Questions about Filtering and Note Onsets?
1. Is 'Detection Function' the same as using Filters on the audio signal? Or generally, what is the difference between Detection Function, Filtering (pre-processing the signal), and Peak-Picking?
2. I've constantly heard about the Low-Pass (or High-Pass) filter, but I am confused. I read that it works on cancelling out certain frequencies that are below (or above) a certain threshold. However, I am using the Time-Domain for calculating Note Onsets (that is, using the change in signal amplitude/energy). So I am not sure on how I can apply low-pass filtering to the time-domain. Any other good filters for note-onset detection?
3. What is the difference between, Spectral and Phase energy? (I have an idea that spectral refers to the spectogram or frequencies, but I do not know what Phase is)
4. I am having difficulties with working with dynamic thresholding. Any suggestions for a good algorithm? For example, a brief description of my algorithm, I calculate and take note of the energy/amplitude changes that occur in the audio signal. Then I get the maximum 'energy change' and based on the sensitivity, I take a percentage of it and set it as the threshold. So this is where the problem of dealing with varying degrees of amplitude/energy comes in. If I set the sensitivity too low, I come up with 'ghost' onsets and if I set the sensitivity too high, I miss out on some onsets. Any suggestions to improve the algorithm (or suggest a new algorithm) that I am using? (Sorry for not having pictures, but I dont know how to post images in the message)
I am sure that it is difficult to have 100% accuracy but I need to have a better algorithm for note onset detection compared with what I have now. I would appreciate all the help I can get. Thank you very much!