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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. #include "avformat.h"
  27. #include "internal.h"
  28.  
  29. #define LMLM4_I_FRAME   0x00
  30. #define LMLM4_P_FRAME   0x01
  31. #define LMLM4_B_FRAME   0x02
  32. #define LMLM4_INVALID   0x03
  33. #define LMLM4_MPEG1L2   0x04
  34.  
  35. #define LMLM4_MAX_PACKET_SIZE   1024 * 1024
  36.  
  37. static int lmlm4_probe(AVProbeData * pd) {
  38.     const unsigned char *buf = pd->buf;
  39.     unsigned int frame_type, packet_size;
  40.  
  41.     frame_type  = AV_RB16(buf+2);
  42.     packet_size = AV_RB32(buf+4);
  43.  
  44.     if (!AV_RB16(buf) && frame_type <= LMLM4_MPEG1L2 && packet_size &&
  45.         frame_type != LMLM4_INVALID && packet_size <= LMLM4_MAX_PACKET_SIZE) {
  46.  
  47.         if (frame_type == LMLM4_MPEG1L2) {
  48.             if ((AV_RB16(buf+8) & 0xfffe) != 0xfffc)
  49.                 return 0;
  50.             /* I could calculate the audio framesize and compare with
  51.              * packet_size-8, but that seems overkill */
  52.             return AVPROBE_SCORE_MAX / 3;
  53.         } else if (AV_RB24(buf+8) == 0x000001) {    /* PES Signal */
  54.             return AVPROBE_SCORE_MAX / 5;
  55.         }
  56.     }
  57.  
  58.     return 0;
  59. }
  60.  
  61. static int lmlm4_read_header(AVFormatContext *s) {
  62.     AVStream *st;
  63.  
  64.     if (!(st = avformat_new_stream(s, NULL)))
  65.         return AVERROR(ENOMEM);
  66.     st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
  67.     st->codec->codec_id   = AV_CODEC_ID_MPEG4;
  68.     st->need_parsing      = AVSTREAM_PARSE_HEADERS;
  69.     avpriv_set_pts_info(st, 64, 1001, 30000);
  70.  
  71.     if (!(st = avformat_new_stream(s, NULL)))
  72.         return AVERROR(ENOMEM);
  73.     st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
  74.     st->codec->codec_id   = AV_CODEC_ID_MP2;
  75.     st->need_parsing      = AVSTREAM_PARSE_HEADERS;
  76.  
  77.     /* the parameters will be extracted from the compressed bitstream */
  78.     return 0;
  79. }
  80.  
  81. static int lmlm4_read_packet(AVFormatContext *s, AVPacket *pkt) {
  82.     AVIOContext *pb = s->pb;
  83.     int ret;
  84.     unsigned int frame_type, packet_size, padding, frame_size;
  85.  
  86.     avio_rb16(pb);                       /* channel number */
  87.     frame_type  = avio_rb16(pb);
  88.     packet_size = avio_rb32(pb);
  89.     padding     = -packet_size & 511;
  90.     frame_size  = packet_size - 8;
  91.  
  92.     if (frame_type > LMLM4_MPEG1L2 || frame_type == LMLM4_INVALID) {
  93.         av_log(s, AV_LOG_ERROR, "invalid or unsupported frame_type\n");
  94.         return AVERROR(EIO);
  95.     }
  96.     if (packet_size > LMLM4_MAX_PACKET_SIZE || packet_size<=8) {
  97.         av_log(s, AV_LOG_ERROR, "packet size %d is invalid\n", packet_size);
  98.         return AVERROR(EIO);
  99.     }
  100.  
  101.     if ((ret = av_get_packet(pb, pkt, frame_size)) <= 0)
  102.         return AVERROR(EIO);
  103.  
  104.     avio_skip(pb, padding);
  105.  
  106.     switch (frame_type) {
  107.         case LMLM4_I_FRAME:
  108.             pkt->flags = AV_PKT_FLAG_KEY;
  109.         case LMLM4_P_FRAME:
  110.         case LMLM4_B_FRAME:
  111.             pkt->stream_index = 0;
  112.             break;
  113.         case LMLM4_MPEG1L2:
  114.             pkt->stream_index = 1;
  115.             break;
  116.     }
  117.  
  118.     return ret;
  119. }
  120.  
  121. AVInputFormat ff_lmlm4_demuxer = {
  122.     .name           = "lmlm4",
  123.     .long_name      = NULL_IF_CONFIG_SMALL("raw lmlm4"),
  124.     .read_probe     = lmlm4_probe,
  125.     .read_header    = lmlm4_read_header,
  126.     .read_packet    = lmlm4_read_packet,
  127. };
  128.