After Effects Flickering Light

Discussion in 'Digital Video' started by Fredmania, Feb 9, 2012.

  1. Fredmania macrumors newbie

    Joined:
    Feb 8, 2012
    #1
    Hey everyone,

    I have a question about an animation I'm trying to accomplish in AE. I have a layer that I need to make flicker on and off. I don't need any additional effects, like change of lighting around the layer, but this layer just needs to go from fully visible to completely transparent back and forth in a quick flicker motion. How can I do this? Thanks!
     
  2. simsaladimbamba

    Joined:
    Nov 28, 2010
    Location:
    located
    #2
    You could either use the first expression here or try the "wiggle" expression with the transparency channel.
    Code:
    wiggle (5,100)
    The "5" represents the times per second the layer flickers, the "100" is the maximum value (transparency at 100).

    Or if you want a constant off and on, keyframe it for one cycle and copy the keyframes, either from T100 toT0 or from T0 to T100*.

    *T100 = transparency at 100, T0 = transparency at 0.
     
  3. Fredmania thread starter macrumors newbie

    Joined:
    Feb 8, 2012
    #3
    That first one looks great! I'm sorry for such a basic question, but how do I apply that to the layer?
     
  4. simsaladimbamba

    Joined:
    Nov 28, 2010
    Location:
    located
    #4
    You select the layer in the timeline, then access the transparency channel, OPTION click on the keyframe icon (looks like a stopwatch) and then insert the text into the now active text input field, then click somewhere else, as pressing ENTER does not work for applying the expression, just for making a break in the code.
     
  5. Fredmania thread starter macrumors newbie

    Joined:
    Feb 8, 2012
    #5
    Thank you SO much. One final question (another very basic one), these layers are PNGs. How do I access the transparency channel for PNGs?
     
  6. simsaladimbamba

    Joined:
    Nov 28, 2010
    Location:
    located
    #6
    While in the Timeline, press "T" (for transparency), when the layer you want to modify is selected.

    Also have a look at some introductory tutorials to learn AE more effectively.
    VideoCoPilot, AEtuts+ and Lynday and even YouTube are good sources for video tutorials.
    You can also look at the manual/HELP for help.
     
  7. Fredmania thread starter macrumors newbie

    Joined:
    Feb 8, 2012
    #7
    Thank you, I will definitely do that. I really appreciate your help!
     
  8. Kevin Monahan macrumors regular

    Joined:
    Feb 23, 2011
    #8
  9. JayRastaman macrumors newbie

    Joined:
    Feb 3, 2014
    #9
    After I enter the expression, how do I edit it if I want to play around with values? :confused:
     
  10. handsome pete macrumors 68000

    Joined:
    Aug 15, 2008
    #10
    The same way you entered them originally.


    I'm pretty sure he's referring to the alpha channel of the layer, which you are usually prompted to address when importing your graphics/footage files. However, with PNGs, I believe AE recognizes the transparency information automatically.




    Also, if you want to learn more about expressions, I suggest checking out MotionScript.com.
     
  11. mBox macrumors 68020

    Joined:
    Jun 26, 2002
    #11
    If you get lazy like me, just dupe the layer and change each instance expression values.
    Of course make sure the layers are separate, vary length and time position to avoid patterns.
    If someone has a random expression please post now ;)
     

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