gstreamer-devel Digest, Vol 2, Issue 61

[Robert Jobbagy]

I use OpenCV with gstreamer and it works fine.
I tried it with Ubuntu 10.10 and Redhat 6, OpenCV 2.1 and latest
stable gstreamer.

if you need some advice maybe I can help you.

Some Tips,

if you can reduce your cpu usage, you need resize your frames, change
xml files (Haar detection xml's ).
check this :

http://tech.groups.yahoo.com/group/OpenCV/message/77414

and Xml files are in the src, you need download OpenCV src from git repo.


Robert

2011/4/7 wally bkg <wb666greene at gmail.com>:
> On Sat, Mar 26, 2011 at 4:44 AM,
> <gstreamer-devel-request at lists.freedesktop.org> wrote:
>>
>> From: Tiago Katcipis <katcipis at inf.ufsc.br>
>> To: Discussion of the development of and with GStreamer
>> <gstreamer-devel at lists.freedesktop.org>
>> Date: Sat, 26 Mar 2011 01:57:05 -0300
>> Subject: Re: Streaming ... images getting with OpenCV
>>
>> Don't know if it will help you, but i worked together with a friend of
>> mine on a simple code that captures video using gstreamer, process the data
>> on OpenCV (actually it detects faces and draw an rectangle around them using
>> OpenCV Haar features)  and them pushes the processed OpenCV data on another
>> pipeline, using appsrc. The code was just a test of how OpenCV Haar works
>> and how to integrate it with Gstreamer, so it is a mess (lots of commented
>> code and even some commentaries on portuguese)...but maybe it will help you
>> :-).
>>
>> http://gitorious.org/ufscwork/works/blobs/master/c++/opencv-haar/opencv-test.cpp
>> The new_buffer callback should interest you, it basically process a buffer
>> coming from a appsink (pipeline1) and them pushes it on appsrc (pipeline2).
>> Best regards,
>> Tiago Katcipis
>>
>
> Thank you for posting this example.   I'm more interested in the gstreamer
> aspects of it than the openCV parts.
>
> To compile it on Ubuntu 10.04 with openCV 2.1 built from a downloaded
> tarball (the Ubuntu repos only have openCV-2.0 and it seems broken when
> running some examples form the Learning OpenCV book) I had to change the
> build command from what you list in the comments to:
>
> g++ -ggdb -Wall $(pkg-config --cflags opencv gstreamer-0.10
> gstreamer-app-0.10) -o gst-openCV  gst-openCV.cpp  $(pkg-config --libs
> opencv gstreamer-0.10 gstreamer-app-0.10)
>
> Other than a few warnings about guint64 variables not being unsigned long
> long types it builds fine.  However, I can't actually run it without the xml
> files for the Harr classifer.
>
> Is there some place I can grab them?  (Emailing them to me would also
> work).  If this is not possible or practical, could you suggest a simple
> openCV image operation with visible effect I could quickly substitute in
> your detectAndDraw function?
>
>
> As I said, I'm not particularly interested in diving into openCV at this
> time.  But I installed openCV and bought the book when I learned about its
> cvCreateCameraCapture(), cvQueryFrame(), and cvShowImage() functions as a
> possible alternate infrastructure during some serious frustrations with
> gstreamer and video capture.  Unfortunately performance of the simple
> ch2_ex2_9.cpp program from the OpenCV book was horrible so I quickly gave
> up.  Curiously, revisiting it to figure out why your build command wasn't
> working, I find it runs fine now.  Although ~20% cpu seems pretty high for
> what it accomplishes compared to gstreamer's  gst-launch v4l2src !
> xvimagesink ~6% . Been a boatload of Ubuntu updates since then!
>
>
> Might I suggest that putting examples such as this on Google Code or Github
> or SourceForge and getting the real gstreamer experts to improve them and
> point out potential pitfalls,  would go a long way to making gstreamer much
> easier to learn.
>
>
>
> If I comment out the call to your detectAndDraw() and the error returns for
> the missing xml files, I expected more or less a resized copy of my input
> file, but what I got was and empty output file and a bunch of gstreamer
> DEBUG messages:
>
> Running...
> ** (gst-openCV:32262): DEBUG: pipeline:pipeline0 old:NULL new:READY
> pending:VOID_PENDING
> ** (gst-openCV:32262): DEBUG: pipeline:pipeline1 old:NULL new:READY
> pending:VOID_PENDING
>
>
> I assume these are from my test files not being the correct avi format.  I'm
> playing around now with changing your pipeline1_str to match one of my
> sample files or use playbin2 to try and make it as automatic as possible.
>
>
> As a practical matter I find the videoscale plug-in to be a real resource
> hog (at least when dealing with YUV video) and thus try to avoid it if at
> all possible.
>
> If there is interest in setting this up as a "community" sample code I'll
> gladly contribute back what I end up with from playing with this sample.
>
> --wally.
>
>
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>



-- 
Best Regards,

Robert