How to drop first X frames or first X seconds of video

[Stirling Westrup]

Yeah, as far as I know, there really isn't a clean way to discard the first
n seconds of a source via cli. The best I can think of is to use
multifilesink, but that could be really awkward to get working.

I'm afraid you'll need to use python.



On Wed, Jun 5, 2013 at 10:00 AM, a b <genericgroupmail at gmail.com> wrote:

> Thank you very much Angel,
>
> Really appreciate your input on this!
>
> On Wed, Jun 5, 2013 at 2:40 PM, Angel Martin <amartin at vicomtech.org>
> wrote:
> > If you prefer the probe method this links could help you:
> >
> http://gstreamer.freedesktop.org/data/doc/gstreamer/head/manual/html/chapter-dataaccess.html
> >
> http://gstreamer.freedesktop.org/data/doc/gstreamer/head/manual/html/section-dynamic-pipelines.html
> >
> > If you prefer a output-selector this one (ossbuild example):
> >
> http://code.google.com/p/ossbuild/source/browse/trunk/Main/GStreamer/Source/gst-plugins-bad/tests/icles/output-selector-test.c?r=926
> >
> >
> >
> > 2013/6/5 a b <genericgroupmail at gmail.com>
> >>
> >> Hi Angel,
> >>
> >> Thanks for the quick reply!
> >> So sounds like these methods are for programming a solution.
> >> I had planned to look into the python pygst module in order to get
> >> away from relying on executing system calls to gst-launch. Maybe now
> >> is the time to do that.
> >>
> >> Cheers!
> >>
> >>
> >> On Wed, Jun 5, 2013 at 12:52 PM, Angel Martin <amartin at vicomtech.org>
> >> wrote:
> >> > Hi,
> >> >
> >> > Check valve gst element or the probes to check the buffers timestamp
> to
> >> > drop
> >> > or pass the buffer.
> >> >
> >> > Best,
> >> >
> >> > Angel
> >> >
> >> > 2013/6/5 a b <genericgroupmail at gmail.com>
> >> >>
> >> >> Hi all,
> >> >>
> >> >> I have an issue with capturing a single snapshot from one particular
> >> >> device.
> >> >> Very often when starting to stream from one of our capture cards
> using
> >> >> the decklinksrc element the first few seconds of video are badly
> >> >> tuned/rendered before things finally correct themselves and the video
> >> >> appears normal.
> >> >> The way in which i am taking a screen shot means that the first video
> >> >> frame is output to an image file, which for this device means a very
> >> >> poor snapshot.
> >> >> There is no issue with the v4l2src capture cards as the first frame
> is
> >> >> always perfectly tuned/rendered.
> >> >>
> >> >> Here is how i am doing it:
> >> >>
> >> >> gst-launch decklinksrc mode=2 connection=4 ! ffmpegcolorspace !
> >> >> video/x-raw-rgb ! pngenc snapshot=true ! filesink
> location="frame.png"
> >> >>
> >> >> Is there anyway or any element i can use to drop the first few
> seconds
> >> >> of video or the first e.g. 90 frames before taking the snapshot?
> >> >> I had read about the valve element and played with it but didn't see
> >> >> how it was going to work (for a start it causes execution to block).
> >> >> Ideally I'd like the command to run and finish with no further
> >> >> interaction as it does at the moment.
> >> >> If there is no real way to do it via a command line, then it would be
> >> >> useful if anyone could point to a way to do it programatically via
> >> >> python.
> >> >>
> >> >> Thanks in advance.
> >> >> _______________________________________________
> >> >> gstreamer-devel mailing list
> >> >> gstreamer-devel at lists.freedesktop.org
> >> >> http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel
> >> >
> >> >
> >> >
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> >> >
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> >
> >
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-- 
Stirling Westrup
Programmer, Entrepreneur.
https://www.linkedin.com/e/fpf/77228
http://www.linkedin.com/in/swestrup
http://technaut.livejournal.com
http://sourceforge.net/users/stirlingwestrup
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