/*

 * codec2 muxer and demuxers

 * Copyright (c) 2017 Tomas Härdin

 *

 * 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 "config_components.h"

#include "libavcodec/codec2utils.h"

#include "libavutil/channel_layout.h"

#include "libavutil/intreadwrite.h"

#include "libavutil/opt.h"

#include "avio_internal.h"

#include "avformat.h"

#include "demux.h"

#include "internal.h"

#include "mux.h"

#include "rawenc.h"

#include "pcm.h"

#define CODEC2_HEADER_SIZE 7

#define CODEC2_MAGIC       0xC0DEC2

//the lowest version we should ever run across is 0.8

//we may run across later versions as the format evolves

#define EXPECTED_CODEC2_MAJOR_VERSION 0

#define EXPECTED_CODEC2_MINOR_VERSION 8

typedef struct {

    const AVClass *class;

    int mode;

    int frames_per_packet;

} Codec2Context;

static int codec2_probe(const AVProbeData *p)

{

    //must start wih C0 DE C2

    if (AV_RB24(p->buf) != CODEC2_MAGIC) {

        return 0;

    }

    //no .c2 files prior to 0.8

    //be strict about major version while we're at it

    if (p->buf[3] != EXPECTED_CODEC2_MAJOR_VERSION ||

        p->buf[4] <  EXPECTED_CODEC2_MINOR_VERSION) {

        return 0;

    }

    //32 bits of identification -> low score

    return AVPROBE_SCORE_EXTENSION + 1;

}

//Mimics codec2_samples_per_frame()

static int codec2_mode_frame_size(AVFormatContext *s, int mode)

{

    int frame_size_table[CODEC2_MODE_MAX+1] = {

        160,    // 3200

        160,    // 2400

        320,    // 1600

        320,    // 1400

        320,    // 1300

        320,    // 1200

        320,    // 700

        320,    // 700B

        320,    // 700C

    };

    if (mode < 0 || mode > CODEC2_MODE_MAX) {

        av_log(s, AV_LOG_ERROR, "unknown codec2 mode %i, can't find frame_size\n", mode);

        return 0;

    } else {

        return frame_size_table[mode];

    }

}

//Mimics (codec2_bits_per_frame()+7)/8

static int codec2_mode_block_align(AVFormatContext *s, int mode)

{

    int block_align_table[CODEC2_MODE_MAX+1] = {

        8,      // 3200

        6,      // 2400

        8,      // 1600

        7,      // 1400

        7,      // 1300

        6,      // 1200

        4,      // 700

        4,      // 700B

        4,      // 700C

    };

    if (mode < 0 || mode > CODEC2_MODE_MAX) {

        av_log(s, AV_LOG_ERROR, "unknown codec2 mode %i, can't find block_align\n", mode);

        return 0;

    } else {

        return block_align_table[mode];

    }

}

//Computes bitrate from mode, with frames rounded up to the nearest octet.

//So 700 bit/s (28 bits/frame) becomes 800 bits/s (32 bits/frame).

static int codec2_mode_bit_rate(AVFormatContext *s, int mode)

{

    int frame_size  = codec2_mode_frame_size(s, mode);

    int block_align = codec2_mode_block_align(s, mode);

    if (frame_size <= 0 || block_align <= 0) {

        return 0;

    }

    return 8 * 8000 * block_align / frame_size;

}

static int codec2_read_header_common(AVFormatContext *s, AVStream *st)

{

    int mode = codec2_mode_from_extradata(st->codecpar->extradata);

    st->codecpar->codec_type        = AVMEDIA_TYPE_AUDIO;

    st->codecpar->codec_id          = AV_CODEC_ID_CODEC2;

    st->codecpar->sample_rate       = 8000;

    st->codecpar->format            = AV_SAMPLE_FMT_S16;

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

    st->codecpar->bit_rate          = codec2_mode_bit_rate(s, mode);

    st->codecpar->frame_size        = codec2_mode_frame_size(s, mode);

    st->codecpar->block_align       = codec2_mode_block_align(s, mode);

    if (st->codecpar->bit_rate <= 0 ||

        st->codecpar->frame_size <= 0 ||

        st->codecpar->block_align <= 0) {

        return AVERROR_INVALIDDATA;

    }

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

    return 0;

}

static int codec2_read_header(AVFormatContext *s)

{

    AVStream *st = avformat_new_stream(s, NULL);

    int ret, version;

    if (!st) {

        return AVERROR(ENOMEM);

    }

    if (avio_rb24(s->pb) != CODEC2_MAGIC) {

        av_log(s, AV_LOG_ERROR, "not a .c2 file\n");

        return AVERROR_INVALIDDATA;

    }

    ret = ff_alloc_extradata(st->codecpar, CODEC2_EXTRADATA_SIZE);

    if (ret) {

        return ret;

    }

    ret = ffio_read_size(s->pb, st->codecpar->extradata, CODEC2_EXTRADATA_SIZE);

    if (ret < 0) {

        return ret;

    }

    version = AV_RB16(st->codecpar->extradata);

    if ((version >> 8) != EXPECTED_CODEC2_MAJOR_VERSION) {

        avpriv_report_missing_feature(s, "Major version %i", version >> 8);

        return AVERROR_PATCHWELCOME;

    }

    ffformatcontext(s)->data_offset = CODEC2_HEADER_SIZE;

    return codec2_read_header_common(s, st);

}

static int codec2_read_packet(AVFormatContext *s, AVPacket *pkt)

{

    Codec2Context *c2 = s->priv_data;

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

    int ret, size, n, block_align, frame_size;

    block_align = st->codecpar->block_align;

    frame_size  = st->codecpar->frame_size;

    if (block_align <= 0 || frame_size <= 0 || c2->frames_per_packet <= 0) {

        return AVERROR(EINVAL);

    }

    //try to read desired number of frames, compute n from to actual number of bytes read

    size = c2->frames_per_packet * block_align;

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

    if (ret < 0) {

        return ret;

    }

    //only set duration - compute_pkt_fields() and ff_pcm_read_seek() takes care of everything else

    //tested by spamming the seek functionality in ffplay

    n = ret / block_align;

    pkt->duration = n * frame_size;

    return ret;

}

static int codec2_write_header(AVFormatContext *s)

{

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

    if (st->codecpar->extradata_size != CODEC2_EXTRADATA_SIZE) {

        av_log(s, AV_LOG_ERROR, ".c2 files require exactly %i bytes of extradata (got %i)\n",

               CODEC2_EXTRADATA_SIZE, st->codecpar->extradata_size);

        return AVERROR(EINVAL);

    }

    avio_wb24(s->pb, CODEC2_MAGIC);

    avio_write(s->pb, st->codecpar->extradata, CODEC2_EXTRADATA_SIZE);

    return 0;

}

static int codec2raw_read_header(AVFormatContext *s)

{

    Codec2Context *c2 = s->priv_data;

    AVStream *st;

    int ret;

    if (c2->mode < 0) {

        //FIXME: using a default value of -1 for mandatory options is an incredibly ugly hack

        av_log(s, AV_LOG_ERROR, "-mode must be set in order to make sense of raw codec2 files\n");

        return AVERROR(EINVAL);

    }

    st = avformat_new_stream(s, NULL);

    if (!st) {

        return AVERROR(ENOMEM);

    }

    ret = ff_alloc_extradata(st->codecpar, CODEC2_EXTRADATA_SIZE);

    if (ret) {

        return ret;

    }

    codec2_make_extradata(st->codecpar->extradata, c2->mode);

    return codec2_read_header_common(s, st);

}

//transcoding report2074.c2 to wav went from 7.391s to 5.322s with -frames_per_packet 1000 compared to default, same sha1sum

#define FRAMES_PER_PACKET \

    { "frames_per_packet", "Number of frames to read at a time. Higher = faster decoding, lower granularity", \

      offsetof(Codec2Context, frames_per_packet), AV_OPT_TYPE_INT, {.i64 = 1}, 1, INT_MAX, AV_OPT_FLAG_DECODING_PARAM}

static const AVOption codec2_options[] = {

    FRAMES_PER_PACKET,

    { NULL },

};

static const AVOption codec2raw_options[] = {

    CODEC2_AVOPTIONS("codec2 mode [mandatory]", Codec2Context, -1, -1, AV_OPT_FLAG_DECODING_PARAM),

    FRAMES_PER_PACKET,

    { NULL },

};

static const AVClass codec2_demux_class = {

    .class_name = "codec2 demuxer",

    .item_name  = av_default_item_name,

    .option     = codec2_options,

    .version    = LIBAVUTIL_VERSION_INT,

    .category   = AV_CLASS_CATEGORY_DEMUXER,

};

static const AVClass codec2raw_demux_class = {

    .class_name = "codec2raw demuxer",

    .item_name  = av_default_item_name,

    .option     = codec2raw_options,

    .version    = LIBAVUTIL_VERSION_INT,

    .category   = AV_CLASS_CATEGORY_DEMUXER,

};

#if CONFIG_CODEC2_DEMUXER

const FFInputFormat ff_codec2_demuxer = {

    .p.name         = "codec2",

    .p.long_name    = NULL_IF_CONFIG_SMALL("codec2 .c2 demuxer"),

    .p.extensions   = "c2",

    .p.flags        = AVFMT_GENERIC_INDEX,

    .p.priv_class   = &codec2_demux_class,

    .priv_data_size = sizeof(Codec2Context),

    .read_probe     = codec2_probe,

    .read_header    = codec2_read_header,

    .read_packet    = codec2_read_packet,

    .read_seek      = ff_pcm_read_seek,

    .raw_codec_id   = AV_CODEC_ID_CODEC2,

};

#endif

#if CONFIG_CODEC2_MUXER

const FFOutputFormat ff_codec2_muxer = {

    .p.name         = "codec2",

    .p.long_name    = NULL_IF_CONFIG_SMALL("codec2 .c2 muxer"),

    .p.extensions   = "c2",

    .p.audio_codec  = AV_CODEC_ID_CODEC2,

    .p.video_codec  = AV_CODEC_ID_NONE,

    .p.subtitle_codec = AV_CODEC_ID_NONE,

    .p.flags        = AVFMT_NOTIMESTAMPS,

    .flags_internal   = FF_OFMT_FLAG_MAX_ONE_OF_EACH |

                        FF_OFMT_FLAG_ONLY_DEFAULT_CODECS,

    .write_header   = codec2_write_header,

    .write_packet   = ff_raw_write_packet,

};

#endif

#if CONFIG_CODEC2RAW_DEMUXER

const FFInputFormat ff_codec2raw_demuxer = {

    .p.name         = "codec2raw",

    .p.long_name    = NULL_IF_CONFIG_SMALL("raw codec2 demuxer"),

    .p.flags        = AVFMT_GENERIC_INDEX,

    .p.priv_class   = &codec2raw_demux_class,

    .priv_data_size = sizeof(Codec2Context),

    .read_header    = codec2raw_read_header,

    .read_packet    = codec2_read_packet,

    .read_seek      = ff_pcm_read_seek,

    .raw_codec_id   = AV_CODEC_ID_CODEC2,

};

#endif