Subject: Re: [ecasound] making pitch shifter work realtime
From: janne halttunen (jhalttun_AT_pp.htv.fi)
Date: Thu Aug 21 2003 - 22:04:40 EEST
On Thu, 21 Aug 2003 21:37:56 +0300 (EEST)
Kai Vehmanen <k_AT_eca.cx> wrote:
> On Fri, 15 Aug 2003, janne halttunen wrote:
>
> > been thinking about having a player-system with pitch shifting ability.
> > currently it can't be done with ecasound, because the effect cannot
> > handle realtime output audiodevices. ofcourse the pitch shifting could
>
> How about using the LADSPA pitchshifters? They are FFT-based and are thus
> real-time capable.
yes, well they are not the same thing as they only alter the frequencies not the actual speed of the track.
> > so, the trouble is then to pass this information, if it's readily
> > available, from the effect subsystem to the engine. nowdays ecasound
> > uses libresample library for the pitch shifter. is there a function for
> > querying needed amount of bytes in that? in ecaengine then the buffers
> > need be atleast doubled or better quadrupled for insaneous speeds we're
> > going to go with pitch shifter. few kilos of extra memory is nothing,
> > right?
>
> We'd need to continuously read at a faster/slower rate. The most difficult
> problem however is that if multiple chains operate at different speeds,
> chain mixing routines just can't handle it.
that's why it should be done before mixing routines. realtime inputs, such as loopdevices, would be forbidden for chains that do speedshifting.
janne
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