/*

 * 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 <inttypes.h>

#include "libavutil/log.h"

#include "bsf.h"

#include "bsf_internal.h"

#include "cbs.h"

#include "cbs_bsf.h"

#include "cbs_h264.h"

#include "codec_id.h"

#include "h264.h"

#include "packet.h"

#define NEW_GLOBAL_PIC_INIT_QP 26

typedef struct H264RedundantPPSContext {

    CBSBSFContext common;

} H264RedundantPPSContext;

static int h264_redundant_pps_fixup_pps(H264RedundantPPSContext *ctx,

                                        CodedBitstreamUnit *unit)

{

    H264RawPPS *pps;

    int err;

    // The changes we are about to perform affect the parsing process,

    // so we must make sure that the PPS is writable, otherwise the

    // parsing of future slices will be incorrect and even raise errors.

    err = ff_cbs_make_unit_writable(ctx->common.input, unit);

    if (err < 0)

        return err;

    pps = unit->content;

    // Overwrite pic_init_qp with the global value.

    pps->pic_init_qp_minus26 = NEW_GLOBAL_PIC_INIT_QP - 26;

    // Some PPSs have this set, so it must be set in all of them.

    // (Slices which do not use such a PPS on input will still have

    // *_weight_l*flag as zero and therefore write equivalently.)

    pps->weighted_pred_flag = 1;

    return 0;

}

static int h264_redundant_pps_fixup_slice(H264RedundantPPSContext *ctx,

                                          H264RawSliceHeader *slice)

{

    const CodedBitstreamH264Context *const in = ctx->common.input->priv_data;

    const H264RawPPS *const pps = in->pps[slice->pic_parameter_set_id];

    // We modified the PPS's qp value, now offset this by applying

    // the negative offset to the slices.

    slice->slice_qp_delta += pps->pic_init_qp_minus26

                             - (NEW_GLOBAL_PIC_INIT_QP - 26);

    return 0;

}

static int h264_redundant_pps_update_fragment(AVBSFContext *bsf,

                                              AVPacket *pkt,

                                              CodedBitstreamFragment *au)

{

    H264RedundantPPSContext *ctx = bsf->priv_data;

    int err, i;

    for (i = 0; i < au->nb_units; i++) {

        CodedBitstreamUnit *nal = &au->units[i];

        if (nal->type == H264_NAL_PPS) {

            err = h264_redundant_pps_fixup_pps(ctx, nal);

            if (err < 0)

                return err;

        }

        if (nal->type == H264_NAL_SLICE ||

            nal->type == H264_NAL_IDR_SLICE) {

            H264RawSlice *slice = nal->content;

            h264_redundant_pps_fixup_slice(ctx, &slice->header);

        }

    }

    return 0;

}

static const CBSBSFType h264_redundant_pps_type = {

    .codec_id        = AV_CODEC_ID_H264,

    .fragment_name   = "access unit",

    .unit_name       = "NAL unit",

    .update_fragment = &h264_redundant_pps_update_fragment,

};

static int h264_redundant_pps_init(AVBSFContext *bsf)

{

    return ff_cbs_bsf_generic_init(bsf, &h264_redundant_pps_type);

}

static const enum AVCodecID h264_redundant_pps_codec_ids[] = {

    AV_CODEC_ID_H264, AV_CODEC_ID_NONE,

};

const FFBitStreamFilter ff_h264_redundant_pps_bsf = {

    .p.name         = "h264_redundant_pps",

    .p.codec_ids    = h264_redundant_pps_codec_ids,

    .priv_data_size = sizeof(H264RedundantPPSContext),

    .init           = &h264_redundant_pps_init,

    .close          = &ff_cbs_bsf_generic_close,

    .filter         = &ff_cbs_bsf_generic_filter,

};