annotate ffmpeg/libavformat/epafdec.c @ 13:844d341cf643 tip

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/*
 * Ensoniq Paris Audio File demuxer
 * Copyright (c) 2012 Paul B Mahol
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg 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 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg 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 FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include "libavutil/intreadwrite.h"
#include "avformat.h"
#include "internal.h"
#include "pcm.h"

static int epaf_probe(AVProbeData *p)
{
    if (((AV_RL32(p->buf) == MKTAG('f','a','p',' ') &&
          AV_RL32(p->buf + 8) == 1) ||
         (AV_RL32(p->buf) == MKTAG(' ','p','a','f') &&
          AV_RN32(p->buf + 8) == 0)) &&
       !AV_RN32(p->buf +  4) && AV_RN32(p->buf + 12) &&
        AV_RN32(p->buf + 20))
        return AVPROBE_SCORE_MAX / 4 * 3;
    return 0;
}

static int epaf_read_header(AVFormatContext *s)
{
    int le, sample_rate, codec, channels;
    AVStream *st;

    avio_skip(s->pb, 4);
    if (avio_rl32(s->pb))
        return AVERROR_INVALIDDATA;

    le = avio_rl32(s->pb);
    if (le && le != 1)
        return AVERROR_INVALIDDATA;

    if (le) {
        sample_rate = avio_rl32(s->pb);
        codec       = avio_rl32(s->pb);
        channels    = avio_rl32(s->pb);
    } else {
        sample_rate = avio_rb32(s->pb);
        codec       = avio_rb32(s->pb);
        channels    = avio_rb32(s->pb);
    }

    if (!channels || !sample_rate)
        return AVERROR_INVALIDDATA;

    st = avformat_new_stream(s, NULL);
    if (!st)
        return AVERROR(ENOMEM);

    st->codec->codec_type  = AVMEDIA_TYPE_AUDIO;
    st->codec->channels    = channels;
    st->codec->sample_rate = sample_rate;
    switch (codec) {
    case 0:
        st->codec->codec_id = le ? AV_CODEC_ID_PCM_S16LE : AV_CODEC_ID_PCM_S16BE;
        break;
    case 2:
        st->codec->codec_id = AV_CODEC_ID_PCM_S8;
        break;
    case 1:
        avpriv_request_sample(s, "24-bit Paris PCM format");
    default:
        return AVERROR_INVALIDDATA;
    }

    st->codec->bits_per_coded_sample = av_get_bits_per_sample(st->codec->codec_id);
    st->codec->block_align = st->codec->bits_per_coded_sample * st->codec->channels / 8;

    avpriv_set_pts_info(st, 64, 1, st->codec->sample_rate);

    if (avio_skip(s->pb, 2024) < 0)
        return AVERROR_INVALIDDATA;
    return 0;
}

AVInputFormat ff_epaf_demuxer = {
    .name           = "epaf",
    .long_name      = NULL_IF_CONFIG_SMALL("Ensoniq Paris Audio File"),
    .read_probe     = epaf_probe,
    .read_header    = epaf_read_header,
    .read_packet    = ff_pcm_read_packet,
    .read_seek      = ff_pcm_read_seek,
    .extensions     = "paf,fap",
    .flags          = AVFMT_GENERIC_INDEX,
};