Show HN: Resonate – Low-latency, high-resolution spectral analysis

Show HN: Resonate – Low-latency, high-resolution spectral analysis(alexandrefrancois.org)

25 points by arjf 3 days ago | 10 comments

Last April I shared about my Resonate project here (https://news.ycombinator.com/item?id=43694157)

A lot has happened since: the work I presented in much more detail at last June's International Computer Music Conference (ICMC) got best paper award. I also gave a talk at the Audio Developer Conference in Bristol last November, the video is on YouTube).

This year's work, which I recently presented at this year's ICMC, starts with known techniques from the phase vocoder literature to build self-tuning filter banks that extract very efficiently the frequency components that are actually present in the input signal. Overview on the project website, more details in the papers, including applications to super-resolution spectrograms and re-synthesis experiments.

As many people have pointed out, none of the techniques I have used are new (some of them even have different names across different fields), but I haven't seen them applied together in this way, and to me the results are incredibly satisfying and sometimes look magical. See for example this demo: https://youtu.be/LasdoIJJkw8

Of course the best way to experience in person is through the free demo app: https://alexandrefrancois.org/Oscillators

Looking forward to feedback from the community!

RossBencina 23 minutes ago |

Nice. To the folks saying "nothing to see here" this appears to be a variation of filter-bank spectral analysis where each band varies in frequency to track "the" in-band sinusoid. Somewhat like a bank of PLLs each with its own tracking bandpass filter. By using IIR filters rather than FFTs you avoid the latency of buffering up a full frame of data before you can run the FFT analysis. I am curious how this handles input containing broadband transients. It might be interesting to use CIC filters rather than an IIR lowpass to get better time selectivity, but maybe that's already been addressed, I didn't read the papers.

j-river 1 hour ago |

A useful demo for this kind of tool would be a side-by-side on difficult inputs: fast pitch bends, dense chords, and low-SNR recordings. Latency is easy to appreciate visually, but robustness under messy audio is what usually decides whether spectral tools become part of a workflow. Even a small set of repeatable test clips would make the tradeoff much clearer.

jmpman 3 hours ago |

There are some piano tuners I've found who are a bit on the spectrum, who believe they can tune a piano in a way that no digital device can replicate. I'm skeptical, and would like to see how this method holds up against one of these savants.

bialamusic 3 days ago |

And this is a tuner using same algorithm: https://apps.apple.com/us/app/resonance-chromatic-tuner/id16...

Also very old stuff :)

bialamusic 3 days ago |

I have such app for more than 4 years. Your algorithm is not new - it is new for you only :) Here is the app: https://play.google.com/store/apps/details?id=com.bialamusic...

https://apps.apple.com/us/app/chord-detector/id1495811175

arjf 2 days ago | |

Spectral analysis has indeed been around as a concept for centuries and there have been apps based on the FFT for decades, so definitely nothing new there. What I have implemented however, while based in known concepts and techniques, allows to achieve real-time, low latency and high resolution (both in time and frequency dimensions) performance that I believe are out of reach of established (published) methods. The apps you link are most likely making use of the FFT, which has become widely supported with efficient hardware acceleration and easy to use libraries, because of its central role in ubiquitous DSP applications, e.g. compression. I would be interested in any publications or at least technical descriptions of algorithms/systems that achieve similar performance!

rfgplk 3 days ago | |

Is it the same algorithm or a similar domain? Overlap can exist

bialamusic 2 days ago | | |

It is more complex than the one described here. The idea is the same but for a working solution many different coefficients are needed and adjusted properly. Resonances are adjusted to have some match to the human perception. It is all time domain as there are no real frequencies in sound.

It is good to see the idea investigated by more people but the man should not try to claim it as his own. We are doing such tings for years and I want this knowledge stays to people so no one should claim it