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FFmpeg/libavformat/isom.c

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  1. /*

  2.  * ISO Media common code

  3.  * Copyright (c) 2001 Fabrice Bellard

  4.  * Copyright (c) 2002 Francois Revol <revol@free.fr>

  5.  * Copyright (c) 2006 Baptiste Coudurier <baptiste.coudurier@free.fr>

  6.  *

  7.  * This file is part of FFmpeg.

  8.  *

  9.  * FFmpeg is free software; you can redistribute it and/or

  10.  * modify it under the terms of the GNU Lesser General Public

  11.  * License as published by the Free Software Foundation; either

  12.  * version 2.1 of the License, or (at your option) any later version.

  13.  *

  14.  * FFmpeg is distributed in the hope that it will be useful,

  15.  * but WITHOUT ANY WARRANTY; without even the implied warranty of

  16.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

  17.  * Lesser General Public License for more details.

  18.  *

  19.  * You should have received a copy of the GNU Lesser General Public

  20.  * License along with FFmpeg; if not, write to the Free Software

  21.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

  22.  */

  23. 

  24. #include "avformat.h"

  25. #include "internal.h"

  26. #include "isom.h"

  27. #include "libavcodec/mpeg4audio.h"

  28. #include "libavcodec/mpegaudiodata.h"

  29. #include "libavutil/avstring.h"

  30. #include "libavutil/intreadwrite.h"

  31. 

  32. /* http://www.mp4ra.org */

  33. /* ordered by muxing preference */

  34. const AVCodecTag ff_mp4_obj_type[] = {

  35.     { AV_CODEC_ID_MOV_TEXT    , 0x08 },

  36.     { AV_CODEC_ID_MPEG4       , 0x20 },

  37.     { AV_CODEC_ID_H264        , 0x21 },

  38.     { AV_CODEC_ID_HEVC        , 0x23 },

  39.     { AV_CODEC_ID_AAC         , 0x40 },

  40.     { AV_CODEC_ID_MP4ALS      , 0x40 }, /* 14496-3 ALS */

  41.     { AV_CODEC_ID_MPEG2VIDEO  , 0x61 }, /* MPEG-2 Main */

  42.     { AV_CODEC_ID_MPEG2VIDEO  , 0x60 }, /* MPEG-2 Simple */

  43.     { AV_CODEC_ID_MPEG2VIDEO  , 0x62 }, /* MPEG-2 SNR */

  44.     { AV_CODEC_ID_MPEG2VIDEO  , 0x63 }, /* MPEG-2 Spatial */

  45.     { AV_CODEC_ID_MPEG2VIDEO  , 0x64 }, /* MPEG-2 High */

  46.     { AV_CODEC_ID_MPEG2VIDEO  , 0x65 }, /* MPEG-2 422 */

  47.     { AV_CODEC_ID_AAC         , 0x66 }, /* MPEG-2 AAC Main */

  48.     { AV_CODEC_ID_AAC         , 0x67 }, /* MPEG-2 AAC Low */

  49.     { AV_CODEC_ID_AAC         , 0x68 }, /* MPEG-2 AAC SSR */

  50.     { AV_CODEC_ID_MP3         , 0x69 }, /* 13818-3 */

  51.     { AV_CODEC_ID_MP2         , 0x69 }, /* 11172-3 */

  52.     { AV_CODEC_ID_MPEG1VIDEO  , 0x6A }, /* 11172-2 */

  53.     { AV_CODEC_ID_MP3         , 0x6B }, /* 11172-3 */

  54.     { AV_CODEC_ID_MJPEG       , 0x6C }, /* 10918-1 */

  55.     { AV_CODEC_ID_PNG         , 0x6D },

  56.     { AV_CODEC_ID_JPEG2000    , 0x6E }, /* 15444-1 */

  57.     { AV_CODEC_ID_VC1         , 0xA3 },

  58.     { AV_CODEC_ID_DIRAC       , 0xA4 },

  59.     { AV_CODEC_ID_AC3         , 0xA5 },

  60.     { AV_CODEC_ID_EAC3        , 0xA6 },

  61.     { AV_CODEC_ID_DTS         , 0xA9 }, /* mp4ra.org */

  62.     { AV_CODEC_ID_OPUS        , 0xAD }, /* mp4ra.org */

  63.     { AV_CODEC_ID_VP9         , 0xB1 }, /* mp4ra.org */

  64.     { AV_CODEC_ID_FLAC        , 0xC1 }, /* nonstandard, update when there is a standard value */

  65.     { AV_CODEC_ID_TSCC2       , 0xD0 }, /* nonstandard, camtasia uses it */

  66.     { AV_CODEC_ID_EVRC        , 0xD1 }, /* nonstandard, pvAuthor uses it */

  67.     { AV_CODEC_ID_VORBIS      , 0xDD }, /* nonstandard, gpac uses it */

  68.     { AV_CODEC_ID_DVD_SUBTITLE, 0xE0 }, /* nonstandard, see unsupported-embedded-subs-2.mp4 */

  69.     { AV_CODEC_ID_QCELP       , 0xE1 },

  70.     { AV_CODEC_ID_MPEG4SYSTEMS, 0x01 },

  71.     { AV_CODEC_ID_MPEG4SYSTEMS, 0x02 },

  72.     { AV_CODEC_ID_NONE        ,    0 },

  73. };

  74. 

  75. const AVCodecTag ff_codec_movsubtitle_tags[] = {

  76.     { AV_CODEC_ID_MOV_TEXT, MKTAG('t', 'e', 'x', 't') },

  77.     { AV_CODEC_ID_MOV_TEXT, MKTAG('t', 'x', '3', 'g') },

  78.     { AV_CODEC_ID_EIA_608,  MKTAG('c', '6', '0', '8') },

  79.     { AV_CODEC_ID_NONE, 0 },

  80. };

  81. 

  82. const AVCodecTag ff_codec_movdata_tags[] = {

  83.     { AV_CODEC_ID_BIN_DATA, MKTAG('g', 'p', 'm', 'd') },

  84.     { AV_CODEC_ID_NONE, 0 },

  85. };

  86. 

  87. /* map numeric codes from mdhd atom to ISO 639 */

  88. /* cf. QTFileFormat.pdf p253, qtff.pdf p205 */

  89. /* http://developer.apple.com/documentation/mac/Text/Text-368.html */

  90. /* deprecated by putting the code as 3*5 bits ASCII */

  91. static const char mov_mdhd_language_map[][4] = {

  92.     "eng",    /*   0 English */

  93.     "fra",    /*   1 French */

  94.     "ger",    /*   2 German */

  95.     "ita",    /*   3 Italian */

  96.     "dut",    /*   4 Dutch */

  97.     "sve",    /*   5 Swedish */

  98.     "spa",    /*   6 Spanish */

  99.     "dan",    /*   7 Danish */

  100.     "por",    /*   8 Portuguese */

  101.     "nor",    /*   9 Norwegian */

  102.     "heb",    /*  10 Hebrew */

  103.     "jpn",    /*  11 Japanese */

  104.     "ara",    /*  12 Arabic */

  105.     "fin",    /*  13 Finnish */

  106.     "gre",    /*  14 Greek */

  107.     "ice",    /*  15 Icelandic */

  108.     "mlt",    /*  16 Maltese */

  109.     "tur",    /*  17 Turkish */

  110.     "hr ",    /*  18 Croatian */

  111.     "chi",    /*  19 Traditional Chinese */

  112.     "urd",    /*  20 Urdu */

  113.     "hin",    /*  21 Hindi */

  114.     "tha",    /*  22 Thai */

  115.     "kor",    /*  23 Korean */

  116.     "lit",    /*  24 Lithuanian */

  117.     "pol",    /*  25 Polish */

  118.     "hun",    /*  26 Hungarian */

  119.     "est",    /*  27 Estonian */

  120.     "lav",    /*  28 Latvian */

  121.        "",    /*  29 Sami */

  122.     "fo ",    /*  30 Faroese */

  123.        "",    /*  31 Farsi */

  124.     "rus",    /*  32 Russian */

  125.     "chi",    /*  33 Simplified Chinese */

  126.        "",    /*  34 Flemish */

  127.     "iri",    /*  35 Irish */

  128.     "alb",    /*  36 Albanian */

  129.     "ron",    /*  37 Romanian */

  130.     "ces",    /*  38 Czech */

  131.     "slk",    /*  39 Slovak */

  132.     "slv",    /*  40 Slovenian */

  133.     "yid",    /*  41 Yiddish */

  134.     "sr ",    /*  42 Serbian */

  135.     "mac",    /*  43 Macedonian */

  136.     "bul",    /*  44 Bulgarian */

  137.     "ukr",    /*  45 Ukrainian */

  138.     "bel",    /*  46 Belarusian */

  139.     "uzb",    /*  47 Uzbek */

  140.     "kaz",    /*  48 Kazakh */

  141.     "aze",    /*  49 Azerbaijani */

  142.     "aze",    /*  50 AzerbaijanAr */

  143.     "arm",    /*  51 Armenian */

  144.     "geo",    /*  52 Georgian */

  145.     "mol",    /*  53 Moldavian */

  146.     "kir",    /*  54 Kirghiz */

  147.     "tgk",    /*  55 Tajiki */

  148.     "tuk",    /*  56 Turkmen */

  149.     "mon",    /*  57 Mongolian */

  150.        "",    /*  58 MongolianCyr */

  151.     "pus",    /*  59 Pashto */

  152.     "kur",    /*  60 Kurdish */

  153.     "kas",    /*  61 Kashmiri */

  154.     "snd",    /*  62 Sindhi */

  155.     "tib",    /*  63 Tibetan */

  156.     "nep",    /*  64 Nepali */

  157.     "san",    /*  65 Sanskrit */

  158.     "mar",    /*  66 Marathi */

  159.     "ben",    /*  67 Bengali */

  160.     "asm",    /*  68 Assamese */

  161.     "guj",    /*  69 Gujarati */

  162.     "pa ",    /*  70 Punjabi */

  163.     "ori",    /*  71 Oriya */

  164.     "mal",    /*  72 Malayalam */

  165.     "kan",    /*  73 Kannada */

  166.     "tam",    /*  74 Tamil */

  167.     "tel",    /*  75 Telugu */

  168.        "",    /*  76 Sinhala */

  169.     "bur",    /*  77 Burmese */

  170.     "khm",    /*  78 Khmer */

  171.     "lao",    /*  79 Lao */

  172.     "vie",    /*  80 Vietnamese */

  173.     "ind",    /*  81 Indonesian */

  174.     "tgl",    /*  82 Tagalog */

  175.     "may",    /*  83 MalayRoman */

  176.     "may",    /*  84 MalayArabic */

  177.     "amh",    /*  85 Amharic */

  178.     "tir",    /*  86 Galla */

  179.     "orm",    /*  87 Oromo */

  180.     "som",    /*  88 Somali */

  181.     "swa",    /*  89 Swahili */

  182.        "",    /*  90 Kinyarwanda */

  183.     "run",    /*  91 Rundi */

  184.        "",    /*  92 Nyanja */

  185.     "mlg",    /*  93 Malagasy */

  186.     "epo",    /*  94 Esperanto */

  187.        "",    /*  95  */

  188.        "",    /*  96  */

  189.        "",    /*  97  */

  190.        "",    /*  98  */

  191.        "",    /*  99  */

  192.        "",    /* 100  */

  193.        "",    /* 101  */

  194.        "",    /* 102  */

  195.        "",    /* 103  */

  196.        "",    /* 104  */

  197.        "",    /* 105  */

  198.        "",    /* 106  */

  199.        "",    /* 107  */

  200.        "",    /* 108  */

  201.        "",    /* 109  */

  202.        "",    /* 110  */

  203.        "",    /* 111  */

  204.        "",    /* 112  */

  205.        "",    /* 113  */

  206.        "",    /* 114  */

  207.        "",    /* 115  */

  208.        "",    /* 116  */

  209.        "",    /* 117  */

  210.        "",    /* 118  */

  211.        "",    /* 119  */

  212.        "",    /* 120  */

  213.        "",    /* 121  */

  214.        "",    /* 122  */

  215.        "",    /* 123  */

  216.        "",    /* 124  */

  217.        "",    /* 125  */

  218.        "",    /* 126  */

  219.        "",    /* 127  */

  220.     "wel",    /* 128 Welsh */

  221.     "baq",    /* 129 Basque */

  222.     "cat",    /* 130 Catalan */

  223.     "lat",    /* 131 Latin */

  224.     "que",    /* 132 Quechua */

  225.     "grn",    /* 133 Guarani */

  226.     "aym",    /* 134 Aymara */

  227.     "tat",    /* 135 Tatar */

  228.     "uig",    /* 136 Uighur */

  229.     "dzo",    /* 137 Dzongkha */

  230.     "jav",    /* 138 JavaneseRom */

  231. };

  232. 

  233. int ff_mov_iso639_to_lang(const char lang[4], int mp4)

  234. {

  235.     int i, code = 0;

  236. 

  237.     /* old way, only for QT? */

  238.     for (i = 0; lang[0] && !mp4 && i < FF_ARRAY_ELEMS(mov_mdhd_language_map); i++) {

  239.         if (!strcmp(lang, mov_mdhd_language_map[i]))

  240.             return i;

  241.     }

  242.     /* XXX:can we do that in mov too? */

  243.     if (!mp4)

  244.         return -1;

  245.     /* handle undefined as such */

  246.     if (lang[0] == '\0')

  247.         lang = "und";

  248.     /* 5 bits ASCII */

  249.     for (i = 0; i < 3; i++) {

  250.         uint8_t c = lang[i];

  251.         c -= 0x60;

  252.         if (c > 0x1f)

  253.             return -1;

  254.         code <<= 5;

  255.         code |= c;

  256.     }

  257.     return code;

  258. }

  259. 

  260. int ff_mov_lang_to_iso639(unsigned code, char to[4])

  261. {

  262.     int i;

  263.     memset(to, 0, 4);

  264.     /* is it the mangled iso code? */

  265.     /* see http://www.geocities.com/xhelmboyx/quicktime/formats/mp4-layout.txt */

  266.     if (code >= 0x400 && code != 0x7fff) {

  267.         for (i = 2; i >= 0; i--) {

  268.             to[i] = 0x60 + (code & 0x1f);

  269.             code >>= 5;

  270.         }

  271.         return 1;

  272.     }

  273.     /* old fashion apple lang code */

  274.     if (code >= FF_ARRAY_ELEMS(mov_mdhd_language_map))

  275.         return 0;

  276.     if (!mov_mdhd_language_map[code][0])

  277.         return 0;

  278.     memcpy(to, mov_mdhd_language_map[code], 4);

  279.     return 1;

  280. }

  281. 

  282. int ff_mp4_read_descr_len(AVIOContext *pb)

  283. {

  284.     int len = 0;

  285.     int count = 4;

  286.     while (count--) {

  287.         int c = avio_r8(pb);

  288.         len = (len << 7) | (c & 0x7f);

  289.         if (!(c & 0x80))

  290.             break;

  291.     }

  292.     return len;

  293. }

  294. 

  295. int ff_mp4_read_descr(AVFormatContext *fc, AVIOContext *pb, int *tag)

  296. {

  297.     int len;

  298.     *tag = avio_r8(pb);

  299.     len = ff_mp4_read_descr_len(pb);

  300.     av_log(fc, AV_LOG_TRACE, "MPEG-4 description: tag=0x%02x len=%d\n", *tag, len);

  301.     return len;

  302. }

  303. 

  304. void ff_mp4_parse_es_descr(AVIOContext *pb, int *es_id)

  305. {

  306.      int flags;

  307.      if (es_id) *es_id = avio_rb16(pb);

  308.      else                avio_rb16(pb);

  309.      flags = avio_r8(pb);

  310.      if (flags & 0x80) //streamDependenceFlag

  311.          avio_rb16(pb);

  312.      if (flags & 0x40) { //URL_Flag

  313.          int len = avio_r8(pb);

  314.          avio_skip(pb, len);

  315.      }

  316.      if (flags & 0x20) //OCRstreamFlag

  317.          avio_rb16(pb);

  318. }

  319. 

  320. static const AVCodecTag mp4_audio_types[] = {

  321.     { AV_CODEC_ID_MP3ON4, AOT_PS   }, /* old mp3on4 draft */

  322.     { AV_CODEC_ID_MP3ON4, AOT_L1   }, /* layer 1 */

  323.     { AV_CODEC_ID_MP3ON4, AOT_L2   }, /* layer 2 */

  324.     { AV_CODEC_ID_MP3ON4, AOT_L3   }, /* layer 3 */

  325.     { AV_CODEC_ID_MP4ALS, AOT_ALS  }, /* MPEG-4 ALS */

  326.     { AV_CODEC_ID_NONE,   AOT_NULL },

  327. };

  328. 

  329. int ff_mp4_read_dec_config_descr(AVFormatContext *fc, AVStream *st, AVIOContext *pb)

  330. {

  331.     enum AVCodecID codec_id;

  332.     unsigned v;

  333.     int len, tag;

  334.     int ret;

  335.     int object_type_id = avio_r8(pb);

  336.     avio_r8(pb); /* stream type */

  337.     avio_rb24(pb); /* buffer size db */

  338. 

  339.     v = avio_rb32(pb);

  340. 

  341.     // TODO: fix this with codecpar

  342. #if FF_API_LAVF_AVCTX

  343. FF_DISABLE_DEPRECATION_WARNINGS

  344.     if (v < INT32_MAX)

  345.         st->codec->rc_max_rate = v;

  346. FF_ENABLE_DEPRECATION_WARNINGS

  347. #endif

  348. 

  349.     st->codecpar->bit_rate = avio_rb32(pb); /* avg bitrate */

  350. 

  351.     codec_id= ff_codec_get_id(ff_mp4_obj_type, object_type_id);

  352.     if (codec_id)

  353.         st->codecpar->codec_id = codec_id;

  354.     av_log(fc, AV_LOG_TRACE, "esds object type id 0x%02x\n", object_type_id);

  355.     len = ff_mp4_read_descr(fc, pb, &tag);

  356.     if (tag == MP4DecSpecificDescrTag) {

  357.         av_log(fc, AV_LOG_TRACE, "Specific MPEG-4 header len=%d\n", len);

  358.         /* As per 14496-3:2009 9.D.2.2, No decSpecificInfo is defined

  359.            for MPEG-1 Audio or MPEG-2 Audio; MPEG-2 AAC excluded. */

  360.         if (object_type_id == 0x69 || object_type_id == 0x6b)

  361.             return 0;

  362.         if (!len || (uint64_t)len > (1<<30))

  363.             return AVERROR_INVALIDDATA;

  364.         if ((ret = ff_get_extradata(fc, st->codecpar, pb, len)) < 0)

  365.             return ret;

  366.         if (st->codecpar->codec_id == AV_CODEC_ID_AAC) {

  367.             MPEG4AudioConfig cfg = {0};

  368.             ret = avpriv_mpeg4audio_get_config2(&cfg, st->codecpar->extradata,

  369.                                                 st->codecpar->extradata_size, 1, fc);

  370.             if (ret < 0)

  371.                 return ret;

  372.             st->codecpar->channels = cfg.channels;

  373.             if (cfg.object_type == 29 && cfg.sampling_index < 3) // old mp3on4

  374.                 st->codecpar->sample_rate = avpriv_mpa_freq_tab[cfg.sampling_index];

  375.             else if (cfg.ext_sample_rate)

  376.                 st->codecpar->sample_rate = cfg.ext_sample_rate;

  377.             else

  378.                 st->codecpar->sample_rate = cfg.sample_rate;

  379.             av_log(fc, AV_LOG_TRACE, "mp4a config channels %d obj %d ext obj %d "

  380.                     "sample rate %d ext sample rate %d\n", st->codecpar->channels,

  381.                     cfg.object_type, cfg.ext_object_type,

  382.                     cfg.sample_rate, cfg.ext_sample_rate);

  383.             if (!(st->codecpar->codec_id = ff_codec_get_id(mp4_audio_types,

  384.                                                         cfg.object_type)))

  385.                 st->codecpar->codec_id = AV_CODEC_ID_AAC;

  386.         }

  387.     }

  388.     return 0;

  389. }

  390. 

  391. typedef struct MovChannelLayout {

  392.     int64_t  channel_layout;

  393.     uint32_t layout_tag;

  394. } MovChannelLayout;

  395. 

  396. static const MovChannelLayout mov_channel_layout[] = {

  397.     { AV_CH_LAYOUT_MONO,                         (100<<16) | 1}, // kCAFChannelLayoutTag_Mono

  398.     { AV_CH_LAYOUT_STEREO,                       (101<<16) | 2}, // kCAFChannelLayoutTag_Stereo

  399.     { AV_CH_LAYOUT_STEREO,                       (102<<16) | 2}, // kCAFChannelLayoutTag_StereoHeadphones

  400.     { AV_CH_LAYOUT_2_1,                          (131<<16) | 3}, // kCAFChannelLayoutTag_ITU_2_1

  401.     { AV_CH_LAYOUT_QUAD,                         (132<<16) | 4}, // kCAFChannelLayoutTag_ITU_2_2

  402.     { AV_CH_LAYOUT_2_2,                          (132<<16) | 4}, // kCAFChannelLayoutTag_ITU_2_2

  403.     { AV_CH_LAYOUT_QUAD,                         (108<<16) | 4}, // kCAFChannelLayoutTag_Quadraphonic

  404.     { AV_CH_LAYOUT_SURROUND,                     (113<<16) | 3}, // kCAFChannelLayoutTag_MPEG_3_0_A

  405.     { AV_CH_LAYOUT_4POINT0,                      (115<<16) | 4}, // kCAFChannelLayoutTag_MPEG_4_0_A

  406.     { AV_CH_LAYOUT_5POINT0_BACK,                 (117<<16) | 5}, // kCAFChannelLayoutTag_MPEG_5_0_A

  407.     { AV_CH_LAYOUT_5POINT0,                      (117<<16) | 5}, // kCAFChannelLayoutTag_MPEG_5_0_A

  408.     { AV_CH_LAYOUT_5POINT1_BACK,                 (121<<16) | 6}, // kCAFChannelLayoutTag_MPEG_5_1_A

  409.     { AV_CH_LAYOUT_5POINT1,                      (121<<16) | 6}, // kCAFChannelLayoutTag_MPEG_5_1_A

  410.     { AV_CH_LAYOUT_7POINT1,                      (128<<16) | 8}, // kCAFChannelLayoutTag_MPEG_7_1_C

  411.     { AV_CH_LAYOUT_7POINT1_WIDE,                 (126<<16) | 8}, // kCAFChannelLayoutTag_MPEG_7_1_A

  412.     { AV_CH_LAYOUT_5POINT1_BACK|AV_CH_LAYOUT_STEREO_DOWNMIX, (130<<16) | 8}, // kCAFChannelLayoutTag_SMPTE_DTV

  413.     { AV_CH_LAYOUT_STEREO|AV_CH_LOW_FREQUENCY,   (133<<16) | 3}, // kCAFChannelLayoutTag_DVD_4

  414.     { AV_CH_LAYOUT_2_1|AV_CH_LOW_FREQUENCY,      (134<<16) | 4}, // kCAFChannelLayoutTag_DVD_5

  415.     { AV_CH_LAYOUT_QUAD|AV_CH_LOW_FREQUENCY,     (135<<16) | 4}, // kCAFChannelLayoutTag_DVD_6

  416.     { AV_CH_LAYOUT_2_2|AV_CH_LOW_FREQUENCY,      (135<<16) | 4}, // kCAFChannelLayoutTag_DVD_6

  417.     { AV_CH_LAYOUT_SURROUND|AV_CH_LOW_FREQUENCY, (136<<16) | 4}, // kCAFChannelLayoutTag_DVD_10

  418.     { AV_CH_LAYOUT_4POINT0|AV_CH_LOW_FREQUENCY,  (137<<16) | 5}, // kCAFChannelLayoutTag_DVD_11

  419.     { 0, 0},

  420. };

  421. #if 0

  422. int ff_mov_read_chan(AVFormatContext *s, AVStream *st, int64_t size)

  423. {

  424.     AVCodecContext *codec= st->codec;

  425.     uint32_t layout_tag;

  426.     AVIOContext *pb = s->pb;

  427.     const MovChannelLayout *layouts = mov_channel_layout;

  428. 

  429.     if (size < 12)

  430.         return AVERROR_INVALIDDATA;

  431. 

  432.     layout_tag = avio_rb32(pb);

  433.     size -= 4;

  434.     if (layout_tag == 0) { // kCAFChannelLayoutTag_UseChannelDescriptions

  435.         // Channel descriptions not implemented

  436.         av_log_ask_for_sample(s, "Unimplemented container channel layout.\n");

  437.         avio_skip(pb, size);

  438.         return 0;

  439.     }

  440.     if (layout_tag == 0x10000) { // kCAFChannelLayoutTag_UseChannelBitmap

  441.         codec->channel_layout = avio_rb32(pb);

  442.         size -= 4;

  443.         avio_skip(pb, size);

  444.         return 0;

  445.     }

  446.     while (layouts->channel_layout) {

  447.         if (layout_tag == layouts->layout_tag) {

  448.             codec->channel_layout = layouts->channel_layout;

  449.             break;

  450.         }

  451.         layouts++;

  452.     }

  453.     if (!codec->channel_layout)

  454.         av_log(s, AV_LOG_WARNING, "Unknown container channel layout.\n");

  455.     avio_skip(pb, size);

  456. 

  457.     return 0;

  458. }

  459. #endif

  460. 

  461. void ff_mov_write_chan(AVIOContext *pb, int64_t channel_layout)

  462. {

  463.     const MovChannelLayout *layouts;

  464.     uint32_t layout_tag = 0;

  465. 

  466.     for (layouts = mov_channel_layout; layouts->channel_layout; layouts++)

  467.         if (channel_layout == layouts->channel_layout) {

  468.             layout_tag = layouts->layout_tag;

  469.             break;

  470.         }

  471. 

  472.     if (layout_tag) {

  473.         avio_wb32(pb, layout_tag); // mChannelLayoutTag

  474.         avio_wb32(pb, 0);          // mChannelBitmap

  475.     } else {

  476.         avio_wb32(pb, 0x10000);    // kCAFChannelLayoutTag_UseChannelBitmap

  477.         avio_wb32(pb, channel_layout);

  478.     }

  479.     avio_wb32(pb, 0);              // mNumberChannelDescriptions

  480. }