Start with audio you are allowed to use.
An MP3 chord analyzer should work with owned files, rehearsal recordings, demos, and other audio you have the right to analyze. The app listens for pitch energy, chord tones, timing changes, and repeated harmonic patterns.
1. Import the MP3
Decode the audio and prepare it for analysis.
2. Build the timeline
Estimate chord segments and place them where the music changes.
3. Practice the result
Play along, loop, transpose, and fix any wrong cells.