[aravis] Re: Debugging latency & long pause issues with Blackfly camera...
- From: Martin Kielhorn <kielhorn.martin@xxxxxxxxx>
- To: aravis@xxxxxxxxxxxxx
- Date: Tue, 15 Apr 2014 14:56:21 +0200
2014-04-15 14:39 GMT+02:00 Patrick Doyle <wpdster@xxxxxxxxx>:
> Hmmm… I don't think that will address my particular issue. It appears
> that I am not receiving some packets from the camera and that is
> leading to problems. I need to insert a gigabit ethernet sniffer in
> the loop to determine if the camera is not sending the packets (I
> doubt this is the problem), the switch is dropping the packets (I don'
> think this is the problem either), or my embedded board is dropping
> the packets on receipt (I'm guessing this is the problem).
> Unfortunately, my hardware doesn't support jumbo packets, so there is
> ample opportunity to drop packets.
>
Can you run wireshark on this board?
>
> I remain confused by the "do-timestamp" notion. I naively assumed
> that "do-timestamp=true" meant that the gstreamer pipeline would use
> camera timestamps. Now I see that it means the opposite.
>
> For my application (robot navigation), I need the camera timestamp,
> which I hope correlates very strongly with the time at which the image
> frame was captured.
>
I read somewhere in the manuals of my cameras (Basler ace series or
Photonfocus) that
they can append an extra line to each image, where this information is
encoded. Perhaps
your cameras have a similar feature.
>
> What is it about "do-timestamp=true" that makes things work with your
> blackfly camera?
>
> --wpd
>
>
> On Tue, Apr 15, 2014 at 4:32 AM, Emmanuel Pacaud <emmanuel@xxxxxxxxx>
> wrote:
> > Hi,
> >
> > Le lundi 14 avril 2014 à 21:53 +0200, Emmanuel Pacaud a écrit :
> >> > I'm not asking that anybody solve this (although, if you've seen this
> >> > sort of thing with the Blackfly, or other cameras and can tell me what
> >> > to fix, you would have my eternal gratitude), but if anybody has some
> >> > suggestions as to what I might look at, or what tools I might use, to
> >> > diagnose these pauses, I would be grateful.
> >>
> >> I have a blackfly camera with which I face some troubles similar to
> >> yours. I think it's due to the fact the register giving the Time Tick
> >> Frequency returns a wrong value. And this value is used to compute the
> >> image buffer timestamps.
> >
> > I've changed the viewer in git master to always use host time for buffer
> > timestamp. It fixes issues I was seeing using my blackfly camera.
> >
> > Using the gstreamer plugins, do-timestamp=true also allows to work with
> > a blackfly camera. It looks like there is around 100ms of latency in the
> > following pipeline, but I think it comes from the pipeline itself, not
> > aravissrc element:
> >
> > gstreamer 0.10 version:
> >
> > ./gst-aravis-launch aravissrc do-timestamp=true !
> video/x-raw-gray,bpp=8,depth=8 ! ffmpegcolorspace ! autovideosink
> >
> > gstreamer 1.0 version:
> >
> > ./gst-aravis-launch aravissrc do-timestamp=true !
> video/x-raw,format=GRAY8 ! videoconvert ! autovideosink
> >
> > Cheers,
> >
> > Emmanuel.
> >
> >
>
>
--
Martin Kielhorn
Leibniz-Institute of Photonic Technology, Albert-Einstein Str. 9, 07745
Jena,
Germany
Tel.: +49 (0) 3641 206 245
Randall Division of Cell & Molecular Biophysics, King's College London, NHH,
Guy's Campus, London SE1 1UL, U.K.
tel: +44 (0) 207 848 6519, fax: +44 (0) 207 848 6435
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