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Old 21st Jan 2022, 11:31 am   #1
DMcMahon
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Default Tape Speed Adjustment in Audacity

I use Audacity occasionally to digitise tape recordings and do simple editing.

I have never had to do any speed adjustments and looking at the numerous menu commands very unsure how speed adjustments are done.

Can somebody please point me in the right direction.

David
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Old 21st Jan 2022, 1:20 pm   #2
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Default Re: Tape Speed Adjustment in Audacity

See attached.
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Old 21st Jan 2022, 1:39 pm   #3
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Default Re: Tape Speed Adjustment in Audacity

One of those cases when a picture is really worth a thousand words.
 
Old 22nd Jan 2022, 6:46 pm   #4
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Default Re: Tape Speed Adjustment in Audacity

To process a track rather than just play it at a different speed, first select the entire track ( - double click in the track window, or menu: Select/All). Then in the 'Effects' menu click on 'Change Speed...'.

There are then several ways to specify the speed adjustment - a simple multiplier, a percentage change, a slider, or the by setting the new length (time, #samples etc.) of the selection.

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Old 22nd Jan 2022, 10:22 pm   #5
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Default Re: Tape Speed Adjustment in Audacity

It depends on exactly what you want to do. Do you want to change the speed regardless of the pitch or do you want to keep the pitch constant?
If you have a tape which is running slow, lets say for example 10%, and pitch therefore 10% low, then the first thing to do is digitize it at say 44100 Hz. Because it is running 10% slow the effective sampling rate is 48510 Hz. So set the project rate (bottom left) to 48510Hz and then resample to 44100Hz. (You can leave the project rate at 48510Hz and it will play fine in audacity but won't be much use with anything else). If you want to change the speed and keep the pitch constant there is an option but the result can be quite horrible.
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Old 23rd Jan 2022, 11:32 am   #6
DMcMahon
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Default Re: Tape Speed Adjustment in Audacity

Thank you all for the inputs, I will check these out.

David
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Old 23rd Jan 2022, 12:50 pm   #7
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Default Re: Tape Speed Adjustment in Audacity

Quote:
Originally Posted by bluepilot View Post
So set the project rate (bottom left) to 48510Hz
Just realised there were a couple of errors in my post. It's not the project rate you need to change. It's the track rate. Choose "rate" from the drop-down menu in the audio track. (Sorry but my screen shot doesn't work when the menu is dropped down). Also if you reduce something by 10% then you need to increase it by 11.111% to get back to where you were before, not 10%.
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