FFmpeg
scale_eval.c
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1 /*
2  * Copyright (c) 2007 Bobby Bingham
3  *
4  * This file is part of FFmpeg.
5  *
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.
10  *
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.
15  *
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
19  */
20 
21 #include <stdint.h>
22 #include "scale_eval.h"
23 #include "libavutil/eval.h"
24 #include "libavutil/mathematics.h"
25 #include "libavutil/pixdesc.h"
26 
27 static const char *const var_names[] = {
28  "in_w", "iw",
29  "in_h", "ih",
30  "out_w", "ow",
31  "out_h", "oh",
32  "a",
33  "sar",
34  "dar",
35  "hsub",
36  "vsub",
37  "ohsub",
38  "ovsub",
39  NULL
40 };
41 
42 enum var_name {
55 };
56 
57 int ff_scale_eval_dimensions(void *log_ctx,
58  const char *w_expr, const char *h_expr,
59  AVFilterLink *inlink, AVFilterLink *outlink,
60  int *ret_w, int *ret_h)
61 {
63  const AVPixFmtDescriptor *out_desc = av_pix_fmt_desc_get(outlink->format);
64  const char *expr;
65  int eval_w, eval_h;
66  int ret;
67  double var_values[VARS_NB], res;
68 
69  var_values[VAR_IN_W] = var_values[VAR_IW] = inlink->w;
70  var_values[VAR_IN_H] = var_values[VAR_IH] = inlink->h;
71  var_values[VAR_OUT_W] = var_values[VAR_OW] = NAN;
72  var_values[VAR_OUT_H] = var_values[VAR_OH] = NAN;
73  var_values[VAR_A] = (double) inlink->w / inlink->h;
74  var_values[VAR_SAR] = inlink->sample_aspect_ratio.num ?
75  (double) inlink->sample_aspect_ratio.num / inlink->sample_aspect_ratio.den : 1;
76  var_values[VAR_DAR] = var_values[VAR_A] * var_values[VAR_SAR];
77  var_values[VAR_HSUB] = 1 << desc->log2_chroma_w;
78  var_values[VAR_VSUB] = 1 << desc->log2_chroma_h;
79  var_values[VAR_OHSUB] = 1 << out_desc->log2_chroma_w;
80  var_values[VAR_OVSUB] = 1 << out_desc->log2_chroma_h;
81 
82  /* evaluate width and height */
83  av_expr_parse_and_eval(&res, (expr = w_expr),
84  var_names, var_values,
85  NULL, NULL, NULL, NULL, NULL, 0, log_ctx);
86  eval_w = var_values[VAR_OUT_W] = var_values[VAR_OW] = (int) res == 0 ? inlink->w : (int) res;
87 
88  if ((ret = av_expr_parse_and_eval(&res, (expr = h_expr),
89  var_names, var_values,
90  NULL, NULL, NULL, NULL, NULL, 0, log_ctx)) < 0)
91  goto fail;
92  eval_h = var_values[VAR_OUT_H] = var_values[VAR_OH] = (int) res == 0 ? inlink->h : (int) res;
93  /* evaluate again the width, as it may depend on the output height */
94  if ((ret = av_expr_parse_and_eval(&res, (expr = w_expr),
95  var_names, var_values,
96  NULL, NULL, NULL, NULL, NULL, 0, log_ctx)) < 0)
97  goto fail;
98  eval_w = (int) res == 0 ? inlink->w : (int) res;
99 
100  *ret_w = eval_w;
101  *ret_h = eval_h;
102 
103  return 0;
104 
105 fail:
106  av_log(log_ctx, AV_LOG_ERROR,
107  "Error when evaluating the expression '%s'.\n"
108  "Maybe the expression for out_w:'%s' or for out_h:'%s' is self-referencing.\n",
109  expr, w_expr, h_expr);
110  return ret;
111 }
112 
114  int *ret_w, int *ret_h,
115  int force_original_aspect_ratio, int force_divisible_by)
116 {
117  int w, h;
118  int factor_w, factor_h;
119 
120  w = *ret_w;
121  h = *ret_h;
122 
123  /* Check if it is requested that the result has to be divisible by some
124  * factor (w or h = -n with n being the factor). */
125  factor_w = 1;
126  factor_h = 1;
127  if (w < -1) {
128  factor_w = -w;
129  }
130  if (h < -1) {
131  factor_h = -h;
132  }
133 
134  if (w < 0 && h < 0) {
135  w = inlink->w;
136  h = inlink->h;
137  }
138 
139  /* Make sure that the result is divisible by the factor we determined
140  * earlier. If no factor was set, nothing will happen as the default
141  * factor is 1 */
142  if (w < 0)
143  w = av_rescale(h, inlink->w, inlink->h * factor_w) * factor_w;
144  if (h < 0)
145  h = av_rescale(w, inlink->h, inlink->w * factor_h) * factor_h;
146 
147  /* Note that force_original_aspect_ratio may overwrite the previous set
148  * dimensions so that it is not divisible by the set factors anymore
149  * unless force_divisible_by is defined as well */
150  if (force_original_aspect_ratio) {
151  int tmp_w = av_rescale(h, inlink->w, inlink->h);
152  int tmp_h = av_rescale(w, inlink->h, inlink->w);
153 
154  if (force_original_aspect_ratio == 1) {
155  w = FFMIN(tmp_w, w);
156  h = FFMIN(tmp_h, h);
157  if (force_divisible_by > 1) {
158  // round down
159  w = w / force_divisible_by * force_divisible_by;
160  h = h / force_divisible_by * force_divisible_by;
161  }
162  } else {
163  w = FFMAX(tmp_w, w);
164  h = FFMAX(tmp_h, h);
165  if (force_divisible_by > 1) {
166  // round up
167  w = (w + force_divisible_by - 1) / force_divisible_by * force_divisible_by;
168  h = (h + force_divisible_by - 1) / force_divisible_by * force_divisible_by;
169  }
170  }
171  }
172 
173  *ret_w = w;
174  *ret_h = h;
175 
176  return 0;
177 }
#define NULL
Definition: coverity.c:32
const AVPixFmtDescriptor * av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
Definition: pixdesc.c:2573
const char * desc
Definition: libsvtav1.c:79
int num
Numerator.
Definition: rational.h:59
uint8_t log2_chroma_w
Amount to shift the luma width right to find the chroma width.
Definition: pixdesc.h:92
#define av_log(a,...)
int av_expr_parse_and_eval(double *d, const char *s, const char *const *const_names, const double *const_values, const char *const *func1_names, double(*const *funcs1)(void *, double), const char *const *func2_names, double(*const *funcs2)(void *, double, double), void *opaque, int log_offset, void *log_ctx)
Parse and evaluate an expression.
Definition: eval.c:776
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:194
uint8_t log2_chroma_h
Amount to shift the luma height right to find the chroma height.
Definition: pixdesc.h:101
int ff_scale_eval_dimensions(void *log_ctx, const char *w_expr, const char *h_expr, AVFilterLink *inlink, AVFilterLink *outlink, int *ret_w, int *ret_h)
Parse and evaluate string expressions for width and height.
Definition: scale_eval.c:57
#define FFMAX(a, b)
Definition: common.h:94
#define fail()
Definition: checkasm.h:123
var_name
Definition: aeval.c:46
int64_t av_rescale(int64_t a, int64_t b, int64_t c)
Rescale a 64-bit integer with rounding to nearest.
Definition: mathematics.c:129
#define NAN
Definition: mathematics.h:64
#define FFMIN(a, b)
Definition: common.h:96
static const char *const var_names[]
Definition: scale_eval.c:27
uint8_t w
Definition: llviddspenc.c:38
Descriptor that unambiguously describes how the bits of a pixel are stored in the up to 4 data planes...
Definition: pixdesc.h:81
int ff_scale_adjust_dimensions(AVFilterLink *inlink, int *ret_w, int *ret_h, int force_original_aspect_ratio, int force_divisible_by)
Transform evaluated width and height obtained from ff_scale_eval_dimensions into actual target width ...
Definition: scale_eval.c:113
The exact code depends on how similar the blocks are and how related they are to the and needs to apply these operations to the correct inlink or outlink if there are several Macros are available to factor that when no extra processing is inlink
int
int den
Denominator.
Definition: rational.h:60
simple arithmetic expression evaluator