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vf_geq.c
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1 /*
2  * Copyright (C) 2006 Michael Niedermayer <michaelni@gmx.at>
3  * Copyright (C) 2012 Clément Bœsch <ubitux@gmail.com>
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License as published by
9  * the Free Software Foundation; either version 2 of the License, or
10  * (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15  * GNU General Public License for more details.
16  *
17  * You should have received a copy of the GNU General Public License along
18  * with FFmpeg; if not, write to the Free Software Foundation, Inc.,
19  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
20  */
21 
22 /**
23  * @file
24  * Generic equation change filter
25  * Originally written by Michael Niedermayer for the MPlayer project, and
26  * ported by Clément Bœsch for FFmpeg.
27  */
28 
29 #include "libavutil/avstring.h"
30 #include "libavutil/eval.h"
31 #include "libavutil/opt.h"
32 #include "libavutil/pixdesc.h"
33 #include "internal.h"
34 
35 typedef struct {
36  const AVClass *class;
37  AVExpr *e[3]; ///< expressions for each plane
38  char *expr_str[3]; ///< expression strings for each plane
39  int framenum; ///< frame counter
40  AVFilterBufferRef *picref; ///< current input buffer
41  int hsub, vsub; ///< chroma subsampling
42 } GEQContext;
43 
44 #define OFFSET(x) offsetof(GEQContext, x)
45 #define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
46 
47 static const AVOption geq_options[] = {
48  { "lum_expr", "set luminance expression", OFFSET(expr_str), AV_OPT_TYPE_STRING, {.str=NULL}, CHAR_MIN, CHAR_MAX, FLAGS },
49  { "cb_expr", "set chroma blue expression", OFFSET(expr_str) + sizeof(char*), AV_OPT_TYPE_STRING, {.str=NULL}, CHAR_MIN, CHAR_MAX, FLAGS },
50  { "cr_expr", "set chroma red expression", OFFSET(expr_str) + 2*sizeof(char*), AV_OPT_TYPE_STRING, {.str=NULL}, CHAR_MIN, CHAR_MAX, FLAGS },
51  {NULL},
52 };
53 
55 
56 static inline double getpix(void *priv, double x, double y, int plane)
57 {
58  int xi, yi;
59  GEQContext *geq = priv;
60  AVFilterBufferRef *picref = geq->picref;
61  const uint8_t *src = picref->data[plane];
62  const int linesize = picref->linesize[plane];
63  const int w = picref->video->w >> (plane ? geq->hsub : 0);
64  const int h = picref->video->h >> (plane ? geq->vsub : 0);
65 
66  xi = x = av_clipf(x, 0, w - 2);
67  yi = y = av_clipf(y, 0, h - 2);
68 
69  x -= xi;
70  y -= yi;
71 
72  return (1-y)*((1-x)*src[xi + yi * linesize] + x*src[xi + 1 + yi * linesize])
73  + y *((1-x)*src[xi + (yi+1) * linesize] + x*src[xi + 1 + (yi+1) * linesize]);
74 }
75 
76 //TODO: cubic interpolate
77 //TODO: keep the last few frames
78 static double lum(void *priv, double x, double y) { return getpix(priv, x, y, 0); }
79 static double cb(void *priv, double x, double y) { return getpix(priv, x, y, 1); }
80 static double cr(void *priv, double x, double y) { return getpix(priv, x, y, 2); }
81 
82 static const char *const var_names[] = { "X", "Y", "W", "H", "N", "SW", "SH", "T", NULL };
84 
85 static av_cold int geq_init(AVFilterContext *ctx, const char *args)
86 {
87  GEQContext *geq = ctx->priv;
88  int plane, ret = 0;
89  static const char *shorthand[] = { "lum_expr", "cb_expr", "cr_expr", NULL };
90 
91  geq->class = &geq_class;
93 
94  if ((ret = av_opt_set_from_string(geq, args, shorthand, "=", ":")) < 0)
95  return ret;
96 
97  if (!geq->expr_str[0]) {
98  av_log(ctx, AV_LOG_ERROR, "Luminance expression is mandatory\n");
99  ret = AVERROR(EINVAL);
100  goto end;
101  }
102 
103  if (!geq->expr_str[1] && !geq->expr_str[2]) {
104  /* No chroma at all: fallback on luma */
105  geq->expr_str[1] = av_strdup(geq->expr_str[0]);
106  geq->expr_str[2] = av_strdup(geq->expr_str[0]);
107  } else {
108  /* One chroma unspecified, fallback on the other */
109  if (!geq->expr_str[1]) geq->expr_str[1] = av_strdup(geq->expr_str[2]);
110  if (!geq->expr_str[2]) geq->expr_str[2] = av_strdup(geq->expr_str[1]);
111  }
112 
113  if (!geq->expr_str[1] || !geq->expr_str[2]) {
114  ret = AVERROR(ENOMEM);
115  goto end;
116  }
117 
118  for (plane = 0; plane < 3; plane++) {
119  static double (*p[])(void *, double, double) = { lum, cb, cr };
120  static const char *const func2_names[] = { "lum", "cb", "cr", "p", NULL };
121  double (*func2[])(void *, double, double) = { lum, cb, cr, p[plane], NULL };
122 
123  ret = av_expr_parse(&geq->e[plane], geq->expr_str[plane], var_names,
124  NULL, NULL, func2_names, func2, 0, ctx);
125  if (ret < 0)
126  break;
127  }
128 
129 end:
130  return ret;
131 }
132 
134 {
135  static const enum PixelFormat pix_fmts[] = {
140  };
142  return 0;
143 }
144 
145 static int geq_config_props(AVFilterLink *inlink)
146 {
147  GEQContext *geq = inlink->dst->priv;
148  const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
149 
150  geq->hsub = desc->log2_chroma_w;
151  geq->vsub = desc->log2_chroma_h;
152  return 0;
153 }
154 
156 {
157  int plane;
158  GEQContext *geq = inlink->dst->priv;
159  AVFilterLink *outlink = inlink->dst->outputs[0];
160  AVFilterBufferRef *out;
161  double values[VAR_VARS_NB] = {
162  [VAR_N] = geq->framenum++,
163  [VAR_T] = in->pts == AV_NOPTS_VALUE ? NAN : in->pts * av_q2d(inlink->time_base),
164  };
165 
166  geq->picref = in;
167  out = ff_get_video_buffer(outlink, AV_PERM_WRITE, outlink->w, outlink->h);
168  if (!out) {
170  return AVERROR(ENOMEM);
171  }
173 
174  for (plane = 0; plane < 3; plane++) {
175  int x, y;
176  uint8_t *dst = out->data[plane];
177  const int linesize = out->linesize[plane];
178  const int w = inlink->w >> (plane ? geq->hsub : 0);
179  const int h = inlink->h >> (plane ? geq->vsub : 0);
180 
181  values[VAR_W] = w;
182  values[VAR_H] = h;
183  values[VAR_SW] = w / (double)inlink->w;
184  values[VAR_SH] = h / (double)inlink->h;
185 
186  for (y = 0; y < h; y++) {
187  values[VAR_Y] = y;
188  for (x = 0; x < w; x++) {
189  values[VAR_X] = x;
190  dst[x] = av_expr_eval(geq->e[plane], values, geq);
191  }
192  dst += linesize;
193  }
194  }
195 
197  return ff_filter_frame(outlink, out);
198 }
199 
201 {
202  int i;
203  GEQContext *geq = ctx->priv;
204 
205  for (i = 0; i < FF_ARRAY_ELEMS(geq->e); i++)
206  av_expr_free(geq->e[i]);
207  av_opt_free(geq);
208 }
209 
210 static const AVFilterPad geq_inputs[] = {
211  {
212  .name = "default",
213  .type = AVMEDIA_TYPE_VIDEO,
214  .config_props = geq_config_props,
215  .filter_frame = geq_filter_frame,
216  .min_perms = AV_PERM_READ,
217  },
218  { NULL }
219 };
220 
221 static const AVFilterPad geq_outputs[] = {
222  {
223  .name = "default",
224  .type = AVMEDIA_TYPE_VIDEO,
225  },
226  { NULL }
227 };
228 
230  .name = "geq",
231  .description = NULL_IF_CONFIG_SMALL("Apply generic equation to each pixel."),
232  .priv_size = sizeof(GEQContext),
233  .init = geq_init,
234  .uninit = geq_uninit,
236  .inputs = geq_inputs,
237  .outputs = geq_outputs,
238  .priv_class = &geq_class,
239 };