Forums > Jitter

Help with jit.xfade, jit.alphablend or alternative.

Dec 15 2009 | 5:14 pm


This is my first forum post. Here is a link to an archive of my patches + abstractions:

I am showing this as an interactive artwork tomorrow night and am attempting to do some fine tuning. The _xfade and _alphablend patches are two versions of the main project file. The jpg.grabrec & jpg.randomqt are 2 abstractions which reside in the main patch. The a1-c3 folders are empty, they are containers for seperate qt movies from a jit.scissors object. You have to change the pathname in each of the abstractions, sorry for the inconvenience, eventually I want this to work via umenus. There is one umenu which does need an updated pathname via the inspector.

The _xfade and _alphablend patches should be run separately, these are the same patch with slight modifications attempting to address the same issue.

You need to "break" the face tracking several times to see any results. Once you open your camera turn your head from side to side a few times and this will trigger some movies to write.

In the _xfade version I am experiencing a very noticeable darkening of the area outside the "overlay" when I put the crossfader to the desired level, .8 or so.

In the _alphablend version, I am using the subpatcher "bob" which is resulting in a lagging black box behind the "overlay".

Ideally I’d like to have the best of both worlds, no black box with a normal looking background. Any suggestions would be greatly appreciated.



Dec 15 2009 | 8:53 pm

hi. i doubt many people are going to download your patch and follow all those instructions.

instead, i recommend you extract from you patch a simple and clear example of what you are having trouble with and you are much more likely to get help. try and use the default media files (,, etc) in your example.

Dec 15 2009 | 10:54 pm

Good call. Here are two simplified examples. No abstractions, pathnames or videos even, just using jit.qt.grab.

1. jit.xfade example:

— Pasted Max Patch, click to expand. —

2. jit.alphablend example:

— Pasted Max Patch, click to expand. —

Again I am trying to avoid the darkening of the background image in the jit.xfade example and the evil black box in the jit.alphablend example.


Dec 15 2009 | 10:57 pm

I see my loadbang doesn’t work when pasting the compressed patch.

– jit.xfade should be set to .8

– jit.alphablend to .2

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