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My MT music player construction thread
Posted: 03 June 2008 11:45 AM   [ Ignore ]
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Hi everyone. I’m starting this thread to track my project throughout it’s construction and developement and share ideas along the way.

My MT goal is to build an app to play music files with. Not just play it, but run it through virtual modules to phase shift, reverb, LFOs etc. It will also have mixing capabilities just ike DJ hardware with a virtual mixing and effects console. The real world version of this requires mulitple fingered changes to knobs and sliders so, we figured the MT interface would lend itself to acheiving that goal on screen. I have a software engineer friend here that’s helping with code and I’m taking care of hardware. We’re both live sound engineers so I’m sure as we go along in developement, we’ll dream up more ways to manipulate sound.

Here’s the initial specs of my setup:

Screen size: 22” x 16.5” .250” cell cast acrylic, edges beveled @ 45 degrees and polished
Illumination: FTIR with 88 IR LEDs @16 mW radiant power = 1.4 watts total
Camera: Modified Logitech webcam (IR filter removed) with 3 layers exposed film as visible light filter
Projector: Proxima Ultralight SV1+ 700 lumens, 300:1 contrast ratio

I’m still working out what to use as a projection screen Probably Rosco grey.

I’m experimenting with an idea to help with making the surface more compliant. I read here that people have tried many things, and it seems that silicone or PVC in some form does well.
Yesterday, it dawned on me that a coat of PPG automotive clearcoat to the acrylic might work well. I can add a “flexiblizer” to the mix and it will cure with a little more give to it. It might just work as a zero pressure surface. There is a bonus as well. If it gets scratched, I can just sand the clearcoat lightly and spray on another, fresh layer.

I’m going to try this to a small MT setup I have to experiment with. It’s an 8” x 10” mini MT. The first one most of us built. ( :  Now I use it to test out ideas and materials.

I have my $158 projector on the way, as well as LEDs and resistors. Not much tech stuff here on Maui so I use the internet to get my parts and supplies. I have a local plastics shop cutting and polishing my 24” x 18.5” x .250” acrylic. It’ll cost about $40 cut, beveled and polished!

Why the bevel? Because it refracts the incoming light in a way that bounces it around more due to the steep angle. In other words, there are more points of reflected light in a given area. That means that when the surface is touched, there are lots of light rays to bounce off the surface and reflect IR light back at the camera.

I used this very handy applet to show the light reflection angles.
http://www.outgribe.com/jason/ftir/ftir.html

My setup has the LED angle at 0, the beam spread at 22 degrees, edge angle at 45 degrees, LED position at 75. Set it up that way and you’ll se the advantage over straight into a 90 degree edge!

More to come!

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Posted: 03 June 2008 12:39 PM   [ Ignore ]   [ # 1 ]
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I have my $158 projector on the way, as well as LEDs and resistors. Not much tech stuff here on Maui so I use the internet to get my parts and supplies.

What projector are you using ? seems like a great price.

ooops!!! sorry i guess i missed that in your post..

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Posted: 03 June 2008 12:52 PM   [ Ignore ]   [ # 2 ]
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Hi , curently i’m investigating Multitouch exactly for this purpouse.DJ-ing.Would you be willing to colaborate?Even tough i don’t think i can contribuite with code , i can help with the presentation.
Graphics , logo’s etc.

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Posted: 03 June 2008 02:36 PM   [ Ignore ]   [ # 3 ]
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Hi Tinkerman,

I’m working on something very similar, but with video and DMX lighting control integrated as well.  Instead of writing all the software from scratch though, I’m just writing an interface that translates the MT into midi signals that I’m routing via loopback into Ableton and Virtual DJ.  Writing audio software of that quality would be a very long and difficult project, but building midi signals from binary is very simple, with the added benefit of being able to use the same interface with any midi compatible software or hardware.  I’ll be using VVVV for the UI rendering, video and DMX control.  It would be interesting to compare notes.

Parker

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Posted: 03 June 2008 03:01 PM   [ Ignore ]   [ # 4 ]
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Likewise, I am also interested in music applications (which you probably already know since my project is called AudioTouch) lol. Group collab time! Yay! hehe

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Posted: 03 June 2008 03:08 PM   [ Ignore ]   [ # 5 ]
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Hey Parker , what you are working on is exactly what i need.Any chance of releasing it when it’s done?Do you need software with the design department of things?

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Posted: 03 June 2008 05:19 PM   [ Ignore ]   [ # 6 ]
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I am not much of a coder/software person but I would be willing to help you with anything you want… I can help with graphics or video, I’m pretty good with After Effects.

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Posted: 03 June 2008 05:39 PM   [ Ignore ]   [ # 7 ]
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that’s right , i also would like to collaborate in this MT player,
here ‘s an example of a music app ( still very basic),we are workin’ on , Raphael and I ,@ the SassExperience .
It’s in standby (till 9 of June) , cos both of us are busy on different projects ...
it was done on PD

http://sassexperience.free.fr/projectmultitouch1.html

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Posted: 03 June 2008 06:02 PM   [ Ignore ]   [ # 8 ]
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Jimihertz, your work has come a long way wink Look great! I had an idea for a circle based sequencer very similar to that. We’re gonna need to work together eventually =) If you get PD patches to share sometime, i’d love to take a look! =)

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Posted: 03 June 2008 06:02 PM   [ Ignore ]   [ # 9 ]
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@Vlado – I’ll be happy to share anything I come up with.  I’ve run into a bit of a show-stopper, depending on the application – I put together a prototype of the midi generator in VVVV, but the timing is terrible.  Even generating a simple metronome from a LFO sends the note within what sounds like a ~150 ms range of where it should be, and the release is just as inaccurate.  I think this is a limitation of the software, since it is not built specifically with midi generation in mind.  I say “depending on the application” because using the interface for knobs, sliders, and switches is not as time-dependent as something like triggering drum samples.  That being said, I hear Pure Data is much more accurate for audio-related processes, but I haven’t checked to see if it supports midi (I’m sure it does).
I downloaded the timecode track from the Virtual DJ website, and used Virtual Audio Cable to send the output from VVVV directly to the input of VDJ and got good, steady playback.  The problem is when you adjust the speed of the timecode playback it stutters, causing VDJ to audibly skip every time you try to adjust the tempo.  I’m not sure this approach is necessary though, since I think VDJ accepts midi signals for control of the pitch and tempo settings on each deck, but I haven’t looked into it in depth.
I can share the VVVV patches I come up with, and since the client is free for personal use you can use it to send midi to any application you choose with a little adjustment.  I’m working on a proof of concept for the UI, which I’ll be posting shortly. 

@cerupcat - I might need your help with my hardware, since I haven’t quite finished my table enough to start testing the applications.  I’ll probably screw it up the first time. smile

Parker

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Posted: 03 June 2008 06:07 PM   [ Ignore ]   [ # 10 ]
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@ Pakrer: of course PD supports MIDI hehe. PD is probably the best real-time tool for audio. Much better than vvvv (it’s in a while other ballapark wink ). If I didn’t have so much work ahead of me, i could whip up a PD patch that forwards MIDI pretty easily. We might even be able to send midi straight from touchlib just like reactivision option does.

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Posted: 03 June 2008 07:18 PM   [ Ignore ]   [ # 11 ]
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Yeah, ideally the application would be hand-coded and use OpenGL for the interface, but the meta-programming environments are so quick for prototyping, and my C++ is lousy. smile Also, sending midi with VVVV is a serious pain in the arse since you have to build all the channel, note and value data from binary.
The only reason I’m using VVVV at this point is that I’m more familiar with it than PD, and my VJ patches are all in VVVV.  I think for video and 3D rendering VVVV can’t be beat, since it uses DirectX and cheap gaming hardware for blistering speeds at full HD resolutions with anti-aliasing and anisotropic filtering.  A personal requirement for me is that I have to be able to have a thumbnail preview of my VJ patches running in the client, which means my prototype will have to be running in VVVV or in a standalone using shared-memory, which is very slow and CPU intensive, although low resolution thumbnails would be fairly low-bandwidth.  This seems like it will be a problem with any VJ software, and I have no idea what the solution could be.

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Posted: 03 June 2008 08:10 PM   [ Ignore ]   [ # 12 ]
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So, about that idea of the clear coat with the PPG DX814 flex agent added! I think I’ll be goin out to the shop now to spray some nasty polymer chemicals a piece of 8” x 10” acrylic!
I’ll be applying it ONLY to the top surface, not the edges!
I’ll be posting the results this evening. The stuff is a catalyst activated clear coat, with UV inhibitors! Hmmmmm wondering about IR. We’ll see.

If you’re interested, this is the clear coat data sheet:
http://www.pwpaints.com/images/downloads/dcu2021-p-199.pdf

This is the flex agent data sheet:
https://buyat.ppg.com/refinishProductCatalog/ServeFile.ashx?FileID=fc7b48f2-3cf4-459c-ae61-ec510a61a649

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Posted: 03 June 2008 08:25 PM   [ Ignore ]   [ # 13 ]
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I volenteer for beta testing !!!
rasberry
really, i would like to help in any way .
I have a couple working tables (1 DI and 1 FTIR)
and wouldnt mind testing..

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Posted: 03 June 2008 08:59 PM   [ Ignore ]   [ # 14 ]
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OK I just got done spraying the clear coat. The stuff is nasty stinky! Respirator required!! The smell goes away quick enough though.
I have two sheets of acrylic in the benchtop spray booth, all sealed up and curing. In couple hours, I’ll put the 8"x10" one back on the IR mini MT, illuminate it with 5 IR LEDs and see what kind of blob action I get!

I just love trying new stuff. Hope it works.  (:

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Posted: 03 June 2008 09:03 PM   [ Ignore ]   [ # 15 ]
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Looking forward to your results, Tinkerman!

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