Forums > Jitter

jit.qt.grab deinterlace

Feb 27 2014 | 3:31 am


I have a patch with jit.qt.grab and want to deinterlace the incoming video, which is 1080i
How can I do that??


Feb 27 2014 | 12:44 pm

If you send a "singlefield 1" message to jit.grab you can throw away one fieldset, but that cuts your vertical rez in half.

There’s a simple de-interlacer shader included with MAX:
(Cycling 74 folder / jitter-shaders / convolution / cf.deinterlace.jxs)

Or you can try vade’s de-interlace shader v001.deinterlace.jxs (attached to this post – seems to be gone from the internet these days?)

I think both shaders do simple field mixing, so they look better than "singlefield 1", but you won’t get full sharpness either. You can read about smarter de-interlacing methods on the VLC wiki (none are available in MAX though).

Feb 27 2014 | 12:47 pm

Thanks, will try and see how it works out


Feb 27 2014 | 12:50 pm

Tried "If you send a singlefield 1 message to jit.grab you can throw away one fieldset, but of course it lowers your vertical rez." Jit.qt.grab doesn’t understand it??


Feb 27 2014 | 1:10 pm

Perhaps the new QTKit grabber in 6.1.6 / Mavericks lost the singlefield capability? Or maybe some digitizers don’t support it? I’ve used it many time for DV inputs.

Feb 27 2014 | 1:15 pm


I just saw in the help file that’s it’s digitizer dependant. Will try the shader instead.

Thanks again

Feb 06 2017 | 5:55 pm


I’m trying to deinterlace footage captured with jit.grab.

I need some very basic advice as to how to wire up the shader.

I’ve posted the patch with what I suppose are the basic elements needed.


Feb 07 2017 | 7:54 am

it’s a texture processing effect, so you use
also, you can enable output_texture on the jit.grab for improved performance, since you’re going straight into GL land with the deinterlace shader.

— Pasted Max Patch, click to expand. —
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