Play the MP3 into the mic jack...........
If you can run the program from the command line you might be able to just redirect the input.
Request a transcript from the NSA.
I am NOT affiliated we just use these guys at work.
We had to transcribe podcasts and some video at work. This worked for us. I’m sure there are other similar plugins out there but this was free (donationware) and was easy.
Download VB-Cable here:
https://www.vb-audio.com/Cable/
Easy install and then Sound settings, select it for your recording option. May have set it for playback as well.
We then just used the speech to text option in Google docs. Start the audio, then start the speech to text. Looks like if you do anything else on the PC while it is running the document stops typing. The transcription was well over +90% correct. Formatting, punctuation and the occasional homophone still need to be cleaned up.
Best of luck.
transcriptions:
paid service, using an AI $0.10/minute (free trial)
or using human beings, $1.00/minute
HTTP://rev.com
I’m not affiliated with rev, but do use their services professionally predominately for closed captioning.
Many resources if you do a search on ‘mp3 to text’.
One is Top 7 Methods to Convert Mp3 to Text
https://videoconverter.wondershare.com/convert-mp3/mp3-to-text-converter.html
I have used Dragon Naturally Speaking software to transcribe audio spoken into a digital recorder. I connected the recorder to my computer via cable (USB) and the software did a nice job of interpreting the recorded content. I think there are limits on what format of audio file you are using. I know the home version does not permit this transcription but one of the upper (more expensive) versions does (either Profssional version or Premium or both).