Repairing slight tempo/pitch variation heard transferring song from 30 yr old cassette

I’m hearing very slight speed/pitch variation in a couple spots in my old song recording. Can Audacity correct that digitally? I’m assuming the problem is the old cassette and not the ezcap usb cassette capture player.

You can select the bad parts and Effect → Pitch and Tempo → Change Speed and Pitch which changes speed & pitch together just like changing the speed on analog tape or a record. It’s a “simple algorithm” and you are less-likely to get artifacts, than when you change speed & pitch independently.

BUT, since the error is not constant (“in spots”) I suspect it’s going to be VERY difficult to reverse the “damage”.

You can also use Sliding Stretch to accelerate/decelerate.

Thanks for your reply. I didn’t know if I could tell the software to move everything up from a C to C#, covering up the “spots”. It would just move the spots from their C# to a higher pitch too, then you’re saying, everything being moved up together. I suppose I’m looking for something AI might have the abilities to do. If I could freeze the spots in a graph like presentation, that would allow me to “treat” that quarter second of music by manually moving the pitch downward, assisted by my “visual graphic guide”. Haha, I’m dreaming I think. I will play with it some more, taking a look at the Sliding Stretch as well. Thank you, again, for your reply.

There might be some non commercial (not free) solutions.

…I’ve never used any of this software.

Celomony makes Capstan which is specifically for fixing-up tape speed variations. “Crazy expensive”… You can RENT it for 5-days for $200 USD!

Celomony also makes Melodyne, which is similar to Auto Tune, but maybe more powerful/flexible.

Auto Tune might be able to do it too but I think it tries to correct the pitch without changing the speed-tempo.

…Oh, GSnap is a FREE pitch plug-in and I think it works with Audacity. It’s probably worth a try.