Subject: Re: [linux-audio-dev] stream buffering on EVO & pitchbend .... opinions ?
From: Ruben van Royen (rvroyen_AT_wins.uva.nl)
Date: Sun Sep 17 2000 - 20:51:35 EEST
> On Sat, 16 Sep 2000, Josh Green wrote:
> > > (And as far as I know, the normal pitchbend range (at least on general MI
DI is
> > > +2/-2 semitones))
> > >
> > This is actually set on the target MIDI device. It looks like the AWE card
will
> > only pitch shift up by 2 octaves, down shifting doesn't seem to have a limi
t
> > (makes sense to me). Of course its not using a hard disk for its samples.
>
> But I was wondering how many MIDI songs make use of this big
> pitchshifting range.
> (I owned a Roland SoundCanvas some time ago but cannot remember
> what the max pitchbend value was (default was +-2semitiones, and seems
> that most MIDI songs use this value (plus it seems that there is no MIDI
> standard cmd that allows you to change the pitchbend range from within
> a MIDI song).
> But we can always allow extreme shifts in EVO:
> just keep all in RAM and you are ok.
I own a Roland JV80, and it can pitch bend 48 semitones down (which
would not be a problem), and 12 semitones up. I also have an Alesis
QS8, which can pitch-bend 12 semitones up/down. So for pitchbend
purposes you are completely safe if you limit to 12 semitones.
But pitchbending is not the only place where up/down sampling occurs.
You also want to have the ability to play the same sample acros a
section of the keyboard. This is often done because you need less
samples that way. It is quite uncommen that an instrument is sampled
at every pitch. (Although the best samples out there do this more and
more often). For the disk sampler this still makes sence, since you
must buffer the beginning of every sample. Plus it gives you the
ability to create strange effects.
This could ofcourse be limited to 12 semitones, but I think that
restriction is harder than the 12 semitones for pitchbending. plus,
when you allow pitch bend +12 and map the sample to the keyboard at
+12 you still have the posibility of +24, or a 4 times shortening of
the buffer.
Could the buffer allocation be made dynamic, so that samples the might
be played at a higher speed get a larger buffer? But this could
ofcourse only be done for the initial buffer, so thats not really a
solution. Perhaps the editing software should be capable of
automaticaly generating resampled samples every octave or so.
Also, if I find some time I'll hack wav import for Evo, so that I can
play my 1 Gig piano sample in linux :-)
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