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Does Different Audio Software Change Playback Pitch Slightly ?

rhysonsax

Well-Known Member
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Maybe I'm going mad - can't find anything about this using Google.....

I have got an old Playalong book with a cassette and I wanted to import the performance and backing tracks into iTunes.

So first I played the cassette and captured the whole audio as one big WAV file. Then I chopped it up into individual songs and saved them as mp3 files. Next I checked the tuning note and because of the cassette playback speed it was about 30 cents sharp. Next I imported the mp3 files into Audacity and changed the pitch by minus 0.33 semitones to correct the tuning note to A=440Hz and all the other tracks by the same amount.

Now comes the weird bit. When I play the resulting mp3 files back using Audacity or Transcribe! the pitch is pretty much spot on. When I play the same files (I really have checked) back with iTunes or Windows Media Player it is about 12 cents flat. This is measured by using Cleartune on the iPhone held up to the speakers on my PC.

12 cents seems to be a lot of difference and I thought that digital music reproduction was supposed to be stable and consistent (whatever you think of the quality). Could these players somehow have different algorithms that affect pitch ?

Any experience of this ?

Rhys
 

Pete Thomas

Chief of Stuff
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12 cents seems to be a lot of difference and I thought that digital music reproduction was supposed to be stable and consistent (whatever you think of the quality). Could these players somehow have different algorithms that affect pitch ?
Usually it's because of the sample rate difference between two common standards, 44.1kHz (CD standard = recommended) and 48 kHz (used more for video) , however when this is the issue the tracks also play faster/slower and the difference is a lot more than +/- 12 cents, it's over a semitone at least.

To test and troubleshoot, first ascertain that the original capture is 44.1 kHz (CD standard).
 

rhysonsax

Well-Known Member
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4,365
Usually it's because of the sample rate difference between two common standards, 44.1kHz (CD standard = recommended) and 48 kHz (used more for video) , however when this is the issue the tracks also play faster/slower and the difference is a lot more than +/- 12 cents, it's over a semitone at least.

To test and troubleshoot, first ascertain that the original capture is 44.1 kHz (CD standard).
Yes the mp3 original and pitch-shifted tracks are 44.1 kHz as is the one stored by iTunes.

Interestingly, I just imported an Aebersold CD into iTunes in mp3 format and the tuning note on that is 10 cents sharp !

Confused

Rhys
 

old git

Tremendous Bore
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Is this a case of technologytis?

If you just play the track, does it worry you that your personal audio equipment, your ears, tell you it is the wrong pitch or just your tuner? Realise it could lead to the need to retune as you are using it for backing tracks but how accurate is the speed of the average cassette player especially when you allow for tape stretch and ageing machinery?
 

rhysonsax

Well-Known Member
Messages
4,365
Is this a case of technologytis?

If you just play the track, does it worry you that your personal audio equipment, your ears, tell you it is the wrong pitch or just your tuner? Realise it could lead to the need to retune as you are using it for backing tracks but how accurate is the speed of the average cassette player especially when you allow for tape stretch and ageing machinery?
I can cope with the 10 or 15 cents out of tune, provided that it's consistent. When I played along with the tracks last night they weren't even consistent - different songs were out of tune by different amounts, so the tuning note track isn't a lot of help.

And I don't mean tape stretch or wow and flutter, I mean each track being consistently a bit sharp or flat, but by different amounts from each other. The cassette player is a reasonable one and plays at a fairly constant speed, but apparently not exactly the same speed as the tape was originally made at.

The technologically puzzling thing for me is that different mp3 playing software apparently plays the same track at different pitch.

Rhys

PS I checked the Aebersold and the CD is at exactly the same pitch as the mp3 versions ripped from it - they are both 10 cents sharp which surprised me.
 

old git

Tremendous Bore
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Is MP3 just one standard? Zoom H2 have a number of choices if you select MP3.
 

kevgermany

ex Landrover Nut
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MP3 is one standard, but the bit/sampling rate varies, to achieve more compression or more quality.
 
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