[LAD] Tutorial for programming with JACK

Robin Gareus robin at gareus.org
Fri Feb 24 17:05:52 UTC 2012


On 02/24/2012 05:52 PM, Harry van Haaren wrote:
> On Fri, Feb 24, 2012 at 10:12 AM, Joan Quintana <joan_quintana at yahoo.com>wrote:
> 
>> This is more interesting and not simple like the previous. A part of
>> playing back the file, it permits frequency shifting and frequency sweeping
>> in a range between .5 and 2.
> 
> 
> I presume by "frequency shifting & frequency sweeping" you mean resampling
> the signal & playing it back, not true "pitch shift" with time remaining
> constant..?

Jplay-sndfile-1.0.0 does zero-order hold. No up/downsampling, no
interpolation.

It'd actually be easier to just use librubberband for frequency shifting
and time-stretching.

> I'd like to see a simple example of eg: phase vocoder doing variable rate
> pitch shifting / time stretching...

_simple_? well maybe example code that comes with
http://breakfastquay.com/rubberband/

http://www.teuton.org/~gabriel/stretchplayer/ (C++) uses librubberband.
Samplecat's jack_player.c (C) uses LADSPA rubberband and libsamplerate.

The code is not complicated; but probably does not qualify as simple.

> Perhaps you've just provided that...? :) -Harry
>



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