This paper describes our method, submitted to MIREX 2011 task “Multiple Fundamental Frequency Estimation & Tracking”. This task restricted the problem of Multiple F0 Estimation and Tracking to three cases: i) Estimate active fundamental frequencies on a frame-by-frame basis; ii) Track note contours on a continuous time basis (as in audio-to-midi); iii) Track timbre on a continuous time basis. The presented method is a genetic algorithm approach to polyphonic music transcription. Two versions of our method have been submitted: RFF1 and RFF2. RFF1 is intended for transcription of piano music. RFF2 is RFF1 with support to other kinds of pitched instruments.