Steve - been reading a lot of “really old” posts that refer to creating subliminals using (1) either the “Nyquist Prompt” capability or (2) the “Subliminal” plug-in.
What’s the difference? What is the “2017” “best” method, in your opinion, if the targeted playback device is an apple device (m4a format)?
Thanks!
The “Nyquist Prompt” is a general effect that allows you to run “Nyquist” commands.
“Nyquist” is a computer language designed for audio use.
There’s no big difference between running Nyquist code in the Nyquist Prompt and running it as a plug-in. Plug-ins have the added convenience that you can install them and they are then available any time you want them.
M4A is a lossy compressed format. Lossy formats are not not good for this because they lose much of the high frequencies. To retain very high frequencies you really need to be using a lossless format such as WAV or FLAC.
Thanks Steve!
I was wondering what the difference in outcome of the specific Nyquist Prompt for subliminals, namely:
CODE: SELECT ALL
(highpass8
(lowpass8
(mult
(lowpass8 (highpass8 s 300) 7000)
(hzosc 45000)
(hzosc 59500))
20000)
14000)
Set the Project Rate to 44100
versus the “subliminal” plug-in. The results of my testing appear to be different.
Thanks too for the input on Apple formats - a quick web-search shows some options for “lossless” playback on Apple devices - I’ll have to explore these in greater depth.
If you look at the top left corner of each forum post, you will see a button that says “permalink”. That button is a (permanent) link the post that it is attached to.
Please copy the link address of the posts that you are referring to so that we can see what you are talking about.
https://forum.audacityteam.org/t/subliminal-function/45405/2
Thanks Steve!
I was wondering what the difference in outcome of the specific Nyquist Prompt for subliminals, namely:
CODE: SELECT ALL
(highpass8
(lowpass8
(mult
(lowpass8 (highpass8 s 300) 7000)
(hzosc 45000)
(hzosc 59500))
20000)
14000)
Set the Project Rate to 44100
versus the “subliminal” plug-in. The results of my testing appear to be different.
Thanks too for the input on Apple formats - a quick web-search shows some options for “lossless” playback on Apple devices - I’ll have to explore these in greater depth.
Thanks for trying to give a link to the original post. That code actually appears to come from this post: https://forum.audacityteam.org/t/silent-subliminal-function/18148/5
As it says in the text, that code is “a simple implementation of Lowry’s silent subliminal presentation system (US Patent 5,159,703 October 27, 1992)”.
The two oscilators, (hzosc 45000) and (hzosc 59500) provide an overly complex way of producing a 15500 Hz sine wave. I presume that Lowrey generated the sine wave in this manner for practical engineering reasons. The code does it this way for no better reason than to reflect what Lowrey did.
I’m not sure which plug-in you are referring as I think there are several different versions on the forum. I recall that Edgar-rtf published one that was a simple “amplitude modulator”.
Probably a different carrier frequency, and perhaps different filter frequencies.