Hi Martin, there is ly2video by Adam Spiers: https://github.com/aspiers/ly2video
And you will find more in this thread from 2016: http://lilypond.1069038.n5.nabble.com/Generation-of-Notation-Videos-with-Lilypond-Tool-Chain-td188204.html One main idea is to use an infinitely wide page and just one line: https://lilypond.org/doc/v2.20/Documentation/notation/one_002dline-page-breaking and then scroll horizontally trough it. HTH Joram
