[FFmpeg-devel] [PATCH] x11grab: capture a window instead of the whole screen
sgerwk at aol.com
sgerwk at aol.com
Sun Feb 28 14:57:03 EET 2021
Hi,
On Sat, 27 Feb 2021, Andriy Gelman wrote:
> On Mon, 22. Feb 17:53, sgerwk-at-aol.com at ffmpeg.org wrote:
>> Hi,
>>
>> On Sun, 21 Feb 2021, Andriy Gelman wrote:
>> > Hi,
>> >
>> > Thanks for updating the patch. Sorry for the delay in getting you some feedback..
>> >
>> > When I tested with -show_mouse 1 -show_region 1 -window_id xx, the mouse and
>> > border get drawn in the wrong place. There is around (0.6cm error). Can you
>> > reproduce?
>> >
>>
>> I didn't notice the problem because the wm I use places the top-level
>> windows in a window of the same size - at position 0,0. Still, I could
>> reproduce it by capturing a subwindow.
>>
>> The problem was indeed what you suspected: geo->x,geo->y is the position
>> inside the parent, but translate includes it already as it is the position
>> within the root window.
>>
>> > > From e13c1be7abd6989b3ad80fd8086fe6a0819fd810 Mon Sep 17 00:00:00 2001
>> > > From: sgerwk <sgerwk at aol.com>
>> > > Date: Wed, 10 Feb 2021 17:36:00 +0100
>> > > Subject: [PATCH] libavdevice/xcbgrab: option for grabbing a window instead of
>> > > desktop
>> > >
>> > > ---
>> > > doc/indevs.texi | 14 +++++++-
>> > > libavdevice/xcbgrab.c | 79 ++++++++++++++++++++++++++++++++-----------
>> > > 2 files changed, 72 insertions(+), 21 deletions(-)
>> > >
>> > > diff --git a/doc/indevs.texi b/doc/indevs.texi
>> > > index 3924d03..48fd2b1 100644
>> > > --- a/doc/indevs.texi
>> > > +++ b/doc/indevs.texi
>> > > @@ -1564,8 +1564,20 @@ With @var{follow_mouse}:
>> > > ffmpeg -f x11grab -follow_mouse centered -show_region 1 -framerate 25 -video_size cif -i :0.0 out.mpg
>> > > @end example
>> > >
>> > > + at item window_id
>> > > +Grab this window, instead of the whole screen.
>> > > +
>> > > +The id of a window can be found by xwininfo(1), possibly with options -tree and
>> > > +-root.
>> > > +
>> > > +If the window is later enlarged, the new area is not recorded. Video ends when
>> > > +the window is closed, unmapped (i.e., iconified) or shrunk beyond the video
>> > > +size (which defaults to the initial window size).
>> > > +
>> > > +This option disables options @option{follow_mouse} and @option{select_region}.
>> > > +
>> > > @item video_size
>> > > -Set the video frame size. Default is the full desktop.
>> > > +Set the video frame size. Default is the full desktop or window.
>> > >
>> > > @item grab_x
>> > > @item grab_y
>> > > diff --git a/libavdevice/xcbgrab.c b/libavdevice/xcbgrab.c
>> > > index be5d5ea..7697090 100644
>> > > --- a/libavdevice/xcbgrab.c
>> > > +++ b/libavdevice/xcbgrab.c
>> > > @@ -60,6 +60,8 @@ typedef struct XCBGrabContext {
>> > > AVRational time_base;
>> > > int64_t frame_duration;
>> > >
>> > > + xcb_window_t window_id;
>> >
>> > > + int win_x, win_y;
>> >
>> > The position of the window is always recalculated so I don't think win_x and
>> > win_y should be part of the of XCBGrabContext.
>> >
>>
>> Done. Some functions now require win_x and win_y because they no longer
>> find them in XCBGrabContext.
>>
>> > > int x, y;
>> > > int width, height;
>> > > int frame_size;
>> > > @@ -82,6 +84,7 @@ typedef struct XCBGrabContext {
>> > > #define OFFSET(x) offsetof(XCBGrabContext, x)
>> > > #define D AV_OPT_FLAG_DECODING_PARAM
>> > > static const AVOption options[] = {
>> > > + { "window_id", "Window to capture", OFFSET(window_id), AV_OPT_TYPE_INT, { .i64 = XCB_NONE }, 0, UINT32_MAX, D },
>> > > { "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 },
>> > > @@ -157,7 +160,7 @@ 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_drawable_t drawable = c->window_id;
>> > > xcb_generic_error_t *e = NULL;
>> > > uint8_t *data;
>> > > int length;
>> > > @@ -267,7 +270,7 @@ 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;
>> > > + xcb_drawable_t drawable = c->window_id;
>> > > xcb_generic_error_t *e = NULL;
>> > > AVBufferRef *buf;
>> > > xcb_shm_seg_t segment;
>> > > @@ -355,17 +358,17 @@ static void xcbgrab_draw_mouse(AVFormatContext *s, AVPacket *pkt,
>> > > cx = ci->x - ci->xhot;
>> > > cy = ci->y - ci->yhot;
>> > >
>> > > - x = FFMAX(cx, gr->x);
>> > > - y = FFMAX(cy, gr->y);
>> > > + x = FFMAX(cx, gr->win_x + gr->x);
>> > > + y = FFMAX(cy, gr->win_y + gr->y);
>> > >
>> > > - w = FFMIN(cx + ci->width, gr->x + gr->width) - x;
>> > > - h = FFMIN(cy + ci->height, gr->y + gr->height) - y;
>> > > + w = FFMIN(cx + ci->width, gr->win_x + gr->x + gr->width) - x;
>> > > + h = FFMIN(cy + ci->height, gr->win_y + gr->y + gr->height) - y;
>> > >
>> > > c_off = x - cx;
>> > > - i_off = x - gr->x;
>> > > + i_off = x - gr->x - gr->win_x;
>> > >
>> > > cursor += (y - cy) * ci->width;
>> > > - image += (y - gr->y) * gr->width * stride;
>> > > + image += (y - gr->y - gr->win_y) * gr->width * stride;
>> > >
>> > > for (y = 0; y < h; y++) {
>> > > cursor += c_off;
>> > > @@ -403,8 +406,8 @@ static void xcbgrab_draw_mouse(AVFormatContext *s, AVPacket *pkt,
>> > > 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 };
>> > > + const uint32_t args[] = { c->win_x + c->x - c->region_border,
>> > > + c->win_y + c->y - c->region_border };
>> > >
>> > > xcb_configure_window(c->conn,
>> > > c->window,
>> > > @@ -417,16 +420,22 @@ 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_translate_coordinates_cookie_t tc;
>> > > xcb_query_pointer_reply_t *p = NULL;
>> > > xcb_get_geometry_reply_t *geo = NULL;
>> > > + xcb_translate_coordinates_reply_t *translate = NULL;
>> > > int ret = 0;
>> > > int64_t pts;
>> > >
>> > > pts = 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);
>> > > + if (c->window_id == c->screen->root) {
>> > > + c->win_x = 0;
>> > > + c->win_y = 0;
>> > > + }
>> > > + if (c->follow_mouse || c->draw_mouse || c->window_id != c->screen->root) {
>> > > + pc = xcb_query_pointer(c->conn, c->window_id);
>> > > + gc = xcb_get_geometry(c->conn, c->window_id);
>> > > p = xcb_query_pointer_reply(c->conn, pc, NULL);
>> > > if (!p) {
>> > > av_log(s, AV_LOG_ERROR, "Failed to query xcb pointer\n");
>> > > @@ -438,6 +447,12 @@ static int xcbgrab_read_packet(AVFormatContext *s, AVPacket *pkt)
>> > > free(p);
>> > > return AVERROR_EXTERNAL;
>> > > }
>> >
>> > > + tc = xcb_translate_coordinates(c->conn, c->window_id, c->screen->root, geo->x, geo->y);
>> >
>> > It would cleaner if you move win_x,win_y calculation to a separate if statement.
>> > (I don't think you are going to end up reusing geo->x, geo->y anyway because probably
>> > that's what causing the mouse/border offset error).
>> >
>>
>> Actually, this if is executed in the default case because of draw_mouse. But
>> still, the code looks better with a separate if, so I did it.
>>
>> > > + translate = xcb_translate_coordinates_reply(c->conn, tc, NULL);
>> >
>> > > + if (!translate)
>> > > + return AVERROR_EXTERNAL;
>> >
>> > p and geo need to be freed on this error.
>> > You also need free translate when cleaning up at the end of this function.
>>
>> Done. I free translate immediately after getting win_x and win_y.
>>
>> >
>> > > + c->win_x = translate->dst_x;
>> > > + c->win_y = translate->dst_y;
>> > > }
>> > >
>> > > if (c->follow_mouse && p->same_screen)
>> > > @@ -447,7 +462,7 @@ static int xcbgrab_read_packet(AVFormatContext *s, AVPacket *pkt)
>> > > xcbgrab_update_region(s);
>> > >
>> > > #if CONFIG_LIBXCB_SHM
>> >
>> > > - if (c->has_shm && xcbgrab_frame_shm(s, pkt) < 0) {
>> > > + if (c->has_shm && (ret = xcbgrab_frame_shm(s, pkt)) == AVERROR(ENOMEM)) {
>> > > av_log(s, AV_LOG_WARNING, "Continuing without shared memory.\n");
>> > > c->has_shm = 0;
>> > > }
>> >
>> > IMO this should be a separate commit as it changes how EACCESS is
>> > interpreted even when the new option is not used.
>> >
>>
>> I now just don't remember why I changed this, so I restored the previous
>> condition.
>>
>> > > @@ -558,7 +573,9 @@ 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_translate_coordinates_cookie_t tc;
>> > > xcb_get_geometry_reply_t *geo;
>> > > + xcb_translate_coordinates_reply_t *translate;
>> > > int64_t frame_size_bits;
>> > > int ret;
>> > >
>> > > @@ -571,11 +588,20 @@ static int create_stream(AVFormatContext *s)
>> > >
>> > > avpriv_set_pts_info(st, 64, 1, 1000000);
>> > >
>> > > - gc = xcb_get_geometry(c->conn, c->screen->root);
>> > > + gc = xcb_get_geometry(c->conn, c->window_id);
>> > > geo = xcb_get_geometry_reply(c->conn, gc, NULL);
>> > > - if (!geo)
>> > > + if (!geo) {
>> > > + av_log(s, AV_LOG_ERROR, "Can't find window '0x%x', aborting.\n", c->window_id);
>> > > + return AVERROR_EXTERNAL;
>> > > + }
>> > > +
>> > > + tc = xcb_translate_coordinates(c->conn, c->window_id, c->screen->root, geo->x, geo->y);
>> > > + translate = xcb_translate_coordinates_reply(c->conn, tc, NULL);
>> >
>> > > + if (!translate)
>> > > return AVERROR_EXTERNAL;
>> >
>> > error would leak geo.
>> > and translate will need to be freed somewhere if there's no error.
>> >
>> > >
>> > > + c->win_x = translate->dst_x;
>> > > + c->win_y = translate->dst_y;
>> > > if (!c->width || !c->height) {
>> > > c->width = geo->width;
>> > > c->height = geo->height;
>> >
>> > You calculate win_x/win_y, but it actually doesn't end up being used
>> > anywhere in xcbgrab_read_header(), and will get recalculated in
>> > xcbgrab_read_packet().
>> > You probably meant to also update setup_window()?
>> >
>>
>> This calculation doesn't seem necessary, indeed. I removed it.
>>
>> > (btw, currently the border doesn't end being displayed until the first
>> > xcbgrab_read_packet() call because there is no xcb_flush(c->conn) after
>> > setup_window(s). But it could be added to display the initial border.)
>> >
>>
>> I guess this should go in a separate commit, as it also affect the case when
>> window_id is not set.
>>
>> >
>> > > @@ -750,7 +776,7 @@ static int select_region(AVFormatContext *s)
>> > > press_position = (xcb_point_t){ press->event_x, press->event_y };
>> > > rectangle.x = press_position.x;
>> > > rectangle.y = press_position.y;
>> > > - xcb_poly_rectangle(conn, root_window, gc, 1, &rectangle);
>> > > + xcb_poly_rectangle(conn, c->window_id, gc, 1, &rectangle);
>> > > was_pressed = 1;
>> > > break;
>> > > }
>> > > @@ -759,14 +785,14 @@ static int select_region(AVFormatContext *s)
>> > > xcb_motion_notify_event_t *motion =
>> > > (xcb_motion_notify_event_t *)event;
>> > > xcb_point_t cursor_position = { motion->event_x, motion->event_y };
>> > > - xcb_poly_rectangle(conn, root_window, gc, 1, &rectangle);
>> > > + xcb_poly_rectangle(conn, c->window_id, gc, 1, &rectangle);
>> > > rectangle = rectangle_from_corners(&press_position, &cursor_position);
>> > > - xcb_poly_rectangle(conn, root_window, gc, 1, &rectangle);
>> > > + xcb_poly_rectangle(conn, c->window_id, gc, 1, &rectangle);
>> > > }
>> > > break;
>> > > }
>> > > case XCB_BUTTON_RELEASE: {
>> > > - xcb_poly_rectangle(conn, root_window, gc, 1, &rectangle);
>> > > + xcb_poly_rectangle(conn, c->window_id, gc, 1, &rectangle);
>> > > done = 1;
>> > > break;
>> > > }
>> > > @@ -830,6 +856,19 @@ static av_cold int xcbgrab_read_header(AVFormatContext *s)
>> > > return AVERROR(EIO);
>> > > }
>
>> >
>> > You disabled select_region() earlier. These changes can be skipped then.
>> >
>
>>
>> I disagree. The captured window is c->window_id now. Even if this part of
>> code is currently unreachable if window_id is not the root window,
>> a future commit may make it reachable again.
>
> The selection rectangle may still be be drawn on root window.
> The partial change will make it more confusing in the commit history.
> It's better to leave it IMO.
Ok, I removed those changes. But I still believe it's not the best choice
to first generalize the grabbed window to be c->window_id but then
assume it's c->screen->root_window instead only in this case.
>
>>
>> > >
>> > > + if (c->window_id == XCB_NONE)
>> > > + c->window_id = c->screen->root;
>> > > + else {
>> > > + if (c->select_region) {
>> > > + av_log(s, AV_LOG_WARNING, "select_region ignored with window_id.\n");
>> > > + c->select_region = 0;
>> > > + }
>> > > + if (c->follow_mouse) {
>> > > + av_log(s, AV_LOG_WARNING, "follow_mouse ignored with window_id.\n");
>> > > + c->follow_mouse = 0;
>> > > + }
>> > > + }
>> > > +
>> > > if (c->select_region) {
>> > > ret = select_region(s);
>> >
>> > Thanks,
>> > --
>> > Andriy
>> > _______________________________________________
>> > ffmpeg-devel mailing list
>> > ffmpeg-devel at ffmpeg.org
>> > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>> >
>> > To unsubscribe, visit link above, or email
>> > ffmpeg-devel-request at ffmpeg.org with subject "unsubscribe".
>>
>> Thanks!
>
>> From 36e6c5a858415106d4d2d9a76fa45cbd59717c77 Mon Sep 17 00:00:00 2001
>> From: sgerwk <sgerwk at aol.com>
>> Date: Wed, 10 Feb 2021 17:36:00 +0100
>> Subject: [PATCH] libavdevice/xcbgrab: option for grabbing a window instead of
>> desktop
>
>
> The behavior with -select_region 1 -follow_mouse 1 is not correct now. It will
> always reset the origin to 0,0, i.e.
>
> ./ffmpeg -show_region 1 select_region 1 -follow_mouse 1 -f x11grab -i :0 -codec:v mpeg2video out.mp4
>
I used the wrong win_x and win_y in xcbgrab_reposition(). I reverted that
function to its previous state, which also fixed the problem.
>>
>> ---
>> doc/indevs.texi | 14 ++++++-
>> libavdevice/xcbgrab.c | 93 +++++++++++++++++++++++++++++++------------
>> 2 files changed, 80 insertions(+), 27 deletions(-)
>>
>> diff --git a/doc/indevs.texi b/doc/indevs.texi
>> index 3924d03..48fd2b1 100644
>> --- a/doc/indevs.texi
>> +++ b/doc/indevs.texi
>> @@ -1564,8 +1564,20 @@ With @var{follow_mouse}:
>> ffmpeg -f x11grab -follow_mouse centered -show_region 1 -framerate 25 -video_size cif -i :0.0 out.mpg
>> @end example
>>
>> + at item window_id
>> +Grab this window, instead of the whole screen.
>> +
>> +The id of a window can be found by xwininfo(1), possibly with options -tree and
>> +-root.
>> +
>> +If the window is later enlarged, the new area is not recorded. Video ends when
>> +the window is closed, unmapped (i.e., iconified) or shrunk beyond the video
>> +size (which defaults to the initial window size).
>> +
>> +This option disables options @option{follow_mouse} and @option{select_region}.
>> +
>> @item video_size
>> -Set the video frame size. Default is the full desktop.
>> +Set the video frame size. Default is the full desktop or window.
>>
>> @item grab_x
>> @item grab_y
>> diff --git a/libavdevice/xcbgrab.c b/libavdevice/xcbgrab.c
>> index be5d5ea..ae935ad 100644
>> --- a/libavdevice/xcbgrab.c
>> +++ b/libavdevice/xcbgrab.c
>> @@ -60,6 +60,7 @@ typedef struct XCBGrabContext {
>> AVRational time_base;
>> int64_t frame_duration;
>>
>> + xcb_window_t window_id;
>> int x, y;
>> int width, height;
>> int frame_size;
>> @@ -82,6 +83,7 @@ typedef struct XCBGrabContext {
>> #define OFFSET(x) offsetof(XCBGrabContext, x)
>> #define D AV_OPT_FLAG_DECODING_PARAM
>> static const AVOption options[] = {
>> + { "window_id", "Window to capture", OFFSET(window_id), AV_OPT_TYPE_INT, { .i64 = XCB_NONE }, 0, UINT32_MAX, D },
>> { "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 },
>> @@ -108,7 +110,8 @@ static const AVClass xcbgrab_class = {
>>
>> static int xcbgrab_reposition(AVFormatContext *s,
>> xcb_query_pointer_reply_t *p,
>> - xcb_get_geometry_reply_t *geo)
>> + xcb_get_geometry_reply_t *geo,
>> + int win_x, int win_y)
>> {
>> XCBGrabContext *c = s->priv_data;
>> int x = c->x, y = c->y;
>> @@ -118,8 +121,8 @@ static int xcbgrab_reposition(AVFormatContext *s,
>> if (!p || !geo)
>> return AVERROR(EIO);
>>
>> - p_x = p->win_x;
>> - p_y = p->win_y;
>> + p_x = win_x;
>> + p_y = win_y;
>>
>> if (f == FOLLOW_CENTER) {
>> x = p_x - w / 2;
>> @@ -157,7 +160,7 @@ 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_drawable_t drawable = c->window_id;
>> xcb_generic_error_t *e = NULL;
>> uint8_t *data;
>> int length;
>> @@ -267,7 +270,7 @@ 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;
>> + xcb_drawable_t drawable = c->window_id;
>> xcb_generic_error_t *e = NULL;
>> AVBufferRef *buf;
>> xcb_shm_seg_t segment;
>> @@ -333,7 +336,8 @@ static int check_xfixes(xcb_connection_t *conn)
>>
>> static void xcbgrab_draw_mouse(AVFormatContext *s, AVPacket *pkt,
>> xcb_query_pointer_reply_t *p,
>> - xcb_get_geometry_reply_t *geo)
>> + xcb_get_geometry_reply_t *geo,
>> + int win_x, int win_y)
>> {
>> XCBGrabContext *gr = s->priv_data;
>> uint32_t *cursor;
>> @@ -355,17 +359,17 @@ static void xcbgrab_draw_mouse(AVFormatContext *s, AVPacket *pkt,
>> cx = ci->x - ci->xhot;
>> cy = ci->y - ci->yhot;
>>
>> - x = FFMAX(cx, gr->x);
>> - y = FFMAX(cy, gr->y);
>> + x = FFMAX(cx, win_x + gr->x);
>> + y = FFMAX(cy, win_y + gr->y);
>>
>> - w = FFMIN(cx + ci->width, gr->x + gr->width) - x;
>> - h = FFMIN(cy + ci->height, gr->y + gr->height) - y;
>> + w = FFMIN(cx + ci->width, win_x + gr->x + gr->width) - x;
>> + h = FFMIN(cy + ci->height, win_y + gr->y + gr->height) - y;
>>
>> c_off = x - cx;
>> - i_off = x - gr->x;
>> + i_off = x - gr->x - win_x;
>>
>> cursor += (y - cy) * ci->width;
>> - image += (y - gr->y) * gr->width * stride;
>> + image += (y - gr->y - win_y) * gr->width * stride;
>>
>> for (y = 0; y < h; y++) {
>> cursor += c_off;
>> @@ -400,11 +404,11 @@ static void xcbgrab_draw_mouse(AVFormatContext *s, AVPacket *pkt,
>> }
>> #endif /* CONFIG_LIBXCB_XFIXES */
>>
>> -static void xcbgrab_update_region(AVFormatContext *s)
>> +static void xcbgrab_update_region(AVFormatContext *s, int win_x, int win_y)
>> {
>> XCBGrabContext *c = s->priv_data;
>> - const uint32_t args[] = { c->x - c->region_border,
>> - c->y - c->region_border };
>> + const uint32_t args[] = { win_x + c->x - c->region_border,
>> + win_y + c->y - c->region_border };
>>
>> xcb_configure_window(c->conn,
>> c->window,
>> @@ -417,16 +421,23 @@ 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_translate_coordinates_cookie_t tc;
>> xcb_query_pointer_reply_t *p = NULL;
>> xcb_get_geometry_reply_t *geo = NULL;
>> + xcb_translate_coordinates_reply_t *translate = NULL;
>> int ret = 0;
>> int64_t pts;
>> + int win_x, win_y;
>>
>> pts = wait_frame(s, pkt);
>
>>
>> + if (c->window_id == c->screen->root) {
>> + win_x = 0;
>> + win_y = 0;
>> + }
>
> You could zero initialize win_x/win_y and skip this if statement.
Done.
>
>> 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);
>> + pc = xcb_query_pointer(c->conn, c->window_id);
>> + gc = xcb_get_geometry(c->conn, c->window_id);
>> p = xcb_query_pointer_reply(c->conn, pc, NULL);
>> if (!p) {
>> av_log(s, AV_LOG_ERROR, "Failed to query xcb pointer\n");
>> @@ -439,12 +450,27 @@ static int xcbgrab_read_packet(AVFormatContext *s, AVPacket *pkt)
>> return AVERROR_EXTERNAL;
>> }
>> }
>> + if (c->window_id != c->screen->root) {
>> + tc = xcb_translate_coordinates(c->conn, c->window_id, c->screen->root, 0, 0);
>> + translate = xcb_translate_coordinates_reply(c->conn, tc, NULL);
>> + if (!translate) {
>
>> + if (p != NULL)
>> + free(p);
>> + if (geo != NULL)
>> + free(geo);
>
> It's fine to parse NULL to free, so the checks are not needed.
Done.
>
>> + av_log(s, AV_LOG_ERROR, "Failed to translate xcb geometry\n");
>> + return AVERROR_EXTERNAL;
>> + }
>> + win_x = translate->dst_x;
>> + win_y = translate->dst_y;
>> + free(translate);
>> + }
>>
>> if (c->follow_mouse && p->same_screen)
>> - xcbgrab_reposition(s, p, geo);
>> + xcbgrab_reposition(s, p, geo, win_x, win_y);
>
> I don't think we should change the xcbgrab_reposition() code. It's not that
> useful to follow a mouse region in a window, and it's disabled with your option.
>
Done.
>
>> if (c->show_region)
>> - xcbgrab_update_region(s);
>> + xcbgrab_update_region(s, win_x, win_y);
>>
>> #if CONFIG_LIBXCB_SHM
>> if (c->has_shm && xcbgrab_frame_shm(s, pkt) < 0) {
>> @@ -459,7 +485,7 @@ static int xcbgrab_read_packet(AVFormatContext *s, AVPacket *pkt)
>>
>> #if CONFIG_LIBXCB_XFIXES
>> if (ret >= 0 && c->draw_mouse && p->same_screen)
>> - xcbgrab_draw_mouse(s, pkt, p, geo);
>> + xcbgrab_draw_mouse(s, pkt, p, geo, win_x, win_y);
>> #endif
>>
>> free(p);
>> @@ -571,10 +597,12 @@ static int create_stream(AVFormatContext *s)
>>
>> avpriv_set_pts_info(st, 64, 1, 1000000);
>>
>> - gc = xcb_get_geometry(c->conn, c->screen->root);
>> + gc = xcb_get_geometry(c->conn, c->window_id);
>> geo = xcb_get_geometry_reply(c->conn, gc, NULL);
>> - if (!geo)
>> + if (!geo) {
>> + av_log(s, AV_LOG_ERROR, "Can't find window '0x%x', aborting.\n", c->window_id);
>> return AVERROR_EXTERNAL;
>> + }
>>
>> if (!c->width || !c->height) {
>> c->width = geo->width;
>> @@ -750,7 +778,7 @@ static int select_region(AVFormatContext *s)
>> press_position = (xcb_point_t){ press->event_x, press->event_y };
>> rectangle.x = press_position.x;
>> rectangle.y = press_position.y;
>> - xcb_poly_rectangle(conn, root_window, gc, 1, &rectangle);
>> + xcb_poly_rectangle(conn, c->window_id, gc, 1, &rectangle);
>> was_pressed = 1;
>> break;
>> }
>> @@ -759,14 +787,14 @@ static int select_region(AVFormatContext *s)
>> xcb_motion_notify_event_t *motion =
>> (xcb_motion_notify_event_t *)event;
>> xcb_point_t cursor_position = { motion->event_x, motion->event_y };
>> - xcb_poly_rectangle(conn, root_window, gc, 1, &rectangle);
>> + xcb_poly_rectangle(conn, c->window_id, gc, 1, &rectangle);
>> rectangle = rectangle_from_corners(&press_position, &cursor_position);
>> - xcb_poly_rectangle(conn, root_window, gc, 1, &rectangle);
>> + xcb_poly_rectangle(conn, c->window_id, gc, 1, &rectangle);
>> }
>> break;
>> }
>> case XCB_BUTTON_RELEASE: {
>> - xcb_poly_rectangle(conn, root_window, gc, 1, &rectangle);
>> + xcb_poly_rectangle(conn, c->window_id, gc, 1, &rectangle);
>> done = 1;
>> break;
>> }
>> @@ -830,6 +858,19 @@ static av_cold int xcbgrab_read_header(AVFormatContext *s)
>> return AVERROR(EIO);
>> }
>>
>> + if (c->window_id == XCB_NONE)
>> + c->window_id = c->screen->root;
>> + else {
>> + if (c->select_region) {
>> + av_log(s, AV_LOG_WARNING, "select_region ignored with window_id.\n");
>> + c->select_region = 0;
>> + }
>> + if (c->follow_mouse) {
>> + av_log(s, AV_LOG_WARNING, "follow_mouse ignored with window_id.\n");
>> + c->follow_mouse = 0;
>> + }
>> + }
>> +
>> if (c->select_region) {
>> ret = select_region(s);
>> if (ret < 0) {
>> --
>> 2.30.1
>>
>
>> _______________________________________________
>> ffmpeg-devel mailing list
>> ffmpeg-devel at ffmpeg.org
>> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>>
>> To unsubscribe, visit link above, or email
>> ffmpeg-devel-request at ffmpeg.org with subject "unsubscribe".
>
>
> Thanks,
> --
> Andriy
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel at ffmpeg.org
> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>
> To unsubscribe, visit link above, or email
> ffmpeg-devel-request at ffmpeg.org with subject "unsubscribe".
-------------- next part --------------
From 1a350c9de2acbf133d62c1eeb6b5e90dd0a5dc9d Mon Sep 17 00:00:00 2001
From: sgerwk <sgerwk at aol.com>
Date: Wed, 10 Feb 2021 17:36:00 +0100
Subject: [PATCH] libavdevice/xcbgrab: option for grabbing a window instead of
desktop
---
doc/indevs.texi | 14 ++++++++-
libavdevice/xcbgrab.c | 70 ++++++++++++++++++++++++++++++++-----------
2 files changed, 65 insertions(+), 19 deletions(-)
diff --git a/doc/indevs.texi b/doc/indevs.texi
index 3924d03..48fd2b1 100644
--- a/doc/indevs.texi
+++ b/doc/indevs.texi
@@ -1564,8 +1564,20 @@ With @var{follow_mouse}:
ffmpeg -f x11grab -follow_mouse centered -show_region 1 -framerate 25 -video_size cif -i :0.0 out.mpg
@end example
+ at item window_id
+Grab this window, instead of the whole screen.
+
+The id of a window can be found by xwininfo(1), possibly with options -tree and
+-root.
+
+If the window is later enlarged, the new area is not recorded. Video ends when
+the window is closed, unmapped (i.e., iconified) or shrunk beyond the video
+size (which defaults to the initial window size).
+
+This option disables options @option{follow_mouse} and @option{select_region}.
+
@item video_size
-Set the video frame size. Default is the full desktop.
+Set the video frame size. Default is the full desktop or window.
@item grab_x
@item grab_y
diff --git a/libavdevice/xcbgrab.c b/libavdevice/xcbgrab.c
index be5d5ea..956ea32 100644
--- a/libavdevice/xcbgrab.c
+++ b/libavdevice/xcbgrab.c
@@ -60,6 +60,7 @@ typedef struct XCBGrabContext {
AVRational time_base;
int64_t frame_duration;
+ xcb_window_t window_id;
int x, y;
int width, height;
int frame_size;
@@ -82,6 +83,7 @@ typedef struct XCBGrabContext {
#define OFFSET(x) offsetof(XCBGrabContext, x)
#define D AV_OPT_FLAG_DECODING_PARAM
static const AVOption options[] = {
+ { "window_id", "Window to capture", OFFSET(window_id), AV_OPT_TYPE_INT, { .i64 = XCB_NONE }, 0, UINT32_MAX, D },
{ "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 },
@@ -157,7 +159,7 @@ 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_drawable_t drawable = c->window_id;
xcb_generic_error_t *e = NULL;
uint8_t *data;
int length;
@@ -267,7 +269,7 @@ 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;
+ xcb_drawable_t drawable = c->window_id;
xcb_generic_error_t *e = NULL;
AVBufferRef *buf;
xcb_shm_seg_t segment;
@@ -333,7 +335,8 @@ static int check_xfixes(xcb_connection_t *conn)
static void xcbgrab_draw_mouse(AVFormatContext *s, AVPacket *pkt,
xcb_query_pointer_reply_t *p,
- xcb_get_geometry_reply_t *geo)
+ xcb_get_geometry_reply_t *geo,
+ int win_x, int win_y)
{
XCBGrabContext *gr = s->priv_data;
uint32_t *cursor;
@@ -355,17 +358,17 @@ static void xcbgrab_draw_mouse(AVFormatContext *s, AVPacket *pkt,
cx = ci->x - ci->xhot;
cy = ci->y - ci->yhot;
- x = FFMAX(cx, gr->x);
- y = FFMAX(cy, gr->y);
+ x = FFMAX(cx, win_x + gr->x);
+ y = FFMAX(cy, win_y + gr->y);
- w = FFMIN(cx + ci->width, gr->x + gr->width) - x;
- h = FFMIN(cy + ci->height, gr->y + gr->height) - y;
+ w = FFMIN(cx + ci->width, win_x + gr->x + gr->width) - x;
+ h = FFMIN(cy + ci->height, win_y + gr->y + gr->height) - y;
c_off = x - cx;
- i_off = x - gr->x;
+ i_off = x - gr->x - win_x;
cursor += (y - cy) * ci->width;
- image += (y - gr->y) * gr->width * stride;
+ image += (y - gr->y - win_y) * gr->width * stride;
for (y = 0; y < h; y++) {
cursor += c_off;
@@ -400,11 +403,11 @@ static void xcbgrab_draw_mouse(AVFormatContext *s, AVPacket *pkt,
}
#endif /* CONFIG_LIBXCB_XFIXES */
-static void xcbgrab_update_region(AVFormatContext *s)
+static void xcbgrab_update_region(AVFormatContext *s, int win_x, int win_y)
{
XCBGrabContext *c = s->priv_data;
- const uint32_t args[] = { c->x - c->region_border,
- c->y - c->region_border };
+ const uint32_t args[] = { win_x + c->x - c->region_border,
+ win_y + c->y - c->region_border };
xcb_configure_window(c->conn,
c->window,
@@ -417,16 +420,19 @@ 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_translate_coordinates_cookie_t tc;
xcb_query_pointer_reply_t *p = NULL;
xcb_get_geometry_reply_t *geo = NULL;
+ xcb_translate_coordinates_reply_t *translate = NULL;
int ret = 0;
int64_t pts;
+ int win_x = 0, win_y = 0;
pts = 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);
+ pc = xcb_query_pointer(c->conn, c->window_id);
+ gc = xcb_get_geometry(c->conn, c->window_id);
p = xcb_query_pointer_reply(c->conn, pc, NULL);
if (!p) {
av_log(s, AV_LOG_ERROR, "Failed to query xcb pointer\n");
@@ -439,12 +445,25 @@ static int xcbgrab_read_packet(AVFormatContext *s, AVPacket *pkt)
return AVERROR_EXTERNAL;
}
}
+ if (c->window_id != c->screen->root) {
+ tc = xcb_translate_coordinates(c->conn, c->window_id, c->screen->root, 0, 0);
+ translate = xcb_translate_coordinates_reply(c->conn, tc, NULL);
+ if (!translate) {
+ free(p);
+ free(geo);
+ av_log(s, AV_LOG_ERROR, "Failed to translate xcb geometry\n");
+ return AVERROR_EXTERNAL;
+ }
+ win_x = translate->dst_x;
+ win_y = translate->dst_y;
+ free(translate);
+ }
if (c->follow_mouse && p->same_screen)
xcbgrab_reposition(s, p, geo);
if (c->show_region)
- xcbgrab_update_region(s);
+ xcbgrab_update_region(s, win_x, win_y);
#if CONFIG_LIBXCB_SHM
if (c->has_shm && xcbgrab_frame_shm(s, pkt) < 0) {
@@ -459,7 +478,7 @@ static int xcbgrab_read_packet(AVFormatContext *s, AVPacket *pkt)
#if CONFIG_LIBXCB_XFIXES
if (ret >= 0 && c->draw_mouse && p->same_screen)
- xcbgrab_draw_mouse(s, pkt, p, geo);
+ xcbgrab_draw_mouse(s, pkt, p, geo, win_x, win_y);
#endif
free(p);
@@ -571,10 +590,12 @@ static int create_stream(AVFormatContext *s)
avpriv_set_pts_info(st, 64, 1, 1000000);
- gc = xcb_get_geometry(c->conn, c->screen->root);
+ gc = xcb_get_geometry(c->conn, c->window_id);
geo = xcb_get_geometry_reply(c->conn, gc, NULL);
- if (!geo)
+ if (!geo) {
+ av_log(s, AV_LOG_ERROR, "Can't find window '0x%x', aborting.\n", c->window_id);
return AVERROR_EXTERNAL;
+ }
if (!c->width || !c->height) {
c->width = geo->width;
@@ -830,6 +851,19 @@ static av_cold int xcbgrab_read_header(AVFormatContext *s)
return AVERROR(EIO);
}
+ if (c->window_id == XCB_NONE)
+ c->window_id = c->screen->root;
+ else {
+ if (c->select_region) {
+ av_log(s, AV_LOG_WARNING, "select_region ignored with window_id.\n");
+ c->select_region = 0;
+ }
+ if (c->follow_mouse) {
+ av_log(s, AV_LOG_WARNING, "follow_mouse ignored with window_id.\n");
+ c->follow_mouse = 0;
+ }
+ }
+
if (c->select_region) {
ret = select_region(s);
if (ret < 0) {
--
2.30.1
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