Changing sample rate changes frequenty of tone ?

[kara]

I lost quit some time with something stupid and I wonder if it's normal and I don't understand or if it is a bug 

So here goes the story....

I had some instrument samples that where in 48khz and since I want to use them in milkytracker i had to resample them in 44.1kHz.
No problem, just opened the samples in audacity and changed the samplerate of the sample and save, I tought.... so,that was what i was doing.
Until i wanted to use the samples and i noticed that something was very wrong, luckily my ears are still ok 

So, back to audacity, load the sample and analyse the frequenty of it, and surprise ,yes, the frequenty changed around 2 semitones...

Now I wonder... is this normal or it is a bug ?
Why does resampling changes the frequentie of the sample ?

k
 

[Marc JX8P]

It sounds like in this case the sample hasn't been resampled but a marker has been changed from 48 khz to 41 khz, like playing the same record only slower. Presumably it does sound lower in frequency?

I'm thinking that the resampling algorithm you use probably has a switch allowing you to keep the pitch when resampling or something like that. Resampling and keeping the pitch is effectively timestretching.

[kara]

That's exactly what it does Marc
And there isn't any switch, so i consider it as a bug
If nobody can convince me that I'm wrong

k

[rharv]

It sounds to me like the same thing- it's just playing the sample at the other rate and didn't truly convert it.
You could set Powertracks to the rate you want, then open the original files.
PTW will ask if you want to change the samplerate in PT to mact, rather than convert...say no and it will convert the sample to the new rate.  then you would have to 'save track to file' to save it.

Since PT is a recording software this would be a clunky way of doing it.  I bet some other sample-use software would do it better.  Maybe 'chickensys' demeo.(?)
 There must be freeware convertors out there.  I know you know how to search the net, Kara..

[folderol]

This is very strange. I've only ever converted a couple of wav files in audacity previously and didn't have any problems.

To make a test, tonight I got one of my tracks in its original 44.1k wav format and used audacity to upconvert to 48k and downconvert to 16k. These versions I saved then played back in XMMS. They all showed the correct sample rates, all seemed to play at identical speed and pitch. The 16k one was noticably lacking in 'top end' but otherwise I could hear no differences.

[kara]

Thanks Will & Rharv

I wonder what I did wrong then ....
Did you use the change sample rate on the track properties itself or did you just export the audio in an other format ?
Exporting in an other format does work, but changing sample rate of the track itself doesn't here ?

k

[folderol]

I loaded the test file in, changed the project rate (bottom left corner) then exported as wav to a new filename.

Reloading the files, correctly identifies the new sample rates, and a simple filesize check gives sensible results.

[kara]

A yes, there I agree
But did you change the sample rate of track itself ?
Then it goes wrong ....

k

I loaded the test file in, changed the project rate (bottom left corner) then exported as wav to a new filename.

Reloading the files, correctly identifies the new sample rates, and a simple filesize check gives sensible results.

[folderol]

A yes, there I agree
But did you change the sample rate of track itself ?
Then it goes wrong ....

k

No. I didn't try that.

Just attempted it a few minutes ago, and it seems I can't actually resample the tracks. It says it is doing it, but actually changes nothing at all