• Adobe After Effects

  Rendering Alpha

  Posted by Adam Mcewen on June 16, 2007 at 4:27 pm

  Hi,

  I am creating some on screen TV graphics. Id like to give the editors (using Avid) a strap which has transparent and semi-transparent areas. Can i do this by adding an alpha channel? If so how do i do this? What sort of compression do you recomend for TV graphics?

  Appreciate your help,
  Adam.

  Lars Bunch replied 18 years, 11 months ago 2 Members · 1 Reply
• 1 Reply

• 

  Lars Bunch

  June 16, 2007 at 6:50 pm

  Hi,

  Unless the Avids are real old, you should get the Meridian Codec from Avid’s site and render the animations in that format. You MUST make your comp 720×486 (It can be 4×3 or 16×9) at 29.97 fps otherwise it will not render.

  This codec supports an alpha channel. Render it out using the “Straight” setting rather than Pre-multiplied. The resulting quicktime will look ugly and wrong, but it will composite properly in the Avid whereas if you render Pre-multiplied, you will get dark ringing in the semi-transparent areas. If you want to check how it composites, bring the rendered animation back into AE and layer it over a test background. It will look right.

  If for some reason you can’t use the Meridian codec, render using the “Animation” codec. It will take much longer to import, but some old Avids tend to crash when dealing with Meridian codec files. Again, it should be rendered “Straight”

  Hope this helps,

  Lars

Reply to this Discussion! Login or Sign Up