/*
  * 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 <string.h>
 
 #include "libavutil/common.h"
 #include "libavutil/mem.h"
 
 #include "bsf.h"
 #include "cbs.h"
 #include "cbs_h264.h"
 #include "h264.h"
 
 
 typedef struct H264RedundantPPSContext {
     CodedBitstreamContext *input;
     CodedBitstreamContext *output;
 
     CodedBitstreamFragment access_unit;
 
     int global_pic_init_qp;
     int current_pic_init_qp;

     int extradata_pic_init_qp;

 } H264RedundantPPSContext;
 
 
 static int h264_redundant_pps_fixup_pps(H264RedundantPPSContext *ctx,
                                         H264RawPPS *pps)
 {
     // Record the current value of pic_init_qp in order to fix up
     // following slices, then overwrite with the global value.
     ctx->current_pic_init_qp = pps->pic_init_qp_minus26 + 26;
     pps->pic_init_qp_minus26 = ctx->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)
 {
     int qp;
 
     qp = ctx->current_pic_init_qp + slice->slice_qp_delta;
     slice->slice_qp_delta = qp - ctx->global_pic_init_qp;
 
     return 0;
 }
 
 static int h264_redundant_pps_filter(AVBSFContext *bsf, AVPacket *out)
 {
     H264RedundantPPSContext *ctx = bsf->priv_data;
     AVPacket *in;
     CodedBitstreamFragment *au = &ctx->access_unit;
     int au_has_sps;
     int err, i;
 
     err = ff_bsf_get_packet(bsf, &in);
     if (err < 0)
         return err;
 
     err = ff_cbs_read_packet(ctx->input, au, in);
     if (err < 0)
         return err;
 
     au_has_sps = 0;
     for (i = 0; i < au->nb_units; i++) {
         CodedBitstreamUnit *nal = &au->units[i];
 
         if (nal->type == H264_NAL_SPS)
             au_has_sps = 1;
         if (nal->type == H264_NAL_PPS) {
             h264_redundant_pps_fixup_pps(ctx, nal->content);
             if (!au_has_sps) {
                 av_log(ctx, AV_LOG_VERBOSE, "Deleting redundant PPS "
                        "at %"PRId64".\n", in->pts);
                 ff_cbs_delete_unit(ctx->input, au, i);
             }
         }
         if (nal->type == H264_NAL_SLICE ||
             nal->type == H264_NAL_IDR_SLICE) {
             H264RawSlice *slice = nal->content;
             h264_redundant_pps_fixup_slice(ctx, &slice->header);
         }
     }
 
     err = ff_cbs_write_packet(ctx->output, out, au);
     if (err < 0)
         return err;
 
     ff_cbs_fragment_uninit(ctx->output, au);
 
     err = av_packet_copy_props(out, in);
     if (err < 0)
         return err;
 
     av_packet_free(&in);
 
     return 0;
 }
 
 static int h264_redundant_pps_init(AVBSFContext *bsf)
 {
     H264RedundantPPSContext *ctx = bsf->priv_data;
     CodedBitstreamFragment *au = &ctx->access_unit;
     int err, i;
 
     err = ff_cbs_init(&ctx->input, AV_CODEC_ID_H264, bsf);
     if (err < 0)
         return err;
 
     err = ff_cbs_init(&ctx->output, AV_CODEC_ID_H264, bsf);
     if (err < 0)
         return err;
 
     ctx->global_pic_init_qp = 26;
 
     if (bsf->par_in->extradata) {
         err = ff_cbs_read_extradata(ctx->input, au, bsf->par_in);
         if (err < 0) {
             av_log(bsf, AV_LOG_ERROR, "Failed to read extradata.\n");
             return err;
         }
 
         for (i = 0; i < au->nb_units; i++) {
             if (au->units[i].type == H264_NAL_PPS)
                 h264_redundant_pps_fixup_pps(ctx, au->units[i].content);
         }
 

         ctx->extradata_pic_init_qp = ctx->current_pic_init_qp;

         err = ff_cbs_write_extradata(ctx->output, bsf->par_out, au);
         if (err < 0) {
             av_log(bsf, AV_LOG_ERROR, "Failed to write extradata.\n");
             return err;
         }
 
         ff_cbs_fragment_uninit(ctx->output, au);
     }
 
     return 0;
 }
 

 static void h264_redundant_pps_flush(AVBSFContext *bsf)
 {
     H264RedundantPPSContext *ctx = bsf->priv_data;
     ctx->current_pic_init_qp = ctx->extradata_pic_init_qp;
 }
 

 static void h264_redundant_pps_close(AVBSFContext *bsf)
 {
     H264RedundantPPSContext *ctx = bsf->priv_data;
     ff_cbs_close(&ctx->input);
     ff_cbs_close(&ctx->output);
 }
 
 static const enum AVCodecID h264_redundant_pps_codec_ids[] = {
     AV_CODEC_ID_H264, AV_CODEC_ID_NONE,
 };
 
 const AVBitStreamFilter ff_h264_redundant_pps_bsf = {
     .name           = "h264_redundant_pps",
     .priv_data_size = sizeof(H264RedundantPPSContext),
     .init           = &h264_redundant_pps_init,

     .flush          = &h264_redundant_pps_flush,

     .close          = &h264_redundant_pps_close,
     .filter         = &h264_redundant_pps_filter,
     .codec_ids      = h264_redundant_pps_codec_ids,
 };