4 ms·
>The equations that do autocorrelation are computationally exhaustive: for every one point of autocorrelation (each line on the chart above, right), it might’ve
by jeremysalwen 9y ago
>The equations that do autocorrelation are computationally exhaustive: for every one point of autocorrelation (each line on the chart above, right), it might’ve been necessary for Hildebrand to do something like 500 summations of multiply-adds...
>Hildebrand realized he was limited by the technology, and instead of giving up, he found a way to work within it using math. “I realized that most of the arithmetic was redundant, and could be simplified,” he says. “My simplification changed a million multiply adds into just four. It was a trick — a mathematical trick.”
I think this is the article's way of dramatizing the standard way of calculating the autocorrelation using the convolution theorem: https://en.wikipedia.org/wiki/Autocorrelation#Efficient_computation https://en.wikipedia.org/wiki/Autocorrelation#Efficient_comp...
- thearn4 9y agoFFT is a pretty cool thing. But yeah, this "trick" has been used for correlation-based computations for quite awhile. Assuming that it's the trick that the author was referring to, the article is actually a bit sparse on details.
- soundwave106 9y agoThe patent for Autotune can be found here: https://www.google.com/patents/US5973252?dq=5,973,252 https://www.google.com/patents/US5973252?dq=5,973,252 My (very non-expert) reading of the patent is that it uses sample reduction and some specific features of the periodic form of the human voice to simplify the math involved in the auto-correlation routine. Although this routine does seem to be unique as far as I know, I wouldn't be surprised if it shares similarities to other techniques to reduce correlation complexity.
- hamiltonkibbe 9y agoPolyphase filters maybe? It's an approach used primarily in resampling, and its an easy way to skip a LOT of Multiply-by-zero-and-Accumulate-ing
- nejenendn 9y agoIt decoded to a phase vocoder on the nearest semitones.
- dspig 9y agoread the patent - all time domain, no phase vocoder involved.
- amelius 9y ago> “I realized that most of the arithmetic was redundant, and could be simplified,” he says. “My simplification changed a million multiply adds into just four.” Doesn't sound like FFT.
- make3 9y agoat the era of deep learning, no one is impressed by their 500 summations of multiply adds, or 1 million multiply adds. A geforce 1080ti does 11.3 TFlops, with a T, that's 11 300 000 000 000 floating point operations per second..
- deleted 9y ago[deleted]
- kingkawn 9y agoI’m still impressed.
- smelterdemon 9y agoIn 1996 your processor might be running at 150MHz. Using a standard 44.1kHz sampling rate, that doesn't give you very many cycles to get each sample processed to do this in real time.
- pocketsquare2 9y agoI'm impressed by a great product. What are you doing with all those FLOPs?
- deleted 9y ago[deleted]
- hamiltonkibbe 9y agoThat's fine, but being able to run multiple audio tracks worth of VST plugins in real time on a modest laptop is very likely more valuable to their target market
- hamiltonkibbe 9y agoYou'd be surprised how quickly those 500 multiply-accumulates per autocorrelation point add up... a 128-tap filter * 500MAC/point * 2 channels(stereo) * 192ksps is already at 24+billion FLOPS for a single track...
- conistonwater 9y agoI would like to see them dramatize Dijkstra's algorithm in the same style. Instead of looking at all possible paths of arbitrary length within the graph, of which there are infinitely many, ...