arig4711 wrote: ↑Tue Nov 09, 2021 9:49 am
For me this is much better than script player or something else. I use MAC OSX and there you could easily link channels to outputs (MIDI-setup with 4 channels). I have only to start the video and that's it. I think there are also tools like this in a Windows-environment.
With ScriptPlayer all I have to do is drop the mp3 and video in the same folder and start the video. It automatically loads both and plays them in sync without having to do anything else. What is the advantage to messing about with FFMPEG and combining them into a single file?
arig4711 wrote: ↑Tue Nov 09, 2021 9:49 am
As for frequencies I also tried a lot. At the moment I prefer 200,400,800 (don't know why, just by random). What I don't know ist how the three values interact (1: Left channel, 2: common, 3.Right channel or what else ?).
All the carrier frequencies are overlayed the same way on both channels. You can use ten different ones if you want without needing ten channels.
Firstly, a quick primer on how triphase works; The leftA and rightA half-channels both transmit as normal, the common channel is the sum of leftB + rightB. When the left and right channels are in perfect sync; they are both transmit X voltage at the same moment, the common transmits -2X to match and current flows from leftA to common and from rightA to common. When the left and right channels are precisely out of phase (i.e. in anti-phase) the left channel transmits X voltage, the right channel transmits -X voltage but at the common electrode they cancel out (X-X=0), so it doesn't transmit anything. Current flows from left to right and the common is ignored.
The stroking sensations are generated when the two channels gradually move in and out of phase. Current gradually shifts between flowing to the common and flowing to the opposite channel and then back again and our sensation of where it is coming from gradually shifts between the two as well.
The simplest way to test this is to open Audacity (or similar) and generate an 800Hz tone on one channel then an 801Hz tone on the other (any two frequencies will work as long as they're 1Hz apart). Played through a triphase estim box this will give a stroking sensation that repeats once per second (i.e. 1Hz) as the two signals fall out of sync and then back in again. Replace the 801Hz tone with an 802Hz tone and it'll happen twice per second. Use 801Hz left and 802Hz right and it'll be back to once per second - it's the difference between the frequencies that matters, not the frequencies themselves.
This is how the funstim converter works. When it wants to move from the top to the bottom, it reduces the frequency of the right channel fractionally so that it shifts into anti-phase with the left channel. When it wants to move back up again, it increases the frequency so that it shifts the other way.
So what does all that have to do with multiple frequencies? When you tell the funstim converter to use multiple carrier frequencies it applies the same shifts to all of them and then stacks them all together. An 800Hz left 801Hz right signal would stroke once per second and so would a 400Hz-401Hz signal or a 200Hz-201Hz signal. Layer these on top of one another and you can end up cancelling out some of the peaks in the carrier sine-wave without altering the underlying strokes that are a function of the phase.
This is a snapshot of the waves in a funstim file converted using 800Hz only:
- vlcsnap-2021-11-09-13h11m57s962.png (12.76 KiB) Viewed 3603 times
This is the same moment in the same file, but converted using 400Hz, 800Hz:
- vlcsnap-2021-11-09-13h11m29s913.png (12.89 KiB) Viewed 3603 times
Notice how alternate peaks are almost cancelled out, where the 400Hz and 800Hz waves would be opposite one another. This creates a very rapid on-off-on-off effect that feels almost like it's vibrating. It also reduces the amount of current flowing through your body without much reduction in the strength of sensations, which can be helpful if you find yourself losing sensitivity during long files.
That's my understanding of it all anyway - Hope it makes some sort of sense!
