/*

 * RAW AC-4 demuxer

 * Copyright (c) 2019 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/avassert.h"

#include "libavutil/crc.h"

#include "avformat.h"

#include "demux.h"

#include "rawdec.h"

static int ac4_probe(const AVProbeData *p)

{

    const uint8_t *buf = p->buf;

    int left = p->buf_size;

    int max_frames = 0;

    while (left > 7) {

        int size;

        if (buf[0] == 0xAC &&

            (buf[1] == 0x40 ||

             buf[1] == 0x41)) {

            size = (buf[2] << 8) | buf[3];

            if (size == 0xFFFF)

                size = 3 + ((buf[4] << 16) | (buf[5] << 8) | buf[6]);

            size += 4;

            if (buf[1] == 0x41)

                size += 2;

            if (left < size)

                break;

            max_frames++;

            left -= size;

            buf += size;

        } else {

            break;

        }

    }

    return FFMIN(AVPROBE_SCORE_MAX, max_frames * 7);

}

static int ac4_read_header(AVFormatContext *s)

{

    AVStream *st;

    st = avformat_new_stream(s, NULL);

    if (!st)

        return AVERROR(ENOMEM);

    st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;

    st->codecpar->codec_id   = AV_CODEC_ID_AC4;

    return 0;

}

static int ac4_read_packet(AVFormatContext *s, AVPacket *pkt)

{

    AVIOContext *pb = s->pb;

    int64_t pos;

    uint16_t sync;

    int ret, size;

    if (avio_feof(s->pb))

        return AVERROR_EOF;

    pos  = avio_tell(s->pb);

    sync = avio_rb16(pb);

    size = avio_rb16(pb);

    if (size == 0xffff)

        size = avio_rb24(pb);

    ret = av_get_packet(pb, pkt, size);

    pkt->pos = pos;

    pkt->stream_index = 0;

    if (sync == 0xAC41)

        avio_skip(pb, 2);

    return ret;

}

const FFInputFormat ff_ac4_demuxer = {

    .p.name         = "ac4",

    .p.long_name    = NULL_IF_CONFIG_SMALL("raw AC-4"),

    .p.flags        = AVFMT_GENERIC_INDEX,

    .p.extensions   = "ac4",

    .read_probe     = ac4_probe,

    .read_header    = ac4_read_header,

    .read_packet    = ac4_read_packet,

};