xcbgrab: Accept geometries matching the screen size
[libav.git] / libavdevice / xcbgrab.c
1 /*
2 * XCB input grabber
3 * Copyright (C) 2014 Luca Barbato <lu_zero@gentoo.org>
4 *
5 * This file is part of Libav.
6 *
7 * Libav is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * Libav 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 GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with Libav; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 #include "config.h"
23
24 #include <stdlib.h>
25 #include <xcb/xcb.h>
26
27 #if CONFIG_LIBXCB_XFIXES
28 #include <xcb/xfixes.h>
29 #endif
30
31 #if CONFIG_LIBXCB_SHM
32 #include <sys/shm.h>
33 #include <xcb/shm.h>
34 #endif
35
36 #include "libavutil/internal.h"
37 #include "libavutil/mathematics.h"
38 #include "libavutil/opt.h"
39 #include "libavutil/parseutils.h"
40 #include "libavutil/time.h"
41
42 #include "libavformat/avformat.h"
43 #include "libavformat/internal.h"
44
45 typedef struct XCBGrabContext {
46 const AVClass *class;
47
48 xcb_connection_t *conn;
49 xcb_screen_t *screen;
50 xcb_window_t window;
51 #if CONFIG_LIBXCB_SHM
52 xcb_shm_seg_t segment;
53 #endif
54 int64_t time_frame;
55 AVRational time_base;
56
57 int x, y;
58 int width, height;
59 int frame_size;
60 int bpp;
61
62 int draw_mouse;
63 int follow_mouse;
64 int show_region;
65 int region_border;
66 int centered;
67
68 const char *video_size;
69 const char *framerate;
70
71 int has_shm;
72 } XCBGrabContext;
73
74 #define FOLLOW_CENTER -1
75
76 #define OFFSET(x) offsetof(XCBGrabContext, x)
77 #define D AV_OPT_FLAG_DECODING_PARAM
78 static const AVOption options[] = {
79 { "x", "Initial x coordinate.", OFFSET(x), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, D },
80 { "y", "Initial y coordinate.", OFFSET(y), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, D },
81 { "grab_x", "Initial x coordinate.", OFFSET(x), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, D },
82 { "grab_y", "Initial y coordinate.", OFFSET(y), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, D },
83 { "video_size", "A string describing frame size, such as 640x480 or hd720.", OFFSET(video_size), AV_OPT_TYPE_STRING, {.str = "vga" }, 0, 0, D },
84 { "framerate", "", OFFSET(framerate), AV_OPT_TYPE_STRING, {.str = "ntsc" }, 0, 0, D },
85 { "draw_mouse", "Draw the mouse pointer.", OFFSET(draw_mouse), AV_OPT_TYPE_INT, { .i64 = 1 }, 0, 1, D },
86 { "follow_mouse", "Move the grabbing region when the mouse pointer reaches within specified amount of pixels to the edge of region.",
87 OFFSET(follow_mouse), AV_OPT_TYPE_INT, { .i64 = 0 }, FOLLOW_CENTER, INT_MAX, D, "follow_mouse" },
88 { "centered", "Keep the mouse pointer at the center of grabbing region when following.", 0, AV_OPT_TYPE_CONST, { .i64 = -1 }, INT_MIN, INT_MAX, D, "follow_mouse" },
89 { "show_region", "Show the grabbing region.", OFFSET(show_region), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, D },
90 { "region_border", "Set the region border thickness.", OFFSET(region_border), AV_OPT_TYPE_INT, { .i64 = 3 }, 1, 128, D },
91 { NULL },
92 };
93
94 static const AVClass xcbgrab_class = {
95 .class_name = "xcbgrab indev",
96 .item_name = av_default_item_name,
97 .option = options,
98 .version = LIBAVUTIL_VERSION_INT,
99 };
100
101 static int xcbgrab_reposition(AVFormatContext *s,
102 xcb_query_pointer_reply_t *p,
103 xcb_get_geometry_reply_t *geo)
104 {
105 XCBGrabContext *c = s->priv_data;
106 int x = c->x, y = c->y;
107 int w = c->width, h = c->height, f = c->follow_mouse;
108 int p_x, p_y;
109
110 if (!p || !geo)
111 return AVERROR(EIO);
112
113 p_x = p->win_x;
114 p_y = p->win_y;
115
116 if (f == FOLLOW_CENTER) {
117 x = p_x - w / 2;
118 y = p_y - h / 2;
119 } else {
120 int left = x + f;
121 int right = x + w - f;
122 int top = y + f;
123 int bottom = y + h + f;
124 if (p_x > right) {
125 x += p_x - right;
126 } else if (p_x < left) {
127 x -= left - p_x;
128 }
129 if (p_y > bottom) {
130 y += p_y - bottom;
131 } else if (p_y < top) {
132 y -= top - p_y;
133 }
134 }
135
136 c->x = FFMIN(FFMAX(0, x), geo->width - w);
137 c->y = FFMIN(FFMAX(0, y), geo->height - h);
138
139 return 0;
140 }
141
142 static int xcbgrab_frame(AVFormatContext *s, AVPacket *pkt)
143 {
144 XCBGrabContext *c = s->priv_data;
145 xcb_get_image_cookie_t iq;
146 xcb_get_image_reply_t *img;
147 xcb_drawable_t drawable = c->screen->root;
148 xcb_generic_error_t *e = NULL;
149 uint8_t *data;
150 int length, ret;
151
152 iq = xcb_get_image(c->conn, XCB_IMAGE_FORMAT_Z_PIXMAP, drawable,
153 c->x, c->y, c->width, c->height, ~0);
154
155 img = xcb_get_image_reply(c->conn, iq, &e);
156
157 if (e) {
158 av_log(s, AV_LOG_ERROR,
159 "Cannot get the image data "
160 "event_error: response_type:%u error_code:%u "
161 "sequence:%u resource_id:%u minor_code:%u major_code:%u.\n",
162 e->response_type, e->error_code,
163 e->sequence, e->resource_id, e->minor_code, e->major_code);
164 return AVERROR(EACCES);
165 }
166
167 if (!img)
168 return AVERROR(EAGAIN);
169
170 data = xcb_get_image_data(img);
171 length = xcb_get_image_data_length(img);
172
173 ret = av_new_packet(pkt, length);
174
175 if (!ret)
176 memcpy(pkt->data, data, length);
177
178 free(img);
179
180 return ret;
181 }
182
183 static void wait_frame(AVFormatContext *s, AVPacket *pkt)
184 {
185 XCBGrabContext *c = s->priv_data;
186 int64_t curtime, delay;
187 int64_t frame_time = av_rescale_q(1, c->time_base, AV_TIME_BASE_Q);
188
189 c->time_frame += frame_time;
190
191 for (;;) {
192 curtime = av_gettime();
193 delay = c->time_frame - curtime;
194 if (delay <= 0)
195 break;
196 av_usleep(delay);
197 }
198
199 pkt->pts = curtime;
200 }
201
202 #if CONFIG_LIBXCB_SHM
203 static int check_shm(xcb_connection_t *conn)
204 {
205 xcb_shm_query_version_cookie_t cookie = xcb_shm_query_version(conn);
206 xcb_shm_query_version_reply_t *reply;
207
208 reply = xcb_shm_query_version_reply(conn, cookie, NULL);
209 if (reply) {
210 free(reply);
211 return 1;
212 }
213
214 return 0;
215 }
216
217 static void dealloc_shm(void *unused, uint8_t *data)
218 {
219 shmdt(data);
220 }
221
222 static int xcbgrab_frame_shm(AVFormatContext *s, AVPacket *pkt)
223 {
224 XCBGrabContext *c = s->priv_data;
225 xcb_shm_get_image_cookie_t iq;
226 xcb_shm_get_image_reply_t *img;
227 xcb_drawable_t drawable = c->screen->root;
228 uint8_t *data;
229 int size = c->frame_size + FF_INPUT_BUFFER_PADDING_SIZE;
230 int id = shmget(IPC_PRIVATE, size, IPC_CREAT | 0777);
231 xcb_generic_error_t *e = NULL;
232
233 if (id == -1) {
234 char errbuf[1024];
235 int err = AVERROR(errno);
236 av_strerror(err, errbuf, sizeof(errbuf));
237 av_log(s, AV_LOG_ERROR, "Cannot get %d bytes of shared memory: %s.\n",
238 size, errbuf);
239 return err;
240 }
241
242 xcb_shm_attach(c->conn, c->segment, id, 0);
243
244 iq = xcb_shm_get_image(c->conn, drawable,
245 c->x, c->y, c->width, c->height, ~0,
246 XCB_IMAGE_FORMAT_Z_PIXMAP, c->segment, 0);
247
248 xcb_shm_detach(c->conn, c->segment);
249
250 img = xcb_shm_get_image_reply(c->conn, iq, &e);
251
252 xcb_flush(c->conn);
253
254 if (e) {
255 av_log(s, AV_LOG_ERROR,
256 "Cannot get the image data "
257 "event_error: response_type:%u error_code:%u "
258 "sequence:%u resource_id:%u minor_code:%u major_code:%u.\n",
259 e->response_type, e->error_code,
260 e->sequence, e->resource_id, e->minor_code, e->major_code);
261
262 shmctl(id, IPC_RMID, 0);
263 return AVERROR(EACCES);
264 }
265
266 free(img);
267
268 data = shmat(id, NULL, 0);
269 shmctl(id, IPC_RMID, 0);
270
271 if ((intptr_t)data == -1)
272 return AVERROR(errno);
273
274 pkt->buf = av_buffer_create(data, size, dealloc_shm, NULL, 0);
275 if (!pkt->buf) {
276 shmdt(data);
277 return AVERROR(ENOMEM);
278 }
279
280 pkt->data = pkt->buf->data;
281 pkt->size = c->frame_size;
282
283 return 0;
284 }
285 #endif /* CONFIG_LIBXCB_SHM */
286
287 #if CONFIG_LIBXCB_XFIXES
288 static int check_xfixes(xcb_connection_t *conn)
289 {
290 xcb_xfixes_query_version_cookie_t cookie;
291 xcb_xfixes_query_version_reply_t *reply;
292
293 cookie = xcb_xfixes_query_version(conn, XCB_XFIXES_MAJOR_VERSION,
294 XCB_XFIXES_MINOR_VERSION);
295 reply = xcb_xfixes_query_version_reply(conn, cookie, NULL);
296
297 if (reply) {
298 free(reply);
299 return 1;
300 }
301 return 0;
302 }
303
304 #define BLEND(target, source, alpha) \
305 (target) + ((source) * (255 - (alpha)) + 255 / 2) / 255
306
307 static void xcbgrab_draw_mouse(AVFormatContext *s, AVPacket *pkt,
308 xcb_query_pointer_reply_t *p,
309 xcb_get_geometry_reply_t *geo)
310 {
311 XCBGrabContext *gr = s->priv_data;
312 uint32_t *cursor;
313 uint8_t *image = pkt->data;
314 int stride = gr->bpp / 8;
315 xcb_xfixes_get_cursor_image_cookie_t cc;
316 xcb_xfixes_get_cursor_image_reply_t *ci;
317 int cx, cy, x, y, w, h, c_off, i_off;
318
319 cc = xcb_xfixes_get_cursor_image(gr->conn);
320 ci = xcb_xfixes_get_cursor_image_reply(gr->conn, cc, NULL);
321 if (!ci)
322 return;
323
324 cursor = xcb_xfixes_get_cursor_image_cursor_image(ci);
325 if (!cursor)
326 return;
327
328 cx = ci->x - ci->xhot;
329 cy = ci->y - ci->yhot;
330
331 x = FFMAX(cx, gr->x);
332 y = FFMAX(cy, gr->y);
333
334 w = FFMIN(cx + ci->width, gr->x + gr->width) - x;
335 h = FFMIN(cy + ci->height, gr->y + gr->height) - y;
336
337 c_off = x - cx;
338 i_off = x - gr->x;
339
340 cursor += (y - cy) * ci->width;
341 image += (y - gr->y) * gr->width * stride;
342
343 for (y = 0; y < h; y++) {
344 cursor += c_off;
345 image += i_off * stride;
346 for (x = 0; x < w; x++, cursor++, image += stride) {
347 int r, g, b, a;
348
349 r = *cursor & 0xff;
350 g = (*cursor >> 8) & 0xff;
351 b = (*cursor >> 16) & 0xff;
352 a = (*cursor >> 24) & 0xff;
353
354 if (!a)
355 continue;
356
357 if (a == 255) {
358 image[0] = r;
359 image[1] = g;
360 image[2] = b;
361 } else {
362 image[0] = BLEND(r, image[0], a);
363 image[1] = BLEND(g, image[1], a);
364 image[2] = BLEND(b, image[2], a);
365 }
366
367 }
368 cursor += ci->width - w - c_off;
369 image += (gr->width - w - i_off) * stride;
370 }
371
372 free(ci);
373 }
374 #endif /* CONFIG_LIBXCB_XFIXES */
375
376 static void xcbgrab_update_region(AVFormatContext *s)
377 {
378 XCBGrabContext *c = s->priv_data;
379 const uint32_t args[] = { c->x - c->region_border,
380 c->y - c->region_border };
381
382 xcb_configure_window(c->conn,
383 c->window,
384 XCB_CONFIG_WINDOW_X | XCB_CONFIG_WINDOW_Y,
385 args);
386 }
387
388 static int xcbgrab_read_packet(AVFormatContext *s, AVPacket *pkt)
389 {
390 XCBGrabContext *c = s->priv_data;
391 xcb_query_pointer_cookie_t pc;
392 xcb_get_geometry_cookie_t gc;
393 xcb_query_pointer_reply_t *p = NULL;
394 xcb_get_geometry_reply_t *geo = NULL;
395 int ret = 0;
396
397 wait_frame(s, pkt);
398
399 if (c->follow_mouse || c->draw_mouse) {
400 pc = xcb_query_pointer(c->conn, c->screen->root);
401 gc = xcb_get_geometry(c->conn, c->screen->root);
402 p = xcb_query_pointer_reply(c->conn, pc, NULL);
403 geo = xcb_get_geometry_reply(c->conn, gc, NULL);
404 }
405
406 if (c->follow_mouse && p->same_screen)
407 xcbgrab_reposition(s, p, geo);
408
409 if (c->show_region)
410 xcbgrab_update_region(s);
411
412 #if CONFIG_LIBXCB_SHM
413 if (c->has_shm && xcbgrab_frame_shm(s, pkt) < 0)
414 c->has_shm = 0;
415 #endif
416 if (!c->has_shm)
417 ret = xcbgrab_frame(s, pkt);
418
419 #if CONFIG_LIBXCB_XFIXES
420 if (ret >= 0 && c->draw_mouse && p->same_screen)
421 xcbgrab_draw_mouse(s, pkt, p, geo);
422 #endif
423
424 free(p);
425 free(geo);
426
427 return ret;
428 }
429
430 static av_cold int xcbgrab_read_close(AVFormatContext *s)
431 {
432 XCBGrabContext *ctx = s->priv_data;
433
434 xcb_disconnect(ctx->conn);
435
436 return 0;
437 }
438
439 static xcb_screen_t *get_screen(const xcb_setup_t *setup, int screen_num)
440 {
441 xcb_screen_iterator_t it = xcb_setup_roots_iterator(setup);
442 xcb_screen_t *screen = NULL;
443
444 for (; it.rem > 0; xcb_screen_next (&it)) {
445 if (!screen_num) {
446 screen = it.data;
447 break;
448 }
449
450 screen_num--;
451 }
452
453 return screen;
454 }
455
456 static int pixfmt_from_pixmap_format(AVFormatContext *s, int depth,
457 int *pix_fmt)
458 {
459 XCBGrabContext *c = s->priv_data;
460 const xcb_setup_t *setup = xcb_get_setup(c->conn);
461 const xcb_format_t *fmt = xcb_setup_pixmap_formats(setup);
462 int length = xcb_setup_pixmap_formats_length(setup);
463
464 *pix_fmt = 0;
465
466 while (length--) {
467 if (fmt->depth == depth) {
468 switch (depth) {
469 case 32:
470 if (fmt->bits_per_pixel == 32)
471 *pix_fmt = AV_PIX_FMT_ARGB;
472 break;
473 case 24:
474 if (fmt->bits_per_pixel == 32)
475 *pix_fmt = AV_PIX_FMT_RGB32;
476 else if (fmt->bits_per_pixel == 24)
477 *pix_fmt = AV_PIX_FMT_RGB24;
478 break;
479 case 16:
480 if (fmt->bits_per_pixel == 16)
481 *pix_fmt = AV_PIX_FMT_RGB565;
482 break;
483 case 15:
484 if (fmt->bits_per_pixel == 16)
485 *pix_fmt = AV_PIX_FMT_RGB555;
486 break;
487 case 8:
488 if (fmt->bits_per_pixel == 8)
489 *pix_fmt = AV_PIX_FMT_RGB8;
490 break;
491 }
492 }
493
494 if (*pix_fmt) {
495 c->bpp = fmt->bits_per_pixel;
496 c->frame_size = c->width * c->height * fmt->bits_per_pixel / 8;
497 return 0;
498 }
499
500 fmt++;
501 }
502 av_log(s, AV_LOG_ERROR, "Pixmap format not mappable.\n");
503
504 return AVERROR_PATCHWELCOME;
505 }
506
507 static int create_stream(AVFormatContext *s)
508 {
509 XCBGrabContext *c = s->priv_data;
510 AVStream *st = avformat_new_stream(s, NULL);
511 xcb_get_geometry_cookie_t gc;
512 xcb_get_geometry_reply_t *geo;
513 int ret;
514
515 if (!st)
516 return AVERROR(ENOMEM);
517
518 ret = av_parse_video_size(&c->width, &c->height, c->video_size);
519 if (ret < 0)
520 return ret;
521
522 ret = av_parse_video_rate(&st->avg_frame_rate, c->framerate);
523 if (ret < 0)
524 return ret;
525
526 avpriv_set_pts_info(st, 64, 1, 1000000);
527
528 gc = xcb_get_geometry(c->conn, c->screen->root);
529 geo = xcb_get_geometry_reply(c->conn, gc, NULL);
530
531 if (c->x + c->width > geo->width ||
532 c->y + c->height > geo->height) {
533 av_log(s, AV_LOG_ERROR,
534 "Capture area %dx%d at position %d.%d "
535 "outside the screen size %dx%d\n",
536 c->width, c->height,
537 c->x, c->y,
538 geo->width, geo->height);
539 return AVERROR(EINVAL);
540 }
541
542 c->time_base = (AVRational){ st->avg_frame_rate.den,
543 st->avg_frame_rate.num };
544 c->time_frame = av_gettime();
545
546 st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
547 st->codec->codec_id = AV_CODEC_ID_RAWVIDEO;
548 st->codec->width = c->width;
549 st->codec->height = c->height;
550 st->codec->time_base = c->time_base;
551
552 ret = pixfmt_from_pixmap_format(s, geo->depth, &st->codec->pix_fmt);
553
554 free(geo);
555
556 return ret;
557 }
558
559 static void draw_rectangle(AVFormatContext *s)
560 {
561 XCBGrabContext *c = s->priv_data;
562 xcb_gcontext_t gc = xcb_generate_id(c->conn);
563 uint32_t mask = XCB_GC_FOREGROUND |
564 XCB_GC_BACKGROUND |
565 XCB_GC_LINE_WIDTH |
566 XCB_GC_LINE_STYLE |
567 XCB_GC_FILL_STYLE;
568 uint32_t values[] = { c->screen->black_pixel,
569 c->screen->white_pixel,
570 c->region_border,
571 XCB_LINE_STYLE_DOUBLE_DASH,
572 XCB_FILL_STYLE_SOLID };
573 xcb_rectangle_t r = { 1, 1,
574 c->width + c->region_border * 2 - 3,
575 c->height + c->region_border * 2 - 3 };
576
577 xcb_create_gc(c->conn, gc, c->window, mask, values);
578
579 xcb_poly_rectangle(c->conn, c->window, gc, 1, &r);
580 }
581
582 static void setup_window(AVFormatContext *s)
583 {
584 XCBGrabContext *c = s->priv_data;
585 uint32_t mask = XCB_CW_OVERRIDE_REDIRECT | XCB_CW_EVENT_MASK;
586 uint32_t values[] = { 1,
587 XCB_EVENT_MASK_EXPOSURE |
588 XCB_EVENT_MASK_STRUCTURE_NOTIFY };
589 xcb_rectangle_t rect = { 0, 0, c->width, c->height };
590
591 c->window = xcb_generate_id(c->conn);
592
593 xcb_create_window(c->conn, XCB_COPY_FROM_PARENT,
594 c->window,
595 c->screen->root,
596 c->x - c->region_border,
597 c->y - c->region_border,
598 c->width + c->region_border * 2,
599 c->height + c->region_border * 2,
600 0,
601 XCB_WINDOW_CLASS_INPUT_OUTPUT,
602 XCB_COPY_FROM_PARENT,
603 mask, values);
604
605 xcb_shape_rectangles(c->conn, XCB_SHAPE_SO_SUBTRACT,
606 XCB_SHAPE_SK_BOUNDING, XCB_CLIP_ORDERING_UNSORTED,
607 c->window,
608 c->region_border, c->region_border,
609 1, &rect);
610
611 xcb_map_window(c->conn, c->window);
612
613 draw_rectangle(s);
614 }
615
616 static av_cold int xcbgrab_read_header(AVFormatContext *s)
617 {
618 XCBGrabContext *c = s->priv_data;
619 int screen_num, ret;
620 const xcb_setup_t *setup;
621 char *host = s->filename[0] ? s->filename : NULL;
622 const char *opts = strchr(s->filename, '+');
623
624 if (opts) {
625 sscanf(opts, "%d,%d", &c->x, &c->y);
626 host = av_strdup(s->filename);
627 if (!host)
628 return AVERROR(ENOMEM);
629 host[opts - s->filename] = '\0';
630 }
631
632 c->conn = xcb_connect(host, &screen_num);
633
634 if ((ret = xcb_connection_has_error(c->conn))) {
635 av_log(s, AV_LOG_ERROR, "Cannot open display %s, error %d.\n",
636 s->filename[0] ? host : "default", ret);
637 if (opts)
638 av_freep(&host);
639 return AVERROR(EIO);
640 }
641
642 if (opts)
643 av_freep(&host);
644
645 setup = xcb_get_setup(c->conn);
646
647 c->screen = get_screen(setup, screen_num);
648 if (!c->screen) {
649 av_log(s, AV_LOG_ERROR, "The screen %d does not exist.\n",
650 screen_num);
651 xcbgrab_read_close(s);
652 return AVERROR(EIO);
653 }
654
655 ret = create_stream(s);
656
657 if (ret < 0) {
658 xcbgrab_read_close(s);
659 return ret;
660 }
661
662 #if CONFIG_LIBXCB_SHM
663 if ((c->has_shm = check_shm(c->conn)))
664 c->segment = xcb_generate_id(c->conn);
665 #endif
666
667 #if CONFIG_LIBXCB_XFIXES
668 if (c->draw_mouse) {
669 if (!(c->draw_mouse = check_xfixes(c->conn))) {
670 av_log(s, AV_LOG_WARNING,
671 "XFixes not available, cannot draw the mouse.\n");
672 }
673 if (c->bpp < 24) {
674 avpriv_report_missing_feature(s, "%d bits per pixel screen",
675 c->bpp);
676 c->draw_mouse = 0;
677 }
678 }
679 #endif
680
681 if (c->show_region)
682 setup_window(s);
683
684 return 0;
685 }
686
687 AVInputFormat ff_x11grab_xcb_demuxer = {
688 .name = "x11grab",
689 .long_name = NULL_IF_CONFIG_SMALL("X11 screen capture, using XCB"),
690 .priv_data_size = sizeof(XCBGrabContext),
691 .read_header = xcbgrab_read_header,
692 .read_packet = xcbgrab_read_packet,
693 .read_close = xcbgrab_read_close,
694 .flags = AVFMT_NOFILE,
695 .priv_class = &xcbgrab_class,
696 };