Topic by Gilles

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  • Gilles
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  • From: Québec, QC
  • Registered: 18-07-2008
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Topic: Annoying bug during midi playback

I sing in choirs and often provide practice CDs made from midi files that I find online or create myself. These midi files are usually straightforward and use separate voices on separate midi channels with one voice having stronger velocity to help in learning the part.

This time, I used pianoteq because the repertoire is mostly a cappella and is well adapted to a piano output, better accepted by singers than the so-so "instruments" usually provided through soundfonts or other general midi systems.

I also want to profit from pianoteq's faster than real-time wave file production, since I have to render many times the same music with different voices emphasized.

I just ran into a bug that is slightly annoying which I reduced to this small example:

http://lh3.ggpht.com/_TjduP84EQE0/Sye0ty_wlGI/AAAAAAAAB18/uinspHtIMQ8/test.JPG

When the note off event appears for the eight note C on channel 2 (bottom staff) it also cuts the whole note C on channel 1 (top staff)

I tried this example with other midi playback programs, and it renders correctly. I uploaded the corresponding midi file:

http://www.forum-pianoteq.com/uploads.php/TEST.MID

I understand this is a bit specialized (not usual piano playing) and would not happen if I used different instances of pianoteq as a vst instrument, but then I lose the fast wave generating facility of the standalone version.

Reply by julien

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Re: Annoying bug during midi playback

The issue here is that pianoteq simulates 1 piano, with 1 set of strings and hammers, while your midi file would require two independent pianos, or a piano with two independant set of strings and hammers, so fixing that while keeping the physical model consistent is not completely straightforward. This is a problem that people who do microtuning via pitch bend on the 16 midi channels also encounter with pianoteq.

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Reply by Gilles

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Re: Annoying bug during midi playback

Thank you for the fast answer. I also thought that the single instrument model was the reason for this, and I guess I can live with it (doesn't happen that frequently actually, I had a hard time pinpointing the reason for random cuts I heard).

In fact it is worse when a note occupies the full length of its value instead of being cut short a little. In that case, a note off event may appear just after the note on event for a same note on different channels, and cut it off completely.

What is confusing though, is that general midi software usually automatically create different instances of the same instrument (or different sound buffers) when voices set for the same instrument are sent to different channels.

I guess this is the purpose of pianoteq as a vst instrument but it complicates things a lot for me.

Reply by dhalfen

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Re: Annoying bug during midi playback

Yup, as Pianoteq models a _single_ instrument, that second C note will always override the first.  In the "real world," you wouldn't be able to do exactly what is written on your staves with a single piano, either (or _any_ acoustic instrument, really -- that first note would have be re-struck-plucked-bowed-blown-etc.).  A bit of choral influence, perhaps?  ;^)

Solution:  lengthen that second "C" (to "fudge" the first C's sustain), treating it as a second voice, or adapt the first staff to compensate for the "interruption," or use multiple instances of Pianoteq, or I dunno...  (This calls for creativity -- or just more pianos!)

:-)

Last edited by dhalfen (15-12-2009 19:23)
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