Playback tempo

[rettinghaus]

The MIDI file now plays with the correct tempo, but the highlighting of notes still progresses at 120 bpm.

[craigsapp]

That is caused by the update to the latest verovio develop branch. I implemented MIDI tempo conversion from Humdrum to MEI in Leipzip in September, and you implemented MEI to MIDI conversion of tempo recently. But there is one more item seems to be causing the problem:

verovio-humdrum-viewer/scripts/midiplayer.js

Lines 30 to 31 in f0cd691

	var vrvTime = Math.max(0, 2 * time - 800);
	var elementsattime = vrvToolkit.getElementsAtTime(vrvTime);

	var vrvTime = Math.max(0, 2 * time - 800);
	var elementsattime = vrvToolkit.getElementsAtTime(vrvTime);

This JavaScript code is hardwired to tempo 120 for visual playback. Now that MIDI playback is not hardwired to 120, they are not in sync. The question is how to un-hardwire the visual playback tempo...

I took these lines from the MEI viewer. And it looks like the viewer still is using that system (and would likewise have the same bug):

https://github.com/rism-ch/verovio/blob/gh-pages/mei-viewer.xhtml#L288-L289
https://github.com/rism-ch/verovio/blob/gh-pages/midi.xhtml#L56-L58
https://github.com/rism-ch/verovio/blob/gh-pages/mei-player.xhtml#L243-L244

Ideally I would ask the MIDI playback system at what time it is currently being played and then send that value to vhvToolkit.getElementAtTime(). Do you know if this is possible or how to do it? I can also do a work around by calculating the note times from the original Humdrum data (but that would not help if you are starting with MEI data).

Verovio issue related to this:

rism-digital/verovio#379

Embedding MIDI timestamps in the SVG is one way to implement it, but this is inelegant since the SVG would be tied to a specific MIDI file/tempo setting.

[craigsapp]

This is now fixed in verovio 2.0 pre-release (current develop branch of verovio.