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libavformat/lmlm4.c

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00001 /*
00002  * Linux Media Labs MPEG-4 demuxer
00003  * Copyright (c) 2008 Ivo van Poorten
00004  *
00005  * Due to a lack of sample files, only files with one channel are supported.
00006  * u-law and ADPCM audio are unsupported for the same reason.
00007  *
00008  * This file is part of FFmpeg.
00009  *
00010  * FFmpeg is free software; you can redistribute it and/or
00011  * modify it under the terms of the GNU Lesser General Public
00012  * License as published by the Free Software Foundation; either
00013  * version 2.1 of the License, or (at your option) any later version.
00014  *
00015  * FFmpeg is distributed in the hope that it will be useful,
00016  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00017  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00018  * Lesser General Public License for more details.
00019  *
00020  * You should have received a copy of the GNU Lesser General Public
00021  * License along with FFmpeg; if not, write to the Free Software
00022  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00023  */
00024 
00025 #include "libavutil/intreadwrite.h"
00026 #include "avformat.h"
00027 
00028 #define LMLM4_I_FRAME   0x00
00029 #define LMLM4_P_FRAME   0x01
00030 #define LMLM4_B_FRAME   0x02
00031 #define LMLM4_INVALID   0x03
00032 #define LMLM4_MPEG1L2   0x04
00033 
00034 #define LMLM4_MAX_PACKET_SIZE   1024 * 1024
00035 
00036 static int lmlm4_probe(AVProbeData * pd) {
00037     unsigned char *buf = pd->buf;
00038     unsigned int frame_type, packet_size;
00039 
00040     frame_type  = AV_RB16(buf+2);
00041     packet_size = AV_RB32(buf+4);
00042 
00043     if (!AV_RB16(buf) && frame_type <= LMLM4_MPEG1L2 && packet_size &&
00044         frame_type != LMLM4_INVALID && packet_size <= LMLM4_MAX_PACKET_SIZE) {
00045 
00046         if (frame_type == LMLM4_MPEG1L2) {
00047             if ((AV_RB16(buf+8) & 0xfffe) != 0xfffc)
00048                 return 0;
00049             /* I could calculate the audio framesize and compare with
00050              * packet_size-8, but that seems overkill */
00051             return AVPROBE_SCORE_MAX / 3;
00052         } else if (AV_RB24(buf+8) == 0x000001) {    /* PES Signal */
00053             return AVPROBE_SCORE_MAX / 5;
00054         }
00055     }
00056 
00057     return 0;
00058 }
00059 
00060 static int lmlm4_read_header(AVFormatContext *s, AVFormatParameters *ap) {
00061     AVStream *st;
00062 
00063     if (!(st = av_new_stream(s, 0)))
00064         return AVERROR(ENOMEM);
00065     st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
00066     st->codec->codec_id   = CODEC_ID_MPEG4;
00067     st->need_parsing      = AVSTREAM_PARSE_HEADERS;
00068     av_set_pts_info(st, 64, 1001, 30000);
00069 
00070     if (!(st = av_new_stream(s, 1)))
00071         return AVERROR(ENOMEM);
00072     st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
00073     st->codec->codec_id   = CODEC_ID_MP2;
00074     st->need_parsing      = AVSTREAM_PARSE_HEADERS;
00075 
00076     /* the parameters will be extracted from the compressed bitstream */
00077     return 0;
00078 }
00079 
00080 static int lmlm4_read_packet(AVFormatContext *s, AVPacket *pkt) {
00081     ByteIOContext *pb = s->pb;
00082     int ret;
00083     unsigned int frame_type, packet_size, padding, frame_size;
00084 
00085     get_be16(pb);                       /* channel number */
00086     frame_type  = get_be16(pb);
00087     packet_size = get_be32(pb);
00088     padding     = -packet_size & 511;
00089     frame_size  = packet_size - 8;
00090 
00091     if (frame_type > LMLM4_MPEG1L2 || frame_type == LMLM4_INVALID) {
00092         av_log(s, AV_LOG_ERROR, "invalid or unsupported frame_type\n");
00093         return AVERROR(EIO);
00094     }
00095     if (packet_size > LMLM4_MAX_PACKET_SIZE) {
00096         av_log(s, AV_LOG_ERROR, "packet size exceeds maximum\n");
00097         return AVERROR(EIO);
00098     }
00099 
00100     if ((ret = av_get_packet(pb, pkt, frame_size)) <= 0)
00101         return AVERROR(EIO);
00102 
00103     url_fskip(pb, padding);
00104 
00105     switch (frame_type) {
00106         case LMLM4_I_FRAME:
00107             pkt->flags = AV_PKT_FLAG_KEY;
00108         case LMLM4_P_FRAME:
00109         case LMLM4_B_FRAME:
00110             pkt->stream_index = 0;
00111             break;
00112         case LMLM4_MPEG1L2:
00113             pkt->stream_index = 1;
00114             break;
00115     }
00116 
00117     return ret;
00118 }
00119 
00120 AVInputFormat lmlm4_demuxer = {
00121     "lmlm4",
00122     NULL_IF_CONFIG_SMALL("lmlm4 raw format"),
00123     0,
00124     lmlm4_probe,
00125     lmlm4_read_header,
00126     lmlm4_read_packet,
00127 };

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