4-video mixing, some ideas??


    May 18 2008 | 12:36 pm
    Hi all
    I am working these days in an installation that mixes 4 videos at the same time. The amount of mixing is modified by the movements of people in the room (i will track their movement from above). I did some things that try to speed up all the process:
    1)I roughly adapted a patch of video-mixing by Zachary Seldess (thanks!). The uslider represents the person, you can move it.
    2)Although I don't know much about open GL, somebody told me that it was a good idea to use it and to place some tasks in the graphic card instead of the processor. I use jit.gl.slab to mix matrices(??).
    3)Loadram the 4 clips, in principle they are to be short, only 5 to 7 secs long
    Still, my macbook coreduo 2.Ghz and 2GB RAM is doing badly (only 6 fps and less). This taking into account that I still have to do motion tracking with a firewire DV camera and cv.jit objects!!!
    Any suggestion of how to speed everything up? I post my patch Thanks
    Beatriz

    • May 18 2008 | 2:42 pm
      Hi Beatriz,
      Your patch won't open in max4.x or Max5. If you want to attach it, rather than paste the text in to the message body, it's a good idea to zip everything up first.
      best, Zachary
    • May 18 2008 | 3:30 pm
      Oooooeeepss
      Here you have the text version (hope it works now) Beatriz
    • May 18 2008 | 3:57 pm
      Hi Beatriz,
      First, check out Vade's quicktime playback optimization methods. The thread is here:
      And patches on his site: http://abstrakt.vade.info/?p=147
      Also, you may want to do the jit.op on the GPU as well. Below is a patch similar to one in my other recent post, but using one of Vade's optimizations and a shader modified slightly from the Jitter Tutorial 43 (this is attached).
      Having said that though, I'm getting 59-60 fps from your patch with the qmetro set to 16.
      I'm on a Macbook Pro Core2Duo 2.16GHz, 2Gb RAM, with GeForce 8600M GT (512 MB) -- so maybe we're missing some details here.
      best, Zachary
    • May 19 2008 | 4:06 pm
      Hi 3 issues from a confused mind!
      1))) I have been reading carefully the fantastic documentation by Vade about QT optimization, which by the way really works. What surprised me, is that while playing the patches made by Vade, I wasn't getting the fps rate that he specifies. For example, in one of them he writes that he gets a speed of amply 60 fps, and in my computer I hardly get 25 fps!!. Is this a problem of my graphic card, a GMA 950?? I have tested these same patches in other (better) computer, a Mac Book Pro with NVIDIA graphic card and the speed was the correct one,60 fps, so evidently faster. I post in the .zip file the configuration of my "performance options", maybe I can change them and somehow make my graphic card faster (???)
      Also I noticed that using Max 5/ Jitter 1.7 instead of Max 4.6/Jitter 1.5.2. in my computer increases speed.
      2))))) I post in the .zip file included my patch again,made by the way with Max 4.6 / Jitter 1.5.2 and using this QT optimization and Zachary's mixing patch. Still, something is not working properly, it seems that only one clip appears in the screen and the working is not being made. Can you find the problem?
      3)))) I must have messed up something with all this shaders issue!! I changed my patch to a different folder and suddenly I got messages in the max window like : "error: jit.gl.shader:cant find patch>cc.uyvy2rgba.lite.jxs"
      Actually, I copied the shaders file(s) needed to that location. Where are supposed the shaders to be located??? in the patch folder? they exist already in libraryapplication supportcycling74jitter-shaders (which by the way I included in my search path in file preferences) .....still more and more confused about the File Preferences.
      Many questions here, hope to hear some nice suggestions!
      Greetings Beatriz
    • May 19 2008 | 5:22 pm
      > What surprised me, is that while playing the patches made by Vade, I wasn't getting the fps rate that he specifies. For example, in one of them he writes that he gets a speed of amply 60 fps, and in my computer I hardly get 25 fps!!. > Is this a problem of my graphic card, a GMA 950??
      more than likely. gma 950 ain't so hot.
      > Also I noticed that using Max 5/ Jitter 1.7 instead of Max 4.6/Jitter 1.5.2. in my computer increases speed.
      hurray!
      > Actually, I copied the shaders file(s) needed to that location. > Where are supposed the shaders to be located???
      jitter core shaders are located in the cycling '74 folder, so they are in the default search path. any other shaders need to be added to the search path, or in the same folder as the patch that's loading them.
    • May 20 2008 | 11:19 am
      well, questions 1 and 3 are solved,thanks robtherich! ;)
      Still I can't guess what's wrong with my patch and why the clips don't mix in the jit.window. I guess the problem must be in the parameterers I send to jit.gl.slab, it seems like the sliders didn't work....
      Beatriz
    • May 20 2008 | 3:39 pm
      Your earlier patch works fine on my MacBook Pro (with a GeForce 8600M GPU). It might be your card again causing the problem. It sounds to me like you might be better of NOT relying on slab processing with your current video card. You might just want to remove the jit.slabs and go back to a jit.expr @expr "in[0]+in[1]+in[2]+in[3]"
      best, Zachary
    • May 22 2008 | 9:21 am
      thank you Zachary, I will follow your advice
      Beatriz
    • May 22 2008 | 8:08 pm
      but do some comparisons first before jumping fully into one or the other.
      i know the 950 won't be able to do advanced slab processing, but some of the basic ones it might handle just fine.
      only way to know for sure is to test it out.