MIDI dynamics doesn't apply to multi-voice measures

[Pavel Roskin]

Hello!

I'm trying to change relative loudness on the melody and the
accompaniment, by it turn out the MIDI dynamics doesn't apply to the
measures that have multiple voices.  In the attached file, I set
midiMaximumVolume to 0.1 for the accompaniment, and it's quiet indeed,
but only for a few measures.  Then it becomes much louder for some
measures.  The loud measures have two voices, and I believe that's the
reason.

I read that the MIDI dynamics applies only after the first dynamics
symbol.  To placate lilypond, I added \p in the beginning for the
lowermost staff, which wasn't in the original composition.  But it
wasn't enough.  The dynamics doesn't apply to the new voices.  And the
funny thing is that MIDI is still produced!  If lilypond doesn't know
the loudness, maybe it should warn the user rather than produce a
badly-sounding MIDI file with no sings of a problem?

There is one warning about the MIDI output:

programming error: Impossible or ambiguous (de)crescendo in MIDI.

But I don't see what input it applies to and I suspect it's unrelated
to the multi-voice measures.

I'm using the current git checkout of lilypond, commit
4e8daaedf481c243fdb953e1b14717d20115c262.

-- 
Regards,
Pavel Roskin

sure_on.ly
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