Disable GES adding {audio,video}convert?

[amindfv at mailbox.org]

In the docs for GESEffect, there's a note:

> Note: GES always adds converters (`audioconvert ! audioresample !
> audioconvert` for audio effects and `videoconvert` for video effects) to
> make it simpler for end users.

I'd like to disable this behavior. I'm making a pipeline for which these conversions should be no-ops, and I'd like to be informed with an error if they weren't. In other words, I don't want any silent conversions.

The "always" in the comment makes me worry it's not possible to disable, but is there a way?

Thanks!
Tom