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  1. /*
  2.  * Ogg muxer
  3.  * Copyright (c) 2007 Baptiste Coudurier <baptiste dot coudurier at free dot fr>
  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. #include "libavutil/crc.h"
  23. #include "libavutil/mathematics.h"
  24. #include "libavutil/opt.h"
  25. #include "libavutil/random_seed.h"
  26. #include "libavcodec/xiph.h"
  27. #include "libavcodec/bytestream.h"
  28. #include "libavcodec/flac.h"
  29. #include "avformat.h"
  30. #include "avio_internal.h"
  31. #include "internal.h"
  32. #include "vorbiscomment.h"
  33.  
  34. #define MAX_PAGE_SIZE 65025
  35.  
  36. typedef struct {
  37.     int64_t start_granule;
  38.     int64_t granule;
  39.     int stream_index;
  40.     uint8_t flags;
  41.     uint8_t segments_count;
  42.     uint8_t segments[255];
  43.     uint8_t data[MAX_PAGE_SIZE];
  44.     uint16_t size;
  45. } OGGPage;
  46.  
  47. typedef struct {
  48.     unsigned page_counter;
  49.     uint8_t *header[3];
  50.     int header_len[3];
  51.     /** for theora granule */
  52.     int kfgshift;
  53.     int64_t last_kf_pts;
  54.     int vrev;
  55.     int eos;
  56.     unsigned page_count; ///< number of page buffered
  57.     OGGPage page; ///< current page
  58.     unsigned serial_num; ///< serial number
  59.     int64_t last_granule; ///< last packet granule
  60. } OGGStreamContext;
  61.  
  62. typedef struct OGGPageList {
  63.     OGGPage page;
  64.     struct OGGPageList *next;
  65. } OGGPageList;
  66.  
  67. typedef struct {
  68.     const AVClass *class;
  69.     OGGPageList *page_list;
  70.     int pref_size; ///< preferred page size (0 => fill all segments)
  71.     int64_t pref_duration;      ///< preferred page duration (0 => fill all segments)
  72. } OGGContext;
  73.  
  74. #define OFFSET(x) offsetof(OGGContext, x)
  75. #define PARAM AV_OPT_FLAG_ENCODING_PARAM
  76.  
  77. static const AVOption options[] = {
  78.     { "oggpagesize", "Set preferred Ogg page size.",
  79.       offsetof(OGGContext, pref_size), AV_OPT_TYPE_INT, {.i64 = 0}, 0, MAX_PAGE_SIZE, AV_OPT_FLAG_ENCODING_PARAM},
  80.     { "pagesize", "preferred page size in bytes (deprecated)",
  81.         OFFSET(pref_size), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, MAX_PAGE_SIZE, PARAM },
  82.     { "page_duration", "preferred page duration, in microseconds",
  83.         OFFSET(pref_duration), AV_OPT_TYPE_INT64, { .i64 = 1000000 }, 0, INT64_MAX, PARAM },
  84.     { NULL },
  85. };
  86.  
  87. static const AVClass ogg_muxer_class = {
  88.     .class_name = "Ogg muxer",
  89.     .item_name  = av_default_item_name,
  90.     .option     = options,
  91.     .version    = LIBAVUTIL_VERSION_INT,
  92. };
  93.  
  94.  
  95. static void ogg_update_checksum(AVFormatContext *s, AVIOContext *pb, int64_t crc_offset)
  96. {
  97.     int64_t pos = avio_tell(pb);
  98.     uint32_t checksum = ffio_get_checksum(pb);
  99.     avio_seek(pb, crc_offset, SEEK_SET);
  100.     avio_wb32(pb, checksum);
  101.     avio_seek(pb, pos, SEEK_SET);
  102. }
  103.  
  104. static int ogg_write_page(AVFormatContext *s, OGGPage *page, int extra_flags)
  105. {
  106.     OGGStreamContext *oggstream = s->streams[page->stream_index]->priv_data;
  107.     AVIOContext *pb;
  108.     int64_t crc_offset;
  109.     int ret, size;
  110.     uint8_t *buf;
  111.  
  112.     ret = avio_open_dyn_buf(&pb);
  113.     if (ret < 0)
  114.         return ret;
  115.     ffio_init_checksum(pb, ff_crc04C11DB7_update, 0);
  116.     ffio_wfourcc(pb, "OggS");
  117.     avio_w8(pb, 0);
  118.     avio_w8(pb, page->flags | extra_flags);
  119.     avio_wl64(pb, page->granule);
  120.     avio_wl32(pb, oggstream->serial_num);
  121.     avio_wl32(pb, oggstream->page_counter++);
  122.     crc_offset = avio_tell(pb);
  123.     avio_wl32(pb, 0); // crc
  124.     avio_w8(pb, page->segments_count);
  125.     avio_write(pb, page->segments, page->segments_count);
  126.     avio_write(pb, page->data, page->size);
  127.  
  128.     ogg_update_checksum(s, pb, crc_offset);
  129.     avio_flush(pb);
  130.  
  131.     size = avio_close_dyn_buf(pb, &buf);
  132.     if (size < 0)
  133.         return size;
  134.  
  135.     avio_write(s->pb, buf, size);
  136.     avio_flush(s->pb);
  137.     av_free(buf);
  138.     oggstream->page_count--;
  139.     return 0;
  140. }
  141.  
  142. static int ogg_key_granule(OGGStreamContext *oggstream, int64_t granule)
  143. {
  144.     return oggstream->kfgshift && !(granule & ((1<<oggstream->kfgshift)-1));
  145. }
  146.  
  147. static int64_t ogg_granule_to_timestamp(OGGStreamContext *oggstream, int64_t granule)
  148. {
  149.     if (oggstream->kfgshift)
  150.         return (granule>>oggstream->kfgshift) +
  151.             (granule & ((1<<oggstream->kfgshift)-1));
  152.     else
  153.         return granule;
  154. }
  155.  
  156. static int ogg_compare_granule(AVFormatContext *s, OGGPage *next, OGGPage *page)
  157. {
  158.     AVStream *st2 = s->streams[next->stream_index];
  159.     AVStream *st  = s->streams[page->stream_index];
  160.     int64_t next_granule, cur_granule;
  161.  
  162.     if (next->granule == -1 || page->granule == -1)
  163.         return 0;
  164.  
  165.     next_granule = av_rescale_q(ogg_granule_to_timestamp(st2->priv_data, next->granule),
  166.                                 st2->time_base, AV_TIME_BASE_Q);
  167.     cur_granule  = av_rescale_q(ogg_granule_to_timestamp(st->priv_data, page->granule),
  168.                                 st ->time_base, AV_TIME_BASE_Q);
  169.     return next_granule > cur_granule;
  170. }
  171.  
  172. static int ogg_reset_cur_page(OGGStreamContext *oggstream)
  173. {
  174.     oggstream->page.granule = -1;
  175.     oggstream->page.flags = 0;
  176.     oggstream->page.segments_count = 0;
  177.     oggstream->page.size = 0;
  178.     return 0;
  179. }
  180.  
  181. static int ogg_buffer_page(AVFormatContext *s, OGGStreamContext *oggstream)
  182. {
  183.     OGGContext *ogg = s->priv_data;
  184.     OGGPageList **p = &ogg->page_list;
  185.     OGGPageList *l = av_mallocz(sizeof(*l));
  186.  
  187.     if (!l)
  188.         return AVERROR(ENOMEM);
  189.     l->page = oggstream->page;
  190.  
  191.     oggstream->page.start_granule = oggstream->page.granule;
  192.     oggstream->page_count++;
  193.     ogg_reset_cur_page(oggstream);
  194.  
  195.     while (*p) {
  196.         if (ogg_compare_granule(s, &(*p)->page, &l->page))
  197.             break;
  198.         p = &(*p)->next;
  199.     }
  200.     l->next = *p;
  201.     *p = l;
  202.  
  203.     return 0;
  204. }
  205.  
  206. static int ogg_buffer_data(AVFormatContext *s, AVStream *st,
  207.                            uint8_t *data, unsigned size, int64_t granule,
  208.                            int header)
  209. {
  210.     OGGStreamContext *oggstream = st->priv_data;
  211.     OGGContext *ogg = s->priv_data;
  212.     int total_segments = size / 255 + 1;
  213.     uint8_t *p = data;
  214.     int i, segments, len, flush = 0;
  215.  
  216.     // Handles VFR by flushing page because this frame needs to have a timestamp
  217.     // For theora, keyframes also need to have a timestamp to correctly mark
  218.     // them as such, otherwise seeking will not work correctly at the very
  219.     // least with old libogg versions.
  220.     // Do not try to flush header packets though, that will create broken files.
  221.     if (st->codec->codec_id == AV_CODEC_ID_THEORA && !header &&
  222.         (ogg_granule_to_timestamp(oggstream, granule) >
  223.          ogg_granule_to_timestamp(oggstream, oggstream->last_granule) + 1 ||
  224.          ogg_key_granule(oggstream, granule))) {
  225.         if (oggstream->page.granule != -1)
  226.             ogg_buffer_page(s, oggstream);
  227.         flush = 1;
  228.     }
  229.  
  230.     // avoid a continued page
  231.     if (!header && oggstream->page.size > 0 &&
  232.         MAX_PAGE_SIZE - oggstream->page.size < size) {
  233.         ogg_buffer_page(s, oggstream);
  234.     }
  235.  
  236.     for (i = 0; i < total_segments; ) {
  237.         OGGPage *page = &oggstream->page;
  238.  
  239.         segments = FFMIN(total_segments - i, 255 - page->segments_count);
  240.  
  241.         if (i && !page->segments_count)
  242.             page->flags |= 1; // continued packet
  243.  
  244.         memset(page->segments+page->segments_count, 255, segments - 1);
  245.         page->segments_count += segments - 1;
  246.  
  247.         len = FFMIN(size, segments*255);
  248.         page->segments[page->segments_count++] = len - (segments-1)*255;
  249.         memcpy(page->data+page->size, p, len);
  250.         p += len;
  251.         size -= len;
  252.         i += segments;
  253.         page->size += len;
  254.  
  255.         if (i == total_segments)
  256.             page->granule = granule;
  257.  
  258.         if (!header) {
  259.             AVStream *st = s->streams[page->stream_index];
  260.  
  261.             int64_t start = av_rescale_q(page->start_granule, st->time_base,
  262.                                          AV_TIME_BASE_Q);
  263.             int64_t next  = av_rescale_q(page->granule, st->time_base,
  264.                                          AV_TIME_BASE_Q);
  265.  
  266.             if (page->segments_count == 255 ||
  267.                 (ogg->pref_size     > 0 && page->size   >= ogg->pref_size) ||
  268.                 (ogg->pref_duration > 0 && next - start >= ogg->pref_duration)) {
  269.                 ogg_buffer_page(s, oggstream);
  270.             }
  271.         }
  272.     }
  273.  
  274.     if (flush && oggstream->page.granule != -1)
  275.         ogg_buffer_page(s, oggstream);
  276.  
  277.     return 0;
  278. }
  279.  
  280. static uint8_t *ogg_write_vorbiscomment(int offset, int bitexact,
  281.                                         int *header_len, AVDictionary **m, int framing_bit)
  282. {
  283.     const char *vendor = bitexact ? "ffmpeg" : LIBAVFORMAT_IDENT;
  284.     int size;
  285.     uint8_t *p, *p0;
  286.     unsigned int count;
  287.  
  288.     ff_metadata_conv(m, ff_vorbiscomment_metadata_conv, NULL);
  289.  
  290.     size = offset + ff_vorbiscomment_length(*m, vendor, &count) + framing_bit;
  291.     p = av_mallocz(size);
  292.     if (!p)
  293.         return NULL;
  294.     p0 = p;
  295.  
  296.     p += offset;
  297.     ff_vorbiscomment_write(&p, m, vendor, count);
  298.     if (framing_bit)
  299.         bytestream_put_byte(&p, 1);
  300.  
  301.     *header_len = size;
  302.     return p0;
  303. }
  304.  
  305. static int ogg_build_flac_headers(AVCodecContext *avctx,
  306.                                   OGGStreamContext *oggstream, int bitexact,
  307.                                   AVDictionary **m)
  308. {
  309.     enum FLACExtradataFormat format;
  310.     uint8_t *streaminfo;
  311.     uint8_t *p;
  312.  
  313.     if (!avpriv_flac_is_extradata_valid(avctx, &format, &streaminfo))
  314.         return -1;
  315.  
  316.     // first packet: STREAMINFO
  317.     oggstream->header_len[0] = 51;
  318.     oggstream->header[0] = av_mallocz(51); // per ogg flac specs
  319.     p = oggstream->header[0];
  320.     if (!p)
  321.         return AVERROR(ENOMEM);
  322.     bytestream_put_byte(&p, 0x7F);
  323.     bytestream_put_buffer(&p, "FLAC", 4);
  324.     bytestream_put_byte(&p, 1); // major version
  325.     bytestream_put_byte(&p, 0); // minor version
  326.     bytestream_put_be16(&p, 1); // headers packets without this one
  327.     bytestream_put_buffer(&p, "fLaC", 4);
  328.     bytestream_put_byte(&p, 0x00); // streaminfo
  329.     bytestream_put_be24(&p, 34);
  330.     bytestream_put_buffer(&p, streaminfo, FLAC_STREAMINFO_SIZE);
  331.  
  332.     // second packet: VorbisComment
  333.     p = ogg_write_vorbiscomment(4, bitexact, &oggstream->header_len[1], m, 0);
  334.     if (!p)
  335.         return AVERROR(ENOMEM);
  336.     oggstream->header[1] = p;
  337.     bytestream_put_byte(&p, 0x84); // last metadata block and vorbis comment
  338.     bytestream_put_be24(&p, oggstream->header_len[1] - 4);
  339.  
  340.     return 0;
  341. }
  342.  
  343. #define SPEEX_HEADER_SIZE 80
  344.  
  345. static int ogg_build_speex_headers(AVCodecContext *avctx,
  346.                                    OGGStreamContext *oggstream, int bitexact,
  347.                                    AVDictionary **m)
  348. {
  349.     uint8_t *p;
  350.  
  351.     if (avctx->extradata_size < SPEEX_HEADER_SIZE)
  352.         return -1;
  353.  
  354.     // first packet: Speex header
  355.     p = av_mallocz(SPEEX_HEADER_SIZE);
  356.     if (!p)
  357.         return AVERROR(ENOMEM);
  358.     oggstream->header[0] = p;
  359.     oggstream->header_len[0] = SPEEX_HEADER_SIZE;
  360.     bytestream_put_buffer(&p, avctx->extradata, SPEEX_HEADER_SIZE);
  361.     AV_WL32(&oggstream->header[0][68], 0);  // set extra_headers to 0
  362.  
  363.     // second packet: VorbisComment
  364.     p = ogg_write_vorbiscomment(0, bitexact, &oggstream->header_len[1], m, 0);
  365.     if (!p)
  366.         return AVERROR(ENOMEM);
  367.     oggstream->header[1] = p;
  368.  
  369.     return 0;
  370. }
  371.  
  372. #define OPUS_HEADER_SIZE 19
  373.  
  374. static int ogg_build_opus_headers(AVCodecContext *avctx,
  375.                                   OGGStreamContext *oggstream, int bitexact,
  376.                                   AVDictionary **m)
  377. {
  378.     uint8_t *p;
  379.  
  380.     if (avctx->extradata_size < OPUS_HEADER_SIZE)
  381.         return -1;
  382.  
  383.     /* first packet: Opus header */
  384.     p = av_mallocz(avctx->extradata_size);
  385.     if (!p)
  386.         return AVERROR(ENOMEM);
  387.     oggstream->header[0] = p;
  388.     oggstream->header_len[0] = avctx->extradata_size;
  389.     bytestream_put_buffer(&p, avctx->extradata, avctx->extradata_size);
  390.  
  391.     /* second packet: VorbisComment */
  392.     p = ogg_write_vorbiscomment(8, bitexact, &oggstream->header_len[1], m, 0);
  393.     if (!p)
  394.         return AVERROR(ENOMEM);
  395.     oggstream->header[1] = p;
  396.     bytestream_put_buffer(&p, "OpusTags", 8);
  397.  
  398.     return 0;
  399. }
  400.  
  401. static int ogg_write_header(AVFormatContext *s)
  402. {
  403.     OGGContext *ogg = s->priv_data;
  404.     OGGStreamContext *oggstream = NULL;
  405.     int i, j;
  406.  
  407.     if (ogg->pref_size)
  408.         av_log(s, AV_LOG_WARNING, "The pagesize option is deprecated\n");
  409.  
  410.     for (i = 0; i < s->nb_streams; i++) {
  411.         AVStream *st = s->streams[i];
  412.         unsigned serial_num = i;
  413.  
  414.         if (st->codec->codec_type == AVMEDIA_TYPE_AUDIO) {
  415.             if (st->codec->codec_id == AV_CODEC_ID_OPUS)
  416.                 /* Opus requires a fixed 48kHz clock */
  417.                 avpriv_set_pts_info(st, 64, 1, 48000);
  418.             else
  419.                 avpriv_set_pts_info(st, 64, 1, st->codec->sample_rate);
  420.         } else if (st->codec->codec_type == AVMEDIA_TYPE_VIDEO)
  421.             avpriv_set_pts_info(st, 64, st->codec->time_base.num, st->codec->time_base.den);
  422.         if (st->codec->codec_id != AV_CODEC_ID_VORBIS &&
  423.             st->codec->codec_id != AV_CODEC_ID_THEORA &&
  424.             st->codec->codec_id != AV_CODEC_ID_SPEEX  &&
  425.             st->codec->codec_id != AV_CODEC_ID_FLAC   &&
  426.             st->codec->codec_id != AV_CODEC_ID_OPUS) {
  427.             av_log(s, AV_LOG_ERROR, "Unsupported codec id in stream %d\n", i);
  428.             return -1;
  429.         }
  430.  
  431.         if (!st->codec->extradata || !st->codec->extradata_size) {
  432.             av_log(s, AV_LOG_ERROR, "No extradata present\n");
  433.             return -1;
  434.         }
  435.         oggstream = av_mallocz(sizeof(*oggstream));
  436.         oggstream->page.stream_index = i;
  437.  
  438.         if (!(st->codec->flags & CODEC_FLAG_BITEXACT))
  439.             do {
  440.                 serial_num = av_get_random_seed();
  441.                 for (j = 0; j < i; j++) {
  442.                     OGGStreamContext *sc = s->streams[j]->priv_data;
  443.                     if (serial_num == sc->serial_num)
  444.                         break;
  445.                 }
  446.             } while (j < i);
  447.         oggstream->serial_num = serial_num;
  448.  
  449.         av_dict_copy(&st->metadata, s->metadata, AV_DICT_DONT_OVERWRITE);
  450.  
  451.         st->priv_data = oggstream;
  452.         if (st->codec->codec_id == AV_CODEC_ID_FLAC) {
  453.             int err = ogg_build_flac_headers(st->codec, oggstream,
  454.                                              st->codec->flags & CODEC_FLAG_BITEXACT,
  455.                                              &st->metadata);
  456.             if (err) {
  457.                 av_log(s, AV_LOG_ERROR, "Error writing FLAC headers\n");
  458.                 av_freep(&st->priv_data);
  459.                 return err;
  460.             }
  461.         } else if (st->codec->codec_id == AV_CODEC_ID_SPEEX) {
  462.             int err = ogg_build_speex_headers(st->codec, oggstream,
  463.                                               st->codec->flags & CODEC_FLAG_BITEXACT,
  464.                                               &st->metadata);
  465.             if (err) {
  466.                 av_log(s, AV_LOG_ERROR, "Error writing Speex headers\n");
  467.                 av_freep(&st->priv_data);
  468.                 return err;
  469.             }
  470.         } else if (st->codec->codec_id == AV_CODEC_ID_OPUS) {
  471.             int err = ogg_build_opus_headers(st->codec, oggstream,
  472.                                              st->codec->flags & CODEC_FLAG_BITEXACT,
  473.                                              &st->metadata);
  474.             if (err) {
  475.                 av_log(s, AV_LOG_ERROR, "Error writing Opus headers\n");
  476.                 av_freep(&st->priv_data);
  477.                 return err;
  478.             }
  479.         } else {
  480.             uint8_t *p;
  481.             const char *cstr = st->codec->codec_id == AV_CODEC_ID_VORBIS ? "vorbis" : "theora";
  482.             int header_type = st->codec->codec_id == AV_CODEC_ID_VORBIS ? 3 : 0x81;
  483.             int framing_bit = st->codec->codec_id == AV_CODEC_ID_VORBIS ? 1 : 0;
  484.  
  485.             if (avpriv_split_xiph_headers(st->codec->extradata, st->codec->extradata_size,
  486.                                       st->codec->codec_id == AV_CODEC_ID_VORBIS ? 30 : 42,
  487.                                       oggstream->header, oggstream->header_len) < 0) {
  488.                 av_log(s, AV_LOG_ERROR, "Extradata corrupted\n");
  489.                 av_freep(&st->priv_data);
  490.                 return -1;
  491.             }
  492.  
  493.             p = ogg_write_vorbiscomment(7, st->codec->flags & CODEC_FLAG_BITEXACT,
  494.                                         &oggstream->header_len[1], &st->metadata,
  495.                                         framing_bit);
  496.             oggstream->header[1] = p;
  497.             if (!p)
  498.                 return AVERROR(ENOMEM);
  499.  
  500.             bytestream_put_byte(&p, header_type);
  501.             bytestream_put_buffer(&p, cstr, 6);
  502.  
  503.             if (st->codec->codec_id == AV_CODEC_ID_THEORA) {
  504.                 /** KFGSHIFT is the width of the less significant section of the granule position
  505.                     The less significant section is the frame count since the last keyframe */
  506.                 oggstream->kfgshift = ((oggstream->header[0][40]&3)<<3)|(oggstream->header[0][41]>>5);
  507.                 oggstream->vrev = oggstream->header[0][9];
  508.                 av_log(s, AV_LOG_DEBUG, "theora kfgshift %d, vrev %d\n",
  509.                        oggstream->kfgshift, oggstream->vrev);
  510.             }
  511.         }
  512.     }
  513.  
  514.     for (j = 0; j < s->nb_streams; j++) {
  515.         OGGStreamContext *oggstream = s->streams[j]->priv_data;
  516.         ogg_buffer_data(s, s->streams[j], oggstream->header[0],
  517.                         oggstream->header_len[0], 0, 1);
  518.         oggstream->page.flags |= 2; // bos
  519.         ogg_buffer_page(s, oggstream);
  520.     }
  521.     for (j = 0; j < s->nb_streams; j++) {
  522.         AVStream *st = s->streams[j];
  523.         OGGStreamContext *oggstream = st->priv_data;
  524.         for (i = 1; i < 3; i++) {
  525.             if (oggstream->header_len[i])
  526.                 ogg_buffer_data(s, st, oggstream->header[i],
  527.                                 oggstream->header_len[i], 0, 1);
  528.         }
  529.         ogg_buffer_page(s, oggstream);
  530.     }
  531.  
  532.     oggstream->page.start_granule = AV_NOPTS_VALUE;
  533.  
  534.     return 0;
  535. }
  536.  
  537. static void ogg_write_pages(AVFormatContext *s, int flush)
  538. {
  539.     OGGContext *ogg = s->priv_data;
  540.     OGGPageList *next, *p;
  541.  
  542.     if (!ogg->page_list)
  543.         return;
  544.  
  545.     for (p = ogg->page_list; p; ) {
  546.         OGGStreamContext *oggstream =
  547.             s->streams[p->page.stream_index]->priv_data;
  548.         if (oggstream->page_count < 2 && !flush)
  549.             break;
  550.         ogg_write_page(s, &p->page,
  551.                        flush && oggstream->page_count == 1 ? 4 : 0); // eos
  552.         next = p->next;
  553.         av_freep(&p);
  554.         p = next;
  555.     }
  556.     ogg->page_list = p;
  557. }
  558.  
  559. static int ogg_write_packet(AVFormatContext *s, AVPacket *pkt)
  560. {
  561.     AVStream *st = s->streams[pkt->stream_index];
  562.     OGGStreamContext *oggstream = st->priv_data;
  563.     int ret;
  564.     int64_t granule;
  565.  
  566.     if (st->codec->codec_id == AV_CODEC_ID_THEORA) {
  567.         int64_t pts = oggstream->vrev < 1 ? pkt->pts : pkt->pts + pkt->duration;
  568.         int pframe_count;
  569.         if (pkt->flags & AV_PKT_FLAG_KEY)
  570.             oggstream->last_kf_pts = pts;
  571.         pframe_count = pts - oggstream->last_kf_pts;
  572.         // prevent frame count from overflow if key frame flag is not set
  573.         if (pframe_count >= (1<<oggstream->kfgshift)) {
  574.             oggstream->last_kf_pts += pframe_count;
  575.             pframe_count = 0;
  576.         }
  577.         granule = (oggstream->last_kf_pts<<oggstream->kfgshift) | pframe_count;
  578.     } else if (st->codec->codec_id == AV_CODEC_ID_OPUS)
  579.         granule = pkt->pts + pkt->duration + av_rescale_q(st->codec->delay, (AVRational){ 1, st->codec->sample_rate }, st->time_base);
  580.     else
  581.         granule = pkt->pts + pkt->duration;
  582.  
  583.     if (oggstream->page.start_granule == AV_NOPTS_VALUE)
  584.         oggstream->page.start_granule = pkt->pts;
  585.  
  586.     ret = ogg_buffer_data(s, st, pkt->data, pkt->size, granule, 0);
  587.     if (ret < 0)
  588.         return ret;
  589.  
  590.     ogg_write_pages(s, 0);
  591.  
  592.     oggstream->last_granule = granule;
  593.  
  594.     return 0;
  595. }
  596.  
  597. static int ogg_write_trailer(AVFormatContext *s)
  598. {
  599.     int i;
  600.  
  601.     /* flush current page if needed */
  602.     for (i = 0; i < s->nb_streams; i++) {
  603.         OGGStreamContext *oggstream = s->streams[i]->priv_data;
  604.  
  605.         if (oggstream->page.size > 0)
  606.             ogg_buffer_page(s, oggstream);
  607.     }
  608.  
  609.     ogg_write_pages(s, 1);
  610.  
  611.     for (i = 0; i < s->nb_streams; i++) {
  612.         AVStream *st = s->streams[i];
  613.         OGGStreamContext *oggstream = st->priv_data;
  614.         if (st->codec->codec_id == AV_CODEC_ID_FLAC ||
  615.             st->codec->codec_id == AV_CODEC_ID_SPEEX ||
  616.             st->codec->codec_id == AV_CODEC_ID_OPUS) {
  617.             av_freep(&oggstream->header[0]);
  618.         }
  619.         av_freep(&oggstream->header[1]);
  620.         av_freep(&st->priv_data);
  621.     }
  622.     return 0;
  623. }
  624.  
  625. AVOutputFormat ff_ogg_muxer = {
  626.     .name              = "ogg",
  627.     .long_name         = NULL_IF_CONFIG_SMALL("Ogg"),
  628.     .mime_type         = "application/ogg",
  629.     .extensions        = "ogg,ogv,spx,opus",
  630.     .priv_data_size    = sizeof(OGGContext),
  631.     .audio_codec       = AV_CODEC_ID_FLAC,
  632.     .video_codec       = AV_CODEC_ID_THEORA,
  633.     .write_header      = ogg_write_header,
  634.     .write_packet      = ogg_write_packet,
  635.     .write_trailer     = ogg_write_trailer,
  636.     .flags             = AVFMT_TS_NEGATIVE,
  637.     .priv_class        = &ogg_muxer_class,
  638. };
  639.