2 * Copyright (c) 2007 Bobby Bingham
4 * This file is part of FFmpeg.
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23 #include "libavutil/eval.h"
24 #include "libavutil/mathematics.h"
25 #include "libavutil/pixdesc.h"
27 static const char *const var_names[] = {
63 int ff_scale_eval_dimensions(void *log_ctx,
64 const char *w_expr, const char *h_expr,
65 AVFilterLink *inlink, AVFilterLink *outlink,
66 int *ret_w, int *ret_h)
68 const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
69 const AVPixFmtDescriptor *out_desc = av_pix_fmt_desc_get(outlink->format);
72 int factor_w, factor_h;
75 double var_values[VARS_NB], res;
77 var_values[VAR_PI] = M_PI;
78 var_values[VAR_PHI] = M_PHI;
79 var_values[VAR_E] = M_E;
80 var_values[VAR_IN_W] = var_values[VAR_IW] = inlink->w;
81 var_values[VAR_IN_H] = var_values[VAR_IH] = inlink->h;
82 var_values[VAR_OUT_W] = var_values[VAR_OW] = NAN;
83 var_values[VAR_OUT_H] = var_values[VAR_OH] = NAN;
84 var_values[VAR_A] = (double) inlink->w / inlink->h;
85 var_values[VAR_SAR] = inlink->sample_aspect_ratio.num ?
86 (double) inlink->sample_aspect_ratio.num / inlink->sample_aspect_ratio.den : 1;
87 var_values[VAR_DAR] = var_values[VAR_A] * var_values[VAR_SAR];
88 var_values[VAR_HSUB] = 1 << desc->log2_chroma_w;
89 var_values[VAR_VSUB] = 1 << desc->log2_chroma_h;
90 var_values[VAR_OHSUB] = 1 << out_desc->log2_chroma_w;
91 var_values[VAR_OVSUB] = 1 << out_desc->log2_chroma_h;
93 /* evaluate width and height */
94 av_expr_parse_and_eval(&res, (expr = w_expr),
95 var_names, var_values,
96 NULL, NULL, NULL, NULL, NULL, 0, log_ctx);
97 eval_w = var_values[VAR_OUT_W] = var_values[VAR_OW] = res;
99 if ((ret = av_expr_parse_and_eval(&res, (expr = h_expr),
100 var_names, var_values,
101 NULL, NULL, NULL, NULL, NULL, 0, log_ctx)) < 0)
103 eval_h = var_values[VAR_OUT_H] = var_values[VAR_OH] = res;
104 /* evaluate again the width, as it may depend on the output height */
105 if ((ret = av_expr_parse_and_eval(&res, (expr = w_expr),
106 var_names, var_values,
107 NULL, NULL, NULL, NULL, NULL, 0, log_ctx)) < 0)
114 /* Check if it is requested that the result has to be divisible by a some
115 * factor (w or h = -n with n being the factor). */
133 /* Make sure that the result is divisible by the factor we determined
134 * earlier. If no factor was set, it is nothing will happen as the default
137 w = av_rescale(h, inlink->w, inlink->h * factor_w) * factor_w;
139 h = av_rescale(w, inlink->h, inlink->w * factor_h) * factor_h;
147 av_log(log_ctx, AV_LOG_ERROR,
148 "Error when evaluating the expression '%s'.\n"
149 "Maybe the expression for out_w:'%s' or for out_h:'%s' is self-referencing.\n",
150 expr, w_expr, h_expr);