/*

 * MIDI Sample Dump Standard format demuxer

 * Copyright (c) 2017 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 "demux.h"

#include "internal.h"

typedef struct SDSContext {

    uint8_t data[120];

    int bit_depth;

    int size;

    void (*read_block)(const uint8_t *src, uint32_t *dst);

} SDSContext;

static int sds_probe(const AVProbeData *p)

{

    if (AV_RB32(p->buf) == 0xF07E0001 && p->buf[20] == 0xF7 &&

        p->buf[6] >= 8 && p->buf[6] <= 28)

        return AVPROBE_SCORE_EXTENSION;

    return 0;

}

static void byte2_read(const uint8_t *src, uint32_t *dst)

{

    int i;

    for (i = 0; i < 120; i += 2) {

        unsigned sample = ((unsigned)src[i + 0] << 25) + ((unsigned)src[i + 1] << 18);

        dst[i / 2] = sample;

    }

}

static void byte3_read(const uint8_t *src, uint32_t *dst)

{

    int i;

    for (i = 0; i < 120; i += 3) {

        unsigned sample;

        sample = ((unsigned)src[i + 0] << 25) | ((unsigned)src[i + 1] << 18) | ((unsigned)src[i + 2] << 11);

        dst[i / 3] = sample;

    }

}

static void byte4_read(const uint8_t *src, uint32_t *dst)

{

    int i;

    for (i = 0; i < 120; i += 4) {

        unsigned sample;

        sample = ((unsigned)src[i + 0] << 25) | ((unsigned)src[i + 1] << 18) | ((unsigned)src[i + 2] << 11) | ((unsigned)src[i + 3] << 4);

        dst[i / 4] = sample;

    }

}

#define SDS_3BYTE_TO_INT_DECODE(x) (((x) & 0x7F) | (((x) & 0x7F00) >> 1) | (((x) & 0x7F0000) >> 2))

static int sds_read_header(AVFormatContext *ctx)

{

    SDSContext *s = ctx->priv_data;

    unsigned sample_period;

    AVIOContext *pb = ctx->pb;

    AVStream *st;

    st = avformat_new_stream(ctx, NULL);

    if (!st)

        return AVERROR(ENOMEM);

    avio_skip(pb, 4);

    avio_skip(pb, 2);

    s->bit_depth = avio_r8(pb);

    if (s->bit_depth < 8 || s->bit_depth > 28)

        return AVERROR_INVALIDDATA;

    if (s->bit_depth < 14) {

        s->read_block = byte2_read;

        s->size = 60 * 4;

    } else if (s->bit_depth < 21) {

        s->read_block = byte3_read;

        s->size = 40 * 4;

    } else {

        s->read_block = byte4_read;

        s->size = 30 * 4;

    }

    st->codecpar->codec_id = AV_CODEC_ID_PCM_U32LE;

    sample_period = avio_rl24(pb);

    sample_period = SDS_3BYTE_TO_INT_DECODE(sample_period);

    avio_skip(pb, 11);

    st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;

    st->codecpar->ch_layout.nb_channels = 1;

    st->codecpar->sample_rate = sample_period ? 1000000000 / sample_period : 16000;

    st->duration = av_rescale((avio_size(pb) - 21) / 127,  s->size, 4);

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

    return 0;

}

static int sds_read_packet(AVFormatContext *ctx, AVPacket *pkt)

{

    SDSContext *s = ctx->priv_data;

    AVIOContext *pb = ctx->pb;

    int64_t pos;

    int ret;

    if (avio_feof(pb))

        return AVERROR_EOF;

    pos = avio_tell(pb);

    if (avio_rb16(pb) != 0xF07E)

        return AVERROR_INVALIDDATA;

    avio_skip(pb, 3);

    ret = av_new_packet(pkt, s->size);

    if (ret < 0)

        return ret;

    ret = avio_read(pb, s->data, 120);

    s->read_block(s->data, (uint32_t *)pkt->data);

    avio_skip(pb, 1); // checksum

    if (avio_r8(pb) != 0xF7)

        return AVERROR_INVALIDDATA;

    pkt->flags &= ~AV_PKT_FLAG_CORRUPT;

    pkt->stream_index = 0;

    pkt->pos = pos;

    return ret;

}

const FFInputFormat ff_sds_demuxer = {

    .p.name         = "sds",

    .p.long_name    = NULL_IF_CONFIG_SMALL("MIDI Sample Dump Standard"),

    .p.extensions   = "sds",

    .p.flags        = AVFMT_GENERIC_INDEX,

    .priv_data_size = sizeof(SDSContext),

    .read_probe     = sds_probe,

    .read_header    = sds_read_header,

    .read_packet    = sds_read_packet,

};