Comment 6 for bug 784739

I'll post my observations, maybe they'll be helpful for you or other users. Maybe these facts are known to you OpenShot developers, so you'll get a confirmation.

The crash doesn't occur with MLT 0.7.4, and the exact "fix" in MLT that does it is the commit that… updates version number in MLT to 0.7.4 (on top on previous commits, certainly). And as you know, if OpenShot 1.4.0 detects MLT 0.7.4, it does some checks if an effect is available:

> Warning: effect not found in your version of Sox: sox:echo

etc., etc. and doesn't display non-existent effects.
So, with MLT 0.7.4 I got only "Balance" effect in audio effects.
And it turned out that with MLT 0.7.2 the crash I'd described *doesn't* occur if I use the Balance audio effect.

So in a few words: it looks like the crash has been caused by OpenShot (or user) trying to use a sox effect that doesn't exist (but was listed anyway). It's not listed with MLT 0.7.4 and the crash doesn't happen, because a user can't use it.

Ref.: openshot/windows/TreeEffects.py (for 1.4.0), populate_tree. Good to see it fixed!