Using gst-launch with ximagesrc says "There may be a timestamping problem, or this computer is too slow." - how do I solve this?
Desouza, Ederson
ederson.desouza at intel.com
Mon Apr 6 20:44:26 UTC 2020
On Mon, 2020-04-06 at 20:39 +0100, Alain Culos wrote:
> Thanks for this tip,
>
> On Mon, 6 Apr 2020, at 17:26, Desouza, Ederson wrote:
> > Hi,
> >
> > On Sun, 2020-04-05 at 01:20 +0100, Alain Culos wrote:
> > > Dear All,
> > >
> > > I just discovered GStreamer, so apologies if this is a basic error, but no matter how hard I try I can't find what is wrong with my set-up / pipeline.
> > >
> > > ===========
> > > Summary:
> > > When using ximagesrc, error messages appear to tell me buffers are lost and that there may be timestamping issues or that my computer is slow.
> >
> > Have you tried using "use-damage=false" parameter on ximagesrc?
>
> I had not, I now have.
>
> gst-launch-1.0 ximagesrc xid=0x02a00006 use-damage=false ! videoconvert ! autovideosink
>
> The simple pipeline above now works flawlessly, with near real-time mirroring of the original window, great, now I need to make the more complex pipeline work better.
>
> The mixer pipeline below, now updates about once per second (much better than without the "use-damage=false"), but still reports the timestamping error message.
>
> w=1280; h=800; x0=450; y0=200; gst-launch-1.0 \
> v4l2src device=/dev/video0 \
> ! videocrop left=$x0 right=$(( 1920 - $w - $x0 )) top=$y0 bottom=$(( 1080 - $h - $y0 )) \
> ! alpha method=green angle=70 \
> ! mixer.sink_1 \
> \
> ximagesrc xid=0x02a00006 use-damage=false ! videoscale \
> ! video/x-raw,width=$w,height=$h ! mixer.sink_0 \
> \
> videomixer name=mixer sink_0::zorder=0 sink_1::zorder=1 \
> ! videoconvert ! autovideosink
>
Try matching the framerate of both ximagesrc and v4l2src elements.
Maybe add some queues to the pipeline too?
> Output:
>
> Setting pipeline to PAUSED ...
> Pipeline is live and does not need PREROLL ...
> Setting pipeline to PLAYING ...
> New clock: GstSystemClock
> {
> WARNING: from element /GstPipeline:pipeline0/GstAutoVideoSink:autovideosink0/GstXvImageSink:autovideosink0-actual-sink-xvimage: A lot of buffers are being dropped.
> Additional debug info:
> gstbasesink.c(2902): gst_base_sink_is_too_late (): /GstPipeline:pipeline0/GstAutoVideoSink:autovideosink0/GstXvImageSink:autovideosink0-actual-sink-xvimage:
> There may be a timestamping problem, or this computer is too slow.
> } * repeats every second or so.
>
> Thanks & regards,
> Alain.
>
>
> > > I have a beefy desktop, 1yo i7, 6-core hyperthreaded, 64GB RAM ubuntu 18.04).
> > > GStreamer 1.14.5
> > >
> > > ===========
> > > In detail:
> > >
> > > The video shown with this command line is very laggy (it hardly uses any RAM or CPU // other note: my desktop easily copes with e.g. zoom meetings):
> > >
> > > gst-launch-1.0 autovideosrc ! videoconvert ! autovideosink # shows no error message
> > > gst-launch-1.0 v4l2src device=/dev/video0 ! videoconvert ! autovideosink # does exactly the same
> > >
> > >
> > > Preparing the ground for chroma-keying a green screen background, this example works the same way the first two do (laggy but good quality & no error message showing):
> > > w=1280; h=800; x0=450; y0=200; gst-launch-1.0 \
> > > v4l2src device=/dev/video0 \
> > > ! videocrop left=$x0 right=$(( 1920 - $w - $x0 )) top=$y0 bottom=$(( 1080 - $h - $y0 )) \
> > > ! alpha method=green angle=70 \
> > > ! videoconvert \
> > > ! autovideosink
> > >
> > > The background to replace the green screen will be taken from an application window.
> > > This causes issues with buffers dropped & it complains about timestamping issues.
> > > gst-launch-1.0 ximagesrc xid=0x02a00006 ! videoconvert ! autovideosink
> > >
> > > Below is the output of the command above:
> > > Setting pipeline to PAUSED ...
> > > Pipeline is live and does not need PREROLL ...
> > > Setting pipeline to PLAYING ...
> > > New clock: GstSystemClock
> > > WARNING: from element /GstPipeline:pipeline0/GstAutoVideoSink:autovideosink0/GstXvImageSink:autovideosink0-actual-sink-xvimage: A lot of buffers are being dropped.
> > > Additional debug info:
> > > gstbasesink.c(2902): gst_base_sink_is_too_late (): /GstPipeline:pipeline0/GstAutoVideoSink:autovideosink0/GstXvImageSink:autovideosink0-actual-sink-xvimage:
> > > There may be a timestamping problem, or this computer is too slow.
> > >
> > >
> > > Even if I impose a low frame rate, it outputs the same error messages as above, command line:
> > > gst-launch-1.0 ximagesrc xid=0x02a00006 ! video/x-raw,framerate=5/1 ! videoconvert ! autovideosink
> > >
> > > Obviously, if I combine the two, performance gets worse, despite still not hitting the CPU or RAM, and the following command shows exactly the same messages as above:
> > > w=1280; h=800; x0=450; y0=200; gst-launch-1.0 \
> > > v4l2src device=/dev/video0 \
> > > ! videocrop left=$x0 right=$(( 1920 - $w - $x0 )) top=$y0 bottom=$(( 1080 - $h - $y0 )) \
> > > ! alpha method=green angle=70 \
> > > ! mixer.sink_1 \
> > > \
> > > ximagesrc xid=0x02a00006 ! videoscale \
> > > ! video/x-raw,width=$w,height=$h ! mixer.sink_0 \
> > > \
> > > videomixer name=mixer sink_0::zorder=0 sink_1::zorder=1 \
> > > ! videoconvert ! autovideosink
> > >
> > > Whether I put ximagesrc before v4l2src or after changes nothing.
> > >
> > > (next challenges: 1/ channelling this to /dev/video10; 2/ channeling the audio from the webcam (/dev/video0) to the virtual webcam (dev/video10))
> > >
> > > For now I would most appreciate some help with making the above commands works without error/warning messages and good performance. Or in other words how do I resolve timestamping with ximagesrc?
> > >
> > > Best regards,
> > > Alain.
> > >
> > >
> > > On Wed, 1 Apr 2020, at 02:42, Alain Culos wrote:
> > > > Hi,
> > > >
> > > > I am a recent newcomer to gstreamer.
> > > > Trying to use `gst-launch-1.0` to chroma-key my webcam and insert a pdf
> > > > as background.
> > > >
> > > > My attempt is very imperfect:
> > > > 1/ I have not been able to find the right parameters to make the window
> > > > sizes match.
> > > > 2/ gst-launch occasionally complains it loses a lot of buffers.
> > > > 3/ the video output only updates seemingly randomly, infrequently, and
> > > > seems to (but not always) needs the pdf window to have focus and the
> > > > mouse to be over it (but not exclusively).
> > > >
> > > > Maybe there is a better solution.
> > > > My desktop is quite powerful: a modern (about 1yo, i7, 6-core,
> > > > hyperthreaded, 64GB RAM), 4k display, 1080p USB webcam, SSD.
> > > > Linux 5.3.0-40-generic #32~18.04.1-Ubuntu SMP Mon Feb 3 14:05:59 UTC
> > > > 2020 x86_64 x86_64 x86_64 GNU/Linux
> > > > ()
> > > >
> > > > The commands I ran are:
> > > >
> > > > 1/ testing the chroma-key with a chequered background
> > > > gst-launch-1.0 \
> > > > videotestsrc pattern=checkers-8 ! video/x-raw,width=800,height=640 !
> > > > mixer.sink_0 \
> > > > autovideosrc ! video/x-raw,width=800 ! alpha method=custom
> > > > target-r=255 target-g=255 target-b=255 ! mixer.sink_1 \
> > > > videomixer name=mixer sink_0::zorder=0 sink_1::zorder=1 !
> > > > videoconvert ! autovideosink
> > > > -> Very slow video, does not chroma-key on white!
> > > > gst-launch recurrent message: "A lot of buffers are being dropped"
> > > >
> > > > 2/ testing the chroma-key (2nd attempt)
> > > > gst-launch-1.0 \
> > > > videotestsrc pattern=checkers-8 !
> > > > video/x-raw,width=800,height=640,framerate=1/1 ! mixer.sink_0 \
> > > > autovideosrc ! video/x-raw,width=800 ! alpha method=custom
> > > > target-r=255 target-g=255 target-b=255 ! mixer.sink_1 \
> > > > videomixer name=mixer sink_0::zorder=0 sink_1::zorder=1 !
> > > > videoconvert ! autovideosink
> > > > -> Same as above
> > > >
> > > > 3/ testing my video
> > > > gst-launch-1.0 autovideosrc ! video/x-raw,width=800 ! videoconvert !
> > > > autovideosink
> > > > -> Showing my webcam is almost real-time, but has a bit of lag
> > > > The same test at 1080p is very laggy
> > > >
> > > > 4/ testing a source application window (evince, showing a pdf file)
> > > > gst-launch-1.0 \
> > > > ximagesrc xid=0x06800008 ! mixer.sink_0 \
> > > > autovideosrc ! video/x-raw,width=800 ! alpha method=custom
> > > > target-r=255 target-g=255 target-b=255 ! mixer.sink_1 \
> > > > videomixer name=mixer sink_0::zorder=0 sink_1::zorder=1 !
> > > > videoconvert ! autovideosink
> > > > -> Does not update the video in realtime (only updates rarely, at most
> > > > every few seconds, when the application window has the focus or redraw
> > > > events (possibly and/or mouse over)), does not allow me to resize the
> > > > application window video stream.
> > > >
> > > >
> > > > Hoping to find here some pointers to solve the issues highlighted
> > > > above, most importantly performance (framerate).
> > > >
> > > > Next steps: a/ including the audio stream, b/ outputting to a video
> > > > device so I can use this as a source for a video conference
> > > > (zoom/skype/jitsi), c/ using an actual green screen.
> > > >
> > > > Thanks for any help, pointers to documentation or tutorials.
> > > > Regards,
> > > > Alain.
> > > > _______________________________________________
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