[Denemo-devel] Playback View: an important advance for Denemo

[Richard Shann]

I have created a Playback View window in Denemo. It shows the music
typeset by LilyPond with the currently playing notes highlighted.
Starting the playback from a certain note is just a matter of clicking
on the note, playing a range is achieved by dragging from the desired
start note to the desired end note. Looping over a range is achieved by
shift-dragging.

This has the advantage over the current playback regime (which is still
working simultaneously) that you are looking at the music properly
typeset (in the correct key if you have transposed on print) and there
are no pages to turn (the typesetting is done on one long page).

The current visualization in the Denemo Display will continue to be
preferred in the case of a playback that is just a quick check for the
correct notes as you do not have to wait for LilyPond to typeset the
Playback View to do that.

There are some caveats: tempo changes that don't have an explicit beats
per minute are not detected by the Playback View. The text fonts in the
playback view are ugly ones. You have to scroll the view if it runs off
the bottom of your screen - and at the moment a one metre page length is
scripted in.

The windows version does not work - I'll email separately about that. If
someone could check
http://denemo.org/~jjbenham/gub/uploads/denemo-0.0.0-0.darwin-x86.tar.bz2

on an Apple Mac and report back that would be great. Just create a
simple score with a few notes and select Playback->Playback View.

A big thank you is due to Mathieu Demange whose code is re-used to get
this working. A demo of his project can be seen at 

http://www.mathieudemange.fr/lilypond-html-live-score-demo/

(On my browser the highlighting is not very marked and the page needed
reloading between plays last time I tried).

Feedback most welcome! I plan to add auto scrolling (e.g. drifting
upwards) of one sort or another and to substitute LilyPond's MIDI
rendering for the crude MIDI we use at present.

Richard