I saw this animated film on TV in the '90s. To be more precise, it was aired on Hungarian television, so maybe it's some European film.
The background was yellowish, and everything else was black. It looked like sand drawing.
Kids were captives of an old man. This said man sometimes turned into a raven, if I remember correctly. But what I'm sure about is that the children were forced to make coffins. Later on they found out they are making their own coffins.
Any ideas what could this be?