Jeff, Thanks a lot for your feedback ! On Wed, Mar 16, 2011 at 10:24 AM, jeff witz <[email protected]> wrote:
> Hello Sebastian, > > OpenCV hasn't good methods to handle rtp and http flux for now. > We already try all the backend and we finally succeed in getting picture in > compiling the gstreamer form scratch without ffmpeg support. > The problem is that the only way to deal with url, is the module uriscr, > which didn't allow any set-up. So once we get a picture it was with 3 sec. > of delay, which was unacceptable for our realtime purposes. > Yes, uriscr have no parameters, try to auto-guess the pipeline to launch.. and is unreliable if used with OpenCV. I had some e-mail exchange with Nils Hasler <[email protected]> where he wrote that at some point they was considering adding a constructor video source that allows passing a string like this: "rtspsrc location=rtsp://192.168.0.9:554 latency=100 ! rtpjpegdepay ! jpegdec ! OpenCVsink" or similar. You may want to ask for this feature on the opencv-devel list. Best regards, Alexandre > Furthermore, I see that the connection to the camera is quite long and it > can be a problem for our purpose. So we finally choose to convert the camera > stream to a virtual device using v4l2loopBack plugin. As we had some > stability issues with gstreamer, we decide to use the mencoder backend, > which is much more stable. > Depending of the kernel version One can have simultaneous access the > virtual device. So in order to be sure that we can treat the datas and save > the movies we have avticated the multicast option, then we can now work with > OpenCV, with the classical example given for a webcam. > The other issue we have to solve came from the fact that OpenCV hadn't been > designed for big picture at an high framerate. So we had to remove every > windows that come from OpenCV to use Qt which have better performances. > Finally we achieve our realtime process of picture at any framerate. We > succeed in the treatment of 700 FPS. > If you are interested in such methods, you can send me private mail and I > can guide you. But I don't give any help on the windows platform. > Everything work well with an ubuntu LTS, so there is no difficulties to use > it in this particular context. > > Best regards > > > > > >Message: 2 > >Date: Tue, 15 Mar 2011 16:23:46 +0100 > >From: "Schuster, Sebastian" <[email protected]> > >To: <[email protected]> > >Subject: [Elphel-support] issues with OpenCV > >Message-ID: > > <a54007a6d3ada94cbd674d9fe82b13cf05c35...@mu00exv01.kmweg.wtlsh.de> > >Content-Type: text/plain; charset="iso-8859-1" > > > > >Hello, > > > >I try to open a stream to the camera in OpenCV (Windows OS). OpenCV throws > these error messages: > >>>>>>>>>>>> > [>rtsp @ 0xbefd80]Estimating duration from bitrate, this may be inaccurate > >picture size invalid (0x0) > >Last message repeated 1 times > >[rtsp @ 0xbf2480]Estimating duration from bitrate, this may be inaccurate > ><<<<<<<<<<< > >So I have experienced the same issues with the FFMPEG like in this example > <http://wiki.elphel.com/index.php?title=Talk:OpenCV> > >Unfortunately it was not possible for us to rebuild the Windows version of > OpenCV with GStreamer instead of FFMPEG. > >Could you give us some advice for establishing the stream? > > > >Thanks, > >Sebastian > > > > > -- > Jean-François WITZ > > _______________________________________________ > Support-list mailing list > [email protected] > http://support.elphel.com/mailman/listinfo/support-list_support.elphel.com > >
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