[jitter] averaged composite of all frames of a quicktime movie

On Dec 24, 2007, at 12:00 AM, Solomon Bothwell wrote:

>
> Is this possible to do in real time as a movie is being recorded  
> via jit.qt.record? If not is there another way to do this? I want  
> to grab certain frames from my webcam and make a running average of  
> all the selected frames.

One way to do this is to use a temporal low pass filter like  
jit.slide or jit.wake. The nice thing about jit.wake is that it has  
an internal 32 bit fixed point feedback buffer when working with char  
data which can be a little bit faster than jit.slide float32. Set  
jit.wake's bleed/gain/normalize attributes to zero, and just use the  
ff (feedforward) and fb (feedback). For example if you want the  
running average to be 1% of the incoming frame and 99% of your  
history, use @ff 0.01 and @fb 0.99. This is equivalent to jit.slide  
@slide 100.

Or you could also use jit.gl.slab @file tp.slide.jxs @type float32.  
This requires that your graphics card supports floating point data  
(e.g. Intel GMA950 does not, but most ATI/NVidia cards do), but is  
much faster than floating point processing on the CPU.

-Joshua