ilbc.c 4.07 KB
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/*
 * iLBC storage file format
 * Copyright (c) 2012 Martin Storsjo
 *
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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
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
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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
 */

#include "avformat.h"
#include "internal.h"

static const char mode20_header[] = "#!iLBC20\n";
static const char mode30_header[] = "#!iLBC30\n";

static int ilbc_write_header(AVFormatContext *s)
{
    AVIOContext *pb = s->pb;
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    AVCodecParameters *par;
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    if (s->nb_streams != 1) {
        av_log(s, AV_LOG_ERROR, "Unsupported number of streams\n");
        return AVERROR(EINVAL);
    }
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    par = s->streams[0]->codecpar;
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    if (par->codec_id != AV_CODEC_ID_ILBC) {
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        av_log(s, AV_LOG_ERROR, "Unsupported codec\n");
        return AVERROR(EINVAL);
    }

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    if (par->block_align == 50) {
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        avio_write(pb, mode30_header, sizeof(mode30_header) - 1);
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    } else if (par->block_align == 38) {
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        avio_write(pb, mode20_header, sizeof(mode20_header) - 1);
    } else {
        av_log(s, AV_LOG_ERROR, "Unsupported mode\n");
        return AVERROR(EINVAL);
    }
    avio_flush(pb);
    return 0;
}

static int ilbc_write_packet(AVFormatContext *s, AVPacket *pkt)
{
    avio_write(s->pb, pkt->data, pkt->size);
    return 0;
}

static int ilbc_probe(AVProbeData *p)
{
    // Only check for "#!iLBC" which matches both formats
    if (!memcmp(p->buf, mode20_header, 6))
        return AVPROBE_SCORE_MAX;
    else
        return 0;
}

static int ilbc_read_header(AVFormatContext *s)
{
    AVIOContext *pb = s->pb;
    AVStream *st;
    uint8_t header[9];

    avio_read(pb, header, 9);

    st = avformat_new_stream(s, NULL);
    if (!st)
        return AVERROR(ENOMEM);
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    st->codecpar->codec_id = AV_CODEC_ID_ILBC;
    st->codecpar->sample_rate = 8000;
    st->codecpar->channels = 1;
    st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
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    st->start_time = 0;
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    avpriv_set_pts_info(st, 64, 1, st->codecpar->sample_rate);
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    if (!memcmp(header, mode20_header, sizeof(mode20_header) - 1)) {
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        st->codecpar->block_align = 38;
        st->codecpar->bit_rate = 15200;
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    } else if (!memcmp(header, mode30_header, sizeof(mode30_header) - 1)) {
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        st->codecpar->block_align = 50;
        st->codecpar->bit_rate = 13333;
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    } else {
        av_log(s, AV_LOG_ERROR, "Unrecognized iLBC file header\n");
        return AVERROR_INVALIDDATA;
    }

    return 0;
}

static int ilbc_read_packet(AVFormatContext *s,
                          AVPacket *pkt)
{
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    AVCodecParameters *par = s->streams[0]->codecpar;
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    int ret;

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    if ((ret = av_new_packet(pkt, par->block_align)) < 0)
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        return ret;

    pkt->stream_index = 0;
    pkt->pos = avio_tell(s->pb);
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    pkt->duration = par->block_align == 38 ? 160 : 240;
    if ((ret = avio_read(s->pb, pkt->data, par->block_align)) != par->block_align) {
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        av_packet_unref(pkt);
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        return ret < 0 ? ret : AVERROR(EIO);
    }

    return 0;
}

AVInputFormat ff_ilbc_demuxer = {
    .name         = "ilbc",
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    .long_name    = NULL_IF_CONFIG_SMALL("iLBC storage"),
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    .read_probe   = ilbc_probe,
    .read_header  = ilbc_read_header,
    .read_packet  = ilbc_read_packet,
    .flags        = AVFMT_GENERIC_INDEX,
};

AVOutputFormat ff_ilbc_muxer = {
    .name         = "ilbc",
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    .long_name    = NULL_IF_CONFIG_SMALL("iLBC storage"),
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    .mime_type    = "audio/iLBC",
    .extensions   = "lbc",
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    .audio_codec  = AV_CODEC_ID_ILBC,
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    .write_header = ilbc_write_header,
    .write_packet = ilbc_write_packet,
    .flags        = AVFMT_NOTIMESTAMPS,
};