[Interest] QVideoProbe Woes

Jason H scorp1us at yahoo.com
Mon Feb 10 21:36:04 CET 2014

No, I cannot make that assumption.

There are tons of libraries based on non-gpu image processing. I am using (attempting to anyway) ZBar. OpenCV is another (though a few months ago it looks like support was added for OpenCL). I'm not trying to scan a major motion picture for barcodes, I am trying to use a video for a unit test, and a camera on the device device to actually work.

I could use QCamera/Camera to capture, if it didn't hit the disk, but alas, it does and is therefore slow. There is no method for getting an in-memory image. I can of course count and skip 9 frames and process every 10th frame or so. I would be happy with that solution. I would also be happy with a capture() that didn't hit the disk, that I could call periodically without the user noticing while they use the video to adjust the camera position. 

Lastly, I am not a GL developer. I have extensive image experience, but GL is foreign to me. I know a variety of tricks to get things to be fast enough, be it sub-sampling, using only gray scale (Y800), I realize it may not be ideal, but "ideal" is overkill and many hurdles away.

So what should I do?

----- Original Message -----
From: Thiago Macieira <thiago.macieira at intel.com>
To: interest at qt-project.org
Sent: Monday, February 10, 2014 12:51 PM
Subject: Re: [Interest] QVideoProbe Woes

Em seg 10 fev 2014, às 09:09:15, Jason H escreveu:
> Ok thanks. I can work with that.
> But, I know very little of GL. How would I convert from GL texture ID to
> say, a QImage or QVideoFrame? I would suspect that the reason that
> QVideoProbe is so not cross platform is this very reason, would that be
> true? 

You wouldn't. Keep it in GL.

For anything related to video, assume that you will never get access to the 
actual pixels, either because of DRM or because it would just be too slow for 
the CPU. Any and every transformation that you need to do with the video must 
be done with OpenGL, directly on the GPU.

Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel Open Source Technology Center

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