Without exact system info, render settings and so on we can't tell you anything. You haven't even told us your version of AE. And while it may seem a simple enough animation, there could be other factors at play such as color profiles on the PNG as well.
Hi Mylenium. Here is system info asked:
-- Ae CS6 126.96.36.199
-- Windows 8.1 Intel i7 3630 2,4GHz 16Gb NVidia GTX 675MX 4Gb CUDA driver 6.5
-- Render settings: Best settings (default), H.264 (MP4) level 5,1 encoding VBR 1 pass, target and maximum bitrate = 6, everything is default (that is, RGB millions of colors premultiplied (matted)), audio output default (that is, 48000KHz, stereo, AAC hight quality bitrate 128
-- PNGs were obtained with Windows snipping tool (screen shots) - which never caused any trouble before.
-- The MP4 movie background was obtained with Camtasia - which never caused any trouble before.
Is there a hint of what can be causing that error and stopping the renderization? Thanks.
Use the Adobe Media Encoder to change your MP4 background into a proper production codec (QuickTime with the Photo-JPEG codec would be a good one.)
Replace the MP4 with the MOV and see if it works.
I understand what you said! Thanks for the explanation!
Yes, the problem is that Ae seems to not handle well MP4 files. Why is that? The problem was solved, thank you very much!
Yes, the problem is that Ae seems to not handle well MP4 files. Why is that?
After Effects works on a pixel-by-pixel basis. After Effects is not like video editing programs - they just deal with a video stream - in After Effects, each frame is fully uncompressed.
MP4's use interframe compression. That means that they only have a complete frame every once in a while and the rest are filled in using a variety of methods including motion estimation. Depending on the compression settings, a video with interframe compression often won't have a complete frame for a few seconds. That means that, out of every 90 frames or so, only one of those frames actually contains full pixel data for the entire frame (and that frame is usually somewhat compressed using intraframe compression [like a JPEG]). After Effects has to decode a lot of crap and translate it into full-frame, full pixel information before it can even begin to process it.
After Effects is much better with it now than it used to be. CS4 and earlier used to struggle with it bad. Each version since has improved handling of such things. Also, each version implements ways of handling newer versions of codecs. Keep in mind, version 11 (CS6) was written before a lot of modern cameras were even built. The current version (13.2) probably would not have had the issue you did.
Does that explain it?