/*

 * AV1 Annex B demuxer

 * Copyright (c) 2019 James Almer <jamrial@gmail.com>

 *

 * 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 "libavutil/common.h"

#include "libavutil/opt.h"

#include "libavcodec/av1_parse.h"

#include "libavcodec/bsf.h"

#include "avformat.h"

#include "avio_internal.h"

#include "demux.h"

#include "internal.h"

typedef struct AV1DemuxContext {

    const AVClass *class;

    AVBSFContext *bsf;

    AVRational framerate;

    uint32_t temporal_unit_size;

    uint32_t frame_unit_size;

    int64_t pos;

} AV1DemuxContext;

//return < 0 if we need more data

static int get_score(int type, int *seq)

{

    switch (type) {

    case AV1_OBU_SEQUENCE_HEADER:

        *seq = 1;

        return -1;

    case AV1_OBU_FRAME:

    case AV1_OBU_FRAME_HEADER:

        return *seq ? AVPROBE_SCORE_EXTENSION + 1 : 0;

    case AV1_OBU_METADATA:

    case AV1_OBU_PADDING:

        return -1;

    default:

        break;

    }

    return 0;

}

static int av1_read_header(AVFormatContext *s)

{

    AV1DemuxContext *const c = s->priv_data;

    const AVBitStreamFilter *filter = av_bsf_get_by_name("av1_frame_merge");

    AVStream *st;

    FFStream *sti;

    int ret;

    if (!filter) {

        av_log(s, AV_LOG_ERROR, "av1_frame_merge bitstream filter "

               "not found. This is a bug, please report it.\n");

        return AVERROR_BUG;

    }

    st = avformat_new_stream(s, NULL);

    if (!st)

        return AVERROR(ENOMEM);

    sti = ffstream(st);

    st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;

    st->codecpar->codec_id = AV_CODEC_ID_AV1;

    sti->need_parsing = AVSTREAM_PARSE_HEADERS;

    st->avg_frame_rate = c->framerate;

    // taken from rawvideo demuxers

    avpriv_set_pts_info(st, 64, 1, 1200000);

    ret = av_bsf_alloc(filter, &c->bsf);

    if (ret < 0)

        return ret;

    ret = avcodec_parameters_copy(c->bsf->par_in, st->codecpar);

    if (ret < 0)

        return ret;

    ret = av_bsf_init(c->bsf);

    if (ret < 0)

        return ret;

    return 0;

}

static int av1_read_close(AVFormatContext *s)

{

    AV1DemuxContext *const c = s->priv_data;

    av_bsf_free(&c->bsf);

    return 0;

}

#define DEC AV_OPT_FLAG_DECODING_PARAM

#define OFFSET(x) offsetof(AV1DemuxContext, x)

static const AVOption av1_options[] = {

    { "framerate", "", OFFSET(framerate), AV_OPT_TYPE_VIDEO_RATE, {.str = "25"}, 0, INT_MAX, DEC},

    { NULL },

};

#undef OFFSET

static const AVClass av1_demuxer_class = {

    .class_name = "AV1 Annex B/low overhead OBU demuxer",

    .item_name  = av_default_item_name,

    .option     = av1_options,

    .version    = LIBAVUTIL_VERSION_INT,

};

#if CONFIG_AV1_DEMUXER

static int leb(AVIOContext *pb, uint32_t *len, int eof) {

    int more, i = 0;

    *len = 0;

    do {

        unsigned bits;

        int byte = avio_r8(pb);

        if (pb->error)

            return pb->error;

        if (pb->eof_reached)

            return (eof && !i) ? AVERROR_EOF : AVERROR_INVALIDDATA;

        more = byte & 0x80;

        bits = byte & 0x7f;

        if (i <= 3 || (i == 4 && bits < (1 << 4)))

            *len |= bits << (i * 7);

        else if (bits)

            return AVERROR_INVALIDDATA;

        if (++i == 8 && more)

            return AVERROR_INVALIDDATA;

    } while (more);

    return i;

}

static int read_obu(const uint8_t *buf, int size, int64_t *obu_size, int *type)

{

    int start_pos, temporal_id, spatial_id;

    int len;

    len = parse_obu_header(buf, size, obu_size, &start_pos,

                           type, &temporal_id, &spatial_id);

    if (len < 0)

        return len;

    return 0;

}

static int annexb_probe(const AVProbeData *p)

{

    FFIOContext ctx;

    AVIOContext *const pb = &ctx.pub;

    int64_t obu_size;

    uint32_t temporal_unit_size, frame_unit_size, obu_unit_size;

    int seq = 0;

    int ret, type, cnt = 0;

    ffio_init_read_context(&ctx, p->buf, p->buf_size);

    ret = leb(pb, &temporal_unit_size, 1);

    if (ret < 0)

        return 0;

    cnt += ret;

    ret = leb(pb, &frame_unit_size, 0);

    if (ret < 0 || ((int64_t)frame_unit_size + ret) > temporal_unit_size)

        return 0;

    cnt += ret;

    ret = leb(pb, &obu_unit_size, 0);

    if (ret < 0 || ((int64_t)obu_unit_size + ret) >= frame_unit_size)

        return 0;

    cnt += ret;

    frame_unit_size -= obu_unit_size + ret;

    avio_skip(pb, obu_unit_size);

    if (pb->eof_reached || pb->error)

        return 0;

    // Check that the first OBU is a Temporal Delimiter.

    ret = read_obu(p->buf + cnt, FFMIN(p->buf_size - cnt, obu_unit_size), &obu_size, &type);

    if (ret < 0 || type != AV1_OBU_TEMPORAL_DELIMITER || obu_size > 0)

        return 0;

    cnt += obu_unit_size;

    do {

        ret = leb(pb, &obu_unit_size, 0);

        if (ret < 0 || ((int64_t)obu_unit_size + ret) > frame_unit_size)

            return 0;

        cnt += ret;

        avio_skip(pb, obu_unit_size);

        if (pb->eof_reached || pb->error)

            return 0;

        ret = read_obu(p->buf + cnt, FFMIN(p->buf_size - cnt, obu_unit_size), &obu_size, &type);

        if (ret < 0)

            return 0;

        cnt += obu_unit_size;

        ret = get_score(type, &seq);

        if (ret >= 0)

            return ret;

        frame_unit_size -= obu_unit_size + ret;

    } while (frame_unit_size);

    return 0;

}

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

{

    AV1DemuxContext *const c = s->priv_data;

    uint32_t obu_unit_size;

    int64_t pos = c->pos;

    int ret, len;

retry:

    if (avio_feof(s->pb)) {

        if (c->temporal_unit_size || c->frame_unit_size)

            return AVERROR_INVALIDDATA;

        goto end;

    }

    if (!c->temporal_unit_size) {

        c->pos = avio_tell(s->pb);

        len = leb(s->pb, &c->temporal_unit_size, 1);

        if (len == AVERROR_EOF) goto end;

        else if (len < 0) return len;

    }

    if (!c->frame_unit_size) {

        len = leb(s->pb, &c->frame_unit_size, 0);

        if (len < 0)

            return len;

        if (((int64_t)c->frame_unit_size + len) > c->temporal_unit_size)

            return AVERROR_INVALIDDATA;

        c->temporal_unit_size -= len;

    }

    len = leb(s->pb, &obu_unit_size, 0);

    if (len < 0)

        return len;

    if (((int64_t)obu_unit_size + len) > c->frame_unit_size)

        return AVERROR_INVALIDDATA;

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

    if (ret < 0)

        return ret;

    if (ret != obu_unit_size)

        return AVERROR_INVALIDDATA;

    c->temporal_unit_size -= obu_unit_size + len;

    c->frame_unit_size -= obu_unit_size + len;

end:

    ret = av_bsf_send_packet(c->bsf, pkt);

    if (ret < 0) {

        av_log(s, AV_LOG_ERROR, "Failed to send packet to "

                                "av1_frame_merge filter\n");

        return ret;

    }

    ret = av_bsf_receive_packet(c->bsf, pkt);

    if (ret < 0) {

        if (ret == AVERROR(EAGAIN))

            goto retry;

        if (ret != AVERROR_EOF)

            av_log(s, AV_LOG_ERROR, "av1_frame_merge filter failed to "

                                    "send output packet\n");

        return ret;

    }

    pkt->pos = pos;

    return 0;

}

const FFInputFormat ff_av1_demuxer = {

    .p.name         = "av1",

    .p.long_name    = NULL_IF_CONFIG_SMALL("AV1 Annex B"),

    .p.extensions   = "obu",

    .p.flags        = AVFMT_GENERIC_INDEX | AVFMT_NOTIMESTAMPS,

    .p.priv_class   = &av1_demuxer_class,

    .priv_data_size = sizeof(AV1DemuxContext),

    .flags_internal = FF_INFMT_FLAG_INIT_CLEANUP,

    .read_probe     = annexb_probe,

    .read_header    = av1_read_header,

    .read_packet    = annexb_read_packet,

    .read_close     = av1_read_close,

};

#endif

#if CONFIG_OBU_DEMUXER

//For low overhead obu, we can't foresee the obu size before we parsed the header.

//So, we can't use parse_obu_header here, since it will check size <= buf_size

//see c27c7b49dc for more details

static int read_obu_with_size(const uint8_t *buf, int buf_size, int64_t *obu_size, int *type)

{

    GetBitContext gb;

    int ret, extension_flag, start_pos;

    int64_t size;

    ret = init_get_bits8(&gb, buf, FFMIN(buf_size, MAX_OBU_HEADER_SIZE));

    if (ret < 0)

        return ret;

    if (get_bits1(&gb) != 0) // obu_forbidden_bit

        return AVERROR_INVALIDDATA;

    *type      = get_bits(&gb, 4);

    extension_flag = get_bits1(&gb);

    if (!get_bits1(&gb))    // has_size_flag

        return AVERROR_INVALIDDATA;

    skip_bits1(&gb);        // obu_reserved_1bit

    if (extension_flag) {

        get_bits(&gb, 3);   // temporal_id

        get_bits(&gb, 2);   // spatial_id

        skip_bits(&gb, 3);  // extension_header_reserved_3bits

    }

    *obu_size  = get_leb128(&gb);

    if (*obu_size > INT_MAX)

        return AVERROR_INVALIDDATA;

    if (get_bits_left(&gb) < 0)

        return AVERROR_INVALIDDATA;

    start_pos = get_bits_count(&gb) / 8;

    size = *obu_size + start_pos;

    if (size > INT_MAX)

        return AVERROR_INVALIDDATA;

    return size;

}

static int obu_probe(const AVProbeData *p)

{

    int64_t obu_size;

    int seq = 0;

    int ret, type, cnt;

    // Check that the first OBU is a Temporal Delimiter.

    cnt = read_obu_with_size(p->buf, p->buf_size, &obu_size, &type);

    if (cnt < 0 || type != AV1_OBU_TEMPORAL_DELIMITER || obu_size != 0)

        return 0;

    while (1) {

        ret = read_obu_with_size(p->buf + cnt, p->buf_size - cnt, &obu_size, &type);

        if (ret < 0 || obu_size <= 0)

            return 0;

        cnt += FFMIN(ret, p->buf_size - cnt);

        ret = get_score(type, &seq);

        if (ret >= 0)

            return ret;

    }

    return 0;

}

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

{

    AV1DemuxContext *const c = s->priv_data;

    uint8_t header[MAX_OBU_HEADER_SIZE + AV_INPUT_BUFFER_PADDING_SIZE];

    int64_t obu_size;

    int size;

    int ret, len, type;

    if ((ret = ffio_ensure_seekback(s->pb, MAX_OBU_HEADER_SIZE)) < 0)

        return ret;

    size = avio_read(s->pb, header, MAX_OBU_HEADER_SIZE);

    if (size < 0)

        return size;

    memset(header + size, 0, AV_INPUT_BUFFER_PADDING_SIZE);

    len = read_obu_with_size(header, size, &obu_size, &type);

    if (len < 0) {

        av_log(c, AV_LOG_ERROR, "Failed to read obu\n");

        return len;

    }

    avio_seek(s->pb, -size, SEEK_CUR);

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

    if (ret != len) {

        av_log(c, AV_LOG_ERROR, "Failed to get packet for obu\n");

        return ret < 0 ? ret : AVERROR_INVALIDDATA;

    }

    return 0;

}

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

{

    AV1DemuxContext *const c = s->priv_data;

    int ret;

    if (s->io_repositioned) {

        av_bsf_flush(c->bsf);

        s->io_repositioned = 0;

    }

    while (1) {

        ret = obu_get_packet(s, pkt);

        /* In case of AVERROR_EOF we need to flush the BSF. Conveniently

         * obu_get_packet() returns a blank pkt in this case which

         * can be used to signal that the BSF should be flushed. */

        if (ret < 0 && ret != AVERROR_EOF)

            return ret;

        ret = av_bsf_send_packet(c->bsf, pkt);

        if (ret < 0) {

            av_log(s, AV_LOG_ERROR, "Failed to send packet to "

                                    "av1_frame_merge filter\n");

            return ret;

        }

        ret = av_bsf_receive_packet(c->bsf, pkt);

        if (ret < 0 && ret != AVERROR(EAGAIN) && ret != AVERROR_EOF)

            av_log(s, AV_LOG_ERROR, "av1_frame_merge filter failed to "

                                    "send output packet\n");

        if (ret != AVERROR(EAGAIN))

            break;

    }

    return ret;

}

const FFInputFormat ff_obu_demuxer = {

    .p.name         = "obu",

    .p.long_name    = NULL_IF_CONFIG_SMALL("AV1 low overhead OBU"),

    .p.extensions   = "obu",

    .p.flags        = AVFMT_GENERIC_INDEX | AVFMT_NO_BYTE_SEEK | AVFMT_NOTIMESTAMPS,

    .p.priv_class   = &av1_demuxer_class,

    .priv_data_size = sizeof(AV1DemuxContext),

    .flags_internal = FF_INFMT_FLAG_INIT_CLEANUP,

    .read_probe     = obu_probe,

    .read_header    = av1_read_header,

    .read_packet    = obu_read_packet,

    .read_close     = av1_read_close,

};

#endif