FFmpeg
vf_crop.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 /**
22  * @file
23  * video crop filter
24  */
25 
26 #include <stdio.h>
27 
28 #include "avfilter.h"
29 #include "formats.h"
30 #include "internal.h"
31 #include "video.h"
32 #include "libavutil/eval.h"
33 #include "libavutil/avstring.h"
34 #include "libavutil/internal.h"
35 #include "libavutil/libm.h"
36 #include "libavutil/imgutils.h"
37 #include "libavutil/mathematics.h"
38 #include "libavutil/opt.h"
39 
40 static const char *const var_names[] = {
41  "in_w", "iw", ///< width of the input video
42  "in_h", "ih", ///< height of the input video
43  "out_w", "ow", ///< width of the cropped video
44  "out_h", "oh", ///< height of the cropped video
45  "a",
46  "sar",
47  "dar",
48  "hsub",
49  "vsub",
50  "x",
51  "y",
52  "n", ///< number of frame
53  "pos", ///< position in the file
54  "t", ///< timestamp expressed in seconds
55  NULL
56 };
57 
58 enum var_name {
74 };
75 
76 typedef struct CropContext {
77  const AVClass *class;
78  int x; ///< x offset of the non-cropped area with respect to the input area
79  int y; ///< y offset of the non-cropped area with respect to the input area
80  int w; ///< width of the cropped area
81  int h; ///< height of the cropped area
82 
83  AVRational out_sar; ///< output sample aspect ratio
84  int keep_aspect; ///< keep display aspect ratio when cropping
85  int exact; ///< exact cropping, for subsampled formats
86 
87  int max_step[4]; ///< max pixel step for each plane, expressed as a number of bytes
88  int hsub, vsub; ///< chroma subsampling
89  char *x_expr, *y_expr, *w_expr, *h_expr;
90  AVExpr *x_pexpr, *y_pexpr; /* parsed expressions for x and y */
92 } CropContext;
93 
95 {
97  int ret;
98 
100  if (ret < 0)
101  return ret;
102  return ff_set_common_formats(ctx, formats);
103 }
104 
106 {
107  CropContext *s = ctx->priv;
108 
109  av_expr_free(s->x_pexpr);
110  s->x_pexpr = NULL;
111  av_expr_free(s->y_pexpr);
112  s->y_pexpr = NULL;
113 }
114 
115 static inline int normalize_double(int *n, double d)
116 {
117  int ret = 0;
118 
119  if (isnan(d)) {
120  ret = AVERROR(EINVAL);
121  } else if (d > INT_MAX || d < INT_MIN) {
122  *n = d > INT_MAX ? INT_MAX : INT_MIN;
123  ret = AVERROR(EINVAL);
124  } else
125  *n = lrint(d);
126 
127  return ret;
128 }
129 
131 {
132  AVFilterContext *ctx = link->dst;
133  CropContext *s = ctx->priv;
134  const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(link->format);
135  int ret;
136  const char *expr;
137  double res;
138 
139  s->var_values[VAR_IN_W] = s->var_values[VAR_IW] = ctx->inputs[0]->w;
140  s->var_values[VAR_IN_H] = s->var_values[VAR_IH] = ctx->inputs[0]->h;
141  s->var_values[VAR_A] = (float) link->w / link->h;
144  s->var_values[VAR_HSUB] = 1<<pix_desc->log2_chroma_w;
145  s->var_values[VAR_VSUB] = 1<<pix_desc->log2_chroma_h;
146  s->var_values[VAR_X] = NAN;
147  s->var_values[VAR_Y] = NAN;
150  s->var_values[VAR_N] = 0;
151  s->var_values[VAR_T] = NAN;
152  s->var_values[VAR_POS] = NAN;
153 
155 
156  if (pix_desc->flags & AV_PIX_FMT_FLAG_HWACCEL) {
157  s->hsub = 1;
158  s->vsub = 1;
159  } else {
160  s->hsub = pix_desc->log2_chroma_w;
161  s->vsub = pix_desc->log2_chroma_h;
162  }
163 
164  av_expr_parse_and_eval(&res, (expr = s->w_expr),
165  var_names, s->var_values,
166  NULL, NULL, NULL, NULL, NULL, 0, ctx);
167  s->var_values[VAR_OUT_W] = s->var_values[VAR_OW] = res;
168  if ((ret = av_expr_parse_and_eval(&res, (expr = s->h_expr),
169  var_names, s->var_values,
170  NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0)
171  goto fail_expr;
172  s->var_values[VAR_OUT_H] = s->var_values[VAR_OH] = res;
173  /* evaluate again ow as it may depend on oh */
174  if ((ret = av_expr_parse_and_eval(&res, (expr = s->w_expr),
175  var_names, s->var_values,
176  NULL, NULL, NULL, NULL, NULL, 0, ctx)) < 0)
177  goto fail_expr;
178 
179  s->var_values[VAR_OUT_W] = s->var_values[VAR_OW] = res;
180  if (normalize_double(&s->w, s->var_values[VAR_OUT_W]) < 0 ||
181  normalize_double(&s->h, s->var_values[VAR_OUT_H]) < 0) {
182  av_log(ctx, AV_LOG_ERROR,
183  "Too big value or invalid expression for out_w/ow or out_h/oh. "
184  "Maybe the expression for out_w:'%s' or for out_h:'%s' is self-referencing.\n",
185  s->w_expr, s->h_expr);
186  return AVERROR(EINVAL);
187  }
188 
189  if (!s->exact) {
190  s->w &= ~((1 << s->hsub) - 1);
191  s->h &= ~((1 << s->vsub) - 1);
192  }
193 
194  av_expr_free(s->x_pexpr);
195  av_expr_free(s->y_pexpr);
196  s->x_pexpr = s->y_pexpr = NULL;
197  if ((ret = av_expr_parse(&s->x_pexpr, s->x_expr, var_names,
198  NULL, NULL, NULL, NULL, 0, ctx)) < 0 ||
199  (ret = av_expr_parse(&s->y_pexpr, s->y_expr, var_names,
200  NULL, NULL, NULL, NULL, 0, ctx)) < 0)
201  return AVERROR(EINVAL);
202 
203  if (s->keep_aspect) {
205  (AVRational){ link->w, link->h });
206  av_reduce(&s->out_sar.num, &s->out_sar.den,
207  dar.num * s->h, dar.den * s->w, INT_MAX);
208  } else
209  s->out_sar = link->sample_aspect_ratio;
210 
211  av_log(ctx, AV_LOG_VERBOSE, "w:%d h:%d sar:%d/%d -> w:%d h:%d sar:%d/%d\n",
212  link->w, link->h, link->sample_aspect_ratio.num, link->sample_aspect_ratio.den,
213  s->w, s->h, s->out_sar.num, s->out_sar.den);
214 
215  if (s->w <= 0 || s->h <= 0 ||
216  s->w > link->w || s->h > link->h) {
217  av_log(ctx, AV_LOG_ERROR,
218  "Invalid too big or non positive size for width '%d' or height '%d'\n",
219  s->w, s->h);
220  return AVERROR(EINVAL);
221  }
222 
223  /* set default, required in the case the first computed value for x/y is NAN */
224  s->x = (link->w - s->w) / 2;
225  s->y = (link->h - s->h) / 2;
226  if (!s->exact) {
227  s->x &= ~((1 << s->hsub) - 1);
228  s->y &= ~((1 << s->vsub) - 1);
229  }
230  return 0;
231 
232 fail_expr:
233  av_log(ctx, AV_LOG_ERROR, "Error when evaluating the expression '%s'\n", expr);
234  return ret;
235 }
236 
238 {
239  CropContext *s = link->src->priv;
241 
242  if (desc->flags & AV_PIX_FMT_FLAG_HWACCEL) {
243  // Hardware frames adjust the cropping regions rather than
244  // changing the frame size.
245  } else {
246  link->w = s->w;
247  link->h = s->h;
248  }
249  link->sample_aspect_ratio = s->out_sar;
250 
251  return 0;
252 }
253 
255 {
256  AVFilterContext *ctx = link->dst;
257  CropContext *s = ctx->priv;
259  int i;
260 
261  s->var_values[VAR_N] = link->frame_count_out;
262  s->var_values[VAR_T] = frame->pts == AV_NOPTS_VALUE ?
263  NAN : frame->pts * av_q2d(link->time_base);
264  s->var_values[VAR_POS] = frame->pkt_pos == -1 ?
265  NAN : frame->pkt_pos;
268  /* It is necessary if x is expressed from y */
270 
273 
274  if (s->x < 0)
275  s->x = 0;
276  if (s->y < 0)
277  s->y = 0;
278  if ((unsigned)s->x + (unsigned)s->w > link->w)
279  s->x = link->w - s->w;
280  if ((unsigned)s->y + (unsigned)s->h > link->h)
281  s->y = link->h - s->h;
282  if (!s->exact) {
283  s->x &= ~((1 << s->hsub) - 1);
284  s->y &= ~((1 << s->vsub) - 1);
285  }
286 
287  av_log(ctx, AV_LOG_TRACE, "n:%d t:%f pos:%f x:%d y:%d x+w:%d y+h:%d\n",
288  (int)s->var_values[VAR_N], s->var_values[VAR_T], s->var_values[VAR_POS],
289  s->x, s->y, s->x+s->w, s->y+s->h);
290 
291  if (desc->flags & AV_PIX_FMT_FLAG_HWACCEL) {
292  frame->crop_top += s->y;
293  frame->crop_left += s->x;
294  frame->crop_bottom = frame->height - frame->crop_top - frame->crop_bottom - s->h;
295  frame->crop_right = frame->width - frame->crop_left - frame->crop_right - s->w;
296  } else {
297  frame->width = s->w;
298  frame->height = s->h;
299 
300  frame->data[0] += s->y * frame->linesize[0];
301  frame->data[0] += s->x * s->max_step[0];
302 
303  if (!(desc->flags & AV_PIX_FMT_FLAG_PAL || desc->flags & FF_PSEUDOPAL)) {
304  for (i = 1; i < 3; i ++) {
305  if (frame->data[i]) {
306  frame->data[i] += (s->y >> s->vsub) * frame->linesize[i];
307  frame->data[i] += (s->x * s->max_step[i]) >> s->hsub;
308  }
309  }
310  }
311 
312  /* alpha plane */
313  if (frame->data[3]) {
314  frame->data[3] += s->y * frame->linesize[3];
315  frame->data[3] += s->x * s->max_step[3];
316  }
317  }
318 
319  return ff_filter_frame(link->dst->outputs[0], frame);
320 }
321 
322 static int process_command(AVFilterContext *ctx, const char *cmd, const char *args,
323  char *res, int res_len, int flags)
324 {
325  CropContext *s = ctx->priv;
326  int ret;
327 
328  if ( !strcmp(cmd, "out_w") || !strcmp(cmd, "w")
329  || !strcmp(cmd, "out_h") || !strcmp(cmd, "h")
330  || !strcmp(cmd, "x") || !strcmp(cmd, "y")) {
331 
332  int old_x = s->x;
333  int old_y = s->y;
334  int old_w = s->w;
335  int old_h = s->h;
336 
337  AVFilterLink *outlink = ctx->outputs[0];
338  AVFilterLink *inlink = ctx->inputs[0];
339 
340  av_opt_set(s, cmd, args, 0);
341 
342  if ((ret = config_input(inlink)) < 0) {
343  s->x = old_x;
344  s->y = old_y;
345  s->w = old_w;
346  s->h = old_h;
347  return ret;
348  }
349 
350  ret = config_output(outlink);
351 
352  } else
353  ret = AVERROR(ENOSYS);
354 
355  return ret;
356 }
357 
358 #define OFFSET(x) offsetof(CropContext, x)
359 #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
360 #define TFLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_RUNTIME_PARAM
361 
362 static const AVOption crop_options[] = {
363  { "out_w", "set the width crop area expression", OFFSET(w_expr), AV_OPT_TYPE_STRING, {.str = "iw"}, 0, 0, TFLAGS },
364  { "w", "set the width crop area expression", OFFSET(w_expr), AV_OPT_TYPE_STRING, {.str = "iw"}, 0, 0, TFLAGS },
365  { "out_h", "set the height crop area expression", OFFSET(h_expr), AV_OPT_TYPE_STRING, {.str = "ih"}, 0, 0, TFLAGS },
366  { "h", "set the height crop area expression", OFFSET(h_expr), AV_OPT_TYPE_STRING, {.str = "ih"}, 0, 0, TFLAGS },
367  { "x", "set the x crop area expression", OFFSET(x_expr), AV_OPT_TYPE_STRING, {.str = "(in_w-out_w)/2"}, 0, 0, TFLAGS },
368  { "y", "set the y crop area expression", OFFSET(y_expr), AV_OPT_TYPE_STRING, {.str = "(in_h-out_h)/2"}, 0, 0, TFLAGS },
369  { "keep_aspect", "keep aspect ratio", OFFSET(keep_aspect), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS },
370  { "exact", "do exact cropping", OFFSET(exact), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS },
371  { NULL }
372 };
373 
375 
377  {
378  .name = "default",
379  .type = AVMEDIA_TYPE_VIDEO,
380  .filter_frame = filter_frame,
381  .config_props = config_input,
382  },
383  { NULL }
384 };
385 
387  {
388  .name = "default",
389  .type = AVMEDIA_TYPE_VIDEO,
390  .config_props = config_output,
391  },
392  { NULL }
393 };
394 
396  .name = "crop",
397  .description = NULL_IF_CONFIG_SMALL("Crop the input video."),
398  .priv_size = sizeof(CropContext),
399  .priv_class = &crop_class,
401  .uninit = uninit,
402  .inputs = avfilter_vf_crop_inputs,
403  .outputs = avfilter_vf_crop_outputs,
405 };
#define AV_PIX_FMT_FLAG_PAL
Pixel format has a palette in data[1], values are indexes in this palette.
Definition: pixdesc.h:132
#define NULL
Definition: coverity.c:32
AVExpr * x_pexpr
Definition: vf_crop.c:90
const AVPixFmtDescriptor * av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
Definition: pixdesc.c:2573
This structure describes decoded (raw) audio or video data.
Definition: frame.h:308
#define FLAGS
Definition: vf_crop.c:359
AVOption.
Definition: opt.h:248
int64_t pkt_pos
reordered pos from the last AVPacket that has been input into the decoder
Definition: frame.h:579
static int config_input(AVFilterLink *link)
Definition: vf_crop.c:130
const char * desc
Definition: libsvtav1.c:79
misc image utilities
Main libavfilter public API header.
int exact
exact cropping, for subsampled formats
Definition: vf_crop.c:85
int num
Numerator.
Definition: rational.h:59
int av_expr_parse(AVExpr **expr, const char *s, const char *const *const_names, const char *const *func1_names, double(*const *funcs1)(void *, double), const char *const *func2_names, double(*const *funcs2)(void *, double, double), int log_offset, void *log_ctx)
Parse an expression.
Definition: eval.c:685
size_t crop_bottom
Definition: frame.h:669
uint8_t log2_chroma_w
Amount to shift the luma width right to find the chroma width.
Definition: pixdesc.h:92
AVFilter ff_vf_crop
Definition: vf_crop.c:395
Definition: vf_crop.c:61
void av_image_fill_max_pixsteps(int max_pixsteps[4], int max_pixstep_comps[4], const AVPixFmtDescriptor *pixdesc)
Compute the max pixel step for each plane of an image with a format described by pixdesc.
Definition: imgutils.c:35
const char * name
Pad name.
Definition: internal.h:60
AVFilterLink ** inputs
array of pointers to input links
Definition: avfilter.h:349
int ff_filter_frame(AVFilterLink *link, AVFrame *frame)
Send a frame of data to the next filter.
Definition: avfilter.c:1091
int ff_formats_pixdesc_filter(AVFilterFormats **rfmts, unsigned want, unsigned rej)
Construct a formats list containing all pixel formats with certain properties.
Definition: formats.c:368
#define av_cold
Definition: attributes.h:88
int x
x offset of the non-cropped area with respect to the input area
Definition: vf_crop.c:78
AVOptions.
int y
y offset of the non-cropped area with respect to the input area
Definition: vf_crop.c:79
size_t crop_left
Definition: frame.h:670
#define AV_LOG_TRACE
Extremely verbose debugging, useful for libav* development.
Definition: log.h:220
int max_step[4]
max pixel step for each plane, expressed as a number of bytes
Definition: vf_crop.c:87
int64_t pts
Presentation timestamp in time_base units (time when frame should be shown to user).
Definition: frame.h:401
Definition: eval.c:157
static const AVFilterPad avfilter_vf_crop_outputs[]
Definition: vf_crop.c:386
static double av_q2d(AVRational a)
Convert an AVRational to a double.
Definition: rational.h:104
Definition: vf_crop.c:60
#define AV_LOG_VERBOSE
Detailed information.
Definition: log.h:210
char * w_expr
Definition: vf_crop.c:89
static const AVFilterPad avfilter_vf_crop_inputs[]
Definition: vf_crop.c:376
int av_reduce(int *dst_num, int *dst_den, int64_t num, int64_t den, int64_t max)
Reduce a fraction.
Definition: rational.c:35
#define av_log(a,...)
A filter pad used for either input or output.
Definition: internal.h:54
int hsub
Definition: vf_crop.c:88
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
int width
Definition: frame.h:366
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:194
int ff_set_common_formats(AVFilterContext *ctx, AVFilterFormats *formats)
A helper for query_formats() which sets all links to the same list of formats.
Definition: formats.c:588
uint8_t log2_chroma_h
Amount to shift the luma height right to find the chroma height.
Definition: pixdesc.h:101
Definition: vf_crop.c:70
double var_values[VAR_VARS_NB]
Definition: vf_crop.c:91
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:153
void * priv
private data for use by the filter
Definition: avfilter.h:356
#define AV_PIX_FMT_FLAG_HWACCEL
Pixel format is an HW accelerated format.
Definition: pixdesc.h:140
size_t crop_top
Definition: frame.h:668
var_name
Definition: aeval.c:46
common internal API header
uint64_t flags
Combination of AV_PIX_FMT_FLAG_...
Definition: pixdesc.h:106
#define NAN
Definition: mathematics.h:64
char * x_expr
Definition: vf_crop.c:89
static int process_command(AVFilterContext *ctx, const char *cmd, const char *args, char *res, int res_len, int flags)
Definition: vf_crop.c:322
AVRational out_sar
output sample aspect ratio
Definition: vf_crop.c:83
AVFormatContext * ctx
Definition: movenc.c:48
these buffered frames must be flushed immediately if a new input produces new the filter must not call request_frame to get more It must just process the frame or queue it The task of requesting more frames is left to the filter s request_frame method or the application If a filter has several the filter must be ready for frames arriving randomly on any input any filter with several inputs will most likely require some kind of queuing mechanism It is perfectly acceptable to have a limited queue and to drop frames when the inputs are too unbalanced request_frame For filters that do not use the this method is called when a frame is wanted on an output For a it should directly call filter_frame on the corresponding output For a if there are queued frames already one of these frames should be pushed If the filter should request a frame on one of its repeatedly until at least one frame has been pushed Return or at least make progress towards producing a frame
#define s(width, name)
Definition: cbs_vp9.c:257
#define OFFSET(x)
Definition: vf_crop.c:358
AVExpr * y_pexpr
Definition: vf_crop.c:90
static int query_formats(AVFilterContext *ctx)
Definition: vf_crop.c:94
char * h_expr
Definition: vf_crop.c:89
static const AVFilterPad outputs[]
Definition: af_acontrast.c:203
int h
height of the cropped area
Definition: vf_crop.c:81
int vsub
chroma subsampling
Definition: vf_crop.c:88
#define FF_PIX_FMT_FLAG_SW_FLAT_SUB
Definition: formats.h:240
Definition: vf_crop.c:68
void av_expr_free(AVExpr *e)
Free a parsed expression previously created with av_expr_parse().
Definition: eval.c:336
int linesize[AV_NUM_DATA_POINTERS]
For video, size in bytes of each picture line.
Definition: frame.h:339
Descriptor that unambiguously describes how the bits of a pixel are stored in the up to 4 data planes...
Definition: pixdesc.h:81
static av_cold void uninit(AVFilterContext *ctx)
Definition: vf_crop.c:105
Definition: vf_crop.c:59
size_t crop_right
Definition: frame.h:671
these buffered frames must be flushed immediately if a new input produces new the filter must not call request_frame to get more It must just process the frame or queue it The task of requesting more frames is left to the filter s request_frame method or the application If a filter has several inputs
Replacements for frequently missing libm functions.
Describe the class of an AVClass context structure.
Definition: log.h:67
Filter definition.
Definition: avfilter.h:145
Rational number (pair of numerator and denominator).
Definition: rational.h:58
#define isnan(x)
Definition: libm.h:340
const char * name
Filter name.
Definition: avfilter.h:149
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a link
static const AVOption crop_options[]
Definition: vf_crop.c:362
#define AV_PIX_FMT_FLAG_BITSTREAM
All values of a component are bit-wise packed end to end.
Definition: pixdesc.h:136
AVFilterLink ** outputs
array of pointers to output links
Definition: avfilter.h:353
Definition: vf_crop.c:62
static const char *const var_names[]
Definition: vf_crop.c:40
#define flags(name, subs,...)
Definition: cbs_av1.c:560
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:322
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
static int normalize_double(int *n, double d)
Definition: vf_crop.c:115
static int config_output(AVFilterLink *link)
Definition: vf_crop.c:237
Definition: vf_crop.c:69
AVFILTER_DEFINE_CLASS(crop)
int den
Denominator.
Definition: rational.h:60
Definition: vf_crop.c:72
#define FF_PSEUDOPAL
Definition: internal.h:335
Definition: vf_crop.c:63
double av_expr_eval(AVExpr *e, const double *const_values, void *opaque)
Evaluate a previously parsed expression.
Definition: eval.c:766
int keep_aspect
keep display aspect ratio when cropping
Definition: vf_crop.c:84
#define TFLAGS
Definition: vf_crop.c:360
A list of supported formats for one end of a filter link.
Definition: formats.h:65
#define lrint
Definition: tablegen.h:53
An instance of a filter.
Definition: avfilter.h:341
AVRational av_mul_q(AVRational b, AVRational c)
Multiply two rationals.
Definition: rational.c:80
int height
Definition: frame.h:366
formats
Definition: signature.h:48
int w
width of the cropped area
Definition: vf_crop.c:80
internal API functions
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later.That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another.Frame references ownership and permissions
int av_opt_set(void *obj, const char *name, const char *val, int search_flags)
Definition: opt.c:465
int i
Definition: input.c:407
#define AV_NOPTS_VALUE
Undefined timestamp value.
Definition: avutil.h:248
simple arithmetic expression evaluator
static int filter_frame(AVFilterLink *link, AVFrame *frame)
Definition: vf_crop.c:254
char * y_expr
Definition: vf_crop.c:89