Spectral Peaks (Colorize waveforms based on sound brightness)

[X-Raym]

This is just something to think about i don't think it's possible, or if it is it would probably be hard and take months to do.
Anyway, suggest it, in order to know what we can ask from an ultimate waveform display :P
Comparisonics is great because it lets us show the overall frequency of the sound on the waveform itself. It becomes indispensable for DJing and audio mixing analysis.
They do have an API http://www.comparisonics.com/api.html but i think it's written in C (no javascript ready =/)
However, Comparisonics have one major issue for me : the waveform is usualy (always ?) shown in mono, even in their own player and one website that integrated it (as Freesound) despite the fact they have stero files.

That's it for the idea, it far less important than having stereo waveform display, but I think it's pretty cool :P

Edit 2019: non need for comparisonics, Spectral Centroid algo can be used, see below.

[katspaugh]

Thanks for showing their site. There was demand for spectrograms. For instance, #74.
This might work, especially for simple sounds.

[X-Raym]

There is yest some differences between Comparisonics and Spectrogram. The first one use some advanced perceptive analysis and calculate the overgae over small slices of time, not per peak or per sample, and display the waveform with vertical stripes is far more human readable.
http://www.comparisonics.com/AES_ID31.pdf
It is far more easy to spot kick drum with Comparisonics :)

Spectrograms display frequency (from 20 to 20hz) (not amplitude) over time and look more like this http://en.wikipedia.org/wiki/File:Spectrogram-19thC.png wich can be good for spoting "noise" or "hum" frequencies.

[AnthonyDry]

This would be a sick improvement, but i guess it should be a plugin instead. I havent analysed the draw function at all but from the audiobuffer it shouldn't be impossible to analys the audio thru bandpass filters and get peaks from general hz frequencies. such as 50hz and 5k hz for kickdrum.
Save the currentTime or(samplePosition) of the peaks to an array and then from the draw function set a different color. or make a vertical stripe based on the currentTimeArray or(sampleArray). :)

[X-Raym]

I made a bit of research and found that the algo behind that is called Spectral Centroid. Comparisonics used private patented algorithm but Spectral Centroid is a simple math funciton (free / open source etc).

You can see a demo of this implemented in JavaScript on waveforms on the nice fav.js library:

(fav.js has only few documentation but it works).

This feature is implemented in a large variety of software now (REAPER, Serato, RekordDJ, Samplitube, etc...) and since years on the FreeSound.org website. Really handy feature!

[katspaugh]

Looks damn cool!

[X-Raym]

@katspaugh any news about this?

[katspaugh]

I'll reopen it and move it to the Ideas forum.

[realies]

Any updates on this?