/*

 * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>

 *

 * 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/log.h"

#include "libavutil/opt.h"

#include "libavcodec/av1_parse.h"

#include "libavcodec/bsf.h"

#include "libavcodec/bsf_internal.h"

#include "libavcodec/h264.h"

#include "libavcodec/startcode.h"

#include "libavcodec/vc1_common.h"

#include "libavcodec/hevc/hevc.h"

enum RemoveFreq {

    REMOVE_FREQ_KEYFRAME,

    REMOVE_FREQ_ALL,

    REMOVE_FREQ_NONKEYFRAME,

};

#define START_CODE 0x000001

typedef struct RemoveExtradataContext {

    const AVClass *class;

    int freq;

} RemoveExtradataContext;

static int av1_split(const uint8_t *buf, int buf_size, void *logctx)

{

    AV1OBU obu;

    const uint8_t *ptr = buf, *end = buf + buf_size;

    while (ptr < end) {

        int len = ff_av1_extract_obu(&obu, ptr, buf_size, logctx);

        if (len < 0)

            break;

        if (obu.type == AV1_OBU_FRAME_HEADER ||

            obu.type == AV1_OBU_FRAME) {

            return ptr - buf;

        }

        ptr      += len;

        buf_size -= len;

    }

    return 0;

}

static int h264_split(const uint8_t *buf, int buf_size)

{

    const uint8_t *ptr = buf, *end = buf + buf_size;

    uint32_t state = -1;

    int has_sps    = 0;

    int has_pps    = 0;

    int nalu_type;

    while (ptr < end) {

        ptr = avpriv_find_start_code(ptr, end, &state);

        if ((state & 0xFFFFFF00) != 0x100)

            break;

        nalu_type = state & 0x1F;

        if (nalu_type == H264_NAL_SPS) {

            has_sps = 1;

        } else if (nalu_type == H264_NAL_PPS)

            has_pps = 1;

        /* else if (nalu_type == 0x01 ||

         *     nalu_type == 0x02 ||

         *     nalu_type == 0x05) {

         *  }

         */

        else if ((nalu_type != H264_NAL_SEI || has_pps) &&

                  nalu_type != H264_NAL_AUD && nalu_type != H264_NAL_SPS_EXT &&

                  nalu_type != 0x0f) {

            if (has_sps) {

                while (ptr - 4 > buf && ptr[-5] == 0)

                    ptr--;

                return ptr - 4 - buf;

            }

        }

    }

    return 0;

}

// Split after the parameter sets at the beginning of the stream if they exist.

static int hevc_split(const uint8_t *buf, int buf_size)

{

    const uint8_t *ptr = buf, *end = buf + buf_size;

    uint32_t state = -1;

    int has_vps = 0;

    int has_sps = 0;

    int has_pps = 0;

    int nut;

    while (ptr < end) {

        ptr = avpriv_find_start_code(ptr, end, &state);

        if ((state >> 8) != START_CODE)

            break;

        nut = (state >> 1) & 0x3F;

        if (nut == HEVC_NAL_VPS)

            has_vps = 1;

        else if (nut == HEVC_NAL_SPS)

            has_sps = 1;

        else if (nut == HEVC_NAL_PPS)

            has_pps = 1;

        else if ((nut != HEVC_NAL_SEI_PREFIX || has_pps) &&

                  nut != HEVC_NAL_AUD) {

            if (has_vps && has_sps) {

                while (ptr - 4 > buf && ptr[-5] == 0)

                    ptr--;

                return ptr - 4 - buf;

            }

        }

    }

    return 0;

}

static int mpegvideo_split(const uint8_t *buf, int buf_size)

{

    uint32_t state = -1;

    int found = 0;

    for (int i = 0; i < buf_size; i++) {

        state = (state << 8) | buf[i];

        if (state == 0x1B3) {

            found = 1;

        } else if (found && state != 0x1B5 && state < 0x200 && state >= 0x100)

            return i - 3;

    }

    return 0;

}

static int mpeg4video_split(const uint8_t *buf, int buf_size)

{

    const uint8_t *ptr = buf, *end = buf + buf_size;

    uint32_t state = -1;

    while (ptr < end) {

        ptr = avpriv_find_start_code(ptr, end, &state);

        if (state == 0x1B3 || state == 0x1B6)

            return ptr - 4 - buf;

    }

    return 0;

}

static int vc1_split(const uint8_t *buf, int buf_size)

{

    const uint8_t *ptr = buf, *end = buf + buf_size;

    uint32_t state = -1;

    int charged = 0;

    while (ptr < end) {

        ptr = avpriv_find_start_code(ptr, end, &state);

        if (state == VC1_CODE_SEQHDR || state == VC1_CODE_ENTRYPOINT) {

            charged = 1;

        } else if (charged && IS_MARKER(state))

            return ptr - 4 - buf;

    }

    return 0;

}

static int remove_extradata(AVBSFContext *ctx, AVPacket *pkt)

{

    RemoveExtradataContext *s = ctx->priv_data;

    int ret;

    ret = ff_bsf_get_packet_ref(ctx, pkt);

    if (ret < 0)

        return ret;

    if (s->freq == REMOVE_FREQ_ALL ||

        (s->freq == REMOVE_FREQ_NONKEYFRAME && !(pkt->flags & AV_PKT_FLAG_KEY)) ||

        (s->freq == REMOVE_FREQ_KEYFRAME && pkt->flags & AV_PKT_FLAG_KEY)) {

        int i;

        switch (ctx->par_in->codec_id) {

        case AV_CODEC_ID_AV1:

            i = av1_split(pkt->data, pkt->size, ctx);

            break;

        case AV_CODEC_ID_AVS2:

        case AV_CODEC_ID_AVS3:

        case AV_CODEC_ID_CAVS:

        case AV_CODEC_ID_MPEG4:

            i = mpeg4video_split(pkt->data, pkt->size);

            break;

        case AV_CODEC_ID_H264:

            i = h264_split(pkt->data, pkt->size);

            break;

        case AV_CODEC_ID_HEVC:

            i = hevc_split(pkt->data, pkt->size);

            break;

        case AV_CODEC_ID_MPEG1VIDEO:

        case AV_CODEC_ID_MPEG2VIDEO:

            i = mpegvideo_split(pkt->data, pkt->size);

            break;

        case AV_CODEC_ID_VC1:

            i = vc1_split(pkt->data, pkt->size);

            break;

        default:

            i = 0;

        }

        pkt->data += i;

        pkt->size -= i;

    }

    return 0;

}

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

#define FLAGS (AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_BSF_PARAM)

static const AVOption options[] = {

    { "freq", NULL, OFFSET(freq), AV_OPT_TYPE_INT, { .i64 = REMOVE_FREQ_KEYFRAME }, REMOVE_FREQ_KEYFRAME, REMOVE_FREQ_NONKEYFRAME, FLAGS, .unit = "freq" },

        { "k",        NULL, 0, AV_OPT_TYPE_CONST, { .i64 = REMOVE_FREQ_NONKEYFRAME }, .flags = FLAGS, .unit = "freq" },

        { "keyframe", NULL, 0, AV_OPT_TYPE_CONST, { .i64 = REMOVE_FREQ_KEYFRAME }, .flags = FLAGS, .unit = "freq" },

        { "e",        NULL, 0, AV_OPT_TYPE_CONST, { .i64 = REMOVE_FREQ_ALL      }, .flags = FLAGS, .unit = "freq" },

        { "all",      NULL, 0, AV_OPT_TYPE_CONST, { .i64 = REMOVE_FREQ_ALL      }, .flags = FLAGS, .unit = "freq" },

    { NULL },

};

static const AVClass remove_extradata_class = {

    .class_name = "remove_extradata",

    .item_name  = av_default_item_name,

    .option     = options,

    .version    = LIBAVUTIL_VERSION_INT,

};

const FFBitStreamFilter ff_remove_extradata_bsf = {

    .p.name         = "remove_extra",

    .p.priv_class   = &remove_extradata_class,

    .priv_data_size = sizeof(RemoveExtradataContext),

    .filter         = remove_extradata,

};