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Finish Phone / Lofi effect

Open topisani opened this issue 7 years ago • 13 comments

We need dsp and graphics for a lofi/phone/radio type of effect.

topisani avatar Nov 24 '17 22:11 topisani

I will see if i can come up with a cool idea for the graphics. :)

AlbertSmit avatar Nov 25 '17 19:11 AlbertSmit

So, since i can't find a good rundown of the effect on video: What is it? It seems like mostly some bitcrushing - perhaps with some granular elements. There's definitely some glitchyness going on...

jmidt avatar Nov 26 '17 12:11 jmidt

the OP-1 has an effect that does i think a bit of analogue sounding distortion + definately some bit crushing and some "glitchyness", which seems a bit like a randomly/envelope triggered gate. But i dont think this is necessarilly what we have to do with it. I just think we need something to destroy sound, both analogue-like and digital (bit crushing)

topisani avatar Nov 26 '17 13:11 topisani

@jmidt Short video of 'Phone' effect (starts at 3:20 if timestamp doesn't work).

AlbertSmit avatar Nov 26 '17 20:11 AlbertSmit

I don't know about the OP-1 effect, but in general, the reason phones sound the way they do is because of heavy signal filtering (e.g. hard low and high passing), so maybe it could be a combination of hard passing, noise modulation, and bitcrushing.

Hate9 avatar Nov 30 '17 20:11 Hate9

Current state of this effect's UI.

schermafbeelding 2017-12-02 om 00 21 40

F E E D B A C K T I M E !

AlbertSmit avatar Dec 03 '17 11:12 AlbertSmit

@D-I-S-K-U-S That OP1 effect sounds like Linear Predictive Coding, as used in the Speak&Spell, or Bitspeek for instance. I have some material on that, I'll try and see what I can dig up.

As for the 'traditional' lofi phone sound, yeah, it's mostly highpassing at 300Hz and downsampling at 7kHz. Then, predistortion and bitcrushing can be added for good measure.

nebularnoise avatar Jun 13 '18 15:06 nebularnoise

LPC is far from trivial for me to implement from scratch, but there are a couple of open source DSP libraries that do it. We could either import it, or inspire from their code.

Soundpipe looks the most interesting IMHO. The only downside is that Soundpipe's lpc is limited to a 10 pole filter lpc. Don't get me wrong, 10 pole is exactly the kinda sound we're looking for, since it's the rough model used in the S&S, but adjustable filter order could have been nice to have.

Either way, if anyone's interested in the maths that are involved, I found those slides to be reasonably exhaustive.

nebularnoise avatar Jun 16 '18 14:06 nebularnoise

status on this? For me to really be enthusiastic about it, it would need to be not too similar to the OP-1 phone.

Also, @D-I-S-K-U-S We need to rework that UI for the new style. To be honest, I'm not too sure about it anyway, but lets see whats possible in a rework

Do we want to do this before v0.0.1? gives us about two months to have it in

topisani avatar Jul 26 '18 10:07 topisani

Yeah, we/I should probably come up with a new UI concept for this thats a bit more abstract. On it!

AlbertSmit avatar Jul 26 '18 12:07 AlbertSmit

I was just looking through the Faust documentation, and I found there's vocal synthesis. Would that be anything we can work with @nebularnoise? A similar effect at least, not necessarily the same.

AlbertSmit avatar Aug 25 '18 20:08 AlbertSmit

Updated. Added GFI flair.

We need to finish this effect. Most of the DSP has already been written, it just needs to be wrapped up in a proper effects engine struct. The code currently in this PR: https://github.com/topisani/OTTO/pull/104 but should be moved to a proper feature/ branch.

Apart from the code, we also need new UI ideas in the new style.

jmidt avatar Aug 12 '19 13:08 jmidt

I have started work on this again. It is now in the feature/LPC branch

jmidt avatar Aug 22 '19 19:08 jmidt