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From: | James |
Subject: | Re: midi control done twice |
Date: | Mon, 20 Jan 2014 14:01:13 +0000 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 |
On 19/01/14 00:45, Devon Schudy wrote:
I don't understand Midi in any shape or form, but is this worth an @KNOWNISSUE in the midi section?address@hidden wrote:\score { \new Staff { \set Staff.midiInstrument = #"electric bass (finger)" % 34 \set Staff.midiPanPosition = #0 a'1 } \midi { } } ['patch_change', 0, 0, 33], ['control_change', 0, 0, 10, 64], ['control_change', 0, 0, 42, 0], ['patch_change', 0, 0, 33], ['instrument_name', 0, 'electric bass (finger)'], ['control_change', 0, 0, 10, 64], ['control_change', 0, 0, 42, 0], ['control_change', 0, 0, 7, 100], As seen by the output, patch_change and control messages for panning (10 is pan MSB, 42 is LSB pan) are done twice.This is because a quirk of ordering makes Staff_performer treat these properties as both changes and preexisting settings. Staff_performer::acknowledge_audio_element creates the Audio_staff as needed to perform Audio_items, and in this case the first Audio_item is the patch change. This happens during do_announces, after the context properties have already changed, so the Audio_staff starts with extra control messages to set its initial state to match the properties. Immediately afterwards, the control changes are performed. The first copy of each change is the initial setting; the second is the explicit change. This happens only when properties change at the beginning of an Audio_staff (which is not rare). I don't see a simple way to fix it, but fortunately it's harmless.
if so, I'd appreciate a simplified explanation then I can create an appropriate tracker/patch.
James
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