hi batuhan
i was once working in this area: http://romanhaefeli.net/projekte/out_of_frame/
however, at this time i had troubles implementing the idea in a way, so that movies with decent resolution and quality could be rendered. my first try of an implemention did indeed use gem, but in a probably not so elegant way: i used [pix_pix2sig~] to convert the incoming live video stream into an audio-signal, so that i could use tables to store the pixel data. this allowed to random-access particular pixels of particular frames very easily. the patch was very slow and in realtime i could only run 160x120 px at 30fps.
then i decided to go for a python script in order to apply the process offline on prerecorded footage. but also the python script was _very_ slow (rendering 30s of dv-pal video took ~30min), but i didn't care since i could do it now in arbitrary quality/resolution. the videos from the link above are all done using this python script.
after that i started to learn gridflow and encountered, that the implementation of this method is much more straighforward with gridflow than with gem or python (yeah, i know it is kind of stupid to use an interpreted language like python for such an iterative process [720 * 576 * 3subpx * 25fps * 30 s = 933120000 iterations of the very same algorithm for a 30 second movie]. i wouldn't be surprised, if implemented in c it would run in realtime, but i completely lack any c skills). in gridflow you only need a handful of objects and it is faster than my gem-pix-to-sig-to-pix approach and python, though it is still quite slow. i can now run 320x240 * 20fps in realtime. but more important: with gridflow it's quite simple to do and very flexible. ask me again, if you want to see the gridflow patch. a few examples using gridflow in realtime can be shown here: http://romanhaefeli.net/kanada/filmchen/
if you manage to find an implementation that is baed on the gpu, please let us know. at least i would be very much interested.
good luck ;-) roman
On Sun, 2008-01-06 at 11:21 +0200, Batuhan Bozkurt wrote:
Hello,
Let me start off by saying that I don't have much experience with computer graphics, so my knowledge is very limited on this area, I'm more of an audio guy but I have some ideas in mind that would apply to graphics well. I just want to experiment.
I want to give a simple example to show my question. Suppose I have a video running and I want to delay each pixel between 0 and a maximum time seperately. This is the most basic time based effect I can think of. So for a 320x200 video for example, I would need 64000 delaying units running seperately and to be able to do this in realtime, I think I'd need to use GPU for computation.
So I'm thinking of using pixel shaders. But I'm not really sure if this is possible or not with it. I grabbed the orange book to have an idea about the process, I did not have much time tolook in detail but I could not find any references to such an operation that made me think that I'm on the wrong track. So before going any further learning GLSL, I'd like to have your ideas on this.
Is GLSL along with GEM is a nice way to do such an operation? Is it even possible to do it in realtime? If GPU powered realtime operation is not possible, is there any tool that you know that is capable of doing such things(realtime or offline)? I have many ideas on processes that modifies pixels which are dependant on the states of pixels before them(i.e. with memory) and I'm trying to find a way to implement them. Any help is appreciated.
Thanks BB
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