amr.c 4.61 KB
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/*
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 * amr file format
 * Copyright (c) 2001 ffmpeg project
 *
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 * This file is part of FFmpeg.
 *
 * 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
 * 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
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * 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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 */

/*
Write and read amr data according to RFC3267, http://www.ietf.org/rfc/rfc3267.txt?number=3267

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Only mono files are supported.
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*/
#include "avformat.h"

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static const char AMR_header [] = "#!AMR\n";
static const char AMRWB_header [] = "#!AMR-WB\n";
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#if CONFIG_AMR_MUXER
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static int amr_write_header(AVFormatContext *s)
{
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    AVIOContext *pb = s->pb;
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    AVCodecContext *enc = s->streams[0]->codec;
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    s->priv_data = NULL;

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    if (enc->codec_id == CODEC_ID_AMR_NB)
    {
        put_tag(pb, AMR_header);       /* magic number */
    }
    else if(enc->codec_id == CODEC_ID_AMR_WB)
    {
        put_tag(pb, AMRWB_header);       /* magic number */
    }
    else
    {
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        return -1;
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    }
    put_flush_packet(pb);
    return 0;
}

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static int amr_write_packet(AVFormatContext *s, AVPacket *pkt)
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{
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    put_buffer(s->pb, pkt->data, pkt->size);
    put_flush_packet(s->pb);
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    return 0;
}
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#endif /* CONFIG_AMR_MUXER */
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static int amr_probe(AVProbeData *p)
{
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    //Only check for "#!AMR" which could be amr-wb, amr-nb.
    //This will also trigger multichannel files: "#!AMR_MC1.0\n" and
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    //"#!AMR-WB_MC1.0\n" (not supported)

    if(memcmp(p->buf,AMR_header,5)==0)
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        return AVPROBE_SCORE_MAX;
    else
        return 0;
}

/* amr input */
static int amr_read_header(AVFormatContext *s,
                           AVFormatParameters *ap)
{
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    AVIOContext *pb = s->pb;
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    AVStream *st;
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    uint8_t header[9];
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    avio_read(pb, header, 6);
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    st = av_new_stream(s, 0);
    if (!st)
    {
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        return AVERROR(ENOMEM);
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    }
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    if(memcmp(header,AMR_header,6)!=0)
    {
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        avio_read(pb, header+6, 3);
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        if(memcmp(header,AMRWB_header,9)!=0)
        {
            return -1;
        }
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        st->codec->codec_tag = MKTAG('s', 'a', 'w', 'b');
        st->codec->codec_id = CODEC_ID_AMR_WB;
        st->codec->sample_rate = 16000;
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        st->codec->frame_size = 320;
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    }
    else
    {
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        st->codec->codec_tag = MKTAG('s', 'a', 'm', 'r');
        st->codec->codec_id = CODEC_ID_AMR_NB;
        st->codec->sample_rate = 8000;
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        st->codec->frame_size = 160;
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    }
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    st->codec->channels = 1;
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    st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
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    av_set_pts_info(st, 64, 1, st->codec->sample_rate);
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    return 0;
}

static int amr_read_packet(AVFormatContext *s,
                          AVPacket *pkt)
{
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    AVCodecContext *enc = s->streams[0]->codec;
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    int read, size = 0, toc, mode;
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    if (url_feof(s->pb))
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    {
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        return AVERROR(EIO);
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    }
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//FIXME this is wrong, this should rather be in a AVParset
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    toc=avio_r8(s->pb);
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    mode = (toc >> 3) & 0x0F;
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    if (enc->codec_id == CODEC_ID_AMR_NB)
    {
        static const uint8_t packed_size[16] = {12, 13, 15, 17, 19, 20, 26, 31, 5, 0, 0, 0, 0, 0, 0, 0};
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        size=packed_size[mode]+1;
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    }
    else if(enc->codec_id == CODEC_ID_AMR_WB)
    {
        static uint8_t packed_size[16] = {18, 24, 33, 37, 41, 47, 51, 59, 61, 6, 6, 0, 0, 0, 1, 1};
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        size=packed_size[mode];
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    }
    else
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    {
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        assert(0);
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    }
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    if ( (size==0) || av_new_packet(pkt, size))
    {
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        return AVERROR(EIO);
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    }

    pkt->stream_index = 0;
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    pkt->pos= url_ftell(s->pb);
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    pkt->data[0]=toc;
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    pkt->duration= enc->codec_id == CODEC_ID_AMR_NB ? 160 : 320;
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    read = avio_read(s->pb, pkt->data+1, size-1);
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    if (read != size-1)
    {
        av_free_packet(pkt);
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        return AVERROR(EIO);
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    }

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    return 0;
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}

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#if CONFIG_AMR_DEMUXER
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AVInputFormat ff_amr_demuxer = {
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    "amr",
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    NULL_IF_CONFIG_SMALL("3GPP AMR file format"),
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    0, /*priv_data_size*/
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    amr_probe,
    amr_read_header,
    amr_read_packet,
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    NULL,
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};
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#endif
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#if CONFIG_AMR_MUXER
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AVOutputFormat ff_amr_muxer = {
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    "amr",
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    NULL_IF_CONFIG_SMALL("3GPP AMR file format"),
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    "audio/amr",
    "amr",
    0,
    CODEC_ID_AMR_NB,
    CODEC_ID_NONE,
    amr_write_header,
    amr_write_packet,
};
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#endif