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https://git.ffmpeg.org/ffmpeg.git
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128 lines
3.9 KiB
C
128 lines
3.9 KiB
C
/*
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* Linux Media Labs MPEG-4 demuxer
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* Copyright (c) 2008 Ivo van Poorten
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*
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* Due to a lack of sample files, only files with one channel are supported.
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* u-law and ADPCM audio are unsupported for the same reason.
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "libavutil/intreadwrite.h"
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#include "avformat.h"
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#define LMLM4_I_FRAME 0x00
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#define LMLM4_P_FRAME 0x01
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#define LMLM4_B_FRAME 0x02
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#define LMLM4_INVALID 0x03
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#define LMLM4_MPEG1L2 0x04
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#define LMLM4_MAX_PACKET_SIZE 1024 * 1024
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static int lmlm4_probe(AVProbeData * pd) {
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unsigned char *buf = pd->buf;
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unsigned int frame_type, packet_size;
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frame_type = AV_RB16(buf+2);
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packet_size = AV_RB32(buf+4);
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if (!AV_RB16(buf) && frame_type <= LMLM4_MPEG1L2 && packet_size &&
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frame_type != LMLM4_INVALID && packet_size <= LMLM4_MAX_PACKET_SIZE) {
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if (frame_type == LMLM4_MPEG1L2) {
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if ((AV_RB16(buf+8) & 0xfffe) != 0xfffc)
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return 0;
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/* I could calculate the audio framesize and compare with
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* packet_size-8, but that seems overkill */
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return AVPROBE_SCORE_MAX / 3;
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} else if (AV_RB24(buf+8) == 0x000001) { /* PES Signal */
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return AVPROBE_SCORE_MAX / 5;
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}
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}
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return 0;
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}
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static int lmlm4_read_header(AVFormatContext *s, AVFormatParameters *ap) {
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AVStream *st;
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if (!(st = av_new_stream(s, 0)))
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return AVERROR(ENOMEM);
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st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
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st->codec->codec_id = CODEC_ID_MPEG4;
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st->need_parsing = AVSTREAM_PARSE_HEADERS;
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av_set_pts_info(st, 64, 1001, 30000);
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if (!(st = av_new_stream(s, 1)))
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return AVERROR(ENOMEM);
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st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
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st->codec->codec_id = CODEC_ID_MP2;
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st->need_parsing = AVSTREAM_PARSE_HEADERS;
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/* the parameters will be extracted from the compressed bitstream */
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return 0;
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}
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static int lmlm4_read_packet(AVFormatContext *s, AVPacket *pkt) {
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AVIOContext *pb = s->pb;
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int ret;
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unsigned int frame_type, packet_size, padding, frame_size;
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avio_rb16(pb); /* channel number */
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frame_type = avio_rb16(pb);
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packet_size = avio_rb32(pb);
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padding = -packet_size & 511;
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frame_size = packet_size - 8;
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if (frame_type > LMLM4_MPEG1L2 || frame_type == LMLM4_INVALID) {
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av_log(s, AV_LOG_ERROR, "invalid or unsupported frame_type\n");
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return AVERROR(EIO);
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}
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if (packet_size > LMLM4_MAX_PACKET_SIZE) {
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av_log(s, AV_LOG_ERROR, "packet size exceeds maximum\n");
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return AVERROR(EIO);
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}
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if ((ret = av_get_packet(pb, pkt, frame_size)) <= 0)
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return AVERROR(EIO);
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avio_skip(pb, padding);
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switch (frame_type) {
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case LMLM4_I_FRAME:
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pkt->flags = AV_PKT_FLAG_KEY;
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case LMLM4_P_FRAME:
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case LMLM4_B_FRAME:
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pkt->stream_index = 0;
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break;
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case LMLM4_MPEG1L2:
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pkt->stream_index = 1;
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break;
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}
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return ret;
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}
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AVInputFormat ff_lmlm4_demuxer = {
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"lmlm4",
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NULL_IF_CONFIG_SMALL("lmlm4 raw format"),
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0,
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lmlm4_probe,
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lmlm4_read_header,
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lmlm4_read_packet,
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};
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