Re: [linux-audio-dev] Re: streaming from disk to terminatorX added (via mmap)

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Subject: Re: [linux-audio-dev] Re: streaming from disk to terminatorX added (via mmap)
From: Benno Senoner (sbenno_AT_gardena.net)
Date: ke loka   27 1999 - 16:20:17 EDT

On Tue, 26 Oct 1999, Benjamin GOLINVAUX wrote:

>
> Wonder how a sine wave looks like when scratched.
>
> Any comments ?
>
>
> Benjamin-

actually the interpolation algorithm of terminatorX fails when
I load a 15kHz sine wave ( 0dB) into tX, and play it at a mere 103% speed
( 1.03) , there is nice aliasing noise, even if we are not violating Nyquist's
theorem in this case.
(15kHz*1.03 < 22kHz)
Scratching this wave at fast speeds produces quite funny sounds,
IMHO for best quality we should oversample at least 2x - 4x and lowpass the
result:
( BTW: I will try to develop a fast AND high quality interpolator suitable
for these things)

(the real turntable would be bandlimited in frequency too due to the
limitations of the needle and the frequency limitations of the analog circuits
(amplifier etc)).
  
Alexander: what kind of interpolation are you using ?
Are you lowpass filtering the results (I guess no).
( different from your resonant lowpass filter, which fails too (= cracklings)
when I feed my nasty high freq sine wave to it.

regards,
Benno.

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