Wait a few days and post again a link to https://github.com/danielsz/bioscoop with a title like "Bioscoop: DSL in Clojure for FFmpeg Filtergraph composition" that is the title of the PDF but I added Clojure somewhere in the middle. A few minutes later add a comment in HN explaining you are the author and will answer questions, and also a link to the pdf and your question about other similar projects that target filtergraph.