Control Digital Audio With Turntables

Anonymous Coward writes "Harmony Central has a NAMM article about FinalScratch which is a digital audio controller technology for Linux/BeOS, so DJ's can play digital audio and keep the tactile control of the turntable. Some interesting technology there, and a further push for digital audio." Another one for CowboyNeal's birthday list.

Comments

Re:Turntables vs. CD's

[PoiBoy]

Being a member of generation D, condescending elders often ask me if I even know what a vinyl record is. I tell them "sure. It's a giant CD that uses a needle instead of a laser and melts if you leave it in the sun."

Maybe so, but have you recently listened to a well-made record on a good turntable? The sound is absolutely incredible, and I think many people would honestly conclude (1) that analog is not dead and (2) digital recording isn't as great as it's cracked up to be.

Re:Lotta Linux using DJ's out there?

[jovlinger]

Actually...

It matters alot which OS the system uses. There are three important factors in scratching: latency, latency, and ... (wait for it) ... latency.

Older Macs may have been good at this because they weren't preemtively scheduled, so the scratching app could grab control and never let go. Not the best way to make friends, but it does keep latency down.

On the "real" OS side (no, a non preemptively scheduled, non protected OS is not a real OS, which apple understood, and which is why they spent so much time and effort to finally get one) BeOS was the only OS with any decent latency. Understandable; it was designed from the ground up to do this sort of thing w/o breaking a sweat. NB: QNX is realtime, which doesn't guarantee low latency, but rather "merely" guarantees that bounds exist, not that the bounds are low.

You gotta figure, when you're mixing 180 bpm songs, that's ~300ms per beat, so a 150ms latency is the difference between perfect and couldn't-be-worse. Also, you need to take the whole input chain into account -- not just one context switch, but rather: sampling input => timecode conversion => cueing of mp3 track => decode => output. Each one of these will involve several context switches if you are unlucky. Each context switch adds unknown potential latency. It can pretty quickly add up to +/- 150 ms. Worst of all, you don't know how much (can't read the clock -- that's a syscall == latency).

So in summarium: BeOS is a natural. Older macs may be ok, by virtue of being too stupid to be in the way. Neither Mac OS X and Linux stand the proverbial snowball's chance of pulling this off.

Of course, now you throw low latency patches into the mix... round and round it goes, where it will stop nobody knows.

Alternately, a kernel module may be able to do something decent, but that basically a hack to acheive the level of sophistication of old Macs.