I record videos using a mic but the audio is always messed up is the such thing as a cord that connects from the amp to your computer and if so what is it called?
an adaptor. ask in recordings because they'll know better

Ibanez ARX 350
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Recording Forum will give you lots of answers. But basically what you want is called an audio interface. It's pretty much an external soundcard that's a lot better at recording than your computers sound card is. They're not too expensive, depending on what features you're looking for.