FFmpeg  4.4.5
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 {
54  VARS_NB
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  int64_t 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  int64_t tmp_w = av_rescale(h, inlink->w, inlink->h);
152  int64_t 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  if ((int32_t)w != w || (int32_t)h != h)
174  return AVERROR(EINVAL);
175 
176  *ret_w = w;
177  *ret_h = h;
178 
179  return 0;
180 }
int32_t
#define fail()
Definition: checkasm.h:133
#define FFMIN(a, b)
Definition: common.h:105
#define FFMAX(a, b)
Definition: common.h:103
#define NULL
Definition: coverity.c:32
long long int64_t
Definition: coverity.c:34
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
simple arithmetic expression evaluator
int
#define AVERROR(e)
Definition: error.h:43
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:194
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
const char * desc
Definition: libsvtav1.c:79
uint8_t w
Definition: llviddspenc.c:39
#define NAN
Definition: mathematics.h:64
const AVPixFmtDescriptor * av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
Definition: pixdesc.c:2573
@ VAR_VSUB
Definition: scale_eval.c:51
@ VAR_OUT_H
Definition: scale_eval.c:46
@ VARS_NB
Definition: scale_eval.c:54
@ VAR_SAR
Definition: scale_eval.c:48
@ VAR_OH
Definition: scale_eval.c:46
@ VAR_IN_W
Definition: scale_eval.c:43
@ VAR_IW
Definition: scale_eval.c:43
@ VAR_OW
Definition: scale_eval.c:45
@ VAR_OHSUB
Definition: scale_eval.c:52
@ VAR_IH
Definition: scale_eval.c:44
@ VAR_A
Definition: scale_eval.c:47
@ VAR_OUT_W
Definition: scale_eval.c:45
@ VAR_OVSUB
Definition: scale_eval.c:53
@ VAR_HSUB
Definition: scale_eval.c:50
@ VAR_IN_H
Definition: scale_eval.c:44
@ VAR_DAR
Definition: scale_eval.c:49
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
static const char *const var_names[]
Definition: scale_eval.c:27
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
var_name
Definition: setts_bsf.c:50
Descriptor that unambiguously describes how the bits of a pixel are stored in the up to 4 data planes...
Definition: pixdesc.h:81
uint8_t log2_chroma_w
Amount to shift the luma width right to find the chroma width.
Definition: pixdesc.h:92
uint8_t log2_chroma_h
Amount to shift the luma height right to find the chroma height.
Definition: pixdesc.h:101
int num
Numerator.
Definition: rational.h:59
int den
Denominator.
Definition: rational.h:60
#define av_log(a,...)