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  1. /*
  2.  * Linux Media Labs MPEG-4 demuxer
  3.  * Copyright (c) 2008 Ivo van Poorten
  4.  *
  5.  * Due to a lack of sample files, only files with one channel are supported.
  6.  * u-law and ADPCM audio are unsupported for the same reason.
  7.  *
  8.  * This file is part of FFmpeg.
  9.  *
  10.  * FFmpeg is free software; you can redistribute it and/or
  11.  * modify it under the terms of the GNU Lesser General Public
  12.  * License as published by the Free Software Foundation; either
  13.  * version 2.1 of the License, or (at your option) any later version.
  14.  *
  15.  * FFmpeg is distributed in the hope that it will be useful,
  16.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18.  * Lesser General Public License for more details.
  19.  *
  20.  * You should have received a copy of the GNU Lesser General Public
  21.  * License along with FFmpeg; if not, write to the Free Software
  22.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  23.  */
  24.  
  25. #include "libavutil/intreadwrite.h"
  26.  
  27. #include "avformat.h"
  28. #include "internal.h"
  29.  
  30. #define LMLM4_I_FRAME   0x00
  31. #define LMLM4_P_FRAME   0x01
  32. #define LMLM4_B_FRAME   0x02
  33. #define LMLM4_INVALID   0x03
  34. #define LMLM4_MPEG1L2   0x04
  35.  
  36. #define LMLM4_MAX_PACKET_SIZE   1024 * 1024
  37.  
  38. static int lmlm4_probe(AVProbeData *pd)
  39. {
  40.     const unsigned char *buf = pd->buf;
  41.     unsigned int frame_type, packet_size;
  42.  
  43.     frame_type  = AV_RB16(buf + 2);
  44.     packet_size = AV_RB32(buf + 4);
  45.  
  46.     if (!AV_RB16(buf) && frame_type <= LMLM4_MPEG1L2 && packet_size &&
  47.         frame_type != LMLM4_INVALID && packet_size <= LMLM4_MAX_PACKET_SIZE) {
  48.         if (frame_type == LMLM4_MPEG1L2) {
  49.             if ((AV_RB16(buf + 8) & 0xfffe) != 0xfffc)
  50.                 return 0;
  51.             /* I could calculate the audio framesize and compare with
  52.              * packet_size-8, but that seems overkill */
  53.             return AVPROBE_SCORE_MAX / 3;
  54.         } else if (AV_RB24(buf + 8) == 0x000001) {    /* PES Signal */
  55.             return AVPROBE_SCORE_MAX / 5;
  56.         }
  57.     }
  58.  
  59.     return 0;
  60. }
  61.  
  62. static int lmlm4_read_header(AVFormatContext *s)
  63. {
  64.     AVStream *st;
  65.  
  66.     if (!(st = avformat_new_stream(s, NULL)))
  67.         return AVERROR(ENOMEM);
  68.     st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
  69.     st->codec->codec_id   = AV_CODEC_ID_MPEG4;
  70.     st->need_parsing      = AVSTREAM_PARSE_HEADERS;
  71.     avpriv_set_pts_info(st, 64, 1001, 30000);
  72.  
  73.     if (!(st = avformat_new_stream(s, NULL)))
  74.         return AVERROR(ENOMEM);
  75.     st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
  76.     st->codec->codec_id   = AV_CODEC_ID_MP2;
  77.     st->need_parsing      = AVSTREAM_PARSE_HEADERS;
  78.  
  79.     /* the parameters will be extracted from the compressed bitstream */
  80.     return 0;
  81. }
  82.  
  83. static int lmlm4_read_packet(AVFormatContext *s, AVPacket *pkt)
  84. {
  85.     AVIOContext *pb = s->pb;
  86.     int ret;
  87.     unsigned int frame_type, packet_size, padding, frame_size;
  88.  
  89.     avio_rb16(pb);                       /* channel number */
  90.     frame_type  = avio_rb16(pb);
  91.     packet_size = avio_rb32(pb);
  92.     padding     = -packet_size & 511;
  93.     frame_size  = packet_size - 8;
  94.  
  95.     if (frame_type > LMLM4_MPEG1L2 || frame_type == LMLM4_INVALID) {
  96.         av_log(s, AV_LOG_ERROR, "invalid or unsupported frame_type\n");
  97.         return AVERROR(EIO);
  98.     }
  99.     if (packet_size > LMLM4_MAX_PACKET_SIZE || packet_size<=8) {
  100.         av_log(s, AV_LOG_ERROR, "packet size %d is invalid\n", packet_size);
  101.         return AVERROR(EIO);
  102.     }
  103.  
  104.     if ((ret = av_get_packet(pb, pkt, frame_size)) <= 0)
  105.         return AVERROR(EIO);
  106.  
  107.     avio_skip(pb, padding);
  108.  
  109.     switch (frame_type) {
  110.     case LMLM4_I_FRAME:
  111.         pkt->flags = AV_PKT_FLAG_KEY;
  112.     case LMLM4_P_FRAME:
  113.     case LMLM4_B_FRAME:
  114.         pkt->stream_index = 0;
  115.         break;
  116.     case LMLM4_MPEG1L2:
  117.         pkt->stream_index = 1;
  118.         break;
  119.     }
  120.  
  121.     return ret;
  122. }
  123.  
  124. AVInputFormat ff_lmlm4_demuxer = {
  125.     .name           = "lmlm4",
  126.     .long_name      = NULL_IF_CONFIG_SMALL("raw lmlm4"),
  127.     .read_probe     = lmlm4_probe,
  128.     .read_header    = lmlm4_read_header,
  129.     .read_packet    = lmlm4_read_packet,
  130. };
  131.