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  1. /*
  2.  * Copyright (c) 2013 Matthew Heaney
  3.  *
  4.  * This file is part of FFmpeg.
  5.  *
  6.  * FFmpeg is free software; you can redistribute it and/or
  7.  * modify it under the terms of the GNU Lesser General Public
  8.  * License as published by the Free Software Foundation; either
  9.  * version 2.1 of the License, or (at your option) any later version.
  10.  *
  11.  * FFmpeg is distributed in the hope that it will be useful,
  12.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14.  * Lesser General Public License for more details.
  15.  *
  16.  * You should have received a copy of the GNU Lesser General Public
  17.  * License along with FFmpeg; if not, write to the Free Software
  18.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  19.  */
  20.  
  21. /**
  22.  * @file
  23.  * WebVTT subtitle muxer
  24.  * @see http://dev.w3.org/html5/webvtt/
  25.  */
  26.  
  27. #include "avformat.h"
  28. #include "internal.h"
  29.  
  30. static void webvtt_write_time(AVIOContext *pb, int64_t millisec)
  31. {
  32.     int64_t sec, min, hour;
  33.     sec = millisec / 1000;
  34.     millisec -= 1000 * sec;
  35.     min = sec / 60;
  36.     sec -= 60 * min;
  37.     hour = min / 60;
  38.     min -= 60 * hour;
  39.  
  40.     if (hour > 0)
  41.         avio_printf(pb, "%"PRId64":", hour);
  42.  
  43.     avio_printf(pb, "%02"PRId64":%02"PRId64".%03"PRId64"", min, sec, millisec);
  44. }
  45.  
  46. static int webvtt_write_header(AVFormatContext *ctx)
  47. {
  48.     AVStream     *s = ctx->streams[0];
  49.     AVCodecContext *avctx = ctx->streams[0]->codec;
  50.     AVIOContext *pb = ctx->pb;
  51.  
  52.     if (ctx->nb_streams != 1 || avctx->codec_id != AV_CODEC_ID_WEBVTT) {
  53.         av_log(ctx, AV_LOG_ERROR, "Exactly one WebVTT stream is needed.\n");
  54.         return AVERROR(EINVAL);
  55.     }
  56.  
  57.     avpriv_set_pts_info(s, 64, 1, 1000);
  58.  
  59.     avio_printf(pb, "WEBVTT\n");
  60.     avio_flush(pb);
  61.  
  62.     return 0;
  63. }
  64.  
  65. static int webvtt_write_packet(AVFormatContext *ctx, AVPacket *pkt)
  66. {
  67.     AVIOContext  *pb = ctx->pb;
  68.     int id_size, settings_size;
  69.     uint8_t *id, *settings;
  70.  
  71.     avio_printf(pb, "\n");
  72.  
  73.     id = av_packet_get_side_data(pkt, AV_PKT_DATA_WEBVTT_IDENTIFIER,
  74.                                  &id_size);
  75.  
  76.     if (id && id_size > 0)
  77.         avio_printf(pb, "%.*s\n", id_size, id);
  78.  
  79.     webvtt_write_time(pb, pkt->pts);
  80.     avio_printf(pb, " --> ");
  81.     webvtt_write_time(pb, pkt->pts + pkt->duration);
  82.  
  83.     settings = av_packet_get_side_data(pkt, AV_PKT_DATA_WEBVTT_SETTINGS,
  84.                                        &settings_size);
  85.  
  86.     if (settings && settings_size > 0)
  87.         avio_printf(pb, " %.*s", settings_size, settings);
  88.  
  89.     avio_printf(pb, "\n");
  90.  
  91.     avio_write(pb, pkt->data, pkt->size);
  92.     avio_printf(pb, "\n");
  93.  
  94.     return 0;
  95. }
  96.  
  97. AVOutputFormat ff_webvtt_muxer = {
  98.     .name              = "webvtt",
  99.     .long_name         = NULL_IF_CONFIG_SMALL("WebVTT subtitle"),
  100.     .extensions        = "vtt",
  101.     .mime_type         = "text/vtt",
  102.     .flags             = AVFMT_VARIABLE_FPS | AVFMT_TS_NONSTRICT,
  103.     .subtitle_codec    = AV_CODEC_ID_WEBVTT,
  104.     .write_header      = webvtt_write_header,
  105.     .write_packet      = webvtt_write_packet,
  106. };
  107.