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scale.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.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  "PI",
29  "PHI",
30  "E",
31  "in_w", "iw",
32  "in_h", "ih",
33  "out_w", "ow",
34  "out_h", "oh",
35  "a",
36  "sar",
37  "dar",
38  "hsub",
39  "vsub",
40  "ohsub",
41  "ovsub",
42  NULL
43 };
44 
45 enum var_name {
61 };
62 
63 /**
64  * This must be kept in sync with var_names so that it is always a
65  * complete list of var_names with the scale2ref specific names
66  * appended. scale2ref values must appear in the order they appear
67  * in the var_name_scale2ref enum but also be below all of the
68  * non-scale2ref specific values.
69  */
70 static const char *const var_names_scale2ref[] = {
71  "PI",
72  "PHI",
73  "E",
74  "in_w", "iw",
75  "in_h", "ih",
76  "out_w", "ow",
77  "out_h", "oh",
78  "a",
79  "sar",
80  "dar",
81  "hsub",
82  "vsub",
83  "ohsub",
84  "ovsub",
85  "main_w",
86  "main_h",
87  "main_a",
88  "main_sar",
89  "main_dar", "mdar",
90  "main_hsub",
91  "main_vsub",
92  NULL
93 };
94 
104 };
105 
106 int ff_scale_eval_dimensions(void *log_ctx,
107  const char *w_expr, const char *h_expr,
108  AVFilterLink *inlink, AVFilterLink *outlink,
109  int *ret_w, int *ret_h)
110 {
112  const AVPixFmtDescriptor *out_desc = av_pix_fmt_desc_get(outlink->format);
113  const char *expr;
114  int w, h;
115  int factor_w, factor_h;
116  int eval_w, eval_h;
117  int ret;
118  const char scale2ref = outlink->src->nb_inputs == 2 && outlink->src->inputs[1] == inlink;
119  double var_values[VARS_NB + VARS_S2R_NB], res;
120  const AVPixFmtDescriptor *main_desc;
121  const AVFilterLink *main_link;
122  const char *const *names = scale2ref ? var_names_scale2ref : var_names;
123 
124  if (scale2ref) {
125  main_link = outlink->src->inputs[0];
126  main_desc = av_pix_fmt_desc_get(main_link->format);
127  }
128 
129  var_values[VAR_PI] = M_PI;
130  var_values[VAR_PHI] = M_PHI;
131  var_values[VAR_E] = M_E;
132  var_values[VAR_IN_W] = var_values[VAR_IW] = inlink->w;
133  var_values[VAR_IN_H] = var_values[VAR_IH] = inlink->h;
134  var_values[VAR_OUT_W] = var_values[VAR_OW] = NAN;
135  var_values[VAR_OUT_H] = var_values[VAR_OH] = NAN;
136  var_values[VAR_A] = (double) inlink->w / inlink->h;
137  var_values[VAR_SAR] = inlink->sample_aspect_ratio.num ?
138  (double) inlink->sample_aspect_ratio.num / inlink->sample_aspect_ratio.den : 1;
139  var_values[VAR_DAR] = var_values[VAR_A] * var_values[VAR_SAR];
140  var_values[VAR_HSUB] = 1 << desc->log2_chroma_w;
141  var_values[VAR_VSUB] = 1 << desc->log2_chroma_h;
142  var_values[VAR_OHSUB] = 1 << out_desc->log2_chroma_w;
143  var_values[VAR_OVSUB] = 1 << out_desc->log2_chroma_h;
144 
145  if (scale2ref) {
146  var_values[VARS_NB + VAR_S2R_MAIN_W] = main_link->w;
147  var_values[VARS_NB + VAR_S2R_MAIN_H] = main_link->h;
148  var_values[VARS_NB + VAR_S2R_MAIN_A] = (double) main_link->w / main_link->h;
149  var_values[VARS_NB + VAR_S2R_MAIN_SAR] = main_link->sample_aspect_ratio.num ?
150  (double) main_link->sample_aspect_ratio.num / main_link->sample_aspect_ratio.den : 1;
151  var_values[VARS_NB + VAR_S2R_MAIN_DAR] = var_values[VARS_NB + VAR_S2R_MDAR] =
152  var_values[VARS_NB + VAR_S2R_MAIN_A] * var_values[VARS_NB + VAR_S2R_MAIN_SAR];
153  var_values[VARS_NB + VAR_S2R_MAIN_HSUB] = 1 << main_desc->log2_chroma_w;
154  var_values[VARS_NB + VAR_S2R_MAIN_VSUB] = 1 << main_desc->log2_chroma_h;
155  }
156 
157  /* evaluate width and height */
158  av_expr_parse_and_eval(&res, (expr = w_expr),
159  names, var_values,
160  NULL, NULL, NULL, NULL, NULL, 0, log_ctx);
161  eval_w = var_values[VAR_OUT_W] = var_values[VAR_OW] = (int) res == 0 ? inlink->w : (int) res;
162 
163  if ((ret = av_expr_parse_and_eval(&res, (expr = h_expr),
164  names, var_values,
165  NULL, NULL, NULL, NULL, NULL, 0, log_ctx)) < 0)
166  goto fail;
167  eval_h = var_values[VAR_OUT_H] = var_values[VAR_OH] = (int) res == 0 ? inlink->h : (int) res;
168  /* evaluate again the width, as it may depend on the output height */
169  if ((ret = av_expr_parse_and_eval(&res, (expr = w_expr),
170  names, var_values,
171  NULL, NULL, NULL, NULL, NULL, 0, log_ctx)) < 0)
172  goto fail;
173  eval_w = (int) res == 0 ? inlink->w : (int) res;
174 
175  w = eval_w;
176  h = eval_h;
177 
178  /* Check if it is requested that the result has to be divisible by a some
179  * factor (w or h = -n with n being the factor). */
180  factor_w = 1;
181  factor_h = 1;
182  if (w < -1) {
183  factor_w = -w;
184  }
185  if (h < -1) {
186  factor_h = -h;
187  }
188 
189  if (w < 0 && h < 0) {
190  w = inlink->w;
191  h = inlink->h;
192  }
193 
194  /* Make sure that the result is divisible by the factor we determined
195  * earlier. If no factor was set, it is nothing will happen as the default
196  * factor is 1 */
197  if (w < 0)
198  w = av_rescale(h, inlink->w, inlink->h * factor_w) * factor_w;
199  if (h < 0)
200  h = av_rescale(w, inlink->h, inlink->w * factor_h) * factor_h;
201 
202  *ret_w = w;
203  *ret_h = h;
204 
205  return 0;
206 
207 fail:
208  av_log(log_ctx, AV_LOG_ERROR,
209  "Error when evaluating the expression '%s'.\n"
210  "Maybe the expression for out_w:'%s' or for out_h:'%s' is self-referencing.\n",
211  expr, w_expr, h_expr);
212  return ret;
213 }
Definition: scale.c:50
#define NULL
Definition: coverity.c:32
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)
Definition: scale.c:106
const AVPixFmtDescriptor * av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
Definition: pixdesc.c:2406
const char * desc
Definition: nvenc.c:65
int num
Numerator.
Definition: rational.h:59
Definition: scale.c:54
uint8_t log2_chroma_w
Amount to shift the luma width right to find the chroma width.
Definition: pixdesc.h:92
Definition: scale.c:47
AVFilterLink ** inputs
array of pointers to input links
Definition: avfilter.h:346
Definition: scale.c:50
#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:744
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
uint8_t log2_chroma_h
Amount to shift the luma height right to find the chroma height.
Definition: pixdesc.h:101
#define M_E
Definition: mathematics.h:37
Definition: scale.c:60
#define fail()
Definition: checkasm.h:117
var_name
Definition: aeval.c:46
Definition: scale.c:56
unsigned nb_inputs
number of input pads
Definition: avfilter.h:347
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
Definition: scale.c:52
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
#define M_PHI
Definition: mathematics.h:49
static const char *const var_names[]
Definition: scale.c:27
Definition: scale.c:53
int
Definition: scale.c:51
int den
Denominator.
Definition: rational.h:60
Definition: scale.c:46
var_name_scale2ref
Definition: scale.c:95
Definition: scale.c:57
Definition: scale.c:48
static const char *const var_names_scale2ref[]
This must be kept in sync with var_names so that it is always a complete list of var_names with the s...
Definition: scale.c:70
#define M_PI
Definition: mathematics.h:52
Definition: scale.c:55
simple arithmetic expression evaluator
Definition: scale.c:49
Definition: scale.c:49