First off let me say “thank you!” so much for creating Audacity; it is by far the best open-source audio editing software out there and I just plain love it. I am currently using the linux build of 1.3.4 on my 64-bit Arch Linux system. I have recorded in two sides of an audio cassette tape. Unfortunately because the speed of the tape across the detector is not perfectly constant, the audio wobbles between slightly sharp and slightly flat. I was wondering if there is any plugin or feature of Audacity I can use to remove that frequency wobbling. I guess I need something that will let me slightly increase or decrease the pitch (with changing the speed of play) on a sinusoidal function. Any ideas anyone?
There is a pitch change tool under effects, but it’s not perfect in 1.2.x. You probably want to fade the effect in and out to avoid sudden, odd pitch shifts and I don’t think you can do that. Further, last time I used it, it actually changed the length of the selection slightly, which means if you did it in the middle of a show, it would be noticed.
Add to all that the ability of the ear to detect changes that are mathematically insignificant.
Good luck.
Koz
Depending on how many tapes you have - it’s probably a good idea to have your tape deck serviced. The rubber parts used in the transport tend to harden, crack and deform over a period of time. This can be a cause of the speed changes you are experiencing. I had my Nakamichi serviced before I did my tape transfers - and it was worth doing.
At the very least it is worth trying to clean both the rotating metal capstan that drives the tape and the rubber pinch-wheel that holds the tape against the capstan. Be careful what you use as many solvents will attack the rubber and make matters worse. I tend to use a nice clean cotton-bud to clean with.
I don’t think you will have much joy in fixing the pitch variations in the recording you have already made. Get the service - or do the cleaning - and then re-record.
WC
Thanks for all the information! I am planning to take the cassette to a professional and see if they can make a better copy.