/*

 * Digital Speech Standard (DSS) demuxer

 * Copyright (c) 2014 Oleksij Rempel <linux@rempel-privat.de>

 *

 * 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/channel_layout.h"

#include "libavutil/intreadwrite.h"

#include "libavutil/mem.h"

#include "avformat.h"

#include "demux.h"

#include "internal.h"

#define DSS_HEAD_OFFSET_AUTHOR        0xc

#define DSS_AUTHOR_SIZE               16

#define DSS_HEAD_OFFSET_START_TIME    0x26

#define DSS_HEAD_OFFSET_END_TIME      0x32

#define DSS_TIME_SIZE                 12

#define DSS_HEAD_OFFSET_ACODEC        0x2a4

#define DSS_ACODEC_DSS_SP             0x0    /* SP mode */

#define DSS_ACODEC_G723_1             0x2    /* LP mode */

#define DSS_HEAD_OFFSET_COMMENT       0x31e

#define DSS_COMMENT_SIZE              64

#define DSS_BLOCK_SIZE                512

#define DSS_AUDIO_BLOCK_HEADER_SIZE   6

#define DSS_FRAME_SIZE                42

static const uint8_t frame_size[4] = { 24, 20, 4, 1 };

typedef struct DSSDemuxContext {

    unsigned int audio_codec;

    int counter;

    int swap;

    int dss_sp_swap_byte;

    int packet_size;

    int dss_header_size;

} DSSDemuxContext;

static int dss_probe(const AVProbeData *p)

{

    if (   AV_RL32(p->buf) != MKTAG(0x2, 'd', 's', 's')

        && AV_RL32(p->buf) != MKTAG(0x3, 'd', 's', 's'))

        return 0;

    return AVPROBE_SCORE_MAX;

}

static int dss_read_metadata_date(AVFormatContext *s, unsigned int offset,

                                  const char *key)

{

    AVIOContext *pb = s->pb;

    char datetime[64], string[DSS_TIME_SIZE + 1] = { 0 };

    int y, month, d, h, minute, sec;

    int ret;

    avio_seek(pb, offset, SEEK_SET);

    ret = avio_read(s->pb, string, DSS_TIME_SIZE);

    if (ret < DSS_TIME_SIZE)

        return ret < 0 ? ret : AVERROR_EOF;

    if (sscanf(string, "%2d%2d%2d%2d%2d%2d", &y, &month, &d, &h, &minute, &sec) != 6)

        return AVERROR_INVALIDDATA;

    /* We deal with a two-digit year here, so set the default date to 2000

     * and hope it will never be used in the next century. */

    snprintf(datetime, sizeof(datetime), "%.4d-%.2d-%.2dT%.2d:%.2d:%.2d",

             y + 2000, month, d, h, minute, sec);

    return av_dict_set(&s->metadata, key, datetime, 0);

}

static int dss_read_metadata_string(AVFormatContext *s, unsigned int offset,

                                    unsigned int size, const char *key)

{

    AVIOContext *pb = s->pb;

    char *value;

    int ret;

    avio_seek(pb, offset, SEEK_SET);

    value = av_mallocz(size + 1);

    if (!value)

        return AVERROR(ENOMEM);

    ret = avio_read(s->pb, value, size);

    if (ret < size) {

        av_free(value);

        return ret < 0 ? ret : AVERROR_EOF;

    }

    return av_dict_set(&s->metadata, key, value, AV_DICT_DONT_STRDUP_VAL);

}

static int dss_read_header(AVFormatContext *s)

{

    DSSDemuxContext *ctx = s->priv_data;

    AVIOContext *pb = s->pb;

    AVStream *st;

    int64_t ret64;

    int ret, version;

    st = avformat_new_stream(s, NULL);

    if (!st)

        return AVERROR(ENOMEM);

    version = avio_r8(pb);

    ctx->dss_header_size = version * DSS_BLOCK_SIZE;

    ret = dss_read_metadata_string(s, DSS_HEAD_OFFSET_AUTHOR,

                                   DSS_AUTHOR_SIZE, "author");

    if (ret)

        return ret;

    ret = dss_read_metadata_date(s, DSS_HEAD_OFFSET_END_TIME, "date");

    if (ret)

        return ret;

    ret = dss_read_metadata_string(s, DSS_HEAD_OFFSET_COMMENT,

                                   DSS_COMMENT_SIZE, "comment");

    if (ret)

        return ret;

    avio_seek(pb, DSS_HEAD_OFFSET_ACODEC, SEEK_SET);

    ctx->audio_codec = avio_r8(pb);

    if (ctx->audio_codec == DSS_ACODEC_DSS_SP) {

        st->codecpar->codec_id    = AV_CODEC_ID_DSS_SP;

        st->codecpar->sample_rate = 11025;

        s->bit_rate = 8 * (DSS_FRAME_SIZE - 1) * st->codecpar->sample_rate

                        * 512 / (506 * 264);

    } else if (ctx->audio_codec == DSS_ACODEC_G723_1) {

        st->codecpar->codec_id    = AV_CODEC_ID_G723_1;

        st->codecpar->sample_rate = 8000;

    } else {

        avpriv_request_sample(s, "Support for codec %x in DSS",

                              ctx->audio_codec);

        return AVERROR_PATCHWELCOME;

    }

    st->codecpar->codec_type     = AVMEDIA_TYPE_AUDIO;

    st->codecpar->ch_layout      = (AVChannelLayout)AV_CHANNEL_LAYOUT_MONO;

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

    st->start_time = 0;

    /* Jump over header */

    if ((ret64 = avio_seek(pb, ctx->dss_header_size, SEEK_SET)) < 0)

        return (int)ret64;

    ctx->counter = 0;

    ctx->swap    = 0;

    return 0;

}

static void dss_skip_audio_header(AVFormatContext *s, AVPacket *pkt)

{

    DSSDemuxContext *ctx = s->priv_data;

    AVIOContext *pb = s->pb;

    avio_skip(pb, DSS_AUDIO_BLOCK_HEADER_SIZE);

    ctx->counter += DSS_BLOCK_SIZE - DSS_AUDIO_BLOCK_HEADER_SIZE;

}

static void dss_sp_byte_swap(DSSDemuxContext *ctx, uint8_t *data)

{

    int i;

    if (ctx->swap) {

        for (i = 0; i < DSS_FRAME_SIZE - 2; i += 2)

            data[i] = data[i + 4];

        /* Zero the padding. */

        data[DSS_FRAME_SIZE] = 0;

        data[1] = ctx->dss_sp_swap_byte;

    } else {

        ctx->dss_sp_swap_byte = data[DSS_FRAME_SIZE - 2];

    }

    /* make sure byte 40 is always 0 */

    data[DSS_FRAME_SIZE - 2] = 0;

    ctx->swap             ^= 1;

}

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

{

    DSSDemuxContext *ctx = s->priv_data;

    int read_size, ret, offset = 0, buff_offset = 0;

    int64_t pos = avio_tell(s->pb);

    if (ctx->counter == 0)

        dss_skip_audio_header(s, pkt);

    if (ctx->swap) {

        read_size   = DSS_FRAME_SIZE - 2;

        buff_offset = 3;

    } else

        read_size = DSS_FRAME_SIZE;

    ret = av_new_packet(pkt, DSS_FRAME_SIZE);

    if (ret < 0)

        return ret;

    pkt->duration     = 264;

    pkt->pos = pos;

    pkt->stream_index = 0;

    if (ctx->counter < read_size) {

        ret = avio_read(s->pb, pkt->data + buff_offset,

                        ctx->counter);

        if (ret < ctx->counter)

            goto error_eof;

        offset = ctx->counter;

        dss_skip_audio_header(s, pkt);

    }

    ctx->counter -= read_size;

    /* This will write one byte into pkt's padding if buff_offset == 3 */

    ret = avio_read(s->pb, pkt->data + offset + buff_offset,

                    read_size - offset);

    if (ret < read_size - offset)

        goto error_eof;

    dss_sp_byte_swap(ctx, pkt->data);

    if (ctx->dss_sp_swap_byte < 0) {

        return AVERROR(EAGAIN);

    }

    return 0;

error_eof:

    return ret < 0 ? ret : AVERROR_EOF;

}

static int dss_723_1_read_packet(AVFormatContext *s, AVPacket *pkt)

{

    DSSDemuxContext *ctx = s->priv_data;

    AVStream *st = s->streams[0];

    int size, byte, ret, offset;

    int64_t pos = avio_tell(s->pb);

    if (ctx->counter == 0)

        dss_skip_audio_header(s, pkt);

    /* We make one byte-step here. Don't forget to add offset. */

    byte = avio_r8(s->pb);

    if (byte == 0xff)

        return AVERROR_INVALIDDATA;

    size = frame_size[byte & 3];

    ctx->packet_size = size;

    ctx->counter--;

    ret = av_new_packet(pkt, size);

    if (ret < 0)

        return ret;

    pkt->pos = pos;

    pkt->data[0]  = byte;

    offset        = 1;

    pkt->duration = 240;

    s->bit_rate = 8LL * size-- * st->codecpar->sample_rate * 512 / (506 * pkt->duration);

    pkt->stream_index = 0;

    if (ctx->counter < size) {

        ret = avio_read(s->pb, pkt->data + offset,

                        ctx->counter);

        if (ret < ctx->counter)

            return ret < 0 ? ret : AVERROR_EOF;

        offset += ctx->counter;

        size   -= ctx->counter;

        ctx->counter = 0;

        dss_skip_audio_header(s, pkt);

    }

    ctx->counter -= size;

    ret = avio_read(s->pb, pkt->data + offset, size);

    if (ret < size)

        return ret < 0 ? ret : AVERROR_EOF;

    return 0;

}

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

{

    DSSDemuxContext *ctx = s->priv_data;

    if (ctx->audio_codec == DSS_ACODEC_DSS_SP)

        return dss_sp_read_packet(s, pkt);

    else

        return dss_723_1_read_packet(s, pkt);

}

static int dss_read_seek(AVFormatContext *s, int stream_index,

                         int64_t timestamp, int flags)

{

    DSSDemuxContext *ctx = s->priv_data;

    int64_t ret, seekto;

    uint8_t header[DSS_AUDIO_BLOCK_HEADER_SIZE];

    int offset;

    if (ctx->audio_codec == DSS_ACODEC_DSS_SP)

        seekto = timestamp / 264 * 41 / 506 * 512;

    else

        seekto = timestamp / 240 * ctx->packet_size / 506 * 512;

    if (seekto < 0)

        seekto = 0;

    seekto += ctx->dss_header_size;

    ret = avio_seek(s->pb, seekto, SEEK_SET);

    if (ret < 0)

        return ret;

    avio_read(s->pb, header, DSS_AUDIO_BLOCK_HEADER_SIZE);

    ctx->swap = !!(header[0] & 0x80);

    offset = 2*header[1] + 2*ctx->swap;

    if (offset < DSS_AUDIO_BLOCK_HEADER_SIZE)

        return AVERROR_INVALIDDATA;

    if (offset == DSS_AUDIO_BLOCK_HEADER_SIZE) {

        ctx->counter = 0;

        offset = avio_skip(s->pb, -DSS_AUDIO_BLOCK_HEADER_SIZE);

    } else {

        ctx->counter = DSS_BLOCK_SIZE - offset;

        offset = avio_skip(s->pb, offset - DSS_AUDIO_BLOCK_HEADER_SIZE);

    }

    ctx->dss_sp_swap_byte = -1;

    return 0;

}

const FFInputFormat ff_dss_demuxer = {

    .p.name         = "dss",

    .p.long_name    = NULL_IF_CONFIG_SMALL("Digital Speech Standard (DSS)"),

    .p.extensions   = "dss",

    .priv_data_size = sizeof(DSSDemuxContext),

    .read_probe     = dss_probe,

    .read_header    = dss_read_header,

    .read_packet    = dss_read_packet,

    .read_seek      = dss_read_seek,

};