Help identify circa 1970s animated movie with bizarre wedding [closed]

I remember a movie from my childhood that was based on a common folk tale. It was in a very odd animation style (though I cannot remember which). The strongest memory was that there was a very strange wedding with a fairly scary song and the guests were something like wavering creatures enchanted by an evil witch. The wedding was between "A princess?" and some kind of huge and ugly ogre.

I strongly remember talking to many friends about the film so it had a fairly good 'release' but I don't seem to have enough strong memories to hang it off of. The multitude of symbols makes it difficult to remember which folk tale it was. The vagueness of the terms haven't turned up anything in attempts to google search.