xcbgrab: XCB-based screen capture

Matches the x11grab screen capture by features.

4 files changed, 659 insertions, 2 deletions

diff --git a/libavdevice/Makefile b/libavdevice/Makefile
index 25e126c6b6..1f113dd432 100644
--- a/libavdevice/Makefile
+++ b/libavdevice/Makefile
@@ -22,7 +22,8 @@ OBJS-$(CONFIG_SNDIO_INDEV)               += sndio_common.o sndio_dec.o
 OBJS-$(CONFIG_SNDIO_OUTDEV)              += sndio_common.o sndio_enc.o
 OBJS-$(CONFIG_V4L2_INDEV)                += v4l2.o
 OBJS-$(CONFIG_VFWCAP_INDEV)              += vfwcap.o
-OBJS-$(CONFIG_X11GRAB_INDEV)             += x11grab.o
+OBJS-$(CONFIG_X11GRAB_XLIB_INDEV)        += x11grab.o
+OBJS-$(CONFIG_X11GRAB_XCB_INDEV)         += xcbgrab.o
 
 # external libraries
 OBJS-$(CONFIG_LIBCDIO_INDEV)             += libcdio.o
diff --git a/libavdevice/alldevices.c b/libavdevice/alldevices.c
index 155f7a8ee6..5dbe2777ee 100644
--- a/libavdevice/alldevices.c
+++ b/libavdevice/alldevices.c
@@ -58,6 +58,7 @@ void avdevice_register_all(void)
     REGISTER_INDEV   (V4L2,             v4l2);
     REGISTER_INDEV   (VFWCAP,           vfwcap);
     REGISTER_INDEV   (X11GRAB,          x11grab);
+    REGISTER_INDEV   (X11GRAB_XCB,      x11grab_xcb);
 
     /* external libraries */
     REGISTER_INDEV   (LIBCDIO,          libcdio);
diff --git a/libavdevice/version.h b/libavdevice/version.h
index 3d82c97d2e..9453234bf8 100644
--- a/libavdevice/version.h
+++ b/libavdevice/version.h
@@ -28,7 +28,7 @@
 #include "libavutil/version.h"
 
 #define LIBAVDEVICE_VERSION_MAJOR 55
-#define LIBAVDEVICE_VERSION_MINOR  0
+#define LIBAVDEVICE_VERSION_MINOR  1
 #define LIBAVDEVICE_VERSION_MICRO  0
 
 #define LIBAVDEVICE_VERSION_INT AV_VERSION_INT(LIBAVDEVICE_VERSION_MAJOR, \
diff --git a/libavdevice/xcbgrab.c b/libavdevice/xcbgrab.c
new file mode 100644
index 0000000000..5055fde0c9
--- /dev/null
+++ b/libavdevice/xcbgrab.c
@@ -0,0 +1,655 @@
+/*
+ * XCB input grabber
+ * Copyright (C) 2014 Luca Barbato <lu_zero@gentoo.org>
+ *
+ * This file is part of Libav.
+ *
+ * Libav 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.
+ *
+ * Libav 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 Libav; 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
+
+#include "libavformat/avformat.h"
+#include "libavformat/internal.h"
+
+#include "libavutil/mathematics.h"
+#include "libavutil/opt.h"
+#include "libavutil/parseutils.h"
+#include "libavutil/time.h"
+
+typedef struct XCBGrabContext {
+    const AVClass *class;
+
+    xcb_connection_t *conn;
+    xcb_screen_t *screen;
+    xcb_window_t window;
+    xcb_shm_seg_t segment;
+
+    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 },
+    { "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,
+};
+
+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, p_x = p->win_x, p_y = p->win_y;
+    int w = c->width, h = c->height, f = c->follow_mouse;
+
+    if (!p || !geo)
+        return AVERROR(EIO);
+
+    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;
+    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, NULL);
+    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 + FF_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 (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_ARGB;
+                break;
+            case 24:
+                if (fmt->bits_per_pixel == 32)
+                    *pix_fmt = AV_PIX_FMT_RGB32;
+                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);
+    const char *opts  = strchr(s->filename, '+');
+    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;
+
+    if (opts)
+        sscanf(opts, "%d,%d", &c->x, &c->y);
+
+    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);
+
+    c->width      = FFMIN(geo->width, c->width);
+    c->height     = FFMIN(geo->height, c->height);
+    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 };
+    xcb_rectangle_t rect = { c->x, c->y, 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);
+
+    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);
+
+    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;
+
+    c->conn = xcb_connect(s->filename, &screen_num);
+    if ((ret = xcb_connection_has_error(c->conn))) {
+        av_log(s, AV_LOG_ERROR, "Cannot open display %s, error %d.\n",
+               s->filename ? 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);
+    }
+
+    c->segment = xcb_generate_id(c->conn);
+
+    ret = create_stream(s);
+
+    if (ret < 0) {
+        xcbgrab_read_close(s);
+        return ret;
+    }
+
+#if CONFIG_LIBXCB_SHM
+    c->has_shm = check_shm(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,
+};