Do you have your Output Render settings to complete comp or work area? Where you might have your work area shorter then your comp....
*************PS While I have your attention....Do you have a minus, reduce, and x or close in the top RH corner of your screen to close AE or reduce / minus your screen? Mine is not there?
That's not much to go on. Do some of your comps have work areas that are shorter than the videos?
You will have to provide exact info about your render settings and comp settings. This could be a million reasons like having set a work area, framerate mismatches or even issues with your storage location...
Thanks to all for your responses! Changin' output renders settings didn't solve the problem. But I'll try to add some keys:
1) I'm trying to do concurrent renders (so I launch 2 or 3 'arender' commands with different projects).
2) If I launch renders in a batch (one at a time) it almost work. I've got to add -mp and -mem_usage options to aerender.
I supose that After Effects isn't intended to be used as I'm using it now.
Have you tried to do something like that?
What does "almost" work mean? Do you get a full, working file? Your use of AE render is no doubt hacky, but that doesn't explain the problem. It's more likely some timeout problem with a certain footage I/O - source or render - or some effect lagging in processing and the render process shutting down...
It means that "almost" all projects are rendered ok. One or two of them are rendered incomplete with no errors in the logs. If I add those options (mp and mem_usage) it works ok (but rendering one project at a time).
If I add mp and mem_usage options from the beginning (when trying to do concurrent renders), the problem arises again.
Thank you for your attention.
If I change those settings nothing seems to change.
PS: Yes, I have minus, reduce an x to close/reduce/max AE screen.
Ok, it seems that I've got a workaround now. The problem was that my script didn't save the project file at the end. I've started to save the changes at the end and things seems to work... partially.
Now the AE project file gets corrupted, as described here: http://forums.adobe.com/thread/1029302
Anyway, we modify, render and delete the project, so now it's not an important issue for us.
Thanks to all for your help!