Libav
vf_scale.c
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1 /*
2  * Copyright (c) 2007 Bobby Bingham
3  *
4  * This file is part of Libav.
5  *
6  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
26 #include <stdio.h>
27 #include <string.h>
28 
29 #include "avfilter.h"
30 #include "formats.h"
31 #include "internal.h"
32 #include "video.h"
33 #include "libavutil/avstring.h"
34 #include "libavutil/eval.h"
35 #include "libavutil/internal.h"
36 #include "libavutil/mathematics.h"
37 #include "libavutil/opt.h"
38 #include "libavutil/pixdesc.h"
39 #include "libswscale/swscale.h"
40 
41 static const char *const var_names[] = {
42  "PI",
43  "PHI",
44  "E",
45  "in_w", "iw",
46  "in_h", "ih",
47  "out_w", "ow",
48  "out_h", "oh",
49  "a", "dar",
50  "sar",
51  "hsub",
52  "vsub",
53  NULL
54 };
55 
56 enum var_name {
69 };
70 
71 typedef struct {
72  const AVClass *class;
73  struct SwsContext *sws;
74 
80  int w, h;
81  unsigned int flags;
82 
83  int hsub, vsub;
84  int slice_y;
86 
87  char *w_expr;
88  char *h_expr;
89  char *flags_str;
90 } ScaleContext;
91 
92 static av_cold int init(AVFilterContext *ctx)
93 {
94  ScaleContext *scale = ctx->priv;
95 
96  if (scale->flags_str) {
97  const AVClass *class = sws_get_class();
98  const AVOption *o = av_opt_find(&class, "sws_flags", NULL, 0,
100  int ret = av_opt_eval_flags(&class, o, scale->flags_str, &scale->flags);
101 
102  if (ret < 0)
103  return ret;
104  }
105 
106  return 0;
107 }
108 
109 static av_cold void uninit(AVFilterContext *ctx)
110 {
111  ScaleContext *scale = ctx->priv;
112  sws_freeContext(scale->sws);
113  scale->sws = NULL;
114 }
115 
117 {
119  enum AVPixelFormat pix_fmt;
120  int ret;
121 
122  if (ctx->inputs[0]) {
123  formats = NULL;
124  for (pix_fmt = 0; pix_fmt < AV_PIX_FMT_NB; pix_fmt++)
125  if ((sws_isSupportedInput(pix_fmt) ||
127  && (ret = ff_add_format(&formats, pix_fmt)) < 0) {
128  ff_formats_unref(&formats);
129  return ret;
130  }
131  ff_formats_ref(formats, &ctx->inputs[0]->out_formats);
132  }
133  if (ctx->outputs[0]) {
134  formats = NULL;
135  for (pix_fmt = 0; pix_fmt < AV_PIX_FMT_NB; pix_fmt++)
136  if ((sws_isSupportedOutput(pix_fmt) ||
138  && (ret = ff_add_format(&formats, pix_fmt)) < 0) {
139  ff_formats_unref(&formats);
140  return ret;
141  }
142  ff_formats_ref(formats, &ctx->outputs[0]->in_formats);
143  }
144 
145  return 0;
146 }
147 
148 static int config_props(AVFilterLink *outlink)
149 {
150  AVFilterContext *ctx = outlink->src;
151  AVFilterLink *inlink = outlink->src->inputs[0];
152  ScaleContext *scale = ctx->priv;
153  const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
154  int64_t w, h;
155  double var_values[VARS_NB], res;
156  char *expr;
157  int ret;
158 
159  var_values[VAR_PI] = M_PI;
160  var_values[VAR_PHI] = M_PHI;
161  var_values[VAR_E] = M_E;
162  var_values[VAR_IN_W] = var_values[VAR_IW] = inlink->w;
163  var_values[VAR_IN_H] = var_values[VAR_IH] = inlink->h;
164  var_values[VAR_OUT_W] = var_values[VAR_OW] = NAN;
165  var_values[VAR_OUT_H] = var_values[VAR_OH] = NAN;
166  var_values[VAR_A] = (double) inlink->w / inlink->h;
167  var_values[VAR_SAR] = inlink->sample_aspect_ratio.num ?
168  (double) inlink->sample_aspect_ratio.num / inlink->sample_aspect_ratio.den : 1;
169  var_values[VAR_DAR] = var_values[VAR_A] * var_values[VAR_SAR];
170  var_values[VAR_HSUB] = 1 << desc->log2_chroma_w;
171  var_values[VAR_VSUB] = 1 << desc->log2_chroma_h;
172 
173  /* evaluate width and height */
174  av_expr_parse_and_eval(&res, (expr = scale->w_expr),
175  var_names, var_values,
176  NULL, NULL, NULL, NULL, NULL, 0, ctx);
177  scale->w = var_values[VAR_OUT_W] = var_values[VAR_OW] = res;
178  if ((ret = av_expr_parse_and_eval(&res, (expr = scale->h_expr),
179  var_names, var_values,
180  NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0)
181  goto fail;
182  scale->h = var_values[VAR_OUT_H] = var_values[VAR_OH] = res;
183  /* evaluate again the width, as it may depend on the output height */
184  if ((ret = av_expr_parse_and_eval(&res, (expr = scale->w_expr),
185  var_names, var_values,
186  NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0)
187  goto fail;
188  scale->w = res;
189 
190  w = scale->w;
191  h = scale->h;
192 
193  /* sanity check params */
194  if (w < -1 || h < -1) {
195  av_log(ctx, AV_LOG_ERROR, "Size values less than -1 are not acceptable.\n");
196  return AVERROR(EINVAL);
197  }
198  if (w == -1 && h == -1)
199  scale->w = scale->h = 0;
200 
201  if (!(w = scale->w))
202  w = inlink->w;
203  if (!(h = scale->h))
204  h = inlink->h;
205  if (w == -1)
206  w = av_rescale(h, inlink->w, inlink->h);
207  if (h == -1)
208  h = av_rescale(w, inlink->h, inlink->w);
209 
210  if (w > INT_MAX || h > INT_MAX ||
211  (h * inlink->w) > INT_MAX ||
212  (w * inlink->h) > INT_MAX)
213  av_log(ctx, AV_LOG_ERROR, "Rescaled value for width or height is too big.\n");
214 
215  outlink->w = w;
216  outlink->h = h;
217 
218  /* TODO: make algorithm configurable */
219  av_log(ctx, AV_LOG_VERBOSE, "w:%d h:%d fmt:%s -> w:%d h:%d fmt:%s flags:0x%0x\n",
220  inlink ->w, inlink ->h, av_get_pix_fmt_name(inlink->format),
221  outlink->w, outlink->h, av_get_pix_fmt_name(outlink->format),
222  scale->flags);
223 
224  scale->input_is_pal = desc->flags & AV_PIX_FMT_FLAG_PAL ||
226 
227  if (scale->sws)
228  sws_freeContext(scale->sws);
229  if (inlink->w == outlink->w && inlink->h == outlink->h &&
230  inlink->format == outlink->format)
231  scale->sws = NULL;
232  else {
233  scale->sws = sws_getContext(inlink ->w, inlink ->h, inlink ->format,
234  outlink->w, outlink->h, outlink->format,
235  scale->flags, NULL, NULL, NULL);
236  if (!scale->sws)
237  return AVERROR(EINVAL);
238  }
239 
240 
241  if (inlink->sample_aspect_ratio.num)
242  outlink->sample_aspect_ratio = av_mul_q((AVRational){outlink->h*inlink->w,
243  outlink->w*inlink->h},
244  inlink->sample_aspect_ratio);
245  else
246  outlink->sample_aspect_ratio = inlink->sample_aspect_ratio;
247 
248  return 0;
249 
250 fail:
252  "Error when evaluating the expression '%s'\n", expr);
253  return ret;
254 }
255 
256 static int filter_frame(AVFilterLink *link, AVFrame *in)
257 {
258  ScaleContext *scale = link->dst->priv;
259  AVFilterLink *outlink = link->dst->outputs[0];
260  AVFrame *out;
261  const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(link->format);
262 
263  if (!scale->sws)
264  return ff_filter_frame(outlink, in);
265 
266  scale->hsub = desc->log2_chroma_w;
267  scale->vsub = desc->log2_chroma_h;
268 
269  out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
270  if (!out) {
271  av_frame_free(&in);
272  return AVERROR(ENOMEM);
273  }
274 
275  av_frame_copy_props(out, in);
276  out->width = outlink->w;
277  out->height = outlink->h;
278 
280  (int64_t)in->sample_aspect_ratio.num * outlink->h * link->w,
281  (int64_t)in->sample_aspect_ratio.den * outlink->w * link->h,
282  INT_MAX);
283 
284  sws_scale(scale->sws, in->data, in->linesize, 0, in->height,
285  out->data, out->linesize);
286 
287  av_frame_free(&in);
288  return ff_filter_frame(outlink, out);
289 }
290 
291 #define OFFSET(x) offsetof(ScaleContext, x)
292 #define FLAGS AV_OPT_FLAG_VIDEO_PARAM
293 static const AVOption options[] = {
294  { "w", "Output video width", OFFSET(w_expr), AV_OPT_TYPE_STRING, { .str = "iw" }, .flags = FLAGS },
295  { "h", "Output video height", OFFSET(h_expr), AV_OPT_TYPE_STRING, { .str = "ih" }, .flags = FLAGS },
296  { "flags", "Flags to pass to libswscale", OFFSET(flags_str), AV_OPT_TYPE_STRING, { .str = "bilinear" }, .flags = FLAGS },
297  { NULL },
298 };
299 
300 static const AVClass scale_class = {
301  .class_name = "scale",
302  .item_name = av_default_item_name,
303  .option = options,
304  .version = LIBAVUTIL_VERSION_INT,
305 };
306 
308  {
309  .name = "default",
310  .type = AVMEDIA_TYPE_VIDEO,
311  .filter_frame = filter_frame,
312  },
313  { NULL }
314 };
315 
317  {
318  .name = "default",
319  .type = AVMEDIA_TYPE_VIDEO,
320  .config_props = config_props,
321  },
322  { NULL }
323 };
324 
326  .name = "scale",
327  .description = NULL_IF_CONFIG_SMALL("Scale the input video to width:height size and/or convert the image format."),
328 
329  .init = init,
330  .uninit = uninit,
331 
332  .query_formats = query_formats,
333 
334  .priv_size = sizeof(ScaleContext),
335  .priv_class = &scale_class,
336 
337  .inputs = avfilter_vf_scale_inputs,
338  .outputs = avfilter_vf_scale_outputs,
339 };