/*

 * Copyright (c) 2010 David Conrad

 *

 * 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 "demux.h"

#include "internal.h"

#include "riff.h"

#include "libavutil/intreadwrite.h"

static int probe(const AVProbeData *p)

{

    if (AV_RL32(p->buf) == MKTAG('D','K','I','F')

        && !AV_RL16(p->buf+4) && AV_RL16(p->buf+6) == 32)

        return AVPROBE_SCORE_MAX-2;

    return 0;

}

static int read_header(AVFormatContext *s)

{

    AVStream *st;

    AVRational time_base;

    avio_rl32(s->pb); // DKIF

    avio_rl16(s->pb); // version

    avio_rl16(s->pb); // header size

    st = avformat_new_stream(s, NULL);

    if (!st)

        return AVERROR(ENOMEM);

    st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;

    st->codecpar->codec_tag  = avio_rl32(s->pb);

    st->codecpar->codec_id   = ff_codec_get_id(ff_codec_bmp_tags, st->codecpar->codec_tag);

    st->codecpar->width      = avio_rl16(s->pb);

    st->codecpar->height     = avio_rl16(s->pb);

    time_base.den            = avio_rl32(s->pb);

    time_base.num            = avio_rl32(s->pb);

    st->nb_frames            = avio_rl32(s->pb);

    avio_skip(s->pb, 4); // unused

    // Infer duration from nb_frames, in order to be backward compatible with

    // previous IVF demuxer.

    // It is popular to configure time_base to 1/frame_rate by IVF muxer, that

    // the duration happens to be the same with nb_frames. See

    // `https://chromium.googlesource.com/webm/vp8-test-vectors/+/refs/heads/main`

    st->duration             = st->nb_frames;

    ffstream(st)->need_parsing = AVSTREAM_PARSE_HEADERS;

    if (!time_base.den || !time_base.num) {

        av_log(s, AV_LOG_ERROR, "Invalid frame rate\n");

        return AVERROR_INVALIDDATA;

    }

    avpriv_set_pts_info(st, 64, time_base.num, time_base.den);

    return 0;

}

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

{

    int ret, size = avio_rl32(s->pb);

    int64_t   pts = avio_rl64(s->pb);

    ret = av_get_packet(s->pb, pkt, size);

    pkt->stream_index = 0;

    pkt->pts          = pts;

    pkt->pos         -= 12;

    return ret;

}

const FFInputFormat ff_ivf_demuxer = {

    .p.name         = "ivf",

    .p.long_name    = NULL_IF_CONFIG_SMALL("On2 IVF"),

    .p.flags        = AVFMT_GENERIC_INDEX,

    .p.codec_tag    = (const AVCodecTag* const []){ ff_codec_bmp_tags, 0 },

    .read_probe     = probe,

    .read_header    = read_header,

    .read_packet    = read_packet,

};