Help Regarding PPG signal processing...

Hello friend,I am working on PPG signal.I have extracted the PPG signal from the Mobile phone's video(tried 17fps and 30fps camera).And am able to get fairly signal....But problem with my signal is it contains lots of noise as expected and I have used the btterworth filter(2nd order) and then the signal gets less noise.But I am getting less Heart Rate than expected if I use "findpeaks" function....Expected heart rate is 63 and am getting 45 for green channel and 53 for red channel.what is wrong?what method should I use to get accurate answers?Also not getting how to use FFT of this signal....Plz Help. Thanks