What is a shader, and how do I use it?

On Wed, Feb 27, 2013 at 7:25 PM, Cyrille Henry <ch@chnry.net> wrote:

Le 27/02/2013 19:17, Stephan Elliot Perez a écrit :

Thanks, it works now. For some reason, turning "auto" on and off (with pix_film) causes the video to lag temporarily, but I do not have this problem if I use line-objects to go through the frames. The cpu-usage goes above 100 if I have more than two videos playing at once, but I suppose I don't need more than two for this project...

Also, what can I do if I want an additive blend instead of a normal cross-blend?

i would use a shader for this.
it offer great flexibility, even if it's a bit harder to begin with.
but that's the way openGL wants you to do now.
cheers
c

On Tue, Feb 26, 2013 at 10:16 PM, Cyrille Henry <ch@chnry.net <mailto:ch@chnry.net>> wrote:

    hello,
    Gem is mostly design to work on the GPU, and not on the CPU.
    GPU have hundreds of core, they are faster than CPU for image manipulations.

    pix_add come from the 20th century and should now be avoid since it use cpu not gpu ;-)

    in order to make a fade transition between 2 videos, you can use transparency on one video.
    add a [alpha] object after Gemhead, and send number between 0 and 1 in the last inlet of the colorRGB object to make the video appear / disapear.

    cheers
    c


    Le 26/02/2013 21:33, Stephan Elliot Perez a écrit :

        Hello,
                 So, looking at the help file for [pd~], it seems to be primarily for audio. How can I use multiple cores to work purely with GEM?
                  I am trying to have a simple transition between video clips, but if I have two instances of pix_film and then connect them to pix_add, the CPU-ussage skyrockets well above 100... is there a more efficient object for blending two video clips?

        Best regards,
        Stephan

        On Sun, Feb 3, 2013 at 10:54 PM, Thomas Mayer <thomas@residuum.org <mailto:thomas@residuum.org> <mailto:thomas@residuum.org <mailto:thomas@residuum.org>>> wrote:

             Hi,

             On 03.02.2013 22:48, Stephan Elliot Perez wrote:
              > I am talking about PD's CPU meter. I don't have the impression that PD
              > takes full advantage of 2 quad-core processors. When processing audio,
              > anything over 100 in PD's meter will lead to glitched audio. I am just
              > wondering if it will be much more when I load other videos and transition
              > between them.

             Pd will only use one core, and one core for the GUI. There are ways to
             distribute the load over several cores, e.g. [pd~] or use several
             instances of Pd that communicate with each others:

        http://www.mail-archive.com/__pd-list@iem.at/msg33319.html <http://www.mail-archive.com/pd-list@iem.at/msg33319.html>

             Hth,
             Thomas
             --
             "Spielen Sie Strip Schnipp-Schnapp?" (Adam Weishaupt to Johann
             Wolfgang von Goethe in: Robert Shea & Robert A. Wilson, The Golden
             Apple)
        http://www.residuum.org/

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