I've done a composition with AE and as final step I added a .mp3 soundtrack. Not happy I've added another .wav soundtrack above the last one to "cover" some pieces and hear both.
Well, I tought "Too easy" then I got an error after the rendering: while hearing the sound I get the same effect of sound saturation something like SCRAAAAAAAACTCH.
I tryed everything... heared the tracks and both, heard one by one, are perfects and if I use just one track per time it sounds well!
Video + track 1: well!
Video + track 2: well!
Video + track 1 + track 2: SCRAAATCH è_é
So i've surfed the net and I found that AE doesn't like too much .mp3 extensions so I exported the tracks both in .wav extension at 48 KHz and used them but without results.
You should double-check the audio tracks of your VIDEO files. The audio in them can also be compressed, and they can cause problems, too.
The video itself could also be a problem. Read this:
Dave's Stock Answer #1:
If the footage you imported into AE is any kind of the following -- footage in an HDV acquisition codec, MPEG1, MPEG2, mp4, 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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