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

On Mon, Oct 07, 2002 at 05:34:59PM +0200, CK wrote: 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