23 Apr
2005
23 Apr
'05
8:23 a.m.
Erik de Castro Lopo wrote:
Last time I looked, libsoundtouch used linear
interpolation for
doing vary speed. Linear interpolation is evil. Here is a table
from a talk I presented a the audio minconf attached the LCA.
Linear interpolation is simply no damn good unless you are *positive*
the maximum frequency in your source material is less that 0.06 of
the sample rate. For any real world signal, this is simply not the
case.
My guess was good, then, about libsamplerate providing better quality.
Secondly, I think the pitch shifter in libsoundtouch
works by doing
time stretching first and then vary speed on top of that (someone
please correct me if I am wrong). In this is the case, it might be
possible to replace the second vary speed stage with the vary
speed from libsamplerate.
Together with a Jackbeat user, we agreed that varying the speed is
enough. We don't need (lo-fi) pitch-shifting. I'll stick with libsamplerate.
By the way, thanks for your work !
--
og