FFmpeg/libavformat/mlpdec.c

/*
 * MLP and TrueHD demuxer
 * Copyright (c) 2001 Fabrice Bellard
 * Copyright (c) 2005 Alex Beregszaszi
 * Copyright (c) 2015 Carl Eugen Hoyos
 *
 * 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 "avformat.h"
#include "avio_internal.h"
#include "internal.h"
#include "rawdec.h"
#include "libavutil/intreadwrite.h"
#include "libavcodec/mlp.h"
#include "libavcodec/mlp_parse.h"

static int av_always_inline mlp_thd_probe(const AVProbeData *p, uint32_t sync)
{
    const uint8_t *buf, *last_buf = p->buf, *end = p->buf + p->buf_size;
    int frames = 0, valid = 0, size = 0;
    int nsubframes = 0;

    for (buf = p->buf; buf + 8 <= end; buf++) {
        if (AV_RB32(buf + 4) == sync) {
            frames++;
            if (last_buf + size == buf) {
                valid += 1 + nsubframes / 8;
            }
            nsubframes = 0;
            last_buf = buf;
            size = (AV_RB16(buf) & 0xfff) * 2;
        } else if (buf - last_buf == size) {
            nsubframes++;
            size += (AV_RB16(buf) & 0xfff) * 2;
        }
    }
    if (valid >= 100)
        return AVPROBE_SCORE_MAX;
    return 0;
}

static int mlp_read_header(AVFormatContext *s)
{
    int ret = ff_raw_audio_read_header(s);

    if (ret < 0)
        return ret;

    ret = ffio_ensure_seekback(s->pb, 10);
    if (ret == 0) {
        uint8_t buffer[10];
        int read, sample_rate = 0;

        read = avio_read(s->pb, buffer, 10);
        if (read == 10) {
            switch (buffer[7]) {
            case SYNC_TRUEHD:
                sample_rate = mlp_samplerate(buffer[8] >> 4);
                break;
            case SYNC_MLP:
                sample_rate = mlp_samplerate(buffer[9] >> 4);
                break;
            }

            if (sample_rate)
                avpriv_set_pts_info(s->streams[0], 64, 1, sample_rate);
        }

        if (read > 0)
            avio_seek(s->pb, -read, SEEK_CUR);
    }

    return 0;
}

#if CONFIG_MLP_DEMUXER
static int mlp_probe(const AVProbeData *p)
{
    return mlp_thd_probe(p, 0xf8726fbb);
}

const AVInputFormat ff_mlp_demuxer = {
    .name           = "mlp",
    .long_name      = NULL_IF_CONFIG_SMALL("raw MLP"),
    .read_probe     = mlp_probe,
    .read_header    = mlp_read_header,
    .read_packet    = ff_raw_read_partial_packet,
    .flags          = AVFMT_GENERIC_INDEX | AVFMT_NOTIMESTAMPS,
    .extensions     = "mlp",
    .raw_codec_id   = AV_CODEC_ID_MLP,
    .priv_data_size = sizeof(FFRawDemuxerContext),
    .priv_class     = &ff_raw_demuxer_class,
};
#endif

#if CONFIG_TRUEHD_DEMUXER
static int thd_probe(const AVProbeData *p)
{
    return mlp_thd_probe(p, 0xf8726fba);
}

const AVInputFormat ff_truehd_demuxer = {
    .name           = "truehd",
    .long_name      = NULL_IF_CONFIG_SMALL("raw TrueHD"),
    .read_probe     = thd_probe,
    .read_header    = mlp_read_header,
    .read_packet    = ff_raw_read_partial_packet,
    .flags          = AVFMT_GENERIC_INDEX | AVFMT_NOTIMESTAMPS,
    .extensions     = "thd",
    .raw_codec_id   = AV_CODEC_ID_TRUEHD,
    .priv_data_size = sizeof(FFRawDemuxerContext),
    .priv_class     = &ff_raw_demuxer_class,
};
#endif