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x11grab.c
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1 /*
2  * X11 video grab interface
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg integration:
7  * Copyright (C) 2006 Clemens Fruhwirth <clemens@endorphin.org>
8  * Edouard Gomez <ed.gomez@free.fr>
9  *
10  * This file contains code from grab.c:
11  * Copyright (c) 2000-2001 Fabrice Bellard
12  *
13  * This file contains code from the xvidcap project:
14  * Copyright (C) 1997-1998 Rasca, Berlin
15  * 2003-2004 Karl H. Beckers, Frankfurt
16  *
17  * FFmpeg is free software; you can redistribute it and/or modify
18  * it under the terms of the GNU General Public License as published by
19  * the Free Software Foundation; either version 2 of the License, or
20  * (at your option) any later version.
21  *
22  * FFmpeg is distributed in the hope that it will be useful,
23  * but WITHOUT ANY WARRANTY; without even the implied warranty of
24  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
25  * GNU General Public License for more details.
26  *
27  * You should have received a copy of the GNU General Public License
28  * along with FFmpeg; if not, write to the Free Software
29  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
30  */
31 
32 /**
33  * @file
34  * X11 frame device demuxer
35  * @author Clemens Fruhwirth <clemens@endorphin.org>
36  * @author Edouard Gomez <ed.gomez@free.fr>
37  */
38 
39 #include "config.h"
40 
41 #include <time.h>
42 #include <sys/shm.h>
43 
44 #include <X11/cursorfont.h>
45 #include <X11/X.h>
46 #include <X11/Xlib.h>
47 #include <X11/Xlibint.h>
48 #include <X11/Xproto.h>
49 #include <X11/Xutil.h>
50 
51 #include <X11/extensions/shape.h>
52 #include <X11/extensions/Xfixes.h>
53 #include <X11/extensions/XShm.h>
54 
55 #include "avdevice.h"
56 
57 #include "libavutil/log.h"
58 #include "libavutil/opt.h"
59 #include "libavutil/parseutils.h"
60 #include "libavutil/time.h"
61 
62 #include "libavformat/internal.h"
63 
64 /** X11 device demuxer context */
65 typedef struct X11GrabContext {
66  const AVClass *class; /**< Class for private options. */
67  int frame_size; /**< Size in bytes of a grabbed frame */
68  AVRational time_base; /**< Time base */
69  int64_t time_frame; /**< Current time */
70 
71  int width; /**< Width of the grab frame */
72  int height; /**< Height of the grab frame */
73  int x_off; /**< Horizontal top-left corner coordinate */
74  int y_off; /**< Vertical top-left corner coordinate */
75 
76  Display *dpy; /**< X11 display from which x11grab grabs frames */
77  XImage *image; /**< X11 image holding the grab */
78  int use_shm; /**< !0 when using XShm extension */
79  XShmSegmentInfo shminfo; /**< When using XShm, keeps track of XShm infos */
80  int draw_mouse; /**< Set by a private option. */
81  int follow_mouse; /**< Set by a private option. */
82  int show_region; /**< set by a private option. */
83  AVRational framerate; /**< Set by a private option. */
85  uint32_t palette[256];
86 
87  Cursor c;
88  Window region_win; /**< This is used by show_region option. */
90 
91 #define REGION_WIN_BORDER 3
92 
93 /**
94  * Draw grabbing region window
95  *
96  * @param s x11grab context
97  */
99 {
100  Display *dpy = s->dpy;
101  Window win = s->region_win;
102  int screen = DefaultScreen(dpy);
103  GC gc = XCreateGC(dpy, win, 0, 0);
104 
105  XSetForeground(dpy, gc, WhitePixel(dpy, screen));
106  XSetBackground(dpy, gc, BlackPixel(dpy, screen));
107  XSetLineAttributes(dpy, gc, REGION_WIN_BORDER, LineDoubleDash, 0, 0);
108  XDrawRectangle(dpy, win, gc, 1, 1,
109  (s->width + REGION_WIN_BORDER * 2) - 1 * 2 - 1,
110  (s->height + REGION_WIN_BORDER * 2) - 1 * 2 - 1);
111  XFreeGC(dpy, gc);
112 }
113 
114 /**
115  * Initialize grabbing region window
116  *
117  * @param s x11grab context
118  */
120 {
121  Display *dpy = s->dpy;
122  XRectangle rect;
123  XSetWindowAttributes attribs = { .override_redirect = True };
124  int screen = DefaultScreen(dpy);
125 
126  s->region_win = XCreateWindow(dpy, RootWindow(dpy, screen),
129  s->width + REGION_WIN_BORDER * 2,
130  s->height + REGION_WIN_BORDER * 2,
131  0, CopyFromParent,
132  InputOutput, CopyFromParent,
133  CWOverrideRedirect, &attribs);
134  rect.x = 0;
135  rect.y = 0;
136  rect.width = s->width;
137  rect.height = s->height;
138  XShapeCombineRectangles(dpy, s->region_win,
139  ShapeBounding, REGION_WIN_BORDER, REGION_WIN_BORDER,
140  &rect, 1, ShapeSubtract, 0);
141  XMapWindow(dpy, s->region_win);
142  XSelectInput(dpy, s->region_win, ExposureMask | StructureNotifyMask);
144 }
145 
146 static int setup_shm(AVFormatContext *s, Display *dpy, XImage **image)
147 {
148  X11GrabContext *g = s->priv_data;
149  int scr = XDefaultScreen(dpy);
150  XImage *img = XShmCreateImage(dpy, DefaultVisual(dpy, scr),
151  DefaultDepth(dpy, scr), ZPixmap, NULL,
152  &g->shminfo, g->width, g->height);
153 
154  g->shminfo.shmid = shmget(IPC_PRIVATE, img->bytes_per_line * img->height,
155  IPC_CREAT | 0777);
156 
157  if (g->shminfo.shmid == -1) {
158  av_log(s, AV_LOG_ERROR, "Cannot get shared memory!\n");
159  return AVERROR(ENOMEM);
160  }
161 
162  g->shminfo.shmaddr = img->data = shmat(g->shminfo.shmid, 0, 0);
163  g->shminfo.readOnly = False;
164 
165  if (!XShmAttach(dpy, &g->shminfo)) {
166  av_log(s, AV_LOG_ERROR, "Failed to attach shared memory!\n");
167  /* needs some better error subroutine :) */
168  return AVERROR(EIO);
169  }
170 
171  *image = img;
172  return 0;
173 }
174 
175 static int setup_mouse(Display *dpy, int screen)
176 {
177  int ev_ret, ev_err;
178 
179  if (XFixesQueryExtension(dpy, &ev_ret, &ev_err)) {
180  Window root = RootWindow(dpy, screen);
181  XFixesSelectCursorInput(dpy, root, XFixesDisplayCursorNotifyMask);
182  return 0;
183  }
184 
185  return AVERROR(ENOSYS);
186 }
187 
188 static int pixfmt_from_image(AVFormatContext *s, XImage *image, int *pix_fmt)
189 {
190  av_log(s, AV_LOG_DEBUG,
191  "Image r 0x%.6lx g 0x%.6lx b 0x%.6lx and depth %i\n",
192  image->red_mask,
193  image->green_mask,
194  image->blue_mask,
195  image->bits_per_pixel);
196 
197  *pix_fmt = AV_PIX_FMT_NONE;
198 
199  switch (image->bits_per_pixel) {
200  case 8:
201  *pix_fmt = AV_PIX_FMT_PAL8;
202  break;
203  case 16:
204  if (image->red_mask == 0xf800 &&
205  image->green_mask == 0x07e0 &&
206  image->blue_mask == 0x001f) {
207  *pix_fmt = AV_PIX_FMT_RGB565;
208  } else if (image->red_mask == 0x7c00 &&
209  image->green_mask == 0x03e0 &&
210  image->blue_mask == 0x001f) {
211  *pix_fmt = AV_PIX_FMT_RGB555;
212  }
213  break;
214  case 24:
215  if (image->red_mask == 0xff0000 &&
216  image->green_mask == 0x00ff00 &&
217  image->blue_mask == 0x0000ff) {
218  *pix_fmt = AV_PIX_FMT_BGR24;
219  } else if (image->red_mask == 0x0000ff &&
220  image->green_mask == 0x00ff00 &&
221  image->blue_mask == 0xff0000) {
222  *pix_fmt = AV_PIX_FMT_RGB24;
223  }
224  break;
225  case 32:
226  if (image->red_mask == 0xff0000 &&
227  image->green_mask == 0x00ff00 &&
228  image->blue_mask == 0x0000ff ) {
229  *pix_fmt = AV_PIX_FMT_0RGB32;
230  }
231  break;
232  }
233  if (*pix_fmt == AV_PIX_FMT_NONE) {
234  av_log(s, AV_LOG_ERROR,
235  "XImages with RGB mask 0x%.6lx 0x%.6lx 0x%.6lx and depth %i "
236  "are currently not supported.\n",
237  image->red_mask,
238  image->green_mask,
239  image->blue_mask,
240  image->bits_per_pixel);
241 
242  return AVERROR_PATCHWELCOME;
243  }
244 
245  return 0;
246 }
247 
248 /**
249  * Initialize the x11 grab device demuxer (public device demuxer API).
250  *
251  * @param s1 Context from avformat core
252  * @return <ul>
253  * <li>AVERROR(ENOMEM) no memory left</li>
254  * <li>AVERROR(EIO) other failure case</li>
255  * <li>0 success</li>
256  * </ul>
257  */
259 {
260  X11GrabContext *x11grab = s1->priv_data;
261  Display *dpy;
262  AVStream *st = NULL;
263  XImage *image;
264  int x_off = 0, y_off = 0, ret = 0, screen, use_shm = 0;
265  char *dpyname, *offset;
266  Colormap color_map;
267  XColor color[256];
268  int i;
269 
270  dpyname = av_strdup(s1->filename);
271  if (!dpyname)
272  goto out;
273 
274  offset = strchr(dpyname, '+');
275  if (offset) {
276  sscanf(offset, "%d,%d", &x_off, &y_off);
277  if (strstr(offset, "nomouse")) {
279  "'nomouse' specification in argument is deprecated: "
280  "use 'draw_mouse' option with value 0 instead\n");
281  x11grab->draw_mouse = 0;
282  }
283  *offset = 0;
284  }
285 
286  av_log(s1, AV_LOG_INFO,
287  "device: %s -> display: %s x: %d y: %d width: %d height: %d\n",
288  s1->filename, dpyname, x_off, y_off, x11grab->width, x11grab->height);
289 
290  dpy = XOpenDisplay(dpyname);
291  av_freep(&dpyname);
292  if (!dpy) {
293  av_log(s1, AV_LOG_ERROR, "Could not open X display.\n");
294  ret = AVERROR(EIO);
295  goto out;
296  }
297 
298  st = avformat_new_stream(s1, NULL);
299  if (!st) {
300  ret = AVERROR(ENOMEM);
301  goto out;
302  }
303  avpriv_set_pts_info(st, 64, 1, 1000000); /* 64 bits pts in us */
304 
305  screen = DefaultScreen(dpy);
306 
307  if (x11grab->follow_mouse) {
308  int screen_w, screen_h;
309  Window w;
310 
311  screen_w = DisplayWidth(dpy, screen);
312  screen_h = DisplayHeight(dpy, screen);
313  XQueryPointer(dpy, RootWindow(dpy, screen), &w, &w, &x_off, &y_off,
314  &ret, &ret, &ret);
315  x_off -= x11grab->width / 2;
316  y_off -= x11grab->height / 2;
317  x_off = FFMIN(FFMAX(x_off, 0), screen_w - x11grab->width);
318  y_off = FFMIN(FFMAX(y_off, 0), screen_h - x11grab->height);
319  av_log(s1, AV_LOG_INFO,
320  "followmouse is enabled, resetting grabbing region to x: %d y: %d\n",
321  x_off, y_off);
322  }
323 
324  if (x11grab->use_shm) {
325  use_shm = XShmQueryExtension(dpy);
326  av_log(s1, AV_LOG_INFO,
327  "shared memory extension %sfound\n", use_shm ? "" : "not ");
328  }
329 
330  if (use_shm && setup_shm(s1, dpy, &image) < 0) {
331  av_log(s1, AV_LOG_WARNING, "Falling back to XGetImage\n");
332  use_shm = 0;
333  }
334 
335  if (!use_shm) {
336  image = XGetImage(dpy, RootWindow(dpy, screen),
337  x_off, y_off,
338  x11grab->width, x11grab->height,
339  AllPlanes, ZPixmap);
340  }
341 
342  if (x11grab->draw_mouse && setup_mouse(dpy, screen) < 0) {
344  "XFixes not available, cannot draw the mouse cursor\n");
345  x11grab->draw_mouse = 0;
346  }
347 
348  x11grab->frame_size = x11grab->width * x11grab->height * image->bits_per_pixel / 8;
349  x11grab->dpy = dpy;
350  x11grab->time_base = av_inv_q(x11grab->framerate);
351  x11grab->time_frame = av_gettime() / av_q2d(x11grab->time_base);
352  x11grab->x_off = x_off;
353  x11grab->y_off = y_off;
354  x11grab->image = image;
355  x11grab->use_shm = use_shm;
356 
357  ret = pixfmt_from_image(s1, image, &st->codec->pix_fmt);
358  if (ret < 0)
359  goto out;
360 
361  if (st->codec->pix_fmt == AV_PIX_FMT_PAL8) {
362  color_map = DefaultColormap(dpy, screen);
363  for (i = 0; i < 256; ++i)
364  color[i].pixel = i;
365  XQueryColors(dpy, color_map, color, 256);
366  for (i = 0; i < 256; ++i)
367  x11grab->palette[i] = (color[i].red & 0xFF00) << 8 |
368  (color[i].green & 0xFF00) |
369  (color[i].blue & 0xFF00) >> 8;
370  x11grab->palette_changed = 1;
371  }
372 
373 
376  st->codec->width = x11grab->width;
377  st->codec->height = x11grab->height;
378  st->codec->time_base = x11grab->time_base;
379  st->codec->bit_rate = x11grab->frame_size * 1 / av_q2d(x11grab->time_base) * 8;
380 
381 out:
382  av_free(dpyname);
383  return ret;
384 }
385 
386 /**
387  * Paint a mouse pointer in an X11 image.
388  *
389  * @param image image to paint the mouse pointer to
390  * @param s context used to retrieve original grabbing rectangle
391  * coordinates
392  */
393 static void paint_mouse_pointer(XImage *image, AVFormatContext *s1)
394 {
395  X11GrabContext *s = s1->priv_data;
396  int x_off = s->x_off;
397  int y_off = s->y_off;
398  int width = s->width;
399  int height = s->height;
400  Display *dpy = s->dpy;
401  XFixesCursorImage *xcim;
402  int x, y;
403  int line, column;
404  int to_line, to_column;
405  int pixstride = image->bits_per_pixel >> 3;
406  /* Warning: in its insanity, xlib provides unsigned image data through a
407  * char* pointer, so we have to make it uint8_t to make things not break.
408  * Anyone who performs further investigation of the xlib API likely risks
409  * permanent brain damage. */
410  uint8_t *pix = image->data;
411  Window root;
412  XSetWindowAttributes attr;
413 
414  /* Code doesn't currently support 16-bit or PAL8 */
415  if (image->bits_per_pixel != 24 && image->bits_per_pixel != 32)
416  return;
417 
418  if (!s->c)
419  s->c = XCreateFontCursor(dpy, XC_left_ptr);
420  root = DefaultRootWindow(dpy);
421  attr.cursor = s->c;
422  XChangeWindowAttributes(dpy, root, CWCursor, &attr);
423 
424  xcim = XFixesGetCursorImage(dpy);
425  if (!xcim) {
427  "XFixesGetCursorImage failed\n");
428  return;
429  }
430 
431  x = xcim->x - xcim->xhot;
432  y = xcim->y - xcim->yhot;
433 
434  to_line = FFMIN((y + xcim->height), (height + y_off));
435  to_column = FFMIN((x + xcim->width), (width + x_off));
436 
437  for (line = FFMAX(y, y_off); line < to_line; line++) {
438  for (column = FFMAX(x, x_off); column < to_column; column++) {
439  int xcim_addr = (line - y) * xcim->width + column - x;
440  int image_addr = ((line - y_off) * width + column - x_off) * pixstride;
441  int r = (uint8_t)(xcim->pixels[xcim_addr] >> 0);
442  int g = (uint8_t)(xcim->pixels[xcim_addr] >> 8);
443  int b = (uint8_t)(xcim->pixels[xcim_addr] >> 16);
444  int a = (uint8_t)(xcim->pixels[xcim_addr] >> 24);
445 
446  if (a == 255) {
447  pix[image_addr + 0] = r;
448  pix[image_addr + 1] = g;
449  pix[image_addr + 2] = b;
450  } else if (a) {
451  /* pixel values from XFixesGetCursorImage come premultiplied by alpha */
452  pix[image_addr + 0] = r + (pix[image_addr + 0] * (255 - a) + 255 / 2) / 255;
453  pix[image_addr + 1] = g + (pix[image_addr + 1] * (255 - a) + 255 / 2) / 255;
454  pix[image_addr + 2] = b + (pix[image_addr + 2] * (255 - a) + 255 / 2) / 255;
455  }
456  }
457  }
458 
459  XFree(xcim);
460  xcim = NULL;
461 }
462 
463 /**
464  * Read new data in the image structure.
465  *
466  * @param dpy X11 display to grab from
467  * @param d
468  * @param image Image where the grab will be put
469  * @param x Top-Left grabbing rectangle horizontal coordinate
470  * @param y Top-Left grabbing rectangle vertical coordinate
471  * @return 0 if error, !0 if successful
472  */
473 static int xget_zpixmap(Display *dpy, Drawable d, XImage *image, int x, int y)
474 {
475  xGetImageReply rep;
476  xGetImageReq *req;
477  long nbytes;
478 
479  if (!image)
480  return 0;
481 
482  LockDisplay(dpy);
483  GetReq(GetImage, req);
484 
485  /* First set up the standard stuff in the request */
486  req->drawable = d;
487  req->x = x;
488  req->y = y;
489  req->width = image->width;
490  req->height = image->height;
491  req->planeMask = (unsigned int)AllPlanes;
492  req->format = ZPixmap;
493 
494  if (!_XReply(dpy, (xReply *)&rep, 0, xFalse) || !rep.length) {
495  UnlockDisplay(dpy);
496  SyncHandle();
497  return 0;
498  }
499 
500  nbytes = (long)rep.length << 2;
501  _XReadPad(dpy, image->data, nbytes);
502 
503  UnlockDisplay(dpy);
504  SyncHandle();
505  return 1;
506 }
507 
508 /**
509  * Grab a frame from x11 (public device demuxer API).
510  *
511  * @param s1 Context from avformat core
512  * @param pkt Packet holding the brabbed frame
513  * @return frame size in bytes
514  */
516 {
517  X11GrabContext *s = s1->priv_data;
518  Display *dpy = s->dpy;
519  XImage *image = s->image;
520  int x_off = s->x_off;
521  int y_off = s->y_off;
522  int follow_mouse = s->follow_mouse;
523  int screen, pointer_x, pointer_y, _, same_screen = 1;
524  Window w, root;
525  int64_t curtime, delay;
526  struct timespec ts;
527 
528  /* Calculate the time of the next frame */
529  s->time_frame += INT64_C(1000000);
530 
531  /* wait based on the frame rate */
532  for (;;) {
533  curtime = av_gettime();
534  delay = s->time_frame * av_q2d(s->time_base) - curtime;
535  if (delay <= 0) {
536  if (delay < INT64_C(-1000000) * av_q2d(s->time_base))
537  s->time_frame += INT64_C(1000000);
538  break;
539  }
540  ts.tv_sec = delay / 1000000;
541  ts.tv_nsec = (delay % 1000000) * 1000;
542  nanosleep(&ts, NULL);
543  }
544 
545  av_init_packet(pkt);
546  pkt->data = image->data;
547  pkt->size = s->frame_size;
548  pkt->pts = curtime;
549  if (s->palette_changed) {
552  if (!pal) {
553  av_log(s, AV_LOG_ERROR, "Cannot append palette to packet\n");
554  } else {
555  memcpy(pal, s->palette, AVPALETTE_SIZE);
556  s->palette_changed = 0;
557  }
558  }
559 
560  screen = DefaultScreen(dpy);
561  root = RootWindow(dpy, screen);
562 
563  if (follow_mouse || s->draw_mouse)
564  same_screen = XQueryPointer(dpy, root, &w, &w,
565  &pointer_x, &pointer_y, &_, &_, &_);
566 
567  if (follow_mouse && same_screen) {
568  int screen_w, screen_h;
569 
570  screen_w = DisplayWidth(dpy, screen);
571  screen_h = DisplayHeight(dpy, screen);
572  if (follow_mouse == -1) {
573  // follow the mouse, put it at center of grabbing region
574  x_off += pointer_x - s->width / 2 - x_off;
575  y_off += pointer_y - s->height / 2 - y_off;
576  } else {
577  // follow the mouse, but only move the grabbing region when mouse
578  // reaches within certain pixels to the edge.
579  if (pointer_x > x_off + s->width - follow_mouse)
580  x_off += pointer_x - (x_off + s->width - follow_mouse);
581  else if (pointer_x < x_off + follow_mouse)
582  x_off -= (x_off + follow_mouse) - pointer_x;
583  if (pointer_y > y_off + s->height - follow_mouse)
584  y_off += pointer_y - (y_off + s->height - follow_mouse);
585  else if (pointer_y < y_off + follow_mouse)
586  y_off -= (y_off + follow_mouse) - pointer_y;
587  }
588  // adjust grabbing region position if it goes out of screen.
589  s->x_off = x_off = FFMIN(FFMAX(x_off, 0), screen_w - s->width);
590  s->y_off = y_off = FFMIN(FFMAX(y_off, 0), screen_h - s->height);
591 
592  if (s->show_region && s->region_win)
593  XMoveWindow(dpy, s->region_win,
595  s->y_off - REGION_WIN_BORDER);
596  }
597 
598  if (s->show_region && same_screen) {
599  if (s->region_win) {
600  XEvent evt = { .type = NoEventMask };
601  // Clean up the events, and do the initial draw or redraw.
602  while (XCheckMaskEvent(dpy, ExposureMask | StructureNotifyMask,
603  &evt))
604  ;
605  if (evt.type)
607  } else {
609  }
610  }
611 
612  if (s->use_shm) {
613  if (!XShmGetImage(dpy, root, image, x_off, y_off, AllPlanes))
614  av_log(s1, AV_LOG_INFO, "XShmGetImage() failed\n");
615  } else {
616  if (!xget_zpixmap(dpy, root, image, x_off, y_off))
617  av_log(s1, AV_LOG_INFO, "XGetZPixmap() failed\n");
618  }
619 
620  if (s->draw_mouse && same_screen)
621  paint_mouse_pointer(image, s1);
622 
623  return s->frame_size;
624 }
625 
626 /**
627  * Close x11 frame grabber (public device demuxer API).
628  *
629  * @param s1 Context from avformat core
630  * @return 0 success, !0 failure
631  */
633 {
634  X11GrabContext *x11grab = s1->priv_data;
635 
636  /* Detach cleanly from shared mem */
637  if (x11grab->use_shm) {
638  XShmDetach(x11grab->dpy, &x11grab->shminfo);
639  shmdt(x11grab->shminfo.shmaddr);
640  shmctl(x11grab->shminfo.shmid, IPC_RMID, NULL);
641  }
642 
643  /* Destroy X11 image */
644  if (x11grab->image) {
645  XDestroyImage(x11grab->image);
646  x11grab->image = NULL;
647  }
648 
649  if (x11grab->region_win)
650  XDestroyWindow(x11grab->dpy, x11grab->region_win);
651 
652  /* Free X11 display */
653  XCloseDisplay(x11grab->dpy);
654  return 0;
655 }
656 
657 #define OFFSET(x) offsetof(X11GrabContext, x)
658 #define DEC AV_OPT_FLAG_DECODING_PARAM
659 static const AVOption options[] = {
660  { "grab_x", "Initial x coordinate.", OFFSET(x_off), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, DEC },
661  { "grab_y", "Initial y coordinate.", OFFSET(y_off), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, DEC },
662  { "draw_mouse", "draw the mouse pointer", OFFSET(draw_mouse), AV_OPT_TYPE_INT, {.i64 = 1}, 0, 1, DEC },
663 
664  { "follow_mouse", "move the grabbing region when the mouse pointer reaches within specified amount of pixels to the edge of region",
665  OFFSET(follow_mouse), AV_OPT_TYPE_INT, {.i64 = 0}, -1, INT_MAX, DEC, "follow_mouse" },
666  { "centered", "keep the mouse pointer at the center of grabbing region when following",
667  0, AV_OPT_TYPE_CONST, {.i64 = -1}, INT_MIN, INT_MAX, DEC, "follow_mouse" },
668 
669  { "framerate", "set video frame rate", OFFSET(framerate), AV_OPT_TYPE_VIDEO_RATE, {.str = "ntsc"}, 0, 0, DEC },
670  { "show_region", "show the grabbing region", OFFSET(show_region), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, DEC },
671  { "video_size", "set video frame size", OFFSET(width), AV_OPT_TYPE_IMAGE_SIZE, {.str = "vga"}, 0, 0, DEC },
672  { "use_shm", "use MIT-SHM extension", OFFSET(use_shm), AV_OPT_TYPE_INT, {.i64 = 1}, 0, 1, DEC },
673  { NULL },
674 };
675 
676 static const AVClass x11_class = {
677  .class_name = "X11grab indev",
678  .item_name = av_default_item_name,
679  .option = options,
680  .version = LIBAVUTIL_VERSION_INT,
682 };
683 
684 /** x11 grabber device demuxer declaration */
686  .name = "x11grab",
687  .long_name = NULL_IF_CONFIG_SMALL("X11grab"),
688  .priv_data_size = sizeof(X11GrabContext),
692  .flags = AVFMT_NOFILE,
693  .priv_class = &x11_class,
694 };