/*
  * Copyright (C) 2004 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 <math.h>
 #include "libavutil/eval.h"
 #include "libavutil/imgutils.h"
 #include "libavutil/pixdesc.h"
 #include "libavutil/opt.h"
 #include "avfilter.h"
 #include "formats.h"
 #include "internal.h"
 #include "video.h"
 
 typedef struct QPContext {
     const AVClass *class;
     char *qp_expr_str;
     int8_t lut[257];
     int h, qstride;

     int evaluate_per_mb;

 } QPContext;
 
 #define OFFSET(x) offsetof(QPContext, x)
 #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
 
 static const AVOption qp_options[] = {
     { "qp", "set qp expression", OFFSET(qp_expr_str), AV_OPT_TYPE_STRING, {.str=NULL}, 0, 0, FLAGS },
     { NULL }
 };
 
 AVFILTER_DEFINE_CLASS(qp);
 
 static int config_input(AVFilterLink *inlink)
 {
     AVFilterContext *ctx = inlink->dst;
     QPContext *s = ctx->priv;
     int i;

     int ret;
     AVExpr *e = NULL;

     static const char *var_names[] = { "known", "qp", "x", "y", "w", "h", NULL };

 
     if (!s->qp_expr_str)
         return 0;
 

     ret = av_expr_parse(&e, s->qp_expr_str, var_names, NULL, NULL, NULL, NULL, 0, ctx);
     if (ret < 0)
         return ret;
 

     s->h       = (inlink->h + 15) >> 4;
     s->qstride = (inlink->w + 15) >> 4;
     for (i = -129; i < 128; i++) {

         double var_values[] = { i != -129, i, NAN, NAN, s->qstride, s->h, 0};

         double temp_val = av_expr_eval(e, var_values, NULL);

         if (isnan(temp_val)) {

             if(strchr(s->qp_expr_str, 'x') || strchr(s->qp_expr_str, 'y'))
                 s->evaluate_per_mb = 1;
             else {

                 av_expr_free(e);
                 return AVERROR(EINVAL);

             }

         }

 
         s->lut[i + 129] = lrintf(temp_val);
     }

     av_expr_free(e);

 
     return 0;
 }
 
 static int filter_frame(AVFilterLink *inlink, AVFrame *in)
 {
     AVFilterContext *ctx = inlink->dst;
     AVFilterLink *outlink = ctx->outputs[0];
     QPContext *s = ctx->priv;
     AVBufferRef *out_qp_table_buf;

     AVFrame *out = NULL;

     const int8_t *in_qp_table;
     int type, stride, ret;
 
     if (!s->qp_expr_str || ctx->is_disabled)
         return ff_filter_frame(outlink, in);
 
     out_qp_table_buf = av_buffer_alloc(s->h * s->qstride);
     if (!out_qp_table_buf) {
         ret = AVERROR(ENOMEM);
         goto fail;
     }
 
     out = av_frame_clone(in);
     if (!out) {

         av_buffer_unref(&out_qp_table_buf);

         ret = AVERROR(ENOMEM);
         goto fail;
     }
 
     in_qp_table = av_frame_get_qp_table(in, &stride, &type);
     av_frame_set_qp_table(out, out_qp_table_buf, s->qstride, type);
 

 
     if (s->evaluate_per_mb) {
         int y, x;
 
         for (y = 0; y < s->h; y++)
             for (x = 0; x < s->qstride; x++) {
                 int qp = in_qp_table ? in_qp_table[x + stride * y] : NAN;
                 double var_values[] = { !!in_qp_table, qp, x, y, s->qstride, s->h, 0};
                 static const char *var_names[] = { "known", "qp", "x", "y", "w", "h", NULL };
                 double temp_val;
 
                 ret = av_expr_parse_and_eval(&temp_val, s->qp_expr_str,
                                             var_names, var_values,
                                             NULL, NULL, NULL, NULL, 0, 0, ctx);
                 if (ret < 0)

                     goto fail;

                 out_qp_table_buf->data[x + s->qstride * y] = lrintf(temp_val);
             }
     } else if (in_qp_table) {

         int y, x;
 
         for (y = 0; y < s->h; y++)
             for (x = 0; x < s->qstride; x++)
                 out_qp_table_buf->data[x + s->qstride * y] = s->lut[129 +
                     ((int8_t)in_qp_table[x + stride * y])];
     } else {
         int y, x, qp = s->lut[0];
 
         for (y = 0; y < s->h; y++)
             for (x = 0; x < s->qstride; x++)
                 out_qp_table_buf->data[x + s->qstride * y] = qp;
     }
 
     ret = ff_filter_frame(outlink, out);

     out = NULL;

 fail:
     av_frame_free(&in);

     av_frame_free(&out);

     return ret;
 }
 
 static const AVFilterPad qp_inputs[] = {
     {
         .name         = "default",
         .type         = AVMEDIA_TYPE_VIDEO,
         .filter_frame = filter_frame,
         .config_props = config_input,
     },
     { NULL }
 };
 
 static const AVFilterPad qp_outputs[] = {
     {
         .name = "default",
         .type = AVMEDIA_TYPE_VIDEO,
     },
     { NULL }
 };
 
 AVFilter ff_vf_qp = {
     .name          = "qp",
     .description   = NULL_IF_CONFIG_SMALL("Change video quantization parameters."),
     .priv_size     = sizeof(QPContext),
     .inputs        = qp_inputs,
     .outputs       = qp_outputs,
     .priv_class    = &qp_class,
     .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_INTERNAL,
 };