/*

 * RedSpark demuxer

 * Copyright (c) 2013 James Almer

 *

 * 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 "libavcodec/bytestream.h"

#include "libavutil/intreadwrite.h"

#include "avformat.h"

#include "avio.h"

#include "demux.h"

#include "internal.h"

#define HEADER_SIZE 4096

#define rol(value, bits) (((value) << (bits)) | ((value) >> (32 - (bits))))

typedef struct RedSparkContext {

    int         samples_count;

} RedSparkContext;

static int redspark_probe(const AVProbeData *p)

{

    uint32_t key, data;

    uint8_t header[8];

    /* Decrypt first 8 bytes of the header */

    data = AV_RB32(p->buf);

    key  = data ^ 0x52656453;

    data ^= key;

    AV_WB32(header, data);

    key = rol(key, 11);

    key += rol(key, 3);

    data = AV_RB32(p->buf + 4) ^ key;

    AV_WB32(header + 4, data);

    if (AV_RB64(header) == AV_RB64("RedSpark"))

        return AVPROBE_SCORE_MAX;

    return 0;

}

static int redspark_read_header(AVFormatContext *s)

{

    AVIOContext *pb = s->pb;

    RedSparkContext *redspark = s->priv_data;

    AVCodecParameters *par;

    GetByteContext gbc;

    int i, coef_off, ret = 0;

    uint32_t key, data;

    uint8_t header[HEADER_SIZE];

    AVStream *st;

    st = avformat_new_stream(s, NULL);

    if (!st)

        return AVERROR(ENOMEM);

    par = st->codecpar;

    /* Decrypt header */

    data = avio_rb32(pb);

    key  = data ^ 0x52656453;

    data ^= key;

    AV_WB32(header, data);

    key = rol(key, 11);

    for (i = 4; i < HEADER_SIZE; i += 4) {

        key += rol(key, 3);

        data = avio_rb32(pb) ^ key;

        AV_WB32(header + i, data);

    }

    par->codec_id    = AV_CODEC_ID_ADPCM_THP;

    par->codec_type  = AVMEDIA_TYPE_AUDIO;

    bytestream2_init(&gbc, header, HEADER_SIZE);

    bytestream2_seek(&gbc, 0x3c, SEEK_SET);

    par->sample_rate = bytestream2_get_be32u(&gbc);

    if (par->sample_rate <= 0 || par->sample_rate > 96000) {

        av_log(s, AV_LOG_ERROR, "Invalid sample rate: %d\n", par->sample_rate);

        return AVERROR_INVALIDDATA;

    }

    st->duration = bytestream2_get_be32u(&gbc) * 14;

    redspark->samples_count = 0;

    bytestream2_skipu(&gbc, 10);

    par->ch_layout.nb_channels = bytestream2_get_byteu(&gbc);

    if (!par->ch_layout.nb_channels) {

        return AVERROR_INVALIDDATA;

    }

    coef_off = 0x54 + par->ch_layout.nb_channels * 8;

    if (bytestream2_get_byteu(&gbc)) // Loop flag

        coef_off += 16;

    if (coef_off + par->ch_layout.nb_channels * (32 + 14) > HEADER_SIZE) {

        return AVERROR_INVALIDDATA;

    }

    if (ff_alloc_extradata(par, 32 * par->ch_layout.nb_channels)) {

        return AVERROR_INVALIDDATA;

    }

    /* Get the ADPCM table */

    bytestream2_seek(&gbc, coef_off, SEEK_SET);

    for (i = 0; i < par->ch_layout.nb_channels; i++) {

        if (bytestream2_get_bufferu(&gbc, par->extradata + i * 32, 32) != 32) {

            return AVERROR_INVALIDDATA;

        }

        bytestream2_skipu(&gbc, 14);

    }

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

    return ret;

}

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

{

    AVCodecParameters *par = s->streams[0]->codecpar;

    RedSparkContext *redspark = s->priv_data;

    uint32_t size = 8 * par->ch_layout.nb_channels;

    int ret;

    if (avio_feof(s->pb) || redspark->samples_count == s->streams[0]->duration)

        return AVERROR_EOF;

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

    if (ret != size) {

        return AVERROR_INVALIDDATA;

    }

    pkt->duration = 14;

    redspark->samples_count += pkt->duration;

    pkt->stream_index = 0;

    return ret;

}

const FFInputFormat ff_redspark_demuxer = {

    .p.name         =   "redspark",

    .p.long_name    =   NULL_IF_CONFIG_SMALL("RedSpark"),

    .p.extensions   =   "rsd",

    .priv_data_size =   sizeof(RedSparkContext),

    .read_probe     =   redspark_probe,

    .read_header    =   redspark_read_header,

    .read_packet    =   redspark_read_packet,

};