[chuck-users] SndBuf - audio file with samplerate different from 44100

[Spencer Salazar]

Hey Mario,

Thanks so much for your work on the manual, its looking great!

SndBuf/SndBuf2 are designed to resample the audio file to the native rate
when doing audio playback, although off the top of my head I don't know if
valueAt()/samples() are also resampling (seems like they shouldn't, to
allow true sample-level access).

Generally speaking, comparing two floats for exact equality is too rigorous
for digital audio. Its preferred to test that they are "close enough"
within a desired order of magnitude, e.g. Math.fabs(f1-f2) <
Math.fabs(f1)*0.0001
(see e.g. [1]).

Secondly, there are at least two resamplings involved in this test (when
you created perc2.wav, it was resampled from perc1.wav at 44100 to 48000,
and then ChucK might be resampling it back to 44100). Under certain
conditions resampling can be theoretically "perfect," but otherwise its
just making a guess what the sample would be at the new rate. Even under
perfect conditions, the inexact nature of floating point arithmetic means
that resampling from 44100 -> 48000 -> 44100 will most likely result in a
different series of actual values.

Spencer

[1] http://floating-point-gui.de/errors/comparison/


On Sat, Mar 24, 2018 at 8:59 AM, mario buoninfante <
mario.buoninfante at gmail.com> wrote:

> I forgot to say, that the program I posted in the previous mail returns a
> lot of errors, basically 97% of the file length. I suppose the samples
> which are the same are all 0. btw the bit depth is the same, they're both
> 16 bit.
>
>
> cheers,
>
> Mario
>
>
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-- 
Spencer Salazar, PhD
Special Faculty
Music Technology: Interaction, Intelligence, and Design
California Institute of the Arts

ssalazar at calarts.edu | +1 831.277.4654
https://spencersalazar.com
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