libavdevice/xcbgrab.c - nest-android-app/ffmpeg - Git at Google

 /*
  * XCB input grabber
  * Copyright (C) 2014 Luca Barbato <lu_zero@gentoo.org>
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 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
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser 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
  */

 #include "config.h"

 #include <stdlib.h>
 #include <xcb/xcb.h>

 #if CONFIG_LIBXCB_XFIXES
 #include <xcb/xfixes.h>
 #endif

 #if CONFIG_LIBXCB_SHM
 #include <sys/shm.h>
 #include <xcb/shm.h>
 #endif

 #if CONFIG_LIBXCB_SHAPE
 #include <xcb/shape.h>
 #endif

 #include "libavutil/internal.h"
 #include "libavutil/mathematics.h"
 #include "libavutil/opt.h"
 #include "libavutil/parseutils.h"
 #include "libavutil/time.h"

 #include "libavformat/avformat.h"
 #include "libavformat/internal.h"

 typedef struct XCBGrabContext {
     const AVClass *class;

     xcb_connection_t *conn;
     xcb_screen_t *screen;
     xcb_window_t window;
 #if CONFIG_LIBXCB_SHM
     xcb_shm_seg_t segment;
 #endif
     int64_t time_frame;
     AVRational time_base;

     int x, y;
     int width, height;
     int frame_size;
     int bpp;

     int draw_mouse;
     int follow_mouse;
     int show_region;
     int region_border;
     int centered;

     const char *video_size;
     const char *framerate;

     int has_shm;
 } XCBGrabContext;

 #define FOLLOW_CENTER -1

 #define OFFSET(x) offsetof(XCBGrabContext, x)
 #define D AV_OPT_FLAG_DECODING_PARAM
 static const AVOption options[] = {
     { "x", "Initial x coordinate.", OFFSET(x), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, D },
     { "y", "Initial y coordinate.", OFFSET(y), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, D },
     { "grab_x", "Initial x coordinate.", OFFSET(x), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, D },
     { "grab_y", "Initial y coordinate.", OFFSET(y), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, D },
     { "video_size", "A string describing frame size, such as 640x480 or hd720.", OFFSET(video_size), AV_OPT_TYPE_STRING, {.str = "vga" }, 0, 0, D },
     { "framerate", "", OFFSET(framerate), AV_OPT_TYPE_STRING, {.str = "ntsc" }, 0, 0, D },
     { "draw_mouse", "Draw the mouse pointer.", OFFSET(draw_mouse), AV_OPT_TYPE_INT, { .i64 = 1 }, 0, 1, D },
     { "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 },  FOLLOW_CENTER, INT_MAX, D, "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, D, "follow_mouse" },
     { "show_region", "Show the grabbing region.", OFFSET(show_region), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, D },
     { "region_border", "Set the region border thickness.", OFFSET(region_border), AV_OPT_TYPE_INT, { .i64 = 3 }, 1, 128, D },
     { NULL },
 };

 static const AVClass xcbgrab_class = {
     .class_name = "xcbgrab indev",
     .item_name  = av_default_item_name,
     .option     = options,
     .version    = LIBAVUTIL_VERSION_INT,
     .category   = AV_CLASS_CATEGORY_DEVICE_VIDEO_INPUT,
 };

 static int xcbgrab_reposition(AVFormatContext *s,
                               xcb_query_pointer_reply_t *p,
                               xcb_get_geometry_reply_t *geo)
 {
     XCBGrabContext *c = s->priv_data;
     int x = c->x, y = c->y;
     int w = c->width, h = c->height, f = c->follow_mouse;
     int p_x, p_y;

     if (!p || !geo)
         return AVERROR(EIO);

     p_x = p->win_x;
     p_y = p->win_y;

     if (f == FOLLOW_CENTER) {
         x = p_x - w / 2;
         y = p_y - h / 2;
     } else {
         int left   = x + f;
         int right  = x + w - f;
         int top    = y + f;
         int bottom = y + h + f;
         if (p_x > right) {
             x += p_x - right;
         } else if (p_x < left) {
             x -= left - p_x;
         }
         if (p_y > bottom) {
             y += p_y - bottom;
         } else if (p_y < top) {
             y -= top - p_y;
         }
     }

     c->x = FFMIN(FFMAX(0, x), geo->width  - w);
     c->y = FFMIN(FFMAX(0, y), geo->height - h);

     return 0;
 }

 static int xcbgrab_frame(AVFormatContext *s, AVPacket *pkt)
 {
     XCBGrabContext *c = s->priv_data;
     xcb_get_image_cookie_t iq;
     xcb_get_image_reply_t *img;
     xcb_drawable_t drawable = c->screen->root;
     xcb_generic_error_t *e = NULL;
     uint8_t *data;
     int length, ret;

     iq  = xcb_get_image(c->conn, XCB_IMAGE_FORMAT_Z_PIXMAP, drawable,
                         c->x, c->y, c->width, c->height, ~0);

     img = xcb_get_image_reply(c->conn, iq, &e);

     if (e) {
         av_log(s, AV_LOG_ERROR,
                "Cannot get the image data "
                "event_error: response_type:%u error_code:%u "
                "sequence:%u resource_id:%u minor_code:%u major_code:%u.\n",
                e->response_type, e->error_code,
                e->sequence, e->resource_id, e->minor_code, e->major_code);
         return AVERROR(EACCES);
     }

     if (!img)
         return AVERROR(EAGAIN);

     data   = xcb_get_image_data(img);
     length = xcb_get_image_data_length(img);

     ret = av_new_packet(pkt, length);

     if (!ret)
         memcpy(pkt->data, data, length);

     free(img);

     return ret;
 }

 static void wait_frame(AVFormatContext *s, AVPacket *pkt)
 {
     XCBGrabContext *c = s->priv_data;
     int64_t curtime, delay;
     int64_t frame_time = av_rescale_q(1, c->time_base, AV_TIME_BASE_Q);

     c->time_frame += frame_time;

     for (;;) {
         curtime = av_gettime();
         delay   = c->time_frame - curtime;
         if (delay <= 0)
             break;
         av_usleep(delay);
     }

     pkt->pts = curtime;
 }

 #if CONFIG_LIBXCB_SHM
 static int check_shm(xcb_connection_t *conn)
 {
     xcb_shm_query_version_cookie_t cookie = xcb_shm_query_version(conn);
     xcb_shm_query_version_reply_t *reply;

     reply = xcb_shm_query_version_reply(conn, cookie, NULL);
     if (reply) {
         free(reply);
         return 1;
     }

     return 0;
 }

 static void dealloc_shm(void *unused, uint8_t *data)
 {
     shmdt(data);
 }

 static int xcbgrab_frame_shm(AVFormatContext *s, AVPacket *pkt)
 {
     XCBGrabContext *c = s->priv_data;
     xcb_shm_get_image_cookie_t iq;
     xcb_shm_get_image_reply_t *img;
     xcb_drawable_t drawable = c->screen->root;
     uint8_t *data;
     int size = c->frame_size + AV_INPUT_BUFFER_PADDING_SIZE;
     int id   = shmget(IPC_PRIVATE, size, IPC_CREAT | 0777);
     xcb_generic_error_t *e = NULL;

     if (id == -1) {
         char errbuf[1024];
         int err = AVERROR(errno);
         av_strerror(err, errbuf, sizeof(errbuf));
         av_log(s, AV_LOG_ERROR, "Cannot get %d bytes of shared memory: %s.\n",
                size, errbuf);
         return err;
     }

     xcb_shm_attach(c->conn, c->segment, id, 0);

     iq = xcb_shm_get_image(c->conn, drawable,
                            c->x, c->y, c->width, c->height, ~0,
                            XCB_IMAGE_FORMAT_Z_PIXMAP, c->segment, 0);

     xcb_shm_detach(c->conn, c->segment);

     img = xcb_shm_get_image_reply(c->conn, iq, &e);

     xcb_flush(c->conn);

     if (e) {
         av_log(s, AV_LOG_ERROR,
                "Cannot get the image data "
                "event_error: response_type:%u error_code:%u "
                "sequence:%u resource_id:%u minor_code:%u major_code:%u.\n",
                e->response_type, e->error_code,
                e->sequence, e->resource_id, e->minor_code, e->major_code);

         shmctl(id, IPC_RMID, 0);
         return AVERROR(EACCES);
     }

     free(img);

     data = shmat(id, NULL, 0);
     shmctl(id, IPC_RMID, 0);

     if ((intptr_t)data == -1)
         return AVERROR(errno);

     pkt->buf = av_buffer_create(data, size, dealloc_shm, NULL, 0);
     if (!pkt->buf) {
         shmdt(data);
         return AVERROR(ENOMEM);
     }

     pkt->data = pkt->buf->data;
     pkt->size = c->frame_size;

     return 0;
 }
 #endif /* CONFIG_LIBXCB_SHM */

 #if CONFIG_LIBXCB_XFIXES
 static int check_xfixes(xcb_connection_t *conn)
 {
     xcb_xfixes_query_version_cookie_t cookie;
     xcb_xfixes_query_version_reply_t *reply;

     cookie = xcb_xfixes_query_version(conn, XCB_XFIXES_MAJOR_VERSION,
                                       XCB_XFIXES_MINOR_VERSION);
     reply  = xcb_xfixes_query_version_reply(conn, cookie, NULL);

     if (reply) {
         free(reply);
         return 1;
     }
     return 0;
 }

 #define BLEND(target, source, alpha) \
     (target) + ((source) * (255 - (alpha)) + 255 / 2) / 255

 static void xcbgrab_draw_mouse(AVFormatContext *s, AVPacket *pkt,
                                xcb_query_pointer_reply_t *p,
                                xcb_get_geometry_reply_t *geo)
 {
     XCBGrabContext *gr = s->priv_data;
     uint32_t *cursor;
     uint8_t *image = pkt->data;
     int stride     = gr->bpp / 8;
     xcb_xfixes_get_cursor_image_cookie_t cc;
     xcb_xfixes_get_cursor_image_reply_t *ci;
     int cx, cy, x, y, w, h, c_off, i_off;

     cc = xcb_xfixes_get_cursor_image(gr->conn);
     ci = xcb_xfixes_get_cursor_image_reply(gr->conn, cc, NULL);
     if (!ci)
         return;

     cursor = xcb_xfixes_get_cursor_image_cursor_image(ci);
     if (!cursor)
         return;

     cx = ci->x - ci->xhot;
     cy = ci->y - ci->yhot;

     x = FFMAX(cx, gr->x);
     y = FFMAX(cy, gr->y);

     w = FFMIN(cx + ci->width,  gr->x + gr->width)  - x;
     h = FFMIN(cy + ci->height, gr->y + gr->height) - y;

     c_off = x - cx;
     i_off = x - gr->x;

     cursor += (y - cy) * ci->width;
     image  += (y - gr->y) * gr->width * stride;

     for (y = 0; y < h; y++) {
         cursor += c_off;
         image  += i_off * stride;
         for (x = 0; x < w; x++, cursor++, image += stride) {
             int r, g, b, a;

             r =  *cursor        & 0xff;
             g = (*cursor >>  8) & 0xff;
             b = (*cursor >> 16) & 0xff;
             a = (*cursor >> 24) & 0xff;

             if (!a)
                 continue;

             if (a == 255) {
                 image[0] = r;
                 image[1] = g;
                 image[2] = b;
             } else {
                 image[0] = BLEND(r, image[0], a);
                 image[1] = BLEND(g, image[1], a);
                 image[2] = BLEND(b, image[2], a);
             }

         }
         cursor +=  ci->width - w - c_off;
         image  += (gr->width - w - i_off) * stride;
     }

     free(ci);
 }
 #endif /* CONFIG_LIBXCB_XFIXES */

 static void xcbgrab_update_region(AVFormatContext *s)
 {
     XCBGrabContext *c     = s->priv_data;
     const uint32_t args[] = { c->x - c->region_border,
                               c->y - c->region_border };

     xcb_configure_window(c->conn,
                          c->window,
                          XCB_CONFIG_WINDOW_X | XCB_CONFIG_WINDOW_Y,
                          args);
 }

 static int xcbgrab_read_packet(AVFormatContext *s, AVPacket *pkt)
 {
     XCBGrabContext *c = s->priv_data;
     xcb_query_pointer_cookie_t pc;
     xcb_get_geometry_cookie_t gc;
     xcb_query_pointer_reply_t *p  = NULL;
     xcb_get_geometry_reply_t *geo = NULL;
     int ret = 0;

     wait_frame(s, pkt);

     if (c->follow_mouse || c->draw_mouse) {
         pc  = xcb_query_pointer(c->conn, c->screen->root);
         gc  = xcb_get_geometry(c->conn, c->screen->root);
         p   = xcb_query_pointer_reply(c->conn, pc, NULL);
         geo = xcb_get_geometry_reply(c->conn, gc, NULL);
     }

     if (c->follow_mouse && p->same_screen)
         xcbgrab_reposition(s, p, geo);

     if (c->show_region)
         xcbgrab_update_region(s);

 #if CONFIG_LIBXCB_SHM
     if (c->has_shm && xcbgrab_frame_shm(s, pkt) < 0)
         c->has_shm = 0;
 #endif
     if (!c->has_shm)
         ret = xcbgrab_frame(s, pkt);

 #if CONFIG_LIBXCB_XFIXES
     if (ret >= 0 && c->draw_mouse && p->same_screen)
         xcbgrab_draw_mouse(s, pkt, p, geo);
 #endif

     free(p);
     free(geo);

     return ret;
 }

 static av_cold int xcbgrab_read_close(AVFormatContext *s)
 {
     XCBGrabContext *ctx = s->priv_data;

     xcb_disconnect(ctx->conn);

     return 0;
 }

 static xcb_screen_t *get_screen(const xcb_setup_t *setup, int screen_num)
 {
     xcb_screen_iterator_t it = xcb_setup_roots_iterator(setup);
     xcb_screen_t *screen     = NULL;

     for (; it.rem > 0; xcb_screen_next (&it)) {
         if (!screen_num) {
             screen = it.data;
             break;
         }

         screen_num--;
     }

     return screen;
 }

 static int pixfmt_from_pixmap_format(AVFormatContext *s, int depth,
                                      int *pix_fmt)
 {
     XCBGrabContext *c        = s->priv_data;
     const xcb_setup_t *setup = xcb_get_setup(c->conn);
     const xcb_format_t *fmt  = xcb_setup_pixmap_formats(setup);
     int length               = xcb_setup_pixmap_formats_length(setup);

     *pix_fmt = 0;

     while (length--) {
         if (fmt->depth == depth) {
             switch (depth) {
             case 32:
                 if (fmt->bits_per_pixel == 32)
                     *pix_fmt = AV_PIX_FMT_0RGB;
                 break;
             case 24:
                 if (fmt->bits_per_pixel == 32)
                     *pix_fmt = AV_PIX_FMT_0RGB32;
                 else if (fmt->bits_per_pixel == 24)
                     *pix_fmt = AV_PIX_FMT_RGB24;
                 break;
             case 16:
                 if (fmt->bits_per_pixel == 16)
                     *pix_fmt = AV_PIX_FMT_RGB565;
                 break;
             case 15:
                 if (fmt->bits_per_pixel == 16)
                     *pix_fmt = AV_PIX_FMT_RGB555;
                 break;
             case 8:
                 if (fmt->bits_per_pixel == 8)
                     *pix_fmt = AV_PIX_FMT_RGB8;
                 break;
             }
         }

         if (*pix_fmt) {
             c->bpp        = fmt->bits_per_pixel;
             c->frame_size = c->width * c->height * fmt->bits_per_pixel / 8;
             return 0;
         }

         fmt++;
     }
     av_log(s, AV_LOG_ERROR, "Pixmap format not mappable.\n");

     return AVERROR_PATCHWELCOME;
 }

 static int create_stream(AVFormatContext *s)
 {
     XCBGrabContext *c = s->priv_data;
     AVStream *st      = avformat_new_stream(s, NULL);
     xcb_get_geometry_cookie_t gc;
     xcb_get_geometry_reply_t *geo;
     int ret;

     if (!st)
         return AVERROR(ENOMEM);

     ret = av_parse_video_size(&c->width, &c->height, c->video_size);
     if (ret < 0)
         return ret;

     ret = av_parse_video_rate(&st->avg_frame_rate, c->framerate);
     if (ret < 0)
         return ret;

     avpriv_set_pts_info(st, 64, 1, 1000000);

     gc  = xcb_get_geometry(c->conn, c->screen->root);
     geo = xcb_get_geometry_reply(c->conn, gc, NULL);

     if (c->x + c->width > geo->width ||
         c->y + c->height > geo->height) {
         av_log(s, AV_LOG_ERROR,
                "Capture area %dx%d at position %d.%d "
                "outside the screen size %dx%d\n",
                c->width, c->height,
                c->x, c->y,
                geo->width, geo->height);
         return AVERROR(EINVAL);
     }

     c->time_base  = (AVRational){ st->avg_frame_rate.den,
                                   st->avg_frame_rate.num };
     c->time_frame = av_gettime();

     st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
     st->codec->codec_id   = AV_CODEC_ID_RAWVIDEO;
     st->codec->width      = c->width;
     st->codec->height     = c->height;
     st->codec->time_base  = c->time_base;

     ret = pixfmt_from_pixmap_format(s, geo->depth, &st->codec->pix_fmt);

     free(geo);

     return ret;
 }

 static void draw_rectangle(AVFormatContext *s)
 {
     XCBGrabContext *c = s->priv_data;
     xcb_gcontext_t gc = xcb_generate_id(c->conn);
     uint32_t mask     = XCB_GC_FOREGROUND |
                         XCB_GC_BACKGROUND |
                         XCB_GC_LINE_WIDTH |
                         XCB_GC_LINE_STYLE |
                         XCB_GC_FILL_STYLE;
     uint32_t values[] = { c->screen->black_pixel,
                           c->screen->white_pixel,
                           c->region_border,
                           XCB_LINE_STYLE_DOUBLE_DASH,
                           XCB_FILL_STYLE_SOLID };
     xcb_rectangle_t r = { 1, 1,
                           c->width  + c->region_border * 2 - 3,
                           c->height + c->region_border * 2 - 3 };

     xcb_create_gc(c->conn, gc, c->window, mask, values);

     xcb_poly_rectangle(c->conn, c->window, gc, 1, &r);
 }

 static void setup_window(AVFormatContext *s)
 {
     XCBGrabContext *c = s->priv_data;
     uint32_t mask     = XCB_CW_OVERRIDE_REDIRECT | XCB_CW_EVENT_MASK;
     uint32_t values[] = { 1,
                           XCB_EVENT_MASK_EXPOSURE |
                           XCB_EVENT_MASK_STRUCTURE_NOTIFY };
     av_unused xcb_rectangle_t rect = { 0, 0, c->width, c->height };

     c->window = xcb_generate_id(c->conn);

     xcb_create_window(c->conn, XCB_COPY_FROM_PARENT,
                       c->window,
                       c->screen->root,
                       c->x - c->region_border,
                       c->y - c->region_border,
                       c->width + c->region_border * 2,
                       c->height + c->region_border * 2,
                       0,
                       XCB_WINDOW_CLASS_INPUT_OUTPUT,
                       XCB_COPY_FROM_PARENT,
                       mask, values);

 #if CONFIG_LIBXCB_SHAPE
     xcb_shape_rectangles(c->conn, XCB_SHAPE_SO_SUBTRACT,
                          XCB_SHAPE_SK_BOUNDING, XCB_CLIP_ORDERING_UNSORTED,
                          c->window,
                          c->region_border, c->region_border,
                          1, &rect);
 #endif

     xcb_map_window(c->conn, c->window);

     draw_rectangle(s);
 }

 static av_cold int xcbgrab_read_header(AVFormatContext *s)
 {
     XCBGrabContext *c = s->priv_data;
     int screen_num, ret;
     const xcb_setup_t *setup;
     char *display_name = av_strdup(s->filename);

     if (!display_name)
         return AVERROR(ENOMEM);

     if (!sscanf(s->filename, "%[^+]+%d,%d", display_name, &c->x, &c->y)) {
         *display_name = 0;
         sscanf(s->filename, "+%d,%d", &c->x, &c->y);
     }

     c->conn = xcb_connect(display_name[0] ? display_name : NULL, &screen_num);
     av_freep(&display_name);

     if ((ret = xcb_connection_has_error(c->conn))) {
         av_log(s, AV_LOG_ERROR, "Cannot open display %s, error %d.\n",
                s->filename[0] ? s->filename : "default", ret);
         return AVERROR(EIO);
     }

     setup = xcb_get_setup(c->conn);

     c->screen = get_screen(setup, screen_num);
     if (!c->screen) {
         av_log(s, AV_LOG_ERROR, "The screen %d does not exist.\n",
                screen_num);
         xcbgrab_read_close(s);
         return AVERROR(EIO);
     }

     ret = create_stream(s);

     if (ret < 0) {
         xcbgrab_read_close(s);
         return ret;
     }

 #if CONFIG_LIBXCB_SHM
     if ((c->has_shm = check_shm(c->conn)))
         c->segment = xcb_generate_id(c->conn);
 #endif

 #if CONFIG_LIBXCB_XFIXES
     if (c->draw_mouse) {
         if (!(c->draw_mouse = check_xfixes(c->conn))) {
             av_log(s, AV_LOG_WARNING,
                    "XFixes not available, cannot draw the mouse.\n");
         }
         if (c->bpp < 24) {
             avpriv_report_missing_feature(s, "%d bits per pixel screen",
                                           c->bpp);
             c->draw_mouse = 0;
         }
     }
 #endif

     if (c->show_region)
         setup_window(s);

     return 0;
 }

 AVInputFormat ff_x11grab_xcb_demuxer = {
     .name           = "x11grab",
     .long_name      = NULL_IF_CONFIG_SMALL("X11 screen capture, using XCB"),
     .priv_data_size = sizeof(XCBGrabContext),
     .read_header    = xcbgrab_read_header,
     .read_packet    = xcbgrab_read_packet,
     .read_close     = xcbgrab_read_close,
     .flags          = AVFMT_NOFILE,
     .priv_class     = &xcbgrab_class,
 };
	/*
	* XCB input grabber
	* Copyright (C) 2014 Luca Barbato <lu_zero@gentoo.org>
	*
	* This file is part of FFmpeg.
	*
	* FFmpeg is free software; you can redistribute it and/or
	* modify it under the terms of the GNU Lesser General Public
	* License as published by the Free Software Foundation; either
	* version 2.1 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
	* Lesser General Public License for more details.
	*
	* You should have received a copy of the GNU Lesser 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
	*/

	#include "config.h"

	#include <stdlib.h>
	#include <xcb/xcb.h>

	#if CONFIG_LIBXCB_XFIXES
	#include <xcb/xfixes.h>
	#endif

	#if CONFIG_LIBXCB_SHM
	#include <sys/shm.h>
	#include <xcb/shm.h>
	#endif

	#if CONFIG_LIBXCB_SHAPE
	#include <xcb/shape.h>
	#endif

	#include "libavutil/internal.h"
	#include "libavutil/mathematics.h"
	#include "libavutil/opt.h"
	#include "libavutil/parseutils.h"
	#include "libavutil/time.h"

	#include "libavformat/avformat.h"
	#include "libavformat/internal.h"

	typedef struct XCBGrabContext {
	const AVClass *class;

	xcb_connection_t *conn;
	xcb_screen_t *screen;
	xcb_window_t window;
	#if CONFIG_LIBXCB_SHM
	xcb_shm_seg_t segment;
	#endif
	int64_t time_frame;
	AVRational time_base;

	int x, y;
	int width, height;
	int frame_size;
	int bpp;

	int draw_mouse;
	int follow_mouse;
	int show_region;
	int region_border;
	int centered;

	const char *video_size;
	const char *framerate;

	int has_shm;
	} XCBGrabContext;

	#define FOLLOW_CENTER -1

	#define OFFSET(x) offsetof(XCBGrabContext, x)
	#define D AV_OPT_FLAG_DECODING_PARAM
	static const AVOption options[] = {
	{ "x", "Initial x coordinate.", OFFSET(x), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, D },
	{ "y", "Initial y coordinate.", OFFSET(y), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, D },
	{ "grab_x", "Initial x coordinate.", OFFSET(x), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, D },
	{ "grab_y", "Initial y coordinate.", OFFSET(y), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, D },
	{ "video_size", "A string describing frame size, such as 640x480 or hd720.", OFFSET(video_size), AV_OPT_TYPE_STRING, {.str = "vga" }, 0, 0, D },
	{ "framerate", "", OFFSET(framerate), AV_OPT_TYPE_STRING, {.str = "ntsc" }, 0, 0, D },
	{ "draw_mouse", "Draw the mouse pointer.", OFFSET(draw_mouse), AV_OPT_TYPE_INT, { .i64 = 1 }, 0, 1, D },
	{ "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 }, FOLLOW_CENTER, INT_MAX, D, "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, D, "follow_mouse" },
	{ "show_region", "Show the grabbing region.", OFFSET(show_region), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, D },
	{ "region_border", "Set the region border thickness.", OFFSET(region_border), AV_OPT_TYPE_INT, { .i64 = 3 }, 1, 128, D },
	{ NULL },
	};

	static const AVClass xcbgrab_class = {
	.class_name = "xcbgrab indev",
	.item_name = av_default_item_name,
	.option = options,
	.version = LIBAVUTIL_VERSION_INT,
	.category = AV_CLASS_CATEGORY_DEVICE_VIDEO_INPUT,
	};

	static int xcbgrab_reposition(AVFormatContext *s,
	xcb_query_pointer_reply_t *p,
	xcb_get_geometry_reply_t *geo)
	{
	XCBGrabContext *c = s->priv_data;
	int x = c->x, y = c->y;
	int w = c->width, h = c->height, f = c->follow_mouse;
	int p_x, p_y;

	if (!p \|\| !geo)
	return AVERROR(EIO);

	p_x = p->win_x;
	p_y = p->win_y;

	if (f == FOLLOW_CENTER) {
	x = p_x - w / 2;
	y = p_y - h / 2;
	} else {
	int left = x + f;
	int right = x + w - f;
	int top = y + f;
	int bottom = y + h + f;
	if (p_x > right) {
	x += p_x - right;
	} else if (p_x < left) {
	x -= left - p_x;
	}
	if (p_y > bottom) {
	y += p_y - bottom;
	} else if (p_y < top) {
	y -= top - p_y;
	}
	}

	c->x = FFMIN(FFMAX(0, x), geo->width - w);
	c->y = FFMIN(FFMAX(0, y), geo->height - h);

	return 0;
	}

	static int xcbgrab_frame(AVFormatContext s, AVPacket pkt)
	{
	XCBGrabContext *c = s->priv_data;
	xcb_get_image_cookie_t iq;
	xcb_get_image_reply_t *img;
	xcb_drawable_t drawable = c->screen->root;
	xcb_generic_error_t *e = NULL;
	uint8_t *data;
	int length, ret;

	iq = xcb_get_image(c->conn, XCB_IMAGE_FORMAT_Z_PIXMAP, drawable,
	c->x, c->y, c->width, c->height, ~0);

	img = xcb_get_image_reply(c->conn, iq, &e);

	if (e) {
	av_log(s, AV_LOG_ERROR,
	"Cannot get the image data "
	"event_error: response_type:%u error_code:%u "
	"sequence:%u resource_id:%u minor_code:%u major_code:%u.\n",
	e->response_type, e->error_code,
	e->sequence, e->resource_id, e->minor_code, e->major_code);
	return AVERROR(EACCES);
	}

	if (!img)
	return AVERROR(EAGAIN);

	data = xcb_get_image_data(img);
	length = xcb_get_image_data_length(img);

	ret = av_new_packet(pkt, length);

	if (!ret)
	memcpy(pkt->data, data, length);

	free(img);

	return ret;
	}

	static void wait_frame(AVFormatContext s, AVPacket pkt)
	{
	XCBGrabContext *c = s->priv_data;
	int64_t curtime, delay;
	int64_t frame_time = av_rescale_q(1, c->time_base, AV_TIME_BASE_Q);

	c->time_frame += frame_time;

	for (;;) {
	curtime = av_gettime();
	delay = c->time_frame - curtime;
	if (delay <= 0)
	break;
	av_usleep(delay);
	}

	pkt->pts = curtime;
	}

	#if CONFIG_LIBXCB_SHM
	static int check_shm(xcb_connection_t *conn)
	{
	xcb_shm_query_version_cookie_t cookie = xcb_shm_query_version(conn);
	xcb_shm_query_version_reply_t *reply;

	reply = xcb_shm_query_version_reply(conn, cookie, NULL);
	if (reply) {
	free(reply);
	return 1;
	}

	return 0;
	}

	static void dealloc_shm(void unused, uint8_t data)
	{
	shmdt(data);
	}

	static int xcbgrab_frame_shm(AVFormatContext s, AVPacket pkt)
	{
	XCBGrabContext *c = s->priv_data;
	xcb_shm_get_image_cookie_t iq;
	xcb_shm_get_image_reply_t *img;
	xcb_drawable_t drawable = c->screen->root;
	uint8_t *data;
	int size = c->frame_size + AV_INPUT_BUFFER_PADDING_SIZE;
	int id = shmget(IPC_PRIVATE, size, IPC_CREAT \| 0777);
	xcb_generic_error_t *e = NULL;

	if (id == -1) {
	char errbuf[1024];
	int err = AVERROR(errno);
	av_strerror(err, errbuf, sizeof(errbuf));
	av_log(s, AV_LOG_ERROR, "Cannot get %d bytes of shared memory: %s.\n",
	size, errbuf);
	return err;
	}

	xcb_shm_attach(c->conn, c->segment, id, 0);

	iq = xcb_shm_get_image(c->conn, drawable,
	c->x, c->y, c->width, c->height, ~0,
	XCB_IMAGE_FORMAT_Z_PIXMAP, c->segment, 0);

	xcb_shm_detach(c->conn, c->segment);

	img = xcb_shm_get_image_reply(c->conn, iq, &e);

	xcb_flush(c->conn);

	if (e) {
	av_log(s, AV_LOG_ERROR,
	"Cannot get the image data "
	"event_error: response_type:%u error_code:%u "
	"sequence:%u resource_id:%u minor_code:%u major_code:%u.\n",
	e->response_type, e->error_code,
	e->sequence, e->resource_id, e->minor_code, e->major_code);

	shmctl(id, IPC_RMID, 0);
	return AVERROR(EACCES);
	}

	free(img);

	data = shmat(id, NULL, 0);
	shmctl(id, IPC_RMID, 0);

	if ((intptr_t)data == -1)
	return AVERROR(errno);

	pkt->buf = av_buffer_create(data, size, dealloc_shm, NULL, 0);
	if (!pkt->buf) {
	shmdt(data);
	return AVERROR(ENOMEM);
	}

	pkt->data = pkt->buf->data;
	pkt->size = c->frame_size;

	return 0;
	}
	#endif /* CONFIG_LIBXCB_SHM */

	#if CONFIG_LIBXCB_XFIXES
	static int check_xfixes(xcb_connection_t *conn)
	{
	xcb_xfixes_query_version_cookie_t cookie;
	xcb_xfixes_query_version_reply_t *reply;

	cookie = xcb_xfixes_query_version(conn, XCB_XFIXES_MAJOR_VERSION,
	XCB_XFIXES_MINOR_VERSION);
	reply = xcb_xfixes_query_version_reply(conn, cookie, NULL);

	if (reply) {
	free(reply);
	return 1;
	}
	return 0;
	}

	#define BLEND(target, source, alpha) \
	(target) + ((source) * (255 - (alpha)) + 255 / 2) / 255

	static void xcbgrab_draw_mouse(AVFormatContext s, AVPacket pkt,
	xcb_query_pointer_reply_t *p,
	xcb_get_geometry_reply_t *geo)
	{
	XCBGrabContext *gr = s->priv_data;
	uint32_t *cursor;
	uint8_t *image = pkt->data;
	int stride = gr->bpp / 8;
	xcb_xfixes_get_cursor_image_cookie_t cc;
	xcb_xfixes_get_cursor_image_reply_t *ci;
	int cx, cy, x, y, w, h, c_off, i_off;

	cc = xcb_xfixes_get_cursor_image(gr->conn);
	ci = xcb_xfixes_get_cursor_image_reply(gr->conn, cc, NULL);
	if (!ci)
	return;

	cursor = xcb_xfixes_get_cursor_image_cursor_image(ci);
	if (!cursor)
	return;

	cx = ci->x - ci->xhot;
	cy = ci->y - ci->yhot;

	x = FFMAX(cx, gr->x);
	y = FFMAX(cy, gr->y);

	w = FFMIN(cx + ci->width, gr->x + gr->width) - x;
	h = FFMIN(cy + ci->height, gr->y + gr->height) - y;

	c_off = x - cx;
	i_off = x - gr->x;

	cursor += (y - cy) * ci->width;
	image += (y - gr->y) * gr->width * stride;

	for (y = 0; y < h; y++) {
	cursor += c_off;
	image += i_off * stride;
	for (x = 0; x < w; x++, cursor++, image += stride) {
	int r, g, b, a;

	r = *cursor & 0xff;
	g = (*cursor >> 8) & 0xff;
	b = (*cursor >> 16) & 0xff;
	a = (*cursor >> 24) & 0xff;

	if (!a)
	continue;

	if (a == 255) {
	image[0] = r;
	image[1] = g;
	image[2] = b;
	} else {
	image[0] = BLEND(r, image[0], a);
	image[1] = BLEND(g, image[1], a);
	image[2] = BLEND(b, image[2], a);
	}

	}
	cursor += ci->width - w - c_off;
	image += (gr->width - w - i_off) * stride;
	}

	free(ci);
	}
	#endif /* CONFIG_LIBXCB_XFIXES */

	static void xcbgrab_update_region(AVFormatContext *s)
	{
	XCBGrabContext *c = s->priv_data;
	const uint32_t args[] = { c->x - c->region_border,
	c->y - c->region_border };

	xcb_configure_window(c->conn,
	c->window,
	XCB_CONFIG_WINDOW_X \| XCB_CONFIG_WINDOW_Y,
	args);
	}

	static int xcbgrab_read_packet(AVFormatContext s, AVPacket pkt)
	{
	XCBGrabContext *c = s->priv_data;
	xcb_query_pointer_cookie_t pc;
	xcb_get_geometry_cookie_t gc;
	xcb_query_pointer_reply_t *p = NULL;
	xcb_get_geometry_reply_t *geo = NULL;
	int ret = 0;

	wait_frame(s, pkt);

	if (c->follow_mouse \|\| c->draw_mouse) {
	pc = xcb_query_pointer(c->conn, c->screen->root);
	gc = xcb_get_geometry(c->conn, c->screen->root);
	p = xcb_query_pointer_reply(c->conn, pc, NULL);
	geo = xcb_get_geometry_reply(c->conn, gc, NULL);
	}

	if (c->follow_mouse && p->same_screen)
	xcbgrab_reposition(s, p, geo);

	if (c->show_region)
	xcbgrab_update_region(s);

	#if CONFIG_LIBXCB_SHM
	if (c->has_shm && xcbgrab_frame_shm(s, pkt) < 0)
	c->has_shm = 0;
	#endif
	if (!c->has_shm)
	ret = xcbgrab_frame(s, pkt);

	#if CONFIG_LIBXCB_XFIXES
	if (ret >= 0 && c->draw_mouse && p->same_screen)
	xcbgrab_draw_mouse(s, pkt, p, geo);
	#endif

	free(p);
	free(geo);

	return ret;
	}

	static av_cold int xcbgrab_read_close(AVFormatContext *s)
	{
	XCBGrabContext *ctx = s->priv_data;

	xcb_disconnect(ctx->conn);

	return 0;
	}

	static xcb_screen_t get_screen(const xcb_setup_t setup, int screen_num)
	{
	xcb_screen_iterator_t it = xcb_setup_roots_iterator(setup);
	xcb_screen_t *screen = NULL;

	for (; it.rem > 0; xcb_screen_next (&it)) {
	if (!screen_num) {
	screen = it.data;
	break;
	}

	screen_num--;
	}

	return screen;
	}

	static int pixfmt_from_pixmap_format(AVFormatContext *s, int depth,
	int *pix_fmt)
	{
	XCBGrabContext *c = s->priv_data;
	const xcb_setup_t *setup = xcb_get_setup(c->conn);
	const xcb_format_t *fmt = xcb_setup_pixmap_formats(setup);
	int length = xcb_setup_pixmap_formats_length(setup);

	*pix_fmt = 0;

	while (length--) {
	if (fmt->depth == depth) {
	switch (depth) {
	case 32:
	if (fmt->bits_per_pixel == 32)
	*pix_fmt = AV_PIX_FMT_0RGB;
	break;
	case 24:
	if (fmt->bits_per_pixel == 32)
	*pix_fmt = AV_PIX_FMT_0RGB32;
	else if (fmt->bits_per_pixel == 24)
	*pix_fmt = AV_PIX_FMT_RGB24;
	break;
	case 16:
	if (fmt->bits_per_pixel == 16)
	*pix_fmt = AV_PIX_FMT_RGB565;
	break;
	case 15:
	if (fmt->bits_per_pixel == 16)
	*pix_fmt = AV_PIX_FMT_RGB555;
	break;
	case 8:
	if (fmt->bits_per_pixel == 8)
	*pix_fmt = AV_PIX_FMT_RGB8;
	break;
	}
	}

	if (*pix_fmt) {
	c->bpp = fmt->bits_per_pixel;
	c->frame_size = c->width * c->height * fmt->bits_per_pixel / 8;
	return 0;
	}

	fmt++;
	}
	av_log(s, AV_LOG_ERROR, "Pixmap format not mappable.\n");

	return AVERROR_PATCHWELCOME;
	}

	static int create_stream(AVFormatContext *s)
	{
	XCBGrabContext *c = s->priv_data;
	AVStream *st = avformat_new_stream(s, NULL);
	xcb_get_geometry_cookie_t gc;
	xcb_get_geometry_reply_t *geo;
	int ret;

	if (!st)
	return AVERROR(ENOMEM);

	ret = av_parse_video_size(&c->width, &c->height, c->video_size);
	if (ret < 0)
	return ret;

	ret = av_parse_video_rate(&st->avg_frame_rate, c->framerate);
	if (ret < 0)
	return ret;

	avpriv_set_pts_info(st, 64, 1, 1000000);

	gc = xcb_get_geometry(c->conn, c->screen->root);
	geo = xcb_get_geometry_reply(c->conn, gc, NULL);

	if (c->x + c->width > geo->width \|\|
	c->y + c->height > geo->height) {
	av_log(s, AV_LOG_ERROR,
	"Capture area %dx%d at position %d.%d "
	"outside the screen size %dx%d\n",
	c->width, c->height,
	c->x, c->y,
	geo->width, geo->height);
	return AVERROR(EINVAL);
	}

	c->time_base = (AVRational){ st->avg_frame_rate.den,
	st->avg_frame_rate.num };
	c->time_frame = av_gettime();

	st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
	st->codec->codec_id = AV_CODEC_ID_RAWVIDEO;
	st->codec->width = c->width;
	st->codec->height = c->height;
	st->codec->time_base = c->time_base;

	ret = pixfmt_from_pixmap_format(s, geo->depth, &st->codec->pix_fmt);

	free(geo);

	return ret;
	}

	static void draw_rectangle(AVFormatContext *s)
	{
	XCBGrabContext *c = s->priv_data;
	xcb_gcontext_t gc = xcb_generate_id(c->conn);
	uint32_t mask = XCB_GC_FOREGROUND \|
	XCB_GC_BACKGROUND \|
	XCB_GC_LINE_WIDTH \|
	XCB_GC_LINE_STYLE \|
	XCB_GC_FILL_STYLE;
	uint32_t values[] = { c->screen->black_pixel,
	c->screen->white_pixel,
	c->region_border,
	XCB_LINE_STYLE_DOUBLE_DASH,
	XCB_FILL_STYLE_SOLID };
	xcb_rectangle_t r = { 1, 1,
	c->width + c->region_border * 2 - 3,
	c->height + c->region_border * 2 - 3 };

	xcb_create_gc(c->conn, gc, c->window, mask, values);

	xcb_poly_rectangle(c->conn, c->window, gc, 1, &r);
	}

	static void setup_window(AVFormatContext *s)
	{
	XCBGrabContext *c = s->priv_data;
	uint32_t mask = XCB_CW_OVERRIDE_REDIRECT \| XCB_CW_EVENT_MASK;
	uint32_t values[] = { 1,
	XCB_EVENT_MASK_EXPOSURE \|
	XCB_EVENT_MASK_STRUCTURE_NOTIFY };
	av_unused xcb_rectangle_t rect = { 0, 0, c->width, c->height };

	c->window = xcb_generate_id(c->conn);

	xcb_create_window(c->conn, XCB_COPY_FROM_PARENT,
	c->window,
	c->screen->root,
	c->x - c->region_border,
	c->y - c->region_border,
	c->width + c->region_border * 2,
	c->height + c->region_border * 2,
	0,
	XCB_WINDOW_CLASS_INPUT_OUTPUT,
	XCB_COPY_FROM_PARENT,
	mask, values);

	#if CONFIG_LIBXCB_SHAPE
	xcb_shape_rectangles(c->conn, XCB_SHAPE_SO_SUBTRACT,
	XCB_SHAPE_SK_BOUNDING, XCB_CLIP_ORDERING_UNSORTED,
	c->window,
	c->region_border, c->region_border,
	1, &rect);
	#endif

	xcb_map_window(c->conn, c->window);

	draw_rectangle(s);
	}

	static av_cold int xcbgrab_read_header(AVFormatContext *s)
	{
	XCBGrabContext *c = s->priv_data;
	int screen_num, ret;
	const xcb_setup_t *setup;
	char *display_name = av_strdup(s->filename);

	if (!display_name)
	return AVERROR(ENOMEM);

	if (!sscanf(s->filename, "%[^+]+%d,%d", display_name, &c->x, &c->y)) {
	*display_name = 0;
	sscanf(s->filename, "+%d,%d", &c->x, &c->y);
	}

	c->conn = xcb_connect(display_name[0] ? display_name : NULL, &screen_num);
	av_freep(&display_name);

	if ((ret = xcb_connection_has_error(c->conn))) {
	av_log(s, AV_LOG_ERROR, "Cannot open display %s, error %d.\n",
	s->filename[0] ? s->filename : "default", ret);
	return AVERROR(EIO);
	}

	setup = xcb_get_setup(c->conn);

	c->screen = get_screen(setup, screen_num);
	if (!c->screen) {
	av_log(s, AV_LOG_ERROR, "The screen %d does not exist.\n",
	screen_num);
	xcbgrab_read_close(s);
	return AVERROR(EIO);
	}

	ret = create_stream(s);

	if (ret < 0) {
	xcbgrab_read_close(s);
	return ret;
	}

	#if CONFIG_LIBXCB_SHM
	if ((c->has_shm = check_shm(c->conn)))
	c->segment = xcb_generate_id(c->conn);
	#endif

	#if CONFIG_LIBXCB_XFIXES
	if (c->draw_mouse) {
	if (!(c->draw_mouse = check_xfixes(c->conn))) {
	av_log(s, AV_LOG_WARNING,
	"XFixes not available, cannot draw the mouse.\n");
	}
	if (c->bpp < 24) {
	avpriv_report_missing_feature(s, "%d bits per pixel screen",
	c->bpp);
	c->draw_mouse = 0;
	}
	}
	#endif

	if (c->show_region)
	setup_window(s);

	return 0;
	}

	AVInputFormat ff_x11grab_xcb_demuxer = {
	.name = "x11grab",
	.long_name = NULL_IF_CONFIG_SMALL("X11 screen capture, using XCB"),
	.priv_data_size = sizeof(XCBGrabContext),
	.read_header = xcbgrab_read_header,
	.read_packet = xcbgrab_read_packet,
	.read_close = xcbgrab_read_close,
	.flags = AVFMT_NOFILE,
	.priv_class = &xcbgrab_class,
	};