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ffmpeg-4.2.2/libavformat/sccenc.c 3.81 KB
aac5773f   hucm   功能基本完成,接口待打磨
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  /*
   * SCC muxer
   * Copyright (c) 2017 Paul B Mahol
   *
   * 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
   */
  
  #include "avformat.h"
  #include "internal.h"
  #include "libavutil/log.h"
  #include "libavutil/intreadwrite.h"
  
  typedef struct SCCContext {
      int prev_h, prev_m, prev_s, prev_f;
      int inside;
      int n;
  } SCCContext;
  
  static int scc_write_header(AVFormatContext *avf)
  {
      SCCContext *scc = avf->priv_data;
  
      if (avf->nb_streams != 1 ||
          avf->streams[0]->codecpar->codec_type != AVMEDIA_TYPE_SUBTITLE) {
          av_log(avf, AV_LOG_ERROR,
                 "SCC supports only a single subtitles stream.\n");
          return AVERROR(EINVAL);
      }
      if (avf->streams[0]->codecpar->codec_id != AV_CODEC_ID_EIA_608) {
          av_log(avf, AV_LOG_ERROR,
                 "Unsupported subtitles codec: %s\n",
                 avcodec_get_name(avf->streams[0]->codecpar->codec_id));
          return AVERROR(EINVAL);
      }
      avpriv_set_pts_info(avf->streams[0], 64, 1, 1000);
      avio_printf(avf->pb, "Scenarist_SCC V1.0\n");
  
      scc->prev_h = scc->prev_m = scc->prev_s = scc->prev_f = -1;
      scc->inside = 0;
  
      return 0;
  }
  
  static int scc_write_packet(AVFormatContext *avf, AVPacket *pkt)
  {
      SCCContext *scc = avf->priv_data;
      int64_t pts = pkt->pts;
      int i, h, m, s, f;
  
      if (pts == AV_NOPTS_VALUE) {
          av_log(avf, AV_LOG_WARNING,
                 "Insufficient timestamps.\n");
          return 0;
      }
  
      h = (int)(pts / (3600000));
      m = (int)(pts / (60000)) % 60;
      s = (int)(pts /  1000) % 60;
      f = (int)(pts %  1000) / 33;
  
      for (i = 0; i < pkt->size; i+=3) {
          if (pkt->data[i] == 0xfc && ((pkt->data[i + 1] != 0x80 || pkt->data[i + 2] != 0x80)))
              break;
      }
      if (i >= pkt->size)
          return 0;
  
      if (!scc->inside && (scc->prev_h != h || scc->prev_m != m || scc->prev_s != s || scc->prev_f != f)) {
          avio_printf(avf->pb, "\n%02d:%02d:%02d:%02d\t", h, m, s, f);
          scc->inside = 1;
      }
      for (i = 0; i < pkt->size; i+=3) {
          if (i + 3 > pkt->size)
              break;
  
          if (pkt->data[i] != 0xfc || (pkt->data[i + 1] == 0x80 && pkt->data[i + 2] == 0x80))
              continue;
          if (!scc->inside) {
              avio_printf(avf->pb, "\n%02d:%02d:%02d:%02d\t", h, m, s, f);
              scc->inside = 1;
          }
          if (scc->n > 0)
              avio_printf(avf->pb, " ");
          avio_printf(avf->pb, "%02x%02x", pkt->data[i + 1], pkt->data[i + 2]);
          scc->n++;
      }
      if (scc->inside && (scc->prev_h != h || scc->prev_m != m || scc->prev_s != s || scc->prev_f != f)) {
          avio_printf(avf->pb, "\n");
          scc->n = 0;
          scc->inside = 0;
      }
  
      scc->prev_h = h;
      scc->prev_m = m;
      scc->prev_s = s;
      scc->prev_f = f;
      return 0;
  }
  
  AVOutputFormat ff_scc_muxer = {
      .name           = "scc",
      .long_name      = NULL_IF_CONFIG_SMALL("Scenarist Closed Captions"),
      .extensions     = "scc",
      .priv_data_size = sizeof(SCCContext),
      .write_header   = scc_write_header,
      .write_packet   = scc_write_packet,
      .flags          = AVFMT_GLOBALHEADER | AVFMT_VARIABLE_FPS | AVFMT_TS_NONSTRICT,
      .subtitle_codec = AV_CODEC_ID_EIA_608,
  };