Re: [Loopdub-devel] Sample Rate Configuration

[Nick T. <nh...@gm...>]

On Jan 2, 2008 10:49 PM, Stephen Sinclair <rad...@gm...> wrote:
> (If I didn't add the variables to the configuration file, the values
> were initialized to zero, which didn't work too well.  :)
>
:-)

> Ideally the InternalSampleRate wouldn't be specified by the user, but
> loopdub would just use the sample rate information in the wav file
> header.
> This would mean a different call to the resampling algorithm for each
> loop, however, increasing CPU usage.  Not sure it's a good trade-off
> if all my loops are encoded at the same samplerate.  Perhaps something
> more 'intelligent' (i.e., nasty and complicated) could be used to do
> the resampling before or after mixing depending on whether all the
> loop samplerates are the same.
>
Here's a proposal for you:

1. Merge the internal and hardware sample rates.
2. Automatically resample all loops to the hardware sample rate when
they are loaded.

The resampling happens once per loop, at load time, meaning
probably-insignificant CPU usage for resampling; the delay caused by
the resampling would probably be dwarfed by the time spent reading the
file itself. This also means that no resampling is necessary during
mixing, since everything is already at the correct sample rate.

Now, what about the clicking problem? Let's run with the
integer-multiple buffer size solution, and see where it takes us. WAV
files could theoretically be at any sample rate, but in practice will
almost always be one of the sample rates listed here:

http://en.wikipedia.org/wiki/Sample_rate#Audio

So, perhaps we could devise a buffer size that is compatible with most
of those sample rates, and simply print a warning for the user when
they load a sample that is not at one of those sample rates. Not a
fully general solution, but perhaps a practical one?