/*
  * X11 video grab interface

  *

  * This file is part of FFmpeg.

  *

  * FFmpeg integration:
  * Copyright (C) 2006 Clemens Fruhwirth <clemens@endorphin.org>
  *                    Edouard Gomez <ed.gomez@free.fr>

  *

  * This file contains code from grab.c:

  * Copyright (c) 2000-2001 Fabrice Bellard

  *
  * This file contains code from the xvidcap project:

  * Copyright (C) 1997-1998 Rasca, Berlin
  *               2003-2004 Karl H. Beckers, Frankfurt

  *

  * FFmpeg is free software; you can redistribute it and/or modify

  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  *

  * FFmpeg is distributed in the hope that it will be useful,

  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *

  * You should have received a copy of the GNU General Public License
  * along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

  */

 /**

  * @file

  * X11 frame device demuxer
  * @author Clemens Fruhwirth <clemens@endorphin.org>
  * @author Edouard Gomez <ed.gomez@free.fr>

  */
 

 #include "config.h"

 #include <time.h>

 #include <sys/shm.h>
 

 #include <X11/cursorfont.h>

 #include <X11/X.h>
 #include <X11/Xlib.h>
 #include <X11/Xlibint.h>
 #include <X11/Xproto.h>

 #include <X11/Xutil.h>

 #include <X11/extensions/shape.h>

 #include <X11/extensions/Xfixes.h>

 #include <X11/extensions/XShm.h>

 #include "libavutil/internal.h"

 #include "libavutil/log.h"
 #include "libavutil/opt.h"
 #include "libavutil/parseutils.h"
 #include "libavutil/time.h"
 
 #include "libavformat/internal.h"
 

 #include "avdevice.h"
 

 /** X11 device demuxer context */

 typedef struct X11GrabContext {

     const AVClass *class;    /**< Class for private options. */

     int frame_size;          /**< Size in bytes of a grabbed frame */
     AVRational time_base;    /**< Time base */
     int64_t time_frame;      /**< Current time */
 
     int width;               /**< Width of the grab frame */

     int height;              /**< Height of the grab frame */

     int x_off;               /**< Horizontal top-left corner coordinate */
     int y_off;               /**< Vertical top-left corner coordinate */
 
     Display *dpy;            /**< X11 display from which x11grab grabs frames */
     XImage *image;           /**< X11 image holding the grab */
     int use_shm;             /**< !0 when using XShm extension */
     XShmSegmentInfo shminfo; /**< When using XShm, keeps track of XShm infos */

     int draw_mouse;          /**< Set by a private option. */
     int follow_mouse;        /**< Set by a private option. */
     int show_region;         /**< set by a private option. */

     AVRational framerate;    /**< Set by a private option. */

     int palette_changed;
     uint32_t palette[256];

     Cursor c;

     Window region_win;       /**< This is used by show_region option. */

 } X11GrabContext;

 #define REGION_WIN_BORDER 3

 /**
  * Draw grabbing region window
  *

  * @param s x11grab context

  */

 static void x11grab_draw_region_win(X11GrabContext *s)

 {
     Display *dpy = s->dpy;

     Window win   = s->region_win;

     int screen = DefaultScreen(dpy);
     GC gc = XCreateGC(dpy, win, 0, 0);

 
     XSetForeground(dpy, gc, WhitePixel(dpy, screen));
     XSetBackground(dpy, gc, BlackPixel(dpy, screen));
     XSetLineAttributes(dpy, gc, REGION_WIN_BORDER, LineDoubleDash, 0, 0);

     XDrawRectangle(dpy, win, gc, 1, 1,

                    (s->width  + REGION_WIN_BORDER * 2) - 1 * 2 - 1,
                    (s->height + REGION_WIN_BORDER * 2) - 1 * 2 - 1);
     XFreeGC(dpy, gc);
 }
 
 /**
  * Initialize grabbing region window
  *

  * @param s x11grab context

  */

 static void x11grab_region_win_init(X11GrabContext *s)

 {
     Display *dpy = s->dpy;
     XRectangle rect;

     XSetWindowAttributes attribs = { .override_redirect = True };
     int screen = DefaultScreen(dpy);

 
     s->region_win = XCreateWindow(dpy, RootWindow(dpy, screen),
                                   s->x_off  - REGION_WIN_BORDER,
                                   s->y_off  - REGION_WIN_BORDER,
                                   s->width  + REGION_WIN_BORDER * 2,
                                   s->height + REGION_WIN_BORDER * 2,
                                   0, CopyFromParent,
                                   InputOutput, CopyFromParent,
                                   CWOverrideRedirect, &attribs);

     rect.x      = 0;
     rect.y      = 0;

     rect.width  = s->width;
     rect.height = s->height;
     XShapeCombineRectangles(dpy, s->region_win,
                             ShapeBounding, REGION_WIN_BORDER, REGION_WIN_BORDER,
                             &rect, 1, ShapeSubtract, 0);
     XMapWindow(dpy, s->region_win);
     XSelectInput(dpy, s->region_win, ExposureMask | StructureNotifyMask);
     x11grab_draw_region_win(s);
 }
 

 static int setup_shm(AVFormatContext *s, Display *dpy, XImage **image)
 {
     X11GrabContext *g = s->priv_data;
     int scr           = XDefaultScreen(dpy);
     XImage *img       = XShmCreateImage(dpy, DefaultVisual(dpy, scr),
                                         DefaultDepth(dpy, scr), ZPixmap, NULL,
                                         &g->shminfo, g->width, g->height);
 
     g->shminfo.shmid = shmget(IPC_PRIVATE, img->bytes_per_line * img->height,
                               IPC_CREAT | 0777);
 
     if (g->shminfo.shmid == -1) {
         av_log(s, AV_LOG_ERROR, "Cannot get shared memory!\n");
         return AVERROR(ENOMEM);
     }
 
     g->shminfo.shmaddr  = img->data = shmat(g->shminfo.shmid, 0, 0);
     g->shminfo.readOnly = False;
 
     if (!XShmAttach(dpy, &g->shminfo)) {
         av_log(s, AV_LOG_ERROR, "Failed to attach shared memory!\n");
         /* needs some better error subroutine :) */
         return AVERROR(EIO);
     }
 
     *image = img;
     return 0;
 }
 

 static int setup_mouse(Display *dpy, int screen)
 {
     int ev_ret, ev_err;
 
     if (XFixesQueryExtension(dpy, &ev_ret, &ev_err)) {
         Window root = RootWindow(dpy, screen);
         XFixesSelectCursorInput(dpy, root, XFixesDisplayCursorNotifyMask);
         return 0;
     }
 
     return AVERROR(ENOSYS);
 }
 

 static int pixfmt_from_image(AVFormatContext *s, XImage *image, int *pix_fmt)
 {
     av_log(s, AV_LOG_DEBUG,
            "Image r 0x%.6lx g 0x%.6lx b 0x%.6lx and depth %i\n",
            image->red_mask,
            image->green_mask,
            image->blue_mask,
            image->bits_per_pixel);
 

     *pix_fmt = AV_PIX_FMT_NONE;
 

     switch (image->bits_per_pixel) {
     case 8:
         *pix_fmt =  AV_PIX_FMT_PAL8;
         break;
     case 16:
         if (image->red_mask   == 0xf800 &&
             image->green_mask == 0x07e0 &&
             image->blue_mask  == 0x001f) {
             *pix_fmt = AV_PIX_FMT_RGB565;
         } else if (image->red_mask   == 0x7c00 &&
                    image->green_mask == 0x03e0 &&
                    image->blue_mask  == 0x001f) {
             *pix_fmt = AV_PIX_FMT_RGB555;
         }
         break;
     case 24:
         if (image->red_mask   == 0xff0000 &&
             image->green_mask == 0x00ff00 &&
             image->blue_mask  == 0x0000ff) {
             *pix_fmt = AV_PIX_FMT_BGR24;
         } else if (image->red_mask   == 0x0000ff &&
                    image->green_mask == 0x00ff00 &&
                    image->blue_mask  == 0xff0000) {
             *pix_fmt = AV_PIX_FMT_RGB24;
         }
         break;
     case 32:

         if (image->red_mask   == 0xff0000 &&
             image->green_mask == 0x00ff00 &&
             image->blue_mask  == 0x0000ff ) {
             *pix_fmt = AV_PIX_FMT_0RGB32;
         }

         break;

     }
     if (*pix_fmt == AV_PIX_FMT_NONE) {

         av_log(s, AV_LOG_ERROR,
                "XImages with RGB mask 0x%.6lx 0x%.6lx 0x%.6lx and depth %i "
                "are currently not supported.\n",
                image->red_mask,
                image->green_mask,
                image->blue_mask,
                image->bits_per_pixel);
 
         return AVERROR_PATCHWELCOME;
     }
 
     return 0;
 }
 

 /**

  * Initialize the x11 grab device demuxer (public device demuxer API).

  *
  * @param s1 Context from avformat core
  * @return <ul>

  *          <li>AVERROR(ENOMEM) no memory left</li>

  *          <li>AVERROR(EIO) other failure case</li>

  *          <li>0 success</li>
  *         </ul>
  */

 static int x11grab_read_header(AVFormatContext *s1)

 {

     X11GrabContext *x11grab = s1->priv_data;

     Display *dpy;
     AVStream *st = NULL;
     XImage *image;

     int x_off = 0, y_off = 0, ret = 0, screen, use_shm = 0;

     char *dpyname, *offset;

     Colormap color_map;
     XColor color[256];
     int i;

     dpyname = av_strdup(s1->filename);

     if (!dpyname)

         goto out;
 

     offset = strchr(dpyname, '+');

     if (offset) {
         sscanf(offset, "%d,%d", &x_off, &y_off);

         if (strstr(offset, "nomouse")) {
             av_log(s1, AV_LOG_WARNING,
                    "'nomouse' specification in argument is deprecated: "
                    "use 'draw_mouse' option with value 0 instead\n");
             x11grab->draw_mouse = 0;
         }

         *offset = 0;

     }
 

     av_log(s1, AV_LOG_INFO,
            "device: %s -> display: %s x: %d y: %d width: %d height: %d\n",

            s1->filename, dpyname, x_off, y_off, x11grab->width, x11grab->height);

     dpy = XOpenDisplay(dpyname);
     av_freep(&dpyname);

     if (!dpy) {

         av_log(s1, AV_LOG_ERROR, "Could not open X display.\n");

         ret = AVERROR(EIO);
         goto out;

     }

     st = avformat_new_stream(s1, NULL);

     if (!st) {

         ret = AVERROR(ENOMEM);
         goto out;

     }

     avpriv_set_pts_info(st, 64, 1, 1000000); /* 64 bits pts in us */

     screen = DefaultScreen(dpy);
 
     if (x11grab->follow_mouse) {
         int screen_w, screen_h;
         Window w;
 
         screen_w = DisplayWidth(dpy, screen);
         screen_h = DisplayHeight(dpy, screen);

         XQueryPointer(dpy, RootWindow(dpy, screen), &w, &w, &x_off, &y_off,
                       &ret, &ret, &ret);

         x_off -= x11grab->width / 2;
         y_off -= x11grab->height / 2;

         x_off = av_clip(x_off, 0, screen_w - x11grab->width);
         y_off = av_clip(y_off, 0, screen_h - x11grab->height);

         av_log(s1, AV_LOG_INFO,
                "followmouse is enabled, resetting grabbing region to x: %d y: %d\n",
                x_off, y_off);

     }
 

     if (x11grab->use_shm) {

         use_shm = XShmQueryExtension(dpy);

         av_log(s1, AV_LOG_INFO,

                "shared memory extension %sfound\n", use_shm ? "" : "not ");

     }

     if (use_shm && setup_shm(s1, dpy, &image) < 0) {
         av_log(s1, AV_LOG_WARNING, "Falling back to XGetImage\n");
         use_shm = 0;
     }
 
     if (!use_shm) {

         image = XGetImage(dpy, RootWindow(dpy, screen),

                           x_off, y_off,

                           x11grab->width, x11grab->height,

                           AllPlanes, ZPixmap);
     }
 

     if (x11grab->draw_mouse && setup_mouse(dpy, screen) < 0) {
         av_log(s1, AV_LOG_WARNING,
                "XFixes not available, cannot draw the mouse cursor\n");
         x11grab->draw_mouse = 0;
     }
 

     x11grab->frame_size = x11grab->width * x11grab->height * image->bits_per_pixel / 8;
     x11grab->dpy        = dpy;

     x11grab->time_base  = av_inv_q(x11grab->framerate);

     x11grab->time_frame = av_gettime() / av_q2d(x11grab->time_base);

     x11grab->x_off      = x_off;
     x11grab->y_off      = y_off;
     x11grab->image      = image;
     x11grab->use_shm    = use_shm;

     ret = pixfmt_from_image(s1, image, &st->codec->pix_fmt);
     if (ret < 0)
         goto out;
 

     if (st->codec->pix_fmt == AV_PIX_FMT_PAL8) {

         color_map = DefaultColormap(dpy, screen);
         for (i = 0; i < 256; ++i)
             color[i].pixel = i;
         XQueryColors(dpy, color_map, color, 256);
         for (i = 0; i < 256; ++i)
             x11grab->palette[i] = (color[i].red   & 0xFF00) << 8 |
                                   (color[i].green & 0xFF00)      |
                                   (color[i].blue  & 0xFF00) >> 8;
         x11grab->palette_changed = 1;

     }
 
 

     st->codec->codec_type = AVMEDIA_TYPE_VIDEO;

     st->codec->codec_id   = AV_CODEC_ID_RAWVIDEO;
     st->codec->width      = x11grab->width;
     st->codec->height     = x11grab->height;
     st->codec->time_base  = x11grab->time_base;
     st->codec->bit_rate   = x11grab->frame_size * 1 / av_q2d(x11grab->time_base) * 8;

 out:

     av_free(dpyname);

     return ret;

 }
 

 /**

  * Paint a mouse pointer in an X11 image.

  *

  * @param image image to paint the mouse pointer to

  * @param s context used to retrieve original grabbing rectangle
  *          coordinates
  */

 static void paint_mouse_pointer(XImage *image, AVFormatContext *s1)

 {

     X11GrabContext *s = s1->priv_data;

     int x_off    = s->x_off;
     int y_off    = s->y_off;
     int width    = s->width;
     int height   = s->height;

     Display *dpy = s->dpy;
     XFixesCursorImage *xcim;
     int x, y;
     int line, column;
     int to_line, to_column;

     int pixstride = image->bits_per_pixel >> 3;
     /* Warning: in its insanity, xlib provides unsigned image data through a
      * char* pointer, so we have to make it uint8_t to make things not break.
      * Anyone who performs further investigation of the xlib API likely risks
      * permanent brain damage. */
     uint8_t *pix = image->data;

     Window root;

     XSetWindowAttributes attr;

 
     /* Code doesn't currently support 16-bit or PAL8 */
     if (image->bits_per_pixel != 24 && image->bits_per_pixel != 32)
         return;

     if (!s->c)

         s->c = XCreateFontCursor(dpy, XC_left_ptr);

     root = DefaultRootWindow(dpy);

     attr.cursor = s->c;

     XChangeWindowAttributes(dpy, root, CWCursor, &attr);

     xcim = XFixesGetCursorImage(dpy);

     if (!xcim) {
         av_log(s1, AV_LOG_WARNING,

                "XFixesGetCursorImage failed\n");

         return;
     }

     x = xcim->x - xcim->xhot;
     y = xcim->y - xcim->yhot;
 

     to_line   = FFMIN((y + xcim->height), (height + y_off));
     to_column = FFMIN((x + xcim->width),  (width  + x_off));

 
     for (line = FFMAX(y, y_off); line < to_line; line++) {
         for (column = FFMAX(x, x_off); column < to_column; column++) {

             int xcim_addr  = (line  - y)     * xcim->width + column - x;
             int image_addr = ((line - y_off) * width       + column - x_off) * pixstride;
             int r          = (uint8_t)(xcim->pixels[xcim_addr] >>  0);
             int g          = (uint8_t)(xcim->pixels[xcim_addr] >>  8);
             int b          = (uint8_t)(xcim->pixels[xcim_addr] >> 16);
             int a          = (uint8_t)(xcim->pixels[xcim_addr] >> 24);

 
             if (a == 255) {

                 pix[image_addr + 0] = r;
                 pix[image_addr + 1] = g;
                 pix[image_addr + 2] = b;

             } else if (a) {
                 /* pixel values from XFixesGetCursorImage come premultiplied by alpha */

                 pix[image_addr + 0] = r + (pix[image_addr + 0] * (255 - a) + 255 / 2) / 255;
                 pix[image_addr + 1] = g + (pix[image_addr + 1] * (255 - a) + 255 / 2) / 255;
                 pix[image_addr + 2] = b + (pix[image_addr + 2] * (255 - a) + 255 / 2) / 255;

             }

         }
     }

 
     XFree(xcim);
     xcim = NULL;

 }
 

 /**

  * Read new data in the image structure.

  *
  * @param dpy X11 display to grab from

  * @param d

  * @param image Image where the grab will be put
  * @param x Top-Left grabbing rectangle horizontal coordinate
  * @param y Top-Left grabbing rectangle vertical coordinate
  * @return 0 if error, !0 if successful

  */

 static int xget_zpixmap(Display *dpy, Drawable d, XImage *image, int x, int y)

 {

     xGetImageReply rep;
     xGetImageReq *req;
     long nbytes;
 

     if (!image)

         return 0;

 
     LockDisplay(dpy);
     GetReq(GetImage, req);
 
     /* First set up the standard stuff in the request */

     req->drawable  = d;
     req->x         = x;
     req->y         = y;
     req->width     = image->width;
     req->height    = image->height;

     req->planeMask = (unsigned int)AllPlanes;

     req->format    = ZPixmap;

     if (!_XReply(dpy, (xReply *)&rep, 0, xFalse) || !rep.length) {

         UnlockDisplay(dpy);
         SyncHandle();

         return 0;

     }
 
     nbytes = (long)rep.length << 2;
     _XReadPad(dpy, image->data, nbytes);
 
     UnlockDisplay(dpy);
     SyncHandle();

     return 1;

 }
 

 /**

  * Grab a frame from x11 (public device demuxer API).

  *
  * @param s1 Context from avformat core
  * @param pkt Packet holding the brabbed frame
  * @return frame size in bytes
  */

 static int x11grab_read_packet(AVFormatContext *s1, AVPacket *pkt)

 {

     X11GrabContext *s = s1->priv_data;

     Display *dpy      = s->dpy;
     XImage *image     = s->image;
     int x_off         = s->x_off;
     int y_off         = s->y_off;
     int follow_mouse  = s->follow_mouse;

     int screen, pointer_x, pointer_y, _, same_screen = 1;
     Window w, root;

     int64_t curtime, delay;
     struct timespec ts;
 
     /* Calculate the time of the next frame */

     s->time_frame += INT64_C(1000000);

 
     /* wait based on the frame rate */

     for (;;) {

         curtime = av_gettime();

         delay   = s->time_frame * av_q2d(s->time_base) - curtime;

         if (delay <= 0) {

             if (delay < INT64_C(-1000000) * av_q2d(s->time_base))

                 s->time_frame += INT64_C(1000000);

             break;
         }

         ts.tv_sec  = delay / 1000000;

         ts.tv_nsec = (delay % 1000000) * 1000;
         nanosleep(&ts, NULL);
     }
 

     av_init_packet(pkt);
     pkt->data = image->data;
     pkt->size = s->frame_size;

     pkt->pts  = curtime;

     if (s->palette_changed) {
         uint8_t *pal = av_packet_new_side_data(pkt, AV_PKT_DATA_PALETTE,
                                                AVPALETTE_SIZE);
         if (!pal) {
             av_log(s, AV_LOG_ERROR, "Cannot append palette to packet\n");
         } else {
             memcpy(pal, s->palette, AVPALETTE_SIZE);
             s->palette_changed = 0;
         }
     }

     screen = DefaultScreen(dpy);

     root   = RootWindow(dpy, screen);

 
     if (follow_mouse || s->draw_mouse)
         same_screen = XQueryPointer(dpy, root, &w, &w,
                                     &pointer_x, &pointer_y, &_, &_, &_);
 
     if (follow_mouse && same_screen) {

         int screen_w, screen_h;
 
         screen_w = DisplayWidth(dpy, screen);
         screen_h = DisplayHeight(dpy, screen);
         if (follow_mouse == -1) {
             // follow the mouse, put it at center of grabbing region

             x_off += pointer_x - s->width / 2 - x_off;

             y_off += pointer_y - s->height / 2 - y_off;
         } else {
             // follow the mouse, but only move the grabbing region when mouse
             // reaches within certain pixels to the edge.

             if (pointer_x > x_off + s->width - follow_mouse)

                 x_off += pointer_x - (x_off + s->width - follow_mouse);

             else if (pointer_x < x_off + follow_mouse)

                 x_off -= (x_off + follow_mouse) - pointer_x;

             if (pointer_y > y_off + s->height - follow_mouse)

                 y_off += pointer_y - (y_off + s->height - follow_mouse);

             else if (pointer_y < y_off + follow_mouse)

                 y_off -= (y_off + follow_mouse) - pointer_y;
         }
         // adjust grabbing region position if it goes out of screen.

         s->x_off = x_off = av_clip(x_off, 0, screen_w - s->width);
         s->y_off = y_off = av_clip(y_off, 0, screen_h - s->height);

 
         if (s->show_region && s->region_win)
             XMoveWindow(dpy, s->region_win,
                         s->x_off - REGION_WIN_BORDER,
                         s->y_off - REGION_WIN_BORDER);
     }
 

     if (s->show_region && same_screen) {

         if (s->region_win) {

             XEvent evt = { .type = NoEventMask };
             // Clean up the events, and do the initial draw or redraw.
             while (XCheckMaskEvent(dpy, ExposureMask | StructureNotifyMask,
                                    &evt))

                 ;

             if (evt.type)
                 x11grab_draw_region_win(s);
         } else {
             x11grab_region_win_init(s);
         }

     }
 

     if (s->use_shm) {
         if (!XShmGetImage(dpy, root, image, x_off, y_off, AllPlanes))
             av_log(s1, AV_LOG_INFO, "XShmGetImage() failed\n");

     } else {

         if (!xget_zpixmap(dpy, root, image, x_off, y_off))
             av_log(s1, AV_LOG_INFO, "XGetZPixmap() failed\n");

     }
 

     if (s->draw_mouse && same_screen)

         paint_mouse_pointer(image, s1);

 
     return s->frame_size;

 }
 

 /**

  * Close x11 frame grabber (public device demuxer API).

  *
  * @param s1 Context from avformat core
  * @return 0 success, !0 failure
  */

 static int x11grab_read_close(AVFormatContext *s1)

 {

     X11GrabContext *x11grab = s1->priv_data;

 
     /* Detach cleanly from shared mem */
     if (x11grab->use_shm) {
         XShmDetach(x11grab->dpy, &x11grab->shminfo);
         shmdt(x11grab->shminfo.shmaddr);
         shmctl(x11grab->shminfo.shmid, IPC_RMID, NULL);
     }
 
     /* Destroy X11 image */
     if (x11grab->image) {
         XDestroyImage(x11grab->image);
         x11grab->image = NULL;
     }
 

     if (x11grab->region_win)

         XDestroyWindow(x11grab->dpy, x11grab->region_win);
 

     /* Free X11 display */
     XCloseDisplay(x11grab->dpy);
     return 0;

 }
 

 #define OFFSET(x) offsetof(X11GrabContext, x)

 #define DEC AV_OPT_FLAG_DECODING_PARAM
 static const AVOption options[] = {

     { "grab_x", "Initial x coordinate.", OFFSET(x_off), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, DEC },
     { "grab_y", "Initial y coordinate.", OFFSET(y_off), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, DEC },

     { "draw_mouse", "draw the mouse pointer", OFFSET(draw_mouse), AV_OPT_TYPE_INT, {.i64 = 1}, 0, 1, DEC },

 
     { "follow_mouse", "move the grabbing region when the mouse pointer reaches within specified amount of pixels to the edge of region",

       OFFSET(follow_mouse), AV_OPT_TYPE_INT, {.i64 = 0}, -1, INT_MAX, DEC, "follow_mouse" },

     { "centered",     "keep the mouse pointer at the center of grabbing region when following",

       0, AV_OPT_TYPE_CONST, {.i64 = -1}, INT_MIN, INT_MAX, DEC, "follow_mouse" },

     { "framerate",  "set video frame rate",      OFFSET(framerate),   AV_OPT_TYPE_VIDEO_RATE, {.str = "ntsc"}, 0, 0, DEC },

     { "show_region", "show the grabbing region", OFFSET(show_region), AV_OPT_TYPE_INT,        {.i64 = 0}, 0, 1, DEC },

     { "video_size",  "set video frame size",     OFFSET(width),       AV_OPT_TYPE_IMAGE_SIZE, {.str = "vga"}, 0, 0, DEC },

     { "use_shm",     "use MIT-SHM extension",    OFFSET(use_shm),     AV_OPT_TYPE_INT,        {.i64 = 1}, 0, 1, DEC },

     { NULL },
 };
 
 static const AVClass x11_class = {
     .class_name = "X11grab indev",
     .item_name  = av_default_item_name,
     .option     = options,
     .version    = LIBAVUTIL_VERSION_INT,

     .category   = AV_CLASS_CATEGORY_DEVICE_VIDEO_INPUT,

 };
 

 /** x11 grabber device demuxer declaration */

 AVInputFormat ff_x11grab_demuxer = {

     .name           = "x11grab",
     .long_name      = NULL_IF_CONFIG_SMALL("X11grab"),

     .priv_data_size = sizeof(X11GrabContext),

     .read_header    = x11grab_read_header,
     .read_packet    = x11grab_read_packet,
     .read_close     = x11grab_read_close,
     .flags          = AVFMT_NOFILE,
     .priv_class     = &x11_class,

 };