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Hydrogenaudio Forums > Lossy Audio Compression > MP3 > MP3 - Tech
spark
hello,
I want to know the sample rate convert algorithms, anyone help me? Thanks for reply.
milosoftware
Simple (bad quality, great speed):

From 44100 to 22050: Throw away every 2nd sample.


High quality:

from 44100 to 22050:
Low-pass filter the 44100 signal at 1/2 frequency (e.g. using a 160-tap convolution filter as resample.c does...)
Throw away every 2nd sample from the resulting set to get a clean 22050 signal.
Lev
Good answer smile.gif

Just out of interest : I've resampled a few things from 48khz to 44.1khz in Cool Edit Pro - how do you guys rate that as a resampler?
milosoftware
Ideally to go from 48000 to 44100 (or back), first "simple" replicate to 147x48000 = 7056000 Hz, then do the low pass filter and "simple" resample back by a factor 160 to get a 44100 signal. Simple as that.

You can tell by the speed which method is being used... Not sure about CE, but there are proggies doing it right.
spark
QUOTE
(e.g. using a 160-tap convolution filter as resample.c does...)

Where can i find resample.c? Thanks.
ChristianHJW
What about using the one and only resampler, SSRC.exe from Naoki Shibata ?

If you like comfort, use BeSweet including BeSweetGUI from www.doom9.org. Just opne your WAV, select WAV as output and set the output sampling rate in the SSRC window ....
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