enable VideoWriter class for java

[berak]

fixing fourcc
small test case: https://gist.github.com/berak/28ba78093943d3120dd4

hmm, #4006

i guess, this won't get merged into trunk (due to the android issue),
still, please let me run this through the buildbot once, so we know we got a valid patch to send
folks from answers.opencv.org to. (this is asked soo often from desktop java users..)

[vpisarev]

@mshabunin, could it be merged in?

[berak]

i originally thought @sgjava's commit was reverted because of the finalizer issues,
only saw @apavlenko 's objection in #4006 after submitting.

well, if some innocent soul tries it on android, and it crashes without further explanation, - maybe we should not merge it now.

are there plans to add the new standalone mjpg encoder to android ? folks there would definitely like to save a video file now and then... (and this would at least partly solve the 'missing backend' problem there)

again, imho, there's no hurry, as long as there's a simple patch for those desktop java users, who urgently need it.

[sgjava]

This was reverted, but I use patching to fix the memory leaks. See https://github.com/sgjava/opencvmem

[berak]

ah, sorry, @sgjava, probably should not have pinged you.

this is all about the VideoWriter, not about any memory issues.

[sgjava]

My scripts also generate VideoWriter for Java, but I believe they were saying this crashes on Android. I'm using the "Desktop" version of OpenCV. I'm still running this on Android sticks, but they are running Ubuntu :)

[berak]

@sgjava : maybe we can activate you for http://answers.opencv.org/questions/scope:all/sort:activity-desc/page:1/query:java%20netbeans/ ? :)

(you seem to have all the answers lacking there ;)

[sgjava]

Well, if I had unlimited time I'd be happy to. Most of the questions revolve around Windows/NetBeans. I'm primarily developing on Ubuntu and targeting Mini PCs like ODROID C1. See https://github.com/sgjava/ubuntu-mini.

[apavlenko]

@berak , @sgjava , I don't mind enabling VideoWriter in Java - let's just handle it correctly on Android!

[mshabunin]

Thank you!
I've checked VideoWriter on Android (armeabi-v7a with NEON) and desktop java and it works fine with new MotionJPG codec.
👍

[sgjava]

Now we just need to work on const_ignore_list in order to enable required constants. My install script comments out CV_CAP_PROP_FPS, CV_CAP_PROP_FOURCC and CV_CAP_PROP_FRAME_COUNT which work as expected. I haven't tested others yet.

[PhilLab]

👍 for the Android+MJPEG!

[damanzano]

Hi excuse me if this is not the place to post this issue, I have jus clone the repository and built the master branch on a Mac OS Yosemite and the VideoWriter class still does not appear in the java jar. I followed the instructions on this page http://blogs.wcode.org/2014/10/howto-install-build-and-use-opencv-macosx-10-10/ to install opencv on my device. I appreciated any help with this.

[apavlenko]

@damanzano , to get these changes you need to compile opencv master instead of using a public package - they have not been released yet.

[sgjava]

For 3.0.0 release and earlier you can comment out VideoWriter in modules/java/generator/gen_java.py prior to compiling. Master already has this change as apavlenko pointed out.