exact 3d imagination of a stereo groove

[MurphyJax]

hi,

i am searching for someone who has the knowledge about how actually a grooveshape is working in stereo.

How to convert 2 stereo layers into a 3d model of a groove, is the challenge to understand.

Because it doesnt make 100% sense if you think of put two amplitudes within 45° into a groove. How is the final groove depth and shape calculated out of those two waveforms?

[markrob]

Hi,

Its just simple vector addition. The two signals are mechanically summed via the torque tube and linkages on the cutter head. In 3D space, the Left and Right channels are on the X/Z plane and the Y axis is the direction of the stylus movement in the groove (assume its a straight line to keep it simple). The X axis is the lateral component of movement and the Z axis is the vertical. Also note that positive waveform values push downward for the left channel and upward for the right. That way if you have a mono signal (both channels with he same information), you will get lateral only movement. Also note that the vectors are rotated 45 degrees in relation to the X/Z axis. Hope that helps.


Mark

[opcode66]

Are you going to be doing laser etching???

There are other factors to consider. If you are trying to convert a wave file into a 3d map representing the grooves. The size and shape of the cutting stylus and therefore the resulting groove must be modeled. Also, your concept of pitching must be implemented. As stated by Markrob, to make things simple, you plot out a straight line groove in 3d. Then you apply an algorithm to shape that 3d straight line groove into a concentric spiral. The spiral is either a fixed pitch or variable pitch based on how complicated you want to be. Obviously fixed spacing between the sprial lines is easiest to work out. You have to leave a bit of dead space between the information in each spiral pass so the resulting groove never touch or run into each other. Finally you need to add a lead in spiral algorithm and lead out/locked groove. A few other things too. But, generally, that is all.

If you are seriously interested and have money, I have most of this code already written and functional. I just don't have a laser etcher to play with.