninit(&extra);

                return AVERROR(EINVAL);

            }

            if (extra.order == AV_CHANNEL_ORDER_NATIVE) {

                channel_layout->u.mask = extra.u.mask;

            } else {

                channel_layout->order = AV_CHANNEL_ORDER_CUSTOM;

                channel_layout->u.map =

                    av_calloc(channel_layout->nb_channels + extra.nb_channels,

                              sizeof(*channel_layout->u.map));

                if (!channel_layout->u.map) {

                    av_channel_layout_uninit(&extra);

                    return AVERROR(ENOMEM);

                }

                for (i = 0; i < channel_layout->nb_channels; i++)

                    channel_layout->u.map[i].id = AV_CHAN_AMBISONIC_BASE + i;

                for (i = 0; i < extra.nb_channels; i++) {

                    enum AVChannel ch = av_channel_layout_channel_from_index(&extra, i);

                    if (CHAN_IS_AMBI(ch)) {

                        av_channel_layout_uninit(channel_layout);

                        av_channel_layout_uninit(&extra);

                        return AVERROR(EINVAL);

                    }

                    channel_layout->u.map[channel_layout->nb_channels + i].id = ch;

                    if (extra.order == AV_CHANNEL_ORDER_CUSTOM &&

                        extra.u.map[i].name[0])

                        av_strlcpy(channel_layout->u.map[channel_layout->nb_channels + i].name,

                                   extra.u.map[i].name,

                                   sizeof(channel_layout->u.map[channel_layout->nb_channels + i].name));

                }

            }

            channel_layout->nb_channels += extra.nb_channels;

            av_channel_layout_uninit(&extra);

        }

        return 0;

    }

    chlist = av_strdup(str);

    if (!chlist)

        return AVERROR(ENOMEM);

    /* channel names */

    matches = av_sscanf(str, "%d channels (%[^)]", &nb_channels, chlist);

    ret = parse_channel_list(channel_layout, chlist);

    av_freep(&chlist);

    if (ret < 0 && ret != AVERROR(EINVAL))

        return ret;

    if (ret >= 0) {

        const char *end_par = strchr(str, ')');

        if (matches == 2 && (nb_channels != channel_layout->nb_channels || !end_par || *++end_par)) {

            av_channel_layout_uninit(channel_layout);

            return AVERROR(EINVAL);

        }

        return 0;

    }

    errno = 0;

    mask = strtoull(str, &end, 0);

    /* channel layout mask */

    if (!errno && !*end && !strchr(str, '-') && mask) {

        av_channel_layout_from_mask(channel_layout, mask);

        return 0;

    }

    errno = 0;

    channels = strtol(str, &end, 10);

    /* number of channels */

    if (!errno && !strcmp(end, "c") && channels > 0) {

        av_channel_layout_default(channel_layout, channels);

        if (channel_layout->order == AV_CHANNEL_ORDER_NATIVE)

            return 0;

    }

    /* number of unordered channels */

    if (!errno && (!strcmp(end, "C") || !strcmp(end, " channels"))

        && channels > 0) {

        channel_layout->order = AV_CHANNEL_ORDER_UNSPEC;

        channel_layout->nb_channels = channels;

        return 0;

    }

    return AVERROR(EINVAL);

}

void av_channel_layout_uninit(AVChannelLayout *channel_layout)

{

    if (channel_layout->order == AV_CHANNEL_ORDER_CUSTOM)

        av_freep(&channel_layout->u.map);

    memset(channel_layout, 0, sizeof(*channel_layout));

}

int av_channel_layout_copy(AVChannelLayout *dst, const AVChannelLayout *src)

{

    av_channel_layout_uninit(dst);

    *dst = *src;

    if (src->order == AV_CHANNEL_ORDER_CUSTOM) {

        dst->u.map = av_malloc_array(src->nb_channels, sizeof(*dst->u.map));

        if (!dst->u.map)

            return AVERROR(ENOMEM);

        memcpy(dst->u.map, src->u.map, src->nb_channels * sizeof(*src->u.map));

    }

    return 0;

}

static int64_t masked_description(const AVChannelLayout *channel_layout, int start_channel)

{

    uint64_t mask = 0;

    for (int i = start_channel; i < channel_layout->nb_channels; i++) {

        enum AVChannel ch = channel_layout->u.map[i].id;

        if (ch >= 0 && ch < 63 && mask < (1ULL << ch))

            mask |= (1ULL << ch);

        else

            return AVERROR(EINVAL);

    }

    return mask;

}

static int has_channel_names(const AVChannelLayout *channel_layout)

{

    if (channel_layout->order != AV_CHANNEL_ORDER_CUSTOM)

        return 0;

    for (int i = 0; i < channel_layout->nb_channels; i++)

        if (channel_layout->u.map[i].name[0])

            return 1;

    return 0;

}

int av_channel_layout_ambisonic_order(const AVChannelLayout *channel_layout)

{

    int i, highest_ambi, order;

    if (channel_layout->order != AV_CHANNEL_ORDER_AMBISONIC &&

        channel_layout->order != AV_CHANNEL_ORDER_CUSTOM)

        return AVERROR(EINVAL);

    highest_ambi = -1;

    if (channel_layout->order == AV_CHANNEL_ORDER_AMBISONIC)

        highest_ambi = channel_layout->nb_channels - av_popcount64(channel_layout->u.mask) - 1;

    else {

        const AVChannelCustom *map = channel_layout->u.map;

        av_assert0(channel_layout->order == AV_CHANNEL_ORDER_CUSTOM);

        for (i = 0; i < channel_layout->nb_channels; i++) {

            int is_ambi = CHAN_IS_AMBI(map[i].id);

            /* ambisonic following non-ambisonic */

            if (i > 0 && is_ambi && !CHAN_IS_AMBI(map[i - 1].id))

                return AVERROR(EINVAL);

            /* non-default ordering */

            if (is_ambi && map[i].id - AV_CHAN_AMBISONIC_BASE != i)

                return AVERROR(EINVAL);

            if (CHAN_IS_AMBI(map[i].id))

                highest_ambi = i;

        }

    }

    /* no ambisonic channels*/

    if (highest_ambi < 0)

        return AVERROR(EINVAL);

    order = floor(sqrt(highest_ambi));

    /* incomplete order - some harmonics are missing */

    if ((order + 1) * (order + 1) != highest_ambi + 1)

        return AVERROR(EINVAL);

    return order;

}

static enum AVChannelOrder canonical_order(AVChannelLayout *channel_layout)

{

    int has_known_channel = 0;

    int order;

    if (channel_layout->order != AV_CHANNEL_ORDER_CUSTOM)

        return channel_layout->order;

    if (has_channel_names(channel_layout))

        return AV_CHANNEL_ORDER_CUSTOM;

    for (int i = 0; i < channel_layout->nb_channels && !has_known_channel; i++)

        if (channel_layout->u.map[i].id != AV_CHAN_UNKNOWN)

            has_known_channel = 1;

    if (!has_known_channel)

        return AV_CHANNEL_ORDER_UNSPEC;

    if (masked_description(channel_layout, 0) > 0)

        return AV_CHANNEL_ORDER_NATIVE;

    order = av_channel_layout_ambisonic_order(channel_layout);

    if (order >= 0 && masked_description(channel_layout, (order + 1) * (order + 1)) >= 0)

        return AV_CHANNEL_ORDER_AMBISONIC;

    return AV_CHANNEL_ORDER_CUSTOM;

}

/**

 * If the custom layout is n-th order standard-order ambisonic, with optional

 * extra non-diegetic channels at the end, write its string description in bp.

 * Return a negative error code otherwise.

 */

static int try_describe_ambisonic(AVBPrint *bp, const AVChannelLayout *channel_layout)

{

    int nb_ambi_channels;

    int order = av_channel_layout_ambisonic_order(channel_layout);

    if (order < 0)

        return order;

    av_bprintf(bp, "ambisonic %d", order);

    /* extra channels present */

    nb_ambi_channels = (order + 1) * (order + 1);

    if (nb_ambi_channels < channel_layout->nb_channels) {

        AVChannelLayout extra = { 0 };

        if (channel_layout->order == AV_CHANNEL_ORDER_AMBISONIC) {

            extra.order       = AV_CHANNEL_ORDER_NATIVE;

            extra.nb_channels = av_popcount64(channel_layout->u.mask);

            extra.u.mask      = channel_layout->u.mask;

        } else {

            int64_t mask;

            if (!has_channel_names(channel_layout) &&

                (mask = masked_description(channel_layout, nb_ambi_channels)) > 0) {

                extra.order       = AV_CHANNEL_ORDER_NATIVE;

                extra.nb_channels = av_popcount64(mask);

                extra.u.mask      = mask;

            } else {

                extra.order       = AV_CHANNEL_ORDER_CUSTOM;

                extra.nb_channels = channel_layout->nb_channels - nb_ambi_channels;

                extra.u.map       = channel_layout->u.map + nb_ambi_channels;

            }

        }

        av_bprint_chars(bp, '+', 1);

        av_channel_layout_describe_bprint(&extra, bp);

        /* Not calling uninit here on extra because we don't own the u.map pointer */

    }

    return 0;

}

int av_channel_layout_describe_bprint(const AVChannelLayout *channel_layout,

                                      AVBPrint *bp)

{

    int i;

    switch (channel_layout->order) {

    case AV_CHANNEL_ORDER_NATIVE:

        for (i = 0; i < FF_ARRAY_ELEMS(channel_layout_map); i++)

            if (channel_layout->u.mask == channel_layout_map[i].layout.u.mask) {

                av_bprintf(bp, "%s", channel_layout_map[i].name);

                return 0;

            }

        av_fallthrough;

    case AV_CHANNEL_ORDER_CUSTOM:

        if (channel_layout->order == AV_CHANNEL_ORDER_CUSTOM) {

            int64_t mask;

            int res = try_describe_ambisonic(bp, channel_layout);

            if (res >= 0)

                return 0;

            if (!has_channel_names(channel_layout) &&

                (mask = masked_description(channel_layout, 0)) > 0) {

                AVChannelLayout native = { .order       = AV_CHANNEL_ORDER_NATIVE,

                                           .nb_channels = av_popcount64(mask),

                                           .u.mask      = mask };

                return av_channel_layout_describe_bprint(&native, bp);

            }

        }

        if (channel_layout->nb_channels)

            av_bprintf(bp, "%d channels (", channel_layout->nb_channels);

        for (i = 0; i < channel_layout->nb_channels; i++) {

            enum AVChannel ch = av_channel_layout_channel_from_index(channel_layout, i);

            if (i)

                av_bprintf(bp, "+");

            av_channel_name_bprint(bp, ch);

            if (channel_layout->order == AV_CHANNEL_ORDER_CUSTOM &&

                channel_layout->u.map[i].name[0])

                av_bprintf(bp, "@%s", channel_layout->u.map[i].name);

        }

        if (channel_layout->nb_channels) {

            av_bprintf(bp, ")");

            return 0;

        }

        av_fallthrough;

    case AV_CHANNEL_ORDER_UNSPEC:

        av_bprintf(bp, "%d channels", channel_layout->nb_channels);

        return 0;

    case AV_CHANNEL_ORDER_AMBISONIC:

        return try_describe_ambisonic(bp, channel_layout);

    default:

        return AVERROR(EINVAL);

    }

}

int av_channel_layout_describe(const AVChannelLayout *channel_layout,

                               char *buf, size_t buf_size)

{

    AVBPrint bp;

    int ret;

    if (!buf && buf_size)

        return AVERROR(EINVAL);

    av_bprint_init_for_buffer(&bp, buf, buf_size);

    ret = av_channel_layout_describe_bprint(channel_layout, &bp);

    if (ret < 0)

        return ret;

    if (bp.len >= INT_MAX)

        return AVERROR(ERANGE);

    return bp.len + 1;

}

enum AVChannel

av_channel_layout_channel_from_index(const AVChannelLayout *channel_layout,

                                     unsigned int idx)

{

    int i;

    if (idx >= channel_layout->nb_channels)

        return AV_CHAN_NONE;

    switch (channel_layout->order) {

    case AV_CHANNEL_ORDER_CUSTOM:

        return channel_layout->u.map[idx].id;

    case AV_CHANNEL_ORDER_AMBISONIC: {

        int ambi_channels = channel_layout->nb_channels - av_popcount64(channel_layout->u.mask);

        if (idx < ambi_channels)

            return AV_CHAN_AMBISONIC_BASE + idx;

        idx -= ambi_channels;

        }

        av_fallthrough;

    case AV_CHANNEL_ORDER_NATIVE:

        for (i = 0; i < 64; i++) {

            if ((1ULL << i) & channel_layout->u.mask && !idx--)

                return i;

        }

        av_fallthrough;

    default:

        return AV_CHAN_NONE;

    }

}

enum AVChannel

av_channel_layout_channel_from_string(const AVChannelLayout *channel_layout,

                                      const char *str)

{

    int index = av_channel_layout_index_from_string(channel_layout, str);

    if (index < 0)

        return AV_CHAN_NONE;

    return av_channel_layout_channel_from_index(channel_layout, index);

}

int av_channel_layout_index_from_channel(const AVChannelLayout *channel_layout,

                                         enum AVChannel channel)

{

    int i;

    if (channel == AV_CHAN_NONE)

        return AVERROR(EINVAL);

    switch (channel_layout->order) {

    case AV_CHANNEL_ORDER_CUSTOM:

        for (i = 0; i < channel_layout->nb_channels; i++)

            if (channel_layout->u.map[i].id == channel)

                return i;

        return AVERROR(EINVAL);

    case AV_CHANNEL_ORDER_AMBISONIC:

    case AV_CHANNEL_ORDER_NATIVE: {

        uint64_t mask = channel_layout->u.mask;

        int ambi_channels = channel_layout->nb_channels - av_popcount64(mask);

        if (channel_layout->order == AV_CHANNEL_ORDER_AMBISONIC &&

            channel >= AV_CHAN_AMBISONIC_BASE) {

            if (channel - AV_CHAN_AMBISONIC_BASE >= ambi_channels)

                return AVERROR(EINVAL);

            return channel - AV_CHAN_AMBISONIC_BASE;

        }

        if ((unsigned)channel > 63 || !(mask & (1ULL << channel)))

            return AVERROR(EINVAL);

        mask &= (1ULL << channel) - 1;

        return av_popcount64(mask) + ambi_channels;

        }

    default:

        return AVERROR(EINVAL);

    }

}

int av_channel_layout_index_from_string(const AVChannelLayout *channel_layout,

                                        const char *str)

{

    const char *chname;

    enum AVChannel ch = AV_CHAN_NONE;

    switch (channel_layout->order) {

    case AV_CHANNEL_ORDER_CUSTOM:

        chname = strstr(str, "@");

        if (chname) {

            char buf[16];

            chname++;

            av_strlcpy(buf, str, FFMIN(sizeof(buf), chname - str));

            if (!*chname)

                chname = NULL;

            ch = av_channel_from_string(buf);

            if (ch == AV_CHAN_NONE && *buf)

                return AVERROR(EINVAL);

        }

        for (int i = 0; chname && i < channel_layout->nb_channels; i++) {

            if (!strcmp(chname, channel_layout->u.map[i].name) &&

                (ch == AV_CHAN_NONE || ch == channel_layout->u.map[i].id))

                return i;

        }

        av_fallthrough;

    case AV_CHANNEL_ORDER_AMBISONIC:

    case AV_CHANNEL_ORDER_NATIVE:

        ch = av_channel_from_string(str);

        if (ch == AV_CHAN_NONE)

            return AVERROR(EINVAL);

        return av_channel_layout_index_from_channel(channel_layout, ch);

    }

    return AVERROR(EINVAL);

}

int av_channel_layout_check(const AVChannelLayout *channel_layout)

{

    if (channel_layout->nb_channels <= 0)

        return 0;

    switch (channel_layout->order) {

    case AV_CHANNEL_ORDER_NATIVE:

        return av_popcount64(channel_layout->u.mask) == channel_layout->nb_channels;

    case AV_CHANNEL_ORDER_CUSTOM:

        if (!channel_layout->u.map)

            return 0;

        for (int i = 0; i < channel_layout->nb_channels; i++) {

            if (channel_layout->u.map[i].id == AV_CHAN_NONE)

                return 0;

        }

        return 1;

    case AV_CHANNEL_ORDER_AMBISONIC:

        /* If non-diegetic channels are present, ensure they are taken into account */

        return av_popcount64(channel_layout->u.mask) < channel_layout->nb_channels;

    case AV_CHANNEL_ORDER_UNSPEC:

        return 1;

    default:

        return 0;

    }

}

int av_channel_layout_compare(const AVChannelLayout *chl, const AVChannelLayout *chl1)

{

    int i;

    /* different channel counts -> not equal */

    if (chl->nb_channels != chl1->nb_channels)

        return 1;

    /* if only one is unspecified -> not equal */

    if ((chl->order  == AV_CHANNEL_ORDER_UNSPEC) !=

        (chl1->order == AV_CHANNEL_ORDER_UNSPEC))

        return 1;

    /* both are unspecified -> equal */

    else if (chl->order == AV_CHANNEL_ORDER_UNSPEC)

        return 0;

    /* can compare masks directly */

    if ((chl->order == AV_CHANNEL_ORDER_NATIVE ||

         chl->order == AV_CHANNEL_ORDER_AMBISONIC) &&

        chl->order == chl1->order)

        return chl->u.mask != chl1->u.mask;

    /* compare channel by channel */

    for (i = 0; i < chl->nb_channels; i++)

        if (av_channel_layout_channel_from_index(chl,  i) !=

            av_channel_layout_channel_from_index(chl1, i))

            return 1;

    return 0;

}

void av_channel_layout_default(AVChannelLayout *ch_layout, int nb_channels)

{

    int i;

    for (i = 0; i < FF_ARRAY_ELEMS(channel_layout_map); i++)

        if (nb_channels == channel_layout_map[i].layout.nb_channels) {

            *ch_layout = channel_layout_map[i].layout;

            return;

        }

    ch_layout->order       = AV_CHANNEL_ORDER_UNSPEC;

    ch_layout->nb_channels = nb_channels;

}

const AVChannelLayout *av_channel_layout_standard(void **opaque)

{

    uintptr_t i = (uintptr_t)*opaque;

    const AVChannelLayout *ch_layout = NULL;

    if (i < FF_ARRAY_ELEMS(channel_layout_map)) {