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ffmpeg / libavformat / lmlm4.c @ b7effd4e

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/*
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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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    url_fskip(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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};