Digital System Processing (Audio Processing)
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I'm working on project to find the piano notes of a song. From the time domain graph, I was able to find the correct frequency where the note is present. I used: [S,F,T] = spectrogram (y, 512 , [] , 512, fs); to get the frequency of my song. But the size of the matrix S is too big and I cannot find the correcr frequency row. Can someone please help me understand how to get the correct row of frequency knowing the time?
Thanks
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Elimelech Schreiber
2020년 12월 9일
편집: Elimelech Schreiber
2020년 12월 9일
If you have a specific time, then you should probably find the maximum frequency at that time, in the matrix S.
Each column in the matrix S contains the magnitudes of all the processed frequencies at a certain timestep.
e.g. Lets say t=1.13[sec].
first find the correct time index in T, which index 'i' yields T[i] =~ t (= 1.13) :
[~, i ] = min(abs(T - t))
lets say you've found i = 11,
now find the INDEX of the maximum magnitude in the i-th column of S:
[~, maxIdx] = max(S(:, i) ) % S(:, i)- The i-th column, containing freq. magnitudes at timestep i
finaly convert that index into a frequency, using F:
maxFrequency = F[maxIdx];
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Elimelech Schreiber
2020년 12월 9일
Yes, replace it if you have already found it.
And skip that step: that line is meant to find the correct index.
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