[linux-audio-dev] Final Scratch, custom kernel?

[Lance Blisters]

On Mon, Oct 07, 2002 at 05:34:59PM +0200, CK wrote:
> I read:
> > How well does it work? Does it truly work just like a standard turntable setup
> > would, or does it have an artificial feel or sound to it?
> 
> dunno about final scratch but I have built a similar system using dubplates
> with 440hz rising saw, pd and alsaplayer.
> (also tested with my own pd stepsequencer and scratching video using gem)
> 
> works like a charm once calibrated, I'll make this available as soon as I
> find time to clean it up and make the setup process a bit less painful.  
  Great!  How does it present the position/rate data?  Is there any standard 
  protocol which could be used for this information? It would be neat if
  the whole setup could be wrapped as a userspace device, which apps can
  program against.  I can think of at least two open source digital dj apps 
  which could benefit (gdam and terminatorx)

  How do you handle lifting, moving, and setting down the needle?  Could we
  get needle-up and needle-down events?



  Using an actual turntable for a physical interface has benefits and drawbacks.
  Many people have experience with real turntables, so it makes the switch to 
  digital very natural.  Turntables are also a very popular image in pop 
  culture.  Records pack a lot of information into a small space, with
  very quick access to small (along the groove) and large (across the groove)
  position changes.   But at the same time, there are drawbacks to 
  turntables.... they are expensive, large, heavy, need to be positioned
  on a level surface, susceptible to skipping from bumps dust and scratches, 
  pick up noise from tapping on the body or bass vibrations.  I imagine that 
  a simple sawtooth pattern is easy to pick up through a fair amount of
  noise, and some skips could be filtered out by a bit of logic which analyzes
  the output position... nevertheless, scraping diamond on plastic seems crude.

  I'm looking forward to a lightweight, portable, digital turntable-style
  interface which outputs MIDI or some other open protocol.  Similar to the 
  new pioneer cd decks, but without the cd player and audio hardware, and with
  MIDI.  The pioneer has quite good tactile response.  However, there are a 
  few scratches and techniques which rely on the fact that the turntable 
  platter is actually spinning and the record is moving relative to it... 
  until someone makes an interface with a spinning platter (or at least a 
  scheme to make up for it, so these techniques are possible and natural) 
  some dj's will only use real turntables for an interface.  For real
  turntable interfaces, options include reconstructing position from an 
  audio signal, or an optical solution (die-cut, printed, stamped or stickered
  record with optical detectors / optical mouse shining on them)  The
  dubplate / reconstructed audio approach has the benefit that turntables 
  can be used without any modification, or mounting extra hardware.

  -geoff