PeerStreamer

/*

 * amr file format

 * Copyright (c) 2001 ffmpeg project

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2 of the License, or (at your option) any later version.

 *

 * This library is distributed in the hope that it will be useful,

 * 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

 * License along with this library; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

/*

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

Only mono files are supported.

*/

#include "avformat.h"

static const unsigned char AMR_header [] = "#!AMR\n";

static const unsigned char AMRWB_header [] = "#!AMR-WB\n";

static int amr_write_header(AVFormatContext *s)

{

    ByteIOContext *pb = &s->pb;

    AVCodecContext *enc = s->streams[0]->codec;

    s->priv_data = NULL;

    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

    {

        //This is an error!

    }

    put_flush_packet(pb);

    return 0;

}

static int amr_write_packet(AVFormatContext *s, AVPacket *pkt)

{

    put_buffer(&s->pb, pkt->data, pkt->size);

    put_flush_packet(&s->pb);

    return 0;

}

static int amr_write_trailer(AVFormatContext *s)

{

    return 0;

}

static int amr_probe(AVProbeData *p)

{

    //Only check for "#!AMR" which could be amr-wb, amr-nb.

    //This will also trigger multichannel files: "#!AMR_MC1.0\n" and

    //"#!AMR-WB_MC1.0\n" (not supported)

    if (p->buf_size < 5)

        return 0;

    if(memcmp(p->buf,AMR_header,5)==0)

        return AVPROBE_SCORE_MAX;

    else

        return 0;

}

/* amr input */

static int amr_read_header(AVFormatContext *s,

                           AVFormatParameters *ap)

{

    ByteIOContext *pb = &s->pb;

    AVStream *st;

    uint8_t header[9];

    get_buffer(pb, header, 6);

    if(memcmp(header,AMR_header,6)!=0)

    {

        get_buffer(pb, header+6, 3);

        if(memcmp(header,AMRWB_header,9)!=0)

        {

            return -1;

        }

        st = av_new_stream(s, 0);

        if (!st)

        {

            return AVERROR_NOMEM;

        }

        st->codec->codec_type = CODEC_TYPE_AUDIO;

        st->codec->codec_tag = MKTAG('s', 'a', 'w', 'b');

        st->codec->codec_id = CODEC_ID_AMR_WB;

        st->codec->channels = 1;

        st->codec->sample_rate = 16000;

    }

    else

    {

        st = av_new_stream(s, 0);

        if (!st)

        {

            return AVERROR_NOMEM;

        }

        st->codec->codec_type = CODEC_TYPE_AUDIO;

        st->codec->codec_tag = MKTAG('s', 'a', 'm', 'r');

        st->codec->codec_id = CODEC_ID_AMR_NB;

        st->codec->channels = 1;

        st->codec->sample_rate = 8000;

    }

    return 0;

}

#define MAX_SIZE 32

static int amr_read_packet(AVFormatContext *s,

                          AVPacket *pkt)

{

    AVCodecContext *enc = s->streams[0]->codec;

    if (enc->codec_id == CODEC_ID_AMR_NB)

    {

        const static uint8_t packed_size[16] = {12, 13, 15, 17, 19, 20, 26, 31, 5, 0, 0, 0, 0, 0, 0, 0};

        uint8_t toc, q, ft;

        int read;

        int size;

        if (url_feof(&s->pb))

        {

            return AVERROR_IO;

        }

        toc=get_byte(&s->pb);

        q  = (toc >> 2) & 0x01;

        ft = (toc >> 3) & 0x0F;

        size=packed_size[ft];

        if (av_new_packet(pkt, size+1))

        {

            return AVERROR_IO;

        }

        pkt->stream_index = 0;

        pkt->pos= url_ftell(&s->pb);

        pkt->data[0]=toc;

        read = get_buffer(&s->pb, pkt->data+1, size);

        if (read != size)

        {

            av_free_packet(pkt);

            return AVERROR_IO;

        }

        return 0;

    }

    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};

        uint8_t toc, mode;

        int read;

        int size;

        if (url_feof(&s->pb))

        {

            return AVERROR_IO;

        }

        toc=get_byte(&s->pb);

        mode = (uint8_t)((toc >> 3) & 0x0F);

        size = packed_size[mode];

        if ( (size==0) || av_new_packet(pkt, size))

        {

            return AVERROR_IO;

        }

        pkt->stream_index = 0;

        pkt->pos= url_ftell(&s->pb);

        pkt->data[0]=toc;

        read = get_buffer(&s->pb, pkt->data+1, size-1);

        if (read != (size-1))

        {

            av_free_packet(pkt);

            return AVERROR_IO;

        }

        return 0;

    }

    else

    {

        return AVERROR_IO;

    }

}

static int amr_read_close(AVFormatContext *s)

{

    return 0;

}

static AVInputFormat amr_iformat = {

    "amr",

    "3gpp amr file format",

    0, /*priv_data_size*/

    amr_probe,

    amr_read_header,

    amr_read_packet,

    amr_read_close,

};

static AVOutputFormat amr_oformat = {

    "amr",

    "3gpp amr file format",

    "audio/amr",

    "amr",

    0,

    CODEC_ID_AMR_NB,

    CODEC_ID_NONE,

    amr_write_header,

    amr_write_packet,

    amr_write_trailer,

};

int amr_init(void)

{

    av_register_input_format(&amr_iformat);

    av_register_output_format(&amr_oformat);

    return 0;

}