This week I worked on building a verification process for determining beat alignment error. I created some songs as tests so that I know the ground truth of the tempo and beat timestamps for those songs with some math. Then, I compared this with what the beat tracking observed. I focused on tempo invariant songs. For most tempos, the beat alignment error fell within the acceptance criteria of 20ms. For tempos of about 120 BPM or greater, the beat alignment error was 21+ milliseconds. Further work is needed to finetune that.
I also created another method of testing to use for real songs where the exact tempo and beat alignments are unknown. I built a Python program extracts beat timestamps from an audio file then plays back the audio while playing a click sound at the observed beat timestamps. I initially used threading to play the song and the metronome clicks at the same time, but this introduced some lagging glitches in the song. I removed the threading and just played the generated metronome while separately playing the song myself, attempting to minimize human error in starting the song at the exact correct time. With this method, the timestamps sounded highly accurate and stayed on beat throughout.
The audio analysis portion of the project is on schedule. Next week, I want to see if I can find some way to reduce the beat alignment error for songs that are above 120 BPM.