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Hydrogenaudio Forum => General Audio => Topic started by: gilibaus on 2019-03-06 15:31:24

Title: Downsampling issue
Post by: gilibaus on 2019-03-06 15:31:24
Sorry for the noob question. I have downsampled a 48kHz wav file to 44.1kHz. In doing so, I have lost all frequencies between 22kHz and 24kHz. Trouble is now some s's sound like f's. Any way to keep those frequencies? Thanks.
Title: Re: Downsampling issue
Post by: DVDdoug on 2019-03-06 16:28:10
That shouldn't have happened.    What format is the file?    What did you use to downsample?    I assume you still have the original?

Quote
I have lost all frequencies between 22kHz and 24kHz
Yes, of course.  The Nyquist limit is half the sample rate.  But those frequencies are inaudible anyway.   (Even if you have super-bat hearing you can't hear the highest frequencies in the context of music or other normal program material.)
Title: Re: Downsampling issue
Post by: gilibaus on 2019-03-06 18:16:19
The file is .wav and yes I still have the original. To downsample I tried both Audacity and Reaper, but got the best result (i.e. the less noisy spectral analysis) with foobar2000. You are right, those frequencies are inaudible anyway but then I wonder why s's have turned into f's after downsampling (for example the word Mindfulness now sounds something like Mindfulneff).
Title: Re: Downsampling issue
Post by: saratoga on 2019-03-06 18:55:23
The file is .wav and yes I still have the original. To downsample I tried both Audacity and Reaper, but got the best result (i.e. the less noisy spectral analysis) with foobar2000. You are right, those frequencies are inaudible anyway but then I wonder why s's have turned into f's after downsampling (for example the word Mindfulness now sounds something like Mindfulneff).

Clipping? 
Title: Re: Downsampling issue
Post by: lvqcl on 2019-03-06 19:04:27
s's have turned into f's after downsampling (for example the word Mindfulness now sounds something like Mindfulneff).
1) Upload samples (original and downsampled), then we'll look at them.
2) Maybe your player upsamples 44.1 kHz audio to 48 kHz and uses some bad algorithm.
Title: Re: Downsampling issue
Post by: gilibaus on 2019-03-06 19:52:29
Ok here they are. I have used foobar2000 PPHS resampler. Thanks.
Title: Re: Downsampling issue
Post by: lvqcl on 2019-03-06 20:11:09
I can't see or hear anything wrong.
Upsample your 44.1 kHz audio back to 48 kHz and listen to it. If it sounds right then it means that the problem is in your playback chain.
Title: Re: Downsampling issue
Post by: gilibaus on 2019-03-07 08:42:04
Thank you. Here attached is the upsampled version, from 44.1 back to 48kHz. Resampler is foobar2000 PPHS. I still can hear f's instead of s's in the word "mindfulness" which is repeated 3 times in the audio. If everything sounds fine to you, then its definitely my playback chain. Thanks again.
Title: Re: Downsampling issue
Post by: jsdyson on 2019-03-07 11:59:54
I can't see or hear anything wrong.
Upsample your 44.1 kHz audio back to 48 kHz and listen to it. If it sounds right then it means that the problem is in your playback chain.
I agree, cannot hear anything wrong.  I just did a double-check (my hearing is very well trained for verifying signal processing artifacts), and if I hear a difference, it would be insignificant.  (a difference of 1/2 dB below about 10kHz can seriously disturb me, and I don't hear a noticeable difference.  Above about that frequency I have problems distinguishing signal levels)*
* I don't claim absolutely accurate hearing, rather I am very sensitive to certain kinds of defects.


John
Title: Re: Downsampling issue
Post by: dneern on 2019-03-07 22:12:54
It could just be an auditory illusion.

In that case you're not actually hearing a difference in the sound, there is no difference in the sound, but your brain wants you to interpret the Ss as Fs and so you hear Fs.

https://www.youtube.com/watch?v=G-lN8vWm3m0
Title: Re: Downsampling issue
Post by: gilibaus on 2019-03-08 11:20:39
Thanks everyone for your checks and suggestions. Next step will be to ascertain whether its just a playback issue, an auditory illusion or a mix of both.
Title: Re: Downsampling issue
Post by: lvqcl on 2019-03-08 13:44:12
Here attached is the upsampled version, from 44.1 back to 48kHz. Resampler is foobar2000 PPHS. I still can hear f's instead of s's in the word "mindfulness" which is repeated 3 times in the audio.
Next step will be to ascertain whether its just a playback issue, an auditory illusion or a mix of both.

Try to ABX (http://www.foobar2000.org/components/view/foo_abx) the original and twice converted (48->44.1->48) audiosamples.
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