Candle Feedback with Bill Etra

Ive been lucky enough to get to know Bill Etra (of the Rutt-Etra raster based analog video processor fame), and even luckier to to jam with him for a short while at Share. Bill on camera, myself on v.001.

Low Res 3GP camera phone video (apologies): 1 2 3 4 5 6 8 9

Images :

6 Responses to “Candle Feedback with Bill Etra”

  1. michele Says:

    dear vade this is f*****g amazing! super beutyfull! i hope you could give me some tips to improve my jitter patches..please could you explain what’s going on there..
    video>to jitter>gl render>gl texture>texture distorsion/s(?)>videoplanes>out ??
    many thanks
    michele

  2. vade Says:

    Thank you for the kind words – Much appreciated.

    Yup, youre pseudo patch is basically it. Theres a few catches that make things work to get the specific results.. basically, its:

    jit.qt.grab (Live camera input)
    |
    jit.gl.slab (Composite Mixing on GPU) (Second mix input is the OpenGL context captured/rendered as a texture, see last step)
    |
    jit.gl.slab (Luma Displacement)
    |
    jit.gl.videoplane (Blend Mode 6 1 (An Addative Blend Mode , and the video plane is rotated 90 degress or 180 degrees about one axis, which gives everything the somewhat symmetrical look).
    |
    Capured to texture via render to texture and back to the slab composite mixer.. This is the real feedback stage. The other trick is to make the Erase Colors (erase_color message to jit.gl.render) alpha very very low, something like 0.02 or such. This allows the OpenGL to kind of ‘draw’ over itself. Since the video plane is at a blend mode 6 1, and is addative, it will draw over the video plane drawn *last frame*, and since the last frames video plane was swapped 90 or 180 degrees relative to this frame, it adds some symettry about an axis. The luma displacement is also doing its part to make things more ‘liquidy’, and is also set to a very low offset and weight. Feedback is tricky to get right, its a balance of variables, and can blow out either to black or to white very fast, but is very much fun to play with.

    Thats all from memory, but I think it is basically correct. Hope this helps – and thanks again.

    -v

  3. dan Says:

    Hey, where’s the ferret? I demand ferret pics! 😉

    Did you get any shots of Bill’s head in silhouette? Very cool and very deliberate, that Bill.

  4. vade Says:

    This was actually a night a month back – I was late posting it. At Mundial, prior to the Ferret coming out :)

  5. benton-c bainbridge Says:

    very nice visual dialog between anton & bill!

  6. vade Says:

    Hey Benton! Thanks for stopping by. :)

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