[libav.git] / libavdevice / xcbgrab.c

/*
 * 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 "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,
};

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 + 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 (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_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);
    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 };
    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);

    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;
    char *host        = s->filename[0] ? s->filename : NULL;
    const char *opts  = strchr(s->filename, '+');

    if (opts) {
        sscanf(opts, "%d,%d", &c->x, &c->y);
        host = av_strdup(s->filename);
        if (!host)
            return AVERROR(ENOMEM);
        host[opts - s->filename] = '\0';
    }

    c->conn = xcb_connect(host, &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[0] ? host : "default", ret);
        if (opts)
            av_freep(&host);
        return AVERROR(EIO);
    }

    if (opts)
        av_freep(&host);

    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,
};
Commit	Line	Data
a6674d2e LB	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
c201069f	36	#include "libavutil/internal.h"
a6674d2e LB	37	#include "libavutil/mathematics.h"
	38	#include "libavutil/opt.h"
	39	#include "libavutil/parseutils.h"
	40	#include "libavutil/time.h"
	41
c201069f DB	42	#include "libavformat/avformat.h"
	43	#include "libavformat/internal.h"
	44
a6674d2e LB	45	typedef struct XCBGrabContext {
	46	const AVClass *class;
	47
	48	xcb_connection_t *conn;
	49	xcb_screen_t *screen;
	50	xcb_window_t window;
d40815a9	51	#if CONFIG_LIBXCB_SHM
a6674d2e	52	xcb_shm_seg_t segment;
d40815a9	53	#endif
a6674d2e LB	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 },
b31328d0 LB	81	{ "grab_x", "Initial x coordinate.", OFFSET(x), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, D },
b31328d0 LB	82	{ "grab_y", "Initial y coordinate.", OFFSET(y), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, D },
a6674d2e LB	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;
9e06327e	106	int x = c->x, y = c->y;
a6674d2e	107	int w = c->width, h = c->height, f = c->follow_mouse;
9e06327e	108	int p_x, p_y;
a6674d2e LB	109
	110	if (!p \|\| !geo)
	111	return AVERROR(EIO);
	112
9e06327e VG	113	p_x = p->win_x;
	114	p_y = p->win_y;
	115
a6674d2e LB	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;
82a10225	148	xcb_generic_error_t *e = NULL;
a6674d2e LB	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
82a10225 LB	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
a6674d2e LB	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
82a10225	420	if (ret >= 0 && c->draw_mouse && p->same_screen)
a6674d2e LB	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);
a6674d2e LB	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
a6674d2e LB	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
01fdfa51 NG	531	if (c->x + c->width > geo->width \|\|
01fdfa51 NG	532	c->y + c->height > geo->height) {
e8c4db0d LB	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
a6674d2e LB	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 };
51ca3cb6	589	xcb_rectangle_t rect = { 0, 0, c->width, c->height };
a6674d2e LB	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;
85b3b1c4 LB	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);
edca1dd5 VG	627	if (!host)
edca1dd5 VG	628	return AVERROR(ENOMEM);
85b3b1c4 LB	629	host[opts - s->filename] = '\0';
	630	}
	631
	632	c->conn = xcb_connect(host, &screen_num);
	633
a6674d2e LB	634	if ((ret = xcb_connection_has_error(c->conn))) {
a6674d2e LB	635	av_log(s, AV_LOG_ERROR, "Cannot open display %s, error %d.\n",
85b3b1c4	636	s->filename[0] ? host : "default", ret);
5f5b78ac LB	637	if (opts)
5f5b78ac LB	638	av_freep(&host);
a6674d2e LB	639	return AVERROR(EIO);
a6674d2e LB	640	}
5f5b78ac LB	641
	642	if (opts)
	643	av_freep(&host);
	644
a6674d2e LB	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
a6674d2e LB	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
d40815a9 LB	663	if ((c->has_shm = check_shm(c->conn)))
d40815a9 LB	664	c->segment = xcb_generate_id(c->conn);
a6674d2e LB	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	};