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ffmpeg / libavformat / amr.c @ 5509bffa

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/*
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 * amr file format
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 * Copyright (c) 2001 ffmpeg project
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 *
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 * This library 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 of the License, or (at your option) any later version.
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 *
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 * This library 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 this library; 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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/*
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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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*/
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#include "avformat.h"
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static const unsigned char AMR_header [] = "#!AMR\n";
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static const unsigned char AMRWB_header [] = "#!AMR-WB\n";
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static int amr_write_header(AVFormatContext *s)
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{
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    ByteIOContext *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)
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    {
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        put_tag(pb, AMR_header);       /* magic number */
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    }
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    else if(enc->codec_id == CODEC_ID_AMR_WB)
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    {
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        put_tag(pb, AMRWB_header);       /* magic number */
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    }
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    else
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    {
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        //This is an error!
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    }
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    put_flush_packet(pb);
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    return 0;
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}
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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);
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    put_flush_packet(&s->pb);
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    return 0;
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}
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static int amr_write_trailer(AVFormatContext *s)
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{
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    return 0;
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}
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static int amr_probe(AVProbeData *p)
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{
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    //Only check for "#!AMR" which could be amr-wb, amr-nb.
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    //This will also trigger multichannel files: "#!AMR_MC1.0\n" and
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    //"#!AMR-WB_MC1.0\n" (not supported)
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    if (p->buf_size < 5)
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        return 0;
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    if(memcmp(p->buf,AMR_header,5)==0)
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        return AVPROBE_SCORE_MAX;
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    else
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        return 0;
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}
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/* amr input */
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static int amr_read_header(AVFormatContext *s,
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                           AVFormatParameters *ap)
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{
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    ByteIOContext *pb = &s->pb;
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    AVStream *st;
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    uint8_t header[9];
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    get_buffer(pb, header, 6);
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    if(memcmp(header,AMR_header,6)!=0)
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    {
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        get_buffer(pb, header+6, 3);
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        if(memcmp(header,AMRWB_header,9)!=0)
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        {
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            return -1;
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        }
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        st = av_new_stream(s, 0);
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        if (!st)
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        {
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            return AVERROR_NOMEM;
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        }
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        st->codec->codec_type = CODEC_TYPE_AUDIO;
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        st->codec->codec_tag = MKTAG('s', 'a', 'w', 'b');
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        st->codec->codec_id = CODEC_ID_AMR_WB;
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        st->codec->channels = 1;
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        st->codec->sample_rate = 16000;
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    }
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    else
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    {
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        st = av_new_stream(s, 0);
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        if (!st)
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        {
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            return AVERROR_NOMEM;
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        }
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        st->codec->codec_type = CODEC_TYPE_AUDIO;
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        st->codec->codec_tag = MKTAG('s', 'a', 'm', 'r');
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        st->codec->codec_id = CODEC_ID_AMR_NB;
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        st->codec->channels = 1;
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        st->codec->sample_rate = 8000;
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    }
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    return 0;
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}
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#define MAX_SIZE 32
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static int amr_read_packet(AVFormatContext *s,
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                          AVPacket *pkt)
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{
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    AVCodecContext *enc = s->streams[0]->codec;
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    if (enc->codec_id == CODEC_ID_AMR_NB)
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    {
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        const static 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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        uint8_t toc, q, ft;
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        int read;
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        int size;
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        if (url_feof(&s->pb))
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        {
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            return AVERROR_IO;
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        }
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        toc=get_byte(&s->pb);
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        q  = (toc >> 2) & 0x01;
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        ft = (toc >> 3) & 0x0F;
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        size=packed_size[ft];
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        if (av_new_packet(pkt, size+1))
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        {
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            return AVERROR_IO;
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        }
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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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        read = get_buffer(&s->pb, pkt->data+1, size);
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        if (read != size)
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        {
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            av_free_packet(pkt);
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            return AVERROR_IO;
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        }
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        return 0;
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    }
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    else if(enc->codec_id == CODEC_ID_AMR_WB)
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    {
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        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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        uint8_t toc, mode;
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        int read;
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        int size;
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        if (url_feof(&s->pb))
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        {
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            return AVERROR_IO;
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        }
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        toc=get_byte(&s->pb);
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        mode = (uint8_t)((toc >> 3) & 0x0F);
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        size = packed_size[mode];
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        if ( (size==0) || av_new_packet(pkt, size))
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        {
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            return AVERROR_IO;
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        }
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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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        read = get_buffer(&s->pb, pkt->data+1, size-1);
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        if (read != (size-1))
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        {
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            av_free_packet(pkt);
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            return AVERROR_IO;
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        }
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        return 0;
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    }
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    else
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    {
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        return AVERROR_IO;
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    }
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}
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static int amr_read_close(AVFormatContext *s)
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{
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    return 0;
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}
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static AVInputFormat amr_iformat = {
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    "amr",
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    "3gpp amr file format",
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    0, /*priv_data_size*/
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    amr_probe,
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    amr_read_header,
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    amr_read_packet,
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    amr_read_close,
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};
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static AVOutputFormat amr_oformat = {
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    "amr",
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    "3gpp amr file format",
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    "audio/amr",
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    "amr",
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    0,
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    CODEC_ID_AMR_NB,
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    CODEC_ID_NONE,
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    amr_write_header,
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    amr_write_packet,
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    amr_write_trailer,
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};
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int amr_init(void)
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{
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    av_register_input_format(&amr_iformat);
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    av_register_output_format(&amr_oformat);
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    return 0;
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}