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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 #include "libavformat/internal.h"
41 #include "libavutil/log.h"
42 #include "libavutil/opt.h"
43 #include "libavutil/parseutils.h"
44 #include "libavutil/time.h"
45 #include <time.h>
46 #include <X11/cursorfont.h>
47 #include <X11/X.h>
48 #include <X11/Xlib.h>
49 #include <X11/Xlibint.h>
50 #include <X11/Xproto.h>
51 #include <X11/Xutil.h>
52 #include <sys/shm.h>
53 #include <X11/extensions/shape.h>
54 #include <X11/extensions/XShm.h>
55 #include <X11/extensions/Xfixes.h>
56 #include "avdevice.h"
57 
58 /**
59  * X11 Device Demuxer context
60  */
61 struct x11grab {
62  const AVClass *class; /**< Class for private options. */
63  int frame_size; /**< Size in bytes of a grabbed frame */
64  AVRational time_base; /**< Time base */
65  int64_t time_frame; /**< Current time */
66 
67  int width; /**< Width of the grab frame */
68  int height; /**< Height of the grab frame */
69  int x_off; /**< Horizontal top-left corner coordinate */
70  int y_off; /**< Vertical top-left corner coordinate */
71 
72  Display *dpy; /**< X11 display from which x11grab grabs frames */
73  XImage *image; /**< X11 image holding the grab */
74  int use_shm; /**< !0 when using XShm extension */
75  XShmSegmentInfo shminfo; /**< When using XShm, keeps track of XShm infos */
76  int draw_mouse; /**< Set by a private option. */
77  int follow_mouse; /**< Set by a private option. */
78  int show_region; /**< set by a private option. */
79  AVRational framerate; /**< Set by a private option. */
81  uint32_t palette[256];
82 
83  Cursor c;
84  Window region_win; /**< This is used by show_region option. */
85 };
86 
87 #define REGION_WIN_BORDER 3
88 /**
89  * Draw grabbing region window
90  *
91  * @param s x11grab context
92  */
93 static void
95 {
96  Display *dpy = s->dpy;
97  int screen;
98  Window win = s->region_win;
99  GC gc;
100 
101  screen = DefaultScreen(dpy);
102  gc = XCreateGC(dpy, win, 0, 0);
103  XSetForeground(dpy, gc, WhitePixel(dpy, screen));
104  XSetBackground(dpy, gc, BlackPixel(dpy, screen));
105  XSetLineAttributes(dpy, gc, REGION_WIN_BORDER, LineDoubleDash, 0, 0);
106  XDrawRectangle(dpy, win, gc,
107  1, 1,
108  (s->width + REGION_WIN_BORDER * 2) - 1 * 2 - 1,
109  (s->height + REGION_WIN_BORDER * 2) - 1 * 2 - 1);
110  XFreeGC(dpy, gc);
111 }
112 
113 /**
114  * Initialize grabbing region window
115  *
116  * @param s x11grab context
117  */
118 static void
120 {
121  Display *dpy = s->dpy;
122  int screen;
123  XSetWindowAttributes attribs;
124  XRectangle rect;
125 
126  screen = DefaultScreen(dpy);
127  attribs.override_redirect = True;
128  s->region_win = XCreateWindow(dpy, RootWindow(dpy, screen),
131  s->width + REGION_WIN_BORDER * 2,
132  s->height + REGION_WIN_BORDER * 2,
133  0, CopyFromParent,
134  InputOutput, CopyFromParent,
135  CWOverrideRedirect, &attribs);
136  rect.x = 0;
137  rect.y = 0;
138  rect.width = s->width;
139  rect.height = s->height;
140  XShapeCombineRectangles(dpy, s->region_win,
141  ShapeBounding, REGION_WIN_BORDER, REGION_WIN_BORDER,
142  &rect, 1, ShapeSubtract, 0);
143  XMapWindow(dpy, s->region_win);
144  XSelectInput(dpy, s->region_win, ExposureMask | StructureNotifyMask);
146 }
147 
148 /**
149  * Initialize the x11 grab device demuxer (public device demuxer API).
150  *
151  * @param s1 Context from avformat core
152  * @return <ul>
153  * <li>AVERROR(ENOMEM) no memory left</li>
154  * <li>AVERROR(EIO) other failure case</li>
155  * <li>0 success</li>
156  * </ul>
157  */
158 static int
160 {
161  struct x11grab *x11grab = s1->priv_data;
162  Display *dpy;
163  AVStream *st = NULL;
164  enum AVPixelFormat input_pixfmt;
165  XImage *image;
166  int x_off = 0;
167  int y_off = 0;
168  int screen;
169  int use_shm;
170  char *dpyname, *offset;
171  int ret = 0;
172  Colormap color_map;
173  XColor color[256];
174  int i;
175 
176  dpyname = av_strdup(s1->filename);
177  if (!dpyname)
178  goto out;
179 
180  offset = strchr(dpyname, '+');
181  if (offset) {
182  sscanf(offset, "%d,%d", &x_off, &y_off);
183  if (strstr(offset, "nomouse")) {
185  "'nomouse' specification in argument is deprecated: "
186  "use 'draw_mouse' option with value 0 instead\n");
187  x11grab->draw_mouse = 0;
188  }
189  *offset= 0;
190  }
191 
192  av_log(s1, AV_LOG_INFO, "device: %s -> display: %s x: %d y: %d width: %d height: %d\n",
193  s1->filename, dpyname, x_off, y_off, x11grab->width, x11grab->height);
194 
195  dpy = XOpenDisplay(dpyname);
196  av_freep(&dpyname);
197  if(!dpy) {
198  av_log(s1, AV_LOG_ERROR, "Could not open X display.\n");
199  ret = AVERROR(EIO);
200  goto out;
201  }
202 
203  st = avformat_new_stream(s1, NULL);
204  if (!st) {
205  ret = AVERROR(ENOMEM);
206  goto out;
207  }
208  avpriv_set_pts_info(st, 64, 1, 1000000); /* 64 bits pts in us */
209 
210  screen = DefaultScreen(dpy);
211 
212  if (x11grab->follow_mouse) {
213  int screen_w, screen_h;
214  Window w;
215 
216  screen_w = DisplayWidth(dpy, screen);
217  screen_h = DisplayHeight(dpy, screen);
218  XQueryPointer(dpy, RootWindow(dpy, screen), &w, &w, &x_off, &y_off, &ret, &ret, &ret);
219  x_off -= x11grab->width / 2;
220  y_off -= x11grab->height / 2;
221  x_off = FFMIN(FFMAX(x_off, 0), screen_w - x11grab->width);
222  y_off = FFMIN(FFMAX(y_off, 0), screen_h - x11grab->height);
223  av_log(s1, AV_LOG_INFO, "followmouse is enabled, resetting grabbing region to x: %d y: %d\n", x_off, y_off);
224  }
225 
226  use_shm = XShmQueryExtension(dpy);
227  av_log(s1, AV_LOG_INFO, "shared memory extension%s found\n", use_shm ? "" : " not");
228 
229  if(use_shm) {
230  int scr = XDefaultScreen(dpy);
231  image = XShmCreateImage(dpy,
232  DefaultVisual(dpy, scr),
233  DefaultDepth(dpy, scr),
234  ZPixmap,
235  NULL,
236  &x11grab->shminfo,
237  x11grab->width, x11grab->height);
238  x11grab->shminfo.shmid = shmget(IPC_PRIVATE,
239  image->bytes_per_line * image->height,
240  IPC_CREAT|0777);
241  if (x11grab->shminfo.shmid == -1) {
242  av_log(s1, AV_LOG_ERROR, "Fatal: Can't get shared memory!\n");
243  ret = AVERROR(ENOMEM);
244  goto out;
245  }
246  x11grab->shminfo.shmaddr = image->data = shmat(x11grab->shminfo.shmid, 0, 0);
247  x11grab->shminfo.readOnly = False;
248 
249  if (!XShmAttach(dpy, &x11grab->shminfo)) {
250  av_log(s1, AV_LOG_ERROR, "Fatal: Failed to attach shared memory!\n");
251  /* needs some better error subroutine :) */
252  ret = AVERROR(EIO);
253  goto out;
254  }
255  } else {
256  image = XGetImage(dpy, RootWindow(dpy, screen),
257  x_off,y_off,
258  x11grab->width, x11grab->height,
259  AllPlanes, ZPixmap);
260  }
261 
262  switch (image->bits_per_pixel) {
263  case 8:
264  av_log (s1, AV_LOG_DEBUG, "8 bit palette\n");
265  input_pixfmt = AV_PIX_FMT_PAL8;
266  color_map = DefaultColormap(dpy, screen);
267  for (i = 0; i < 256; ++i)
268  color[i].pixel = i;
269  XQueryColors(dpy, color_map, color, 256);
270  for (i = 0; i < 256; ++i)
271  x11grab->palette[i] = (color[i].red & 0xFF00) << 8 |
272  (color[i].green & 0xFF00) |
273  (color[i].blue & 0xFF00) >> 8;
274  x11grab->palette_changed = 1;
275  break;
276  case 16:
277  if ( image->red_mask == 0xf800 &&
278  image->green_mask == 0x07e0 &&
279  image->blue_mask == 0x001f ) {
280  av_log (s1, AV_LOG_DEBUG, "16 bit RGB565\n");
281  input_pixfmt = AV_PIX_FMT_RGB565;
282  } else if (image->red_mask == 0x7c00 &&
283  image->green_mask == 0x03e0 &&
284  image->blue_mask == 0x001f ) {
285  av_log(s1, AV_LOG_DEBUG, "16 bit RGB555\n");
286  input_pixfmt = AV_PIX_FMT_RGB555;
287  } else {
288  av_log(s1, AV_LOG_ERROR, "RGB ordering at image depth %i not supported ... aborting\n", image->bits_per_pixel);
289  av_log(s1, AV_LOG_ERROR, "color masks: r 0x%.6lx g 0x%.6lx b 0x%.6lx\n", image->red_mask, image->green_mask, image->blue_mask);
290  ret = AVERROR(EIO);
291  goto out;
292  }
293  break;
294  case 24:
295  if ( image->red_mask == 0xff0000 &&
296  image->green_mask == 0x00ff00 &&
297  image->blue_mask == 0x0000ff ) {
298  input_pixfmt = AV_PIX_FMT_BGR24;
299  } else if ( image->red_mask == 0x0000ff &&
300  image->green_mask == 0x00ff00 &&
301  image->blue_mask == 0xff0000 ) {
302  input_pixfmt = AV_PIX_FMT_RGB24;
303  } else {
304  av_log(s1, AV_LOG_ERROR,"rgb ordering at image depth %i not supported ... aborting\n", image->bits_per_pixel);
305  av_log(s1, AV_LOG_ERROR, "color masks: r 0x%.6lx g 0x%.6lx b 0x%.6lx\n", image->red_mask, image->green_mask, image->blue_mask);
306  ret = AVERROR(EIO);
307  goto out;
308  }
309  break;
310  case 32:
311  input_pixfmt = AV_PIX_FMT_0RGB32;
312  break;
313  default:
314  av_log(s1, AV_LOG_ERROR, "image depth %i not supported ... aborting\n", image->bits_per_pixel);
315  ret = AVERROR(EINVAL);
316  goto out;
317  }
318 
319  x11grab->frame_size = x11grab->width * x11grab->height * image->bits_per_pixel/8;
320  x11grab->dpy = dpy;
321  x11grab->time_base = av_inv_q(x11grab->framerate);
322  x11grab->time_frame = av_gettime() / av_q2d(x11grab->time_base);
323  x11grab->x_off = x_off;
324  x11grab->y_off = y_off;
325  x11grab->image = image;
326  x11grab->use_shm = use_shm;
327 
330  st->codec->width = x11grab->width;
331  st->codec->height = x11grab->height;
332  st->codec->pix_fmt = input_pixfmt;
333  st->codec->time_base = x11grab->time_base;
334  st->codec->bit_rate = x11grab->frame_size * 1/av_q2d(x11grab->time_base) * 8;
335 
336 out:
337  av_free(dpyname);
338  return ret;
339 }
340 
341 /**
342  * Paint a mouse pointer in an X11 image.
343  *
344  * @param image image to paint the mouse pointer to
345  * @param s context used to retrieve original grabbing rectangle
346  * coordinates
347  */
348 static void
350 {
351  int x_off = s->x_off;
352  int y_off = s->y_off;
353  int width = s->width;
354  int height = s->height;
355  Display *dpy = s->dpy;
356  XFixesCursorImage *xcim;
357  int x, y;
358  int line, column;
359  int to_line, to_column;
360  int pixstride = image->bits_per_pixel >> 3;
361  /* Warning: in its insanity, xlib provides unsigned image data through a
362  * char* pointer, so we have to make it uint8_t to make things not break.
363  * Anyone who performs further investigation of the xlib API likely risks
364  * permanent brain damage. */
365  uint8_t *pix = image->data;
366  Window w;
367  XSetWindowAttributes attr;
368 
369  /* Code doesn't currently support 16-bit or PAL8 */
370  if (image->bits_per_pixel != 24 && image->bits_per_pixel != 32)
371  return;
372 
373  if(!s->c)
374  s->c = XCreateFontCursor(dpy, XC_left_ptr);
375  w = DefaultRootWindow(dpy);
376  attr.cursor = s->c;
377  XChangeWindowAttributes(dpy, w, CWCursor, &attr);
378 
379  xcim = XFixesGetCursorImage(dpy);
380 
381  x = xcim->x - xcim->xhot;
382  y = xcim->y - xcim->yhot;
383 
384  to_line = FFMIN((y + xcim->height), (height + y_off));
385  to_column = FFMIN((x + xcim->width), (width + x_off));
386 
387  for (line = FFMAX(y, y_off); line < to_line; line++) {
388  for (column = FFMAX(x, x_off); column < to_column; column++) {
389  int xcim_addr = (line - y) * xcim->width + column - x;
390  int image_addr = ((line - y_off) * width + column - x_off) * pixstride;
391  int r = (uint8_t)(xcim->pixels[xcim_addr] >> 0);
392  int g = (uint8_t)(xcim->pixels[xcim_addr] >> 8);
393  int b = (uint8_t)(xcim->pixels[xcim_addr] >> 16);
394  int a = (uint8_t)(xcim->pixels[xcim_addr] >> 24);
395 
396  if (a == 255) {
397  pix[image_addr+0] = r;
398  pix[image_addr+1] = g;
399  pix[image_addr+2] = b;
400  } else if (a) {
401  /* pixel values from XFixesGetCursorImage come premultiplied by alpha */
402  pix[image_addr+0] = r + (pix[image_addr+0]*(255-a) + 255/2) / 255;
403  pix[image_addr+1] = g + (pix[image_addr+1]*(255-a) + 255/2) / 255;
404  pix[image_addr+2] = b + (pix[image_addr+2]*(255-a) + 255/2) / 255;
405  }
406  }
407  }
408 
409  XFree(xcim);
410  xcim = NULL;
411 }
412 
413 
414 /**
415  * Read new data in the image structure.
416  *
417  * @param dpy X11 display to grab from
418  * @param d
419  * @param image Image where the grab will be put
420  * @param x Top-Left grabbing rectangle horizontal coordinate
421  * @param y Top-Left grabbing rectangle vertical coordinate
422  * @return 0 if error, !0 if successful
423  */
424 static int
425 xget_zpixmap(Display *dpy, Drawable d, XImage *image, int x, int y)
426 {
427  xGetImageReply rep;
428  xGetImageReq *req;
429  long nbytes;
430 
431  if (!image) {
432  return 0;
433  }
434 
435  LockDisplay(dpy);
436  GetReq(GetImage, req);
437 
438  /* First set up the standard stuff in the request */
439  req->drawable = d;
440  req->x = x;
441  req->y = y;
442  req->width = image->width;
443  req->height = image->height;
444  req->planeMask = (unsigned int)AllPlanes;
445  req->format = ZPixmap;
446 
447  if (!_XReply(dpy, (xReply *)&rep, 0, xFalse) || !rep.length) {
448  UnlockDisplay(dpy);
449  SyncHandle();
450  return 0;
451  }
452 
453  nbytes = (long)rep.length << 2;
454  _XReadPad(dpy, image->data, nbytes);
455 
456  UnlockDisplay(dpy);
457  SyncHandle();
458  return 1;
459 }
460 
461 /**
462  * Grab a frame from x11 (public device demuxer API).
463  *
464  * @param s1 Context from avformat core
465  * @param pkt Packet holding the brabbed frame
466  * @return frame size in bytes
467  */
468 static int
470 {
471  struct x11grab *s = s1->priv_data;
472  Display *dpy = s->dpy;
473  XImage *image = s->image;
474  int x_off = s->x_off;
475  int y_off = s->y_off;
476 
477  int screen;
478  Window root;
479  int follow_mouse = s->follow_mouse;
480 
481  int64_t curtime, delay;
482  struct timespec ts;
483 
484  /* Calculate the time of the next frame */
485  s->time_frame += INT64_C(1000000);
486 
487  /* wait based on the frame rate */
488  for(;;) {
489  curtime = av_gettime();
490  delay = s->time_frame * av_q2d(s->time_base) - curtime;
491  if (delay <= 0) {
492  if (delay < INT64_C(-1000000) * av_q2d(s->time_base)) {
493  s->time_frame += INT64_C(1000000);
494  }
495  break;
496  }
497  ts.tv_sec = delay / 1000000;
498  ts.tv_nsec = (delay % 1000000) * 1000;
499  nanosleep(&ts, NULL);
500  }
501 
502  av_init_packet(pkt);
503  pkt->data = image->data;
504  pkt->size = s->frame_size;
505  pkt->pts = curtime;
506  if (s->palette_changed) {
509  if (!pal) {
510  av_log(s, AV_LOG_ERROR, "Cannot append palette to packet\n");
511  } else {
512  memcpy(pal, s->palette, AVPALETTE_SIZE);
513  s->palette_changed = 0;
514  }
515  }
516 
517  screen = DefaultScreen(dpy);
518  root = RootWindow(dpy, screen);
519  if (follow_mouse) {
520  int screen_w, screen_h;
521  int pointer_x, pointer_y, _;
522  Window w;
523 
524  screen_w = DisplayWidth(dpy, screen);
525  screen_h = DisplayHeight(dpy, screen);
526  XQueryPointer(dpy, root, &w, &w, &pointer_x, &pointer_y, &_, &_, &_);
527  if (follow_mouse == -1) {
528  // follow the mouse, put it at center of grabbing region
529  x_off += pointer_x - s->width / 2 - x_off;
530  y_off += pointer_y - s->height / 2 - y_off;
531  } else {
532  // follow the mouse, but only move the grabbing region when mouse
533  // reaches within certain pixels to the edge.
534  if (pointer_x > x_off + s->width - follow_mouse) {
535  x_off += pointer_x - (x_off + s->width - follow_mouse);
536  } else if (pointer_x < x_off + follow_mouse)
537  x_off -= (x_off + follow_mouse) - pointer_x;
538  if (pointer_y > y_off + s->height - follow_mouse) {
539  y_off += pointer_y - (y_off + s->height - follow_mouse);
540  } else if (pointer_y < y_off + follow_mouse)
541  y_off -= (y_off + follow_mouse) - pointer_y;
542  }
543  // adjust grabbing region position if it goes out of screen.
544  s->x_off = x_off = FFMIN(FFMAX(x_off, 0), screen_w - s->width);
545  s->y_off = y_off = FFMIN(FFMAX(y_off, 0), screen_h - s->height);
546 
547  if (s->show_region && s->region_win)
548  XMoveWindow(dpy, s->region_win,
550  s->y_off - REGION_WIN_BORDER);
551  }
552 
553  if (s->show_region) {
554  if (s->region_win) {
555  XEvent evt;
556  // clean up the events, and do the initinal draw or redraw.
557  for (evt.type = NoEventMask; XCheckMaskEvent(dpy, ExposureMask | StructureNotifyMask, &evt); );
558  if (evt.type)
560  } else {
562  }
563  }
564 
565  if(s->use_shm) {
566  if (!XShmGetImage(dpy, root, image, x_off, y_off, AllPlanes)) {
567  av_log (s1, AV_LOG_INFO, "XShmGetImage() failed\n");
568  }
569  } else {
570  if (!xget_zpixmap(dpy, root, image, x_off, y_off)) {
571  av_log (s1, AV_LOG_INFO, "XGetZPixmap() failed\n");
572  }
573  }
574 
575  if (s->draw_mouse) {
576  paint_mouse_pointer(image, s);
577  }
578 
579  return s->frame_size;
580 }
581 
582 /**
583  * Close x11 frame grabber (public device demuxer API).
584  *
585  * @param s1 Context from avformat core
586  * @return 0 success, !0 failure
587  */
588 static int
590 {
591  struct x11grab *x11grab = s1->priv_data;
592 
593  /* Detach cleanly from shared mem */
594  if (x11grab->use_shm) {
595  XShmDetach(x11grab->dpy, &x11grab->shminfo);
596  shmdt(x11grab->shminfo.shmaddr);
597  shmctl(x11grab->shminfo.shmid, IPC_RMID, NULL);
598  }
599 
600  /* Destroy X11 image */
601  if (x11grab->image) {
602  XDestroyImage(x11grab->image);
603  x11grab->image = NULL;
604  }
605 
606  if (x11grab->region_win) {
607  XDestroyWindow(x11grab->dpy, x11grab->region_win);
608  }
609 
610  /* Free X11 display */
611  XCloseDisplay(x11grab->dpy);
612  return 0;
613 }
614 
615 #define OFFSET(x) offsetof(struct x11grab, x)
616 #define DEC AV_OPT_FLAG_DECODING_PARAM
617 static const AVOption options[] = {
618  { "draw_mouse", "draw the mouse pointer", OFFSET(draw_mouse), AV_OPT_TYPE_INT, {.i64 = 1}, 0, 1, DEC },
619 
620  { "follow_mouse", "move the grabbing region when the mouse pointer reaches within specified amount of pixels to the edge of region",
621  OFFSET(follow_mouse), AV_OPT_TYPE_INT, {.i64 = 0}, -1, INT_MAX, DEC, "follow_mouse" },
622  { "centered", "keep the mouse pointer at the center of grabbing region when following",
623  0, AV_OPT_TYPE_CONST, {.i64 = -1}, INT_MIN, INT_MAX, DEC, "follow_mouse" },
624 
625  { "framerate", "set video frame rate", OFFSET(framerate), AV_OPT_TYPE_VIDEO_RATE, {.str = "ntsc"}, 0, 0, DEC },
626  { "show_region", "show the grabbing region", OFFSET(show_region), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, DEC },
627  { "video_size", "set video frame size", OFFSET(width), AV_OPT_TYPE_IMAGE_SIZE, {.str = "vga"}, 0, 0, DEC },
628  { NULL },
629 };
630 
631 static const AVClass x11_class = {
632  .class_name = "X11grab indev",
633  .item_name = av_default_item_name,
634  .option = options,
635  .version = LIBAVUTIL_VERSION_INT,
636 };
637 
638 /** x11 grabber device demuxer declaration */
640  .name = "x11grab",
641  .long_name = NULL_IF_CONFIG_SMALL("X11grab"),
642  .priv_data_size = sizeof(struct x11grab),
643  .read_header = x11grab_read_header,
644  .read_packet = x11grab_read_packet,
645  .read_close = x11grab_read_close,
646  .flags = AVFMT_NOFILE,
647  .priv_class = &x11_class,
648 };