On Mon, 2023-12-04 at 14:48 -0600, Karlin High wrote: > On 12/1/2023 2:21 PM, Stefano Antonelli wrote: > > trying to modify ly2video to produce a different kind of video > > Have you seen Knut Petersen's MKVIDEO project?
I have, but thanks for the suggestion. MKVIDEO is not nicely distributed (no git repo) so I didn't have a good look. The problem with every lilypond video generation solution I've come across: ly2video lilypond-html-live-score LilypondToBandVideoConverter [1] MKVIDEO and even this unreleased one: https://www.youtube.com/watch?v=JqwrqhPQIWQ Is that page transitions are abrupt. It's hard to follow the music when the page transitions and you can't read ahead. For my intended use, it's not good enough. I know that ly2video can scroll the music and leave the cursor stationary, but that's not a good solution to this problem either. Seeing two lines of music at a time is the right solution for me: the current line and the next line. At least on my phone's screen. Really lilypond-html-live-score is quite impressive. I like how they use svg elements instead of png. If the page would scroll automatically while the music was playing it would very useful to me. At the same time, I would prefer a video to an html page. It's easy to slow a video down to learn more difficult parts. However, ly2video seems to be the only solution that will take a beatmap file to sync up audio with the notation. It's called midi- rubato and this is crucial for the kind of scrolling video scores that I'm interested in making. lilypond-html-live-score uses an engraver with /consists like event- listener.ly. ly2video uses the after-line-breaking callback. The problem is that the line breaks and page breaks don't have such a callback. Having a closer look at mkvideo, it's using after-line-breaking as well. But I noticed something interesting: \paper { #(define (page-post-process layout pages) (after-pb-processing layout pages)) } earlier, after-pb-processing is defined. So I copied that definition with my own alteration: #(define (after-pb-processing layout pages) (format #t "\nafter-pb-processing")) I ran lilypond. There were no complaints and after-pb-processing did print at the very end. Once. There are two pages though so I expected to see it twice. I don't know how I missed page-post-process before. The documentation says: page-post-process (procedure) If this function is defined (within the \paper block), LilyPond uses it to post-process pages, for example, to extract the table of contents and writing the information to an auxiliary file. The call happens after page breaking has been performed. The syntax is #(define (page-post-process layout pages) ... ) It would seem that page-post-process is called after all the page breaking is performed. I need something called when each page break is performed. I had a look at where page-post-process was used, in paper-book.cc, but I didn't see anything else. By the time it's at 'book' it's probably too late. I found page-breaking.cc which looked promising, but there's no callback defined in there. And the comments indicate that the page chunking code is done before any drawing. I also took a look at LilypondToBandVideoConverter, but it's pretty complicated. Ultimately he's using /consists with engravers too. Nothing about page breaks. Unfortunately another dead end, but I appreciate the reply nonetheless Karlin. Thanks, Stef [1] I haven't seen LilypondToBandVideoConverter mentioned on this list so I'm not sure many know about it. Code: <https://github.com/prof-spock/LilypondToBandVideoConverter.git> Write up by author: < https://www.tensi.eu/thomas/music/produce_like_a_nerd/produce-like-a-nerd_1.html > demo from the above write up: < https://www.tensi.eu/thomas/music/produce_like_a_nerd/media/plan-wonderful_song.mp4 >
