Skip to main content ↑ ↓
Topic: Involuntary rubato (Read 5468 times) previous topic - next topic

Involuntary rubato

One of my Noteworthy files seems to have developed a sort of "tempo rubato" in which every now and then it seems to linger over certain notes before getting back up to speed. Can anyone please offer an explanation and a possible cure for this phenomenon?

Re: Involuntary rubato

Reply #1 –
Greetings, John!

I'd be surprised if it's in the NWC file itself.  More likely your computer is just strained for some resource or other, and the result is that it slows down a bit here and there when it has too much to do.  If you haven't already, make sure you have no other applications running; if like me you're running Windows98 (*gag*), it might also help to reboot the system in case there's been memory or other resource leakage.

On the other hand, it may be that it's in your file after all, if it happens to make extreme demands of the MIDI subsystem (drivers, sound card, etc.)  This is more likely to be the case if the glitches you're experiencing happen repeatedly at the same places in the file.  I've never encountered this myself but could imagine that a particularly busy NWC file on an underpowered system, especially with software sound synthesis, might simply overwhelm the CPU and cause delays during playback.

HTH

- Grant

Re: Involuntary rubato

Reply #2 –
This seems to happen on my system as well. The problem usually occurs when there are too many MPCs in one place. It was quite bad on my previous machine (running Windows95 with 200MHz processor and 16M RAM), but is far less frequent on my current system (running WindowsMe with 1GHz processor and 128M RAM).
As for having other apps open, I don’t do that. I’m a dedicated listener/composer/arranger. My daughter Kara likes to play solitaire while listening (listen while playing?), but that doesn’t cause any problems.

Re: Involuntary rubato

Reply #3 –
MPC's can indeed plug up the works if you select too low a resolution. For instance, if you do a volume sweep from 100 to 50 over 1/4 note (let's say at 60 bpm) you end up sending 50 events in a time of one second. If you repeat the mpc on, say, four staves, you're up to 200 events in that one second.

I usually use a resolution of 3-5 for the 7-bit controllers (all except pitch-bend), which keeps the number of events manageable while (usually) not causing any audible "steps."

The data transfer rate for midi is only on the order of about 30 kbps, or in practical terms, about 1500 events per second. Sounds like a lot, but if you're working on an orchestral score and do a volume mpc on 15 staves, you can quite easily over-run the midi stream. In addition, synthesisers have their own hardware or software limitations which can be even more restrictive. The "Microsoft SW synth" (aka DirectMusic, apparently based on Roland's VSC system) is especially finicky about choking on too many controller events.

The situation is even worse with pitch-bend. Let's say you're doing a pitch-bend of a semitone over the same 1/4 note at 60 bpm. If you use the default of 32, then you've got (4096/32) = 128 events -- in addition to everything else you've got going on. I find that a resolution of 256 is a more reasonable "default" for pitch-bend, especially since the ear will automatically do an averaging effect, much as a quick slide on a guitar string sounds like a true glissando rather than a series of semitones.

Hope this helps.
Fred

Re: Involuntary rubato

Reply #4 –
Many thanks Grant, Minnie and Fred for your helpful replies.
I'm not too sure what you mean by MPC's but any how,it seems to have righted itself now. Maybe I had absent mindedly left something else running on my computer at the same time. By the way,my present set up uses a700MHz Athlon with Windows ME and 512Mb of memory, so there should not have been a traffic jam there.

Re: Involuntary rubato

Reply #5 –
MPC = Multi-point Controller, which is on the NWC Insert menu
 

Re: Involuntary rubato

Reply #6 –
Thanks for enlightening me, Eric.my reference books told me "Multimedia PC" !
Cheers,
John.