Draw f0 on cqt's image

Draw f0 on cqt’s image

Draw f0 on cqt’s image for users to read note’s name directly

Is your feature request related to a problem? Please describe.

I’m always frustrated when trying to draw a f0 line into a cqt image.

I use code1 to draw cqt_note - time image. I find it useful because I can read the name of the notes directly from y-axis.

# code1
y, sr = librosa.load("F:\\Script\\Voice\\music\\human.wav", duration=15.0, sr=None)
C = librosa.cqt(y=y, sr=sr)
C_db = librosa.amplitude_to_db(np.abs(C), ref=np.max)
fig, ax = plt.subplots()
img = librosa.display.specshow(C_db, sr=sr, y_axis='cqt_note', x_axis='time', ax=ax, cmap='gray_r')
fig.colorbar(img, ax=ax, format='%+2.0f dB')
plt.show()

But, the pyin didn’t suppprt it, I can draw f0 line by log y-axis in ‘ferequency-time’ image, but I can not directly read out the note’s name on the y-axis.

Describe the solution you’d like

Provide a new function[let’s call itnote_0()]. and the output could be added to the cqt’s ‘ax’ object, just like drawing pyin’s output on ‘db-time’ image

Describe alternatives you’ve considered

I tried to slove it in a physical way. I set all the figures to a certain size, then, mark the notes in one picture’s y-axis by a pen.

Then, I cut it off, and use this piece of paper as a ruler, but it is very funny, and I have to copy the ‘ruler’ a lot of times.😢

Additional context

I want to get a <u>‘line’</u> of f0, not a number of rectangle(s) filled by a color.

this function is very useful for musicians.

Thanks for your reading

[unbadfish]

@lostanlen Thanks for your answer. But Bmcfee showed me how to achieve my goal. https://github.com/librosa/librosa/issues/1227#issuecomment-678241271 Issue close. By the way, I think the code should be added to the document

[lostanlen]

@unbadfish it’s unclear what you’re asking. If what you want is to overlay a fundamental frequency curve on top of a CQT image, specshow and plot will do that in two lines. If what you want is to be able to name pitches extracted by pYIN, then hz_to_note is your friend: https://librosa.org/doc/latest/generated/librosa.hz_to_note.html