text: /*
   * Adobe Filmstrip demuxer
   * Copyright (c) 2010 Peter Ross
   *
   * 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
   * Adobe Filmstrip demuxer
   */
  
  #include "libavutil/intreadwrite.h"
  #include "avformat.h"
  #include "internal.h"
  
  #define RAND_TAG MKBETAG('R','a','n','d')
  
  typedef struct FilmstripDemuxContext {
      int leading;
  } FilmstripDemuxContext;
  
  static int read_header(AVFormatContext *s)
  {
      FilmstripDemuxContext *film = s->priv_data;
      AVIOContext *pb = s->pb;
      AVStream *st;
  
      if (!s->pb->seekable)
          return AVERROR(EIO);
  
      avio_seek(pb, avio_size(pb) - 36, SEEK_SET);
      if (avio_rb32(pb) != RAND_TAG) {
          av_log(s, AV_LOG_ERROR, "magic number not found\n");
          return AVERROR_INVALIDDATA;
      }
  
      st = avformat_new_stream(s, NULL);
      if (!st)
          return AVERROR(ENOMEM);
  
      st->nb_frames = avio_rb32(pb);
      if (avio_rb16(pb) != 0) {
          avpriv_request_sample(s, "Unsupported packing method");
          return AVERROR_PATCHWELCOME;
      }
  
      avio_skip(pb, 2);
      st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
      st->codec->codec_id   = AV_CODEC_ID_RAWVIDEO;
      st->codec->pix_fmt    = AV_PIX_FMT_RGBA;
      st->codec->codec_tag  = 0; /* no fourcc */
      st->codec->width      = avio_rb16(pb);
      st->codec->height     = avio_rb16(pb);
      film->leading         = avio_rb16(pb);
  
      if (st->codec->width * 4LL * st->codec->height >= INT_MAX) {
          av_log(s, AV_LOG_ERROR, "dimensions too large\n");
          return AVERROR_PATCHWELCOME;
      }
  
      avpriv_set_pts_info(st, 64, 1, avio_rb16(pb));
  
      avio_seek(pb, 0, SEEK_SET);
  
      return 0;
  }
  
  static int read_packet(AVFormatContext *s,
                         AVPacket *pkt)
  {
      FilmstripDemuxContext *film = s->priv_data;
      AVStream *st = s->streams[0];
  
      if (avio_feof(s->pb))
          return AVERROR(EIO);
      pkt->dts = avio_tell(s->pb) / (st->codec->width * (int64_t)(st->codec->height + film->leading) * 4);
      pkt->size = av_get_packet(s->pb, pkt, st->codec->width * st->codec->height * 4);
      avio_skip(s->pb, st->codec->width * (int64_t) film->leading * 4);
      if (pkt->size < 0)
          return pkt->size;
      pkt->flags |= AV_PKT_FLAG_KEY;
      return 0;
  }
  
  static int read_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags)
  {
      AVStream *st = s->streams[stream_index];
      if (avio_seek(s->pb, FFMAX(timestamp, 0) * st->codec->width * st->codec->height * 4, SEEK_SET) < 0)
          return -1;
      return 0;
  }
  
  AVInputFormat ff_filmstrip_demuxer = {
      .name           = "filmstrip",
      .long_name      = NULL_IF_CONFIG_SMALL("Adobe Filmstrip"),
      .priv_data_size = sizeof(FilmstripDemuxContext),
      .read_header    = read_header,
      .read_packet    = read_packet,
      .read_seek      = read_seek,
      .extensions     = "flm",
  };
  