Unrecognized function or variable 'chromagram_IF'.

C = chromagram_IF(audio_data,sample_rate,cfftlen);

i want to plot chroma features for an audio file, to detect musical notes for it. Here, specifically, I'm getting the error:

Unrecognized function or variable 'chromagram_IF'.

Anybody know, what can i do that for that?

[audio_data, sample_rate] = audioread(file_path);

Unrecognized function or variable 'file_path'.

% Read an audio waveform

% Calculate the chroma matrix.  Use a long FFT to discriminate
% spectral lines as well as possible (2048 is the default value)
cfftlen=2048;
C = chromagram_IF(audio_data,sample_rate,cfftlen);
% The frame advance is always one quarter of the FFT length.  Thus,
% the columns  of C are at timebase of fftlen/4/sr
tt = (1:size(C,2))*cfftlen/4/sample_rate;
% Plot spectrogram using a shorter window
subplot(311)
sfftlen = 512;
specgram(audio_data,sfftlen,sample_rate);
% Always use a 60 dB colormap range
clim(max(clim)+[-60 0])
% .. and look only at the bottom 4 kHz of spectrum
axis([0 length(d)/sample_rate 0 4000])
title('Original Sound')
% Now the chromagram, also on a dB magnitude scale
subplot(312)
imagesc(tt,1:12,20*log10(C+eps));
axis xy
clim(max(clim)+[-60 0])
title('Chromagram')

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See also — How to plot Chroma_Features for an audio file?