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

From: Olivier Guilyardi <ml@email-addr-hidden>
Date: Mon Jun 13 2005 - 21:18:33 EEST

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
Received on Tue Jun 14 00:15:06 2005

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