[sdiy] MIDI live interface project... suggestion

[Jean-Pierre Desrochers]

The interface reads the DVD incoming NTSC video signal, grabs all the MIDI
info hidden in horizontal video lines and stores them in a big receive buffer,
then it reads back the buffer and outputs all the stored MIDI bytes
to a MIDI out connector.

 On Mon 21/12/09 13:50 , Blake Griffith blake.benjamin.griffith at gmail.com sent:
> Yes but how would you read midi off of  DVD?
> 
> 2009/12/16 Jean-Pierre Desrochers 
> 
> In fact that's what the MIDI interface is for.
> NTSC video lines have around 60usec each to store anything
> and the MIDI bits are 1/31250hz = 32usec wide each.
> So the idea is to grab all the incoming MIDI bits, store them
> in a large buffer and read them back to write them as 1's (100% peak
> white level)
> and 0's (0% black level).
> One MIDI byte is 32usec X 10bits= 320usec wide.
> That represents around 320usec/63.5usec (one horiz. line width) = 5
> horizontal lines time spent
> to receive one MIDI byte.
> So we could write each received MIDI byte in let's say every 6th horiz.
> line
> by putting 8 pulses on that line that represent the actual byte's 0's and
> 1's.
> Almost no delay involved between the MIDI in and video out.
> Any scenario possible here.
> JP
> 
>  On Wed 16/12/09 20:23 , Blake Griffith
> blake.benjamin.griffith at gmail.com sent:
> > Very Interesting but I am confused as to how the midi data is stored on
> a
> > video file.. ???
> >
> > On Wed, Dec 16, 2009 at 10:55 AM, Jean-Pierre Desrochers  wrote:
> >
> > Hi list,
> > This is a 'funky' project suggestion for anybody..
> >
> > Some musicians use live MIDI controled devices
> > (projectors, motors, visual effects, etc..)
> > while playing some stuff at the same time
> > on stage. These devices need some MIDI stream
> > coming "normally" from a sequencer or a PC
> > based MIDI software and a way to sync this all
> > with the music on stage.. So we are talking
> > about many instruments, sequencers, PC, etc..
> > So what about a way to get rid of some stuff
> > here and have a minimum of circuitry installed
> > for live MIDI/music perfomance?
> >
> > Here is the idea:
> >
> > The project I think of is an interface
> > that 'reads' an external MIDI stream (in studio)
> > and... converts it to a NTSC video output
> > that can be recorded using a video capture card.
> > Obviously that capture card will at the same time
> > record the music that needs to be in sync
> > with the MIDI info..
> > Now you have a 'video' that contains the MIDI information
> > (I try to imagine the screen video that this would produce... !!)
> > and the audio in a video file format, on a PC.
> > You then burn a DVD with the saved video file.
> > Finaly in a live performance,
> > you play the DVD with a standard DVD player,
> > connect the video out to the project interface to read back the
> > MIDI stream out and at the same time play
> > the musical audio tracks all sync together.. allways!
> >
> > So on stage you only have this:
> >
> > - DVD player
> > - MIDI interface plugged to DVD player video out
> > - Your normal audio mixing/amplifying stuff
> > - All the normally used MIDI devices (projectors, etc..)
> >
> > No more PC or sequencer stuff..
> >
> > I'm sure I can forget something here
> > but hey, this is just a suggestion on DIY list !
> >
> > JP
> >
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