An Embedded Real-time Musical Note and Beat Transcription System

<ns3:p>Musicians often encounter the need to transcribe notes while they are composing a piece. Novice musicians need real-time feedback during practice in to order to see if they are playing at the correct speed. With the rapid advancements in microcontroller technology, it has become feasible to construct a standalone system to perform the above-mentioned functions. Using an STM32F407 from ST microelectronics and the CMSIS library from ARM, a real-time system to decode notes and extract the timing was built. An electret microphone was used as an input transducer. Using the Fast Fourier Transform to decompose the input signal and using a peak picking algorithm, the played notes are identified. The system was tested using digitally generated pitches and an actual piano, and gave good results. The final system is able to transcribe notes in real time, extract the beats per minute of a piece being played, and, if the time signature is given, the duration of the note can also be derived. The overall results are encouraging and show scope for further development.</ns3:p>