World: r3wp

you can generate sine wave aproximation faster than using sin func

some example code (in C, but easy to rewrite):

float a = 2.f*(float)sin(Pi*frequency/samplerate);

float s[2];

s[0] = 0.5f;
s[1] = 0.f;

loop:
s[0] = s[0] - a*s[1];
s[1] = s[1] + a*s[0];
output_sine = s[0];
output_cosine = s[1]

this is much faster than calling SIN

Very simple indeed. I will test.

have you seen my Sintezar PM-101 in rebol.org library? maybe it will 
be interesting for you. I've got rebcode version on my disk, but 
because rebcode is not part of official rebol, it's not released. 
if you're interested, i can send you some examples. now i'm rewriting 
that synth as VST instrument in C(++), it's much faster then :)

No, I will look at now.

Thanks Rebolek, I reduce the time to produce 6 minutes 44 of music 
from 20 to 15 second.

you're welcome. 25x faster, very nice!

btw, what are you generating? it's your own synth, or some emulation? 
It's very interesting for me :)

It's to emulate the PSG AY-3-8910
Just for the fun and to understand a little about music

oh I see. But I thought AY-3-8910 has 4bit osc. with square and saw 
waves(plus some combinations), no sine? or does it have same lfo 
with better resolution and sine wave? don't remember the architecture 
corectly.

Yes that's right, 3 channel plus one for the noise, and square wave.

But it's enough complex to start and understand music generation 
for me.

With a simple parameter, I can switch between square wave or sine 
wave, it's quiet interresting to listen the difference.

I put the script here : http://www.rebol.org/cgi-bin/cgiwrap/rebol/view-script.r?script=psg-ay-3-8910-study.r

that's great Coccinelle! nice to see more and more people using REBOL 
for audio stuff. Maybe R3 will have the annoying audio-click bug 
fixed ;)

btw, I'm just reading your code, there's [rate: 44200], you probably 
meant [rate: 44100], taht's default CD sampling frequency

If I ever have free time again (not complaining, it's good to have 
work :-), I was thinking it would be fun to do a dialect for binaural 
beats, ala SBAGen.

I didn't know for 44'100. I have seen in some script 44'200, that's 
why I use this value.

The script detect automaticaly if the VM present or not, that's why 
the algorithm is twice.

I will imagine something to draw the wave also using rebcode, it 
should be very similar.

44'100 is correct, as the CD standard anyway.

Coccinelle: that's good idea with auto-detection. I was thinking 
about something simmilar for Sintezar once, auto-switching between 
rebol version, rebcode version and for /PRO C-library version. But 
I never wrote it, as nobody's using it anyway :) 

(I've got all three codes, rebol, rebcode and C-library, but not 
the autoswitch).

Gregg that binaural beat thing looks very interesting. I was interested 
in in ELF (extreme low frequencies) some time ago, but I though you 
need some pretty expensive equipment for it (as normal speakers cannot 
play 7Hz wave very well, but after reading a book by V. Marek, I 
found, that 7Hz frequency can be easily simulated by using one wave 
of frequency X and second wave of frequency X+7Hz. The 7Hz freq. 
is then created thanks to modulation, regardless on equipment. It's 
very interesting, unfortunately I had no time to get deeper into 
this field.

Yes, interesting, and with good headphones you can get subsoncis; 
SBAGen even offers boost options, by frequency, so you can tailor 
the compensation to your equipment.

I've heard that Enya's albums are 'enhanced' by some ELFs, but this 
may be just some urban legend (the reasoning was something like the 
music sounds so positive because it's using some brainwaves stuff, 
but maybe it's all bogus. Actually I bought two MCs from Enya some 
10-15 years ago and I cannot expect so wide freq. spectrum from cassette, 
but the music is still positive enough ;)

:-)  SBAGen, or some other app, has an analysis utility that will 
show you the binaural beats embedded in tracks. SBAGen also lets 
you mix the beats with other sounds, so you could add them to Enya's 
stuff yourself. :-)

can you describe what are binaural beats?

Low freq waves, played through headphones, with different "beats" 
going to each ear; designed to induce/stimulate certain brainwave 
states or patterns.

and these modify your mood, for example?

or make you feel light, or sense gravity, etc?

There are a lot of claims and potential uses.

so basically subliminal sound, just like subliminal images.

I haven't done deep research, but mainly I view them as something 
like a "helper" for meditation, self-hypnosis, etc.

There is another script of the PSG AY-3-8910 from Guest2, it's here 
http://www.rebol.org/cgi-bin/cgiwrap/rebol/view-script.r?script=demo-ay.r

His script was my inspiration and is much more nice than mine. But 
I wanted to understand by myself.

Question : How does work the barb opcode ?

Another question : Is possible to do something like a call within 
rebcode ?

Use the APPLY opcode to get access to any REBOL function. Watch out 
though: When last I checked, repeated calls to APPLY could crash 
REBOL - some kind of leak, I guess.

I forget how many calls were required.

APPLY is quite slow as well, at least when compared to rebcode in 
general.

I guess its because of all of tha context navigation which rebocode 
is freed of.

darn, why does that damn "o" always get added when I write rebcode 
quickly..

I think that function calls recurse into the interpreter.

BRAB is for branch tables like that generated by switch statements 
in C. Words in the target block are changed by the assembler into 
integer offsets to their associated label statements. Any other use 
is only appropriate for compiler-generated rebcode.

As for an equivalent to NONE?, SETT might work.

Looking back on this group, it seems that the APPLY bug may have 
been fixed. Also, BRAB is good for use on the results of CMP or SIGN.

As for reversing the bits in a byte, have you considered a binary 
lookup table?

steeve... told you brian was the reference here  :-)

It's been a while - for some I had to go back and look at my own 
posts :)

is rebcode still incapable to lookup objects?

(still as in... did the last version still have that limitation)

That was part of the planned upcoming features, and then they stopped 
updating it. I recall creating a comprehensive proposal...

You can still APPLY IN and then GETW or SETW.

rebcode really has to be part of 2.7... if we could just have object 
lookup, that would allow me try to make a few tests with liquid and 
mayb optimise so its about 10-30 times faster at managing the dataflow 
 :-)

Have you tried it with APPLY IN and such? How is the speed compared 
to REBOL?