When playing thru external MIDI, sound & display may "freeze/surge" upon restarting
 

Problem description:

If you are playing back through an external MIDI device, such as a USB/MIDI keyboard, and while playing you click a different measure to immediately change the playback point, the playback sound (and the Notation Composer display) may momentarily freeze (for up-to a half-second or so) and then surge to catch-up.

This problem will ONLY occur when you are using a MIDI hardware interface to an external MIDI device/synthesizer. Depending on the particular piece, and whether the sustain pedal is used, and whether the playback measure is more towards the end (and perhaps other factors), this problem may appear as a "very tiny nit" or a "noticeable nuisance".

Workaround:

Installing the custom "JMIDI" program along with the LoopMIDI virtual cable will workaround this problem. See attached PDF for details on this setup.

Details:

When Notation Composer is actively playing a song, and then directed (via the cursor) to play somewhere else in the song, Composer must first stop the current playback before starting the new playback. When stopping playback, Composer must first turn-off any current notes, and release any sustain-pedal commands.

There is a bug in Notation Composer during the stop playback sequence that can result in the MIDI device driver interface being flooded with duplicate/unnecessary "Stop sustain pedal" commands, which can number in the hundreds. As the MIDI hardware interface can only send about a thousand MIDI messages a second, if hundreds of "Stop sustain pedal" commands are sent, sending the following MIDI notes (at the restarted playback location) is delayed. The device driver (as tested on Windows XP with latest fixes only) then attempts to catch-up, resulting in all the frozen notes being sent out in rapid succession.

Note that this same Composer bug can also cause the LoopBe virtual cable to incorrectly sense that a virtual feedback is occurring, when actually there is no feedback. For that reason, use LoopMIDI virtual cable instead -- but be sure to configure it carefully (similar to discussion here http://www.notation.com/vb-forum/sho...6306#post16306 ) to avoid virtual feedback.

If you have questions, problems, or suggestions here, please contact me through the forum. (Please note while I did write the JMIDI.exe program, I am not technically or otherwise employed by Notation.com).

Attached JMIDI.exe tested for viruses at www.virustotal.com
SHA256: 0cca688477fcb27f7e239b56fd5f0cddec2f4029a549d128ba 81479b00c08eaf

Re: When playing thru external MIDI, sound & display may "freeze/surge" upon restarti
 

Hi,

Thanks for posting your app and the directions so that others who may have this problem can benefit from it!

ttfn,
Sherry