Le Mon, 25 Jun 2018 18:31:12 -0400, Tim <termt...@rogers.com> a écrit :
> Hi list, some time ago a coder was asking about > making such an app. I think it's on github. > <snip> > Amazing what DSP audio and image coding can do these days. > Any thoughts on coding techniques? I've read a lot of papers! > Some say using FFTs + auto-correlation comparisons. > Some say non-negative matrix. > My head spins, but this team definitely deserves praise. > Can open source come up with something? To go fast and get a low enough latency, you can use can what time is between 2 consecutive peaks of the signal. Be aware than you would have to smooth the signal because when playing loud and the strings are touching the frets, the harmonic content become so weird you can get false maximums (as seen by a signal analysis of my electrical guitar with a memory oscilloscope), which will give you a much higher fundamental frequency than expected. Normal signal: * * * * * * * * * * * * * * * * * * * * * * *=========*=========*=========*==== * * * * * * * * * * * * * * * * * * Fretted signal: * * * * * ** * * ** * * * * * * * * * * * * * * * * * * * *=========*=========*=========*==== * * * * * * * * * * * * * * * * * * These double peaks can be very huge as an electrical guitar have a huge dynamic during the attack of the notes. Doing a repetitive arithmetic average calculation when the sampling are coming in must be enough to smooth them in real time, and to get ride of other high order harmonics at the same time. The latency will be dependant of the fundamental frequency, something like one period + trigger delay. Cheers, Dom > > Cheers, Tim. > _______________________________________________ > Linux-audio-dev mailing list > Linux-audio-dev@lists.linuxaudio.org > https://lists.linuxaudio.org/listinfo/linux-audio-dev -- If you have a problem and you are not doing anything to fix it, you are at the heart of the problem. _______________________________________________ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org https://lists.linuxaudio.org/listinfo/linux-audio-dev