-
Rendering Problem -> result is different
Hello,
I’ve got a problem with rendering a movie. I rendered it already using the Xvid codec, and now I imported this compressed video as footage into a new project to add some subtitles and other minor stuff.
Now I wanted to render this again, but as soon as the rendering process starts, there are some weird differences: certain keyframes appear to be at different positions (e.g. a few frames delayed) and sometimes even a completely wrong frame gets rendered in between other frames (like, the correct frame order being 123456789 and frame 8 suddenly gets rendered between 2 and 3).
I thought it might be a problem with using a compressed video as footage, so I decompressed it again and replaced the footage. Now the rendering seems to work, but again, the keyframes are delayed (this time, though, it seems like they are all delayed by the same amount – which wasn’t the case in the first try), and the audio is completely distorted.
What is exactly the problem? I’ll later try it with my original uncompressed rendering, but at the moment I haven’t got access to that file. I hope everything will work as it should, but can someone explain me what the problem with uncompressed footage is? In the preview, everything looked perfect…
BTW, the footage interpretation was correct (framerate 25 and non-interlaced).
-
3 Replies
-
BTW, I had a similar problem recently. I did some motion tracking and the result looked perfect in RAM preview. When rendered, it looked like crap because everything was jittering around like crazy (as far as I can tell, everything related to field rendering and so on was set correctly). Because I couldn’t find a proper solution, I just saved the RAM preview and used this as a proxy, which of course worked fine.
I think this problem could have the same reasons… but this time I can’t use that solution, since the whole movie is 3 minutes long and so I can’t make a complete RAM preview :/
-
[Chris Gleinser] “I rendered it already using the Xvid codec, and now I imported this compressed video as footage into a new project to add some subtitles and other minor stuff. “
The codec appears to be an implementation of MPEG-4, which uses interframe (or temporal) compression. Codecs that use this type of compression (HDV, MPEG-2, H.264, etc.) are notoriously bad to use in AE.
From xvid.org:
“Xvid removes information from video that is not important for human perception in order to achieve very high compression rates while still keeping very good visual quality.”
While this ‘removed’ information may not be important for human perception, it helps AE a lot to not have to do guesswork (which it sometimes gets wrong). I’d recommend using a codec that does not use interframe compression (Lossless, Photo JPEG, DVCPRO, etc).
Darby Edelen
Designer
Left Coast Digital
Santa Cruz, CA -
Go Darby!
I have this issue a lot with stuff I shoot on my Mpeg-4 pocket camera. The frames jump around in AE all the time.
My suggestion is to convert it outside AE if possible, or try importing into AE, to convert it there.
– After import, purging the cache (Edit > Purge > All) and then using the Secret Preferences, make sure to have AE dump the cache every 15 frames during render. That usually works for me.
Just render out in another format.
For info on the secret preferences see this tutorial:
Aharon Rabinowitz
Email: arabinowitz (AT) yahoo (DOT) com
All Bets Are Off Productions, Inc.
Creative Cow After Effect Podcast
Internet Killed the Video Star: A Guide to Creating Video for the Web
Reply to this Discussion! Login or Sign Up