I am creating some video insets that Track Matte (alpha matte) with a Shape Layer. For a reason I have yet to figure out, video layer has a few frames of black on a specific layer at seemingly random times throughout the clip. I have investigated this quite a bit and here is what I can figure out.
-It has something to do with the alpha channel. When I turn off the Track Matte using the alpha channel everything think is back to normal.
-When the Track Matte is on AE acts like the black flash is on the source footage. The black frame appears in the footage window when I scrub through the MP4 footage file. But I can view the same file in Premiere Pro and it appears normal.
My AE comps are linked to my Premiere Pro project so they show up on my final outputs.
If the footage you imported into AE is any kind of the following -- footage in an HDV acquisition codec, MPEG1, MPEG2, AVCHD, mp4, mts, m2t, H.261 or H.264 -- you need to convert it to a different codec.
These kinds of footage use temporal, or interframe compression. They have keyframes at regular intervals, containing complete frame information. However, the frames in between do NOT have complete information. Interframe codecs toss out duplicated information.
In order to maintain peak rendering efficiency, AE needs complete information for each and every frame. But because these kinds of footage contain only partial information, AE freaks out, resulting in a wide variety of problems.
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