[linux-audio-dev] Re: Looking for fast integer resampling code

[Olivier Guilyardi]

Erik de Castro Lopo wrote:
> Firstly I see that its basically a drum machine. Drum hits are
> relatively we behaved when linear sample rate converison is used.

It looks like a drummmachine, but that's not the goal of the project. I use 
vocal, guitar, bass and drum tracks. I know a Jackbeat user who does similar 
things. Samples can be pretty long.

> Secondly, why don't you just do the sample rate conversion on
> sample load time and sort the converted version in memory.
> This will mean that you do the conversion once for each drum
> sound rather than on all tracks all the time?

That's what I did at first, but for several reasons I switched to realtime 
conversion. One the most important reason is rate shifting, which is performed 
by the sample rate converter according to the following statement :

ratio = jack_framerate / sample_framerate / pow (2, pitch / 12);

The "pitch" is a per track value that the user can change at anytime.

As you can see I use libsamplerate (or my homemade converter) to perform both 
sample rate conversion and cheap pitch shifting in a single operation. AFAIK 
there just is no difference between a sample rate converter and a so-called 
"rate-shifter". Or please tell me what the difference is...

--
   og