visualization questions

NutritiousTreat · 12th July 2001, 23:57

regarding visualization plugins, can someone explain:

spectrumData
&
waveformData

to me? what is the significance of "576" in the array?

for waveformData, does the array contain amplitudes over time? how does 0..575 correspond to the "current" time? does it represent the samples taken over the last period of delayMs or latencyMS?

for spectrumData, does the array contain ...??... over a range of frequencies? how does 0..575 map to a frequency range?

i'm creating a visualization plugin that uses openGL hardware accelerated rendering. it works right now (it just doesn't use the sound at all.) i'd like it to be beat aware, but it seems like i need AVS for that. but using AVS seems to preclude using openGL.. or does it? is there a reliable way to render (hardware accelerated) to an offscreen surface, then perhaps stretchblt that into a smaller dc bitmap, which i can then chunk into the framebuffer data required by AVS? why don't the normal visualization plugins get beatfinding? how hard would it be to implement beat finding myself?

anyway, i suppose i'm actually more curious about the spectrumData and waveformData stuff than these AVS questions.

thanks for your help.

nutritious treat

Katascope · 13th July 2001, 04:25

The spectrum data is the amplitude of the frequency ranges.
i.e -
0 is (low frequencies/bass)
to
576(high frequencies/treble)

spectrum[0] is noisy and can be discarded
I usually only use up to 512 since there is usually very
little activity past that.

If you want to do beat detection, stick around 1-48. The OpenGL with AVS case could be done, but it would have to be a rig.

omkarsnisal · 1st August 2001, 01:44

hey guys Please help me out!

I want to send this vis data to parallel or serial port.

I want to create disco light and/or histogram just like
what we see on screen with bulbs...

electronics is taken care of.. but i am stuck on
this part.... sending data to the port...

writing bitwise in C was damn easy.. but
using vc++ that code does not work! i guess it need a handle..

sigh.... and ideas??????

1st August 2001, 01:44	#3
omkarsnisal Junior Member Join Date: Jul 2001 Posts: 7	sending this data not to the screen but com/parallel port! hey guys Please help me out! I want to send this vis data to parallel or serial port. I want to create disco light and/or histogram just like what we see on screen with bulbs... electronics is taken care of.. but i am stuck on this part.... sending data to the port... writing bitwise in C was damn easy.. but using vc++ that code does not work! i guess it need a handle.. sigh.... and ideas??????

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12th July 2001, 23:57	#1
NutritiousTreat Junior Member Join Date: Jul 2001 Posts: 1	regarding visualization plugins, can someone explain: spectrumData & waveformData to me? what is the significance of "576" in the array? for waveformData, does the array contain amplitudes over time? how does 0..575 correspond to the "current" time? does it represent the samples taken over the last period of delayMs or latencyMS? for spectrumData, does the array contain ...??... over a range of frequencies? how does 0..575 map to a frequency range? i'm creating a visualization plugin that uses openGL hardware accelerated rendering. it works right now (it just doesn't use the sound at all.) i'd like it to be beat aware, but it seems like i need AVS for that. but using AVS seems to preclude using openGL.. or does it? is there a reliable way to render (hardware accelerated) to an offscreen surface, then perhaps stretchblt that into a smaller dc bitmap, which i can then chunk into the framebuffer data required by AVS? why don't the normal visualization plugins get beatfinding? how hard would it be to implement beat finding myself? anyway, i suppose i'm actually more curious about the spectrumData and waveformData stuff than these AVS questions. thanks for your help. nutritious treat

13th July 2001, 04:25	#2
Katascope Member Join Date: Apr 2001 Posts: 64	The spectrum data is the amplitude of the frequency ranges. i.e - 0 is (low frequencies/bass) to 576(high frequencies/treble) spectrum[0] is noisy and can be discarded I usually only use up to 512 since there is usually very little activity past that. If you want to do beat detection, stick around 1-48. The OpenGL with AVS case could be done, but it would have to be a rig.