text: /*
   * Linux Media Labs MPEG-4 demuxer
   * Copyright (c) 2008 Ivo van Poorten
   *
   * Due to a lack of sample files, only files with one channel are supported.
   * u-law and ADPCM audio are unsupported for the same reason.
   *
   * This file is part of Libav.
   *
   * Libav 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.
   *
   * Libav 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 Libav; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
   */
  
  #include "libavutil/intreadwrite.h"
  
  #include "avformat.h"
  #include "internal.h"
  
  #define LMLM4_I_FRAME   0x00
  #define LMLM4_P_FRAME   0x01
  #define LMLM4_B_FRAME   0x02
  #define LMLM4_INVALID   0x03
  #define LMLM4_MPEG1L2   0x04
  
  #define LMLM4_MAX_PACKET_SIZE   1024 * 1024
  
  static int lmlm4_probe(AVProbeData *pd)
  {
      unsigned char *buf = pd->buf;
      unsigned int frame_type, packet_size;
  
      frame_type  = AV_RB16(buf + 2);
      packet_size = AV_RB32(buf + 4);
  
      if (!AV_RB16(buf) && frame_type <= LMLM4_MPEG1L2 && packet_size &&
          frame_type != LMLM4_INVALID && packet_size <= LMLM4_MAX_PACKET_SIZE) {
          if (frame_type == LMLM4_MPEG1L2) {
              if ((AV_RB16(buf + 8) & 0xfffe) != 0xfffc)
                  return 0;
              /* I could calculate the audio framesize and compare with
               * packet_size-8, but that seems overkill */
              return AVPROBE_SCORE_MAX / 3;
          } else if (AV_RB24(buf + 8) == 0x000001) {    /* PES Signal */
              return AVPROBE_SCORE_MAX / 5;
          }
      }
  
      return 0;
  }
  
  static int lmlm4_read_header(AVFormatContext *s)
  {
      AVStream *st;
  
      if (!(st = avformat_new_stream(s, NULL)))
          return AVERROR(ENOMEM);
      st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
      st->codecpar->codec_id   = AV_CODEC_ID_MPEG4;
      st->need_parsing      = AVSTREAM_PARSE_HEADERS;
      avpriv_set_pts_info(st, 64, 1001, 30000);
  
      if (!(st = avformat_new_stream(s, NULL)))
          return AVERROR(ENOMEM);
      st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
      st->codecpar->codec_id   = AV_CODEC_ID_MP2;
      st->need_parsing      = AVSTREAM_PARSE_HEADERS;
  
      /* the parameters will be extracted from the compressed bitstream */
      return 0;
  }
  
  static int lmlm4_read_packet(AVFormatContext *s, AVPacket *pkt)
  {
      AVIOContext *pb = s->pb;
      int ret;
      unsigned int frame_type, packet_size, padding, frame_size;
  
      avio_rb16(pb);                       /* channel number */
      frame_type  = avio_rb16(pb);
      packet_size = avio_rb32(pb);
      padding     = -packet_size & 511;
      frame_size  = packet_size - 8;
  
      if (frame_type > LMLM4_MPEG1L2 || frame_type == LMLM4_INVALID) {
          av_log(s, AV_LOG_ERROR, "invalid or unsupported frame_type\n");
          return AVERROR(EIO);
      }
      if (packet_size > LMLM4_MAX_PACKET_SIZE) {
          av_log(s, AV_LOG_ERROR, "packet size exceeds maximum\n");
          return AVERROR(EIO);
      }
  
      if ((ret = av_get_packet(pb, pkt, frame_size)) <= 0)
          return AVERROR(EIO);
  
      avio_skip(pb, padding);
  
      switch (frame_type) {
      case LMLM4_I_FRAME:
          pkt->flags = AV_PKT_FLAG_KEY;
      case LMLM4_P_FRAME:
      case LMLM4_B_FRAME:
          pkt->stream_index = 0;
          break;
      case LMLM4_MPEG1L2:
          pkt->stream_index = 1;
          break;
      }
  
      return ret;
  }
  
  AVInputFormat ff_lmlm4_demuxer = {
      .name           = "lmlm4",
      .long_name      = NULL_IF_CONFIG_SMALL("raw lmlm4"),
      .read_probe     = lmlm4_probe,
      .read_header    = lmlm4_read_header,
      .read_packet    = lmlm4_read_packet,
  };
  