Final Scratch: Difference between revisions
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A basic Final Scratch setup consists of five pieces of equipment. |
A basic Final Scratch setup consists of five pieces of equipment. |
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# A computer running a compatible software, usually Native Instrument's Traktor |
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# The ScratchAmp |
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# Two turntables or two CD decks made for DJ'ing |
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# Two time coded vinyl records or time coded cd's |
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# An audio DJ mixer. |
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== Vinyl/CD Time Code == |
== Vinyl/CD Time Code == |
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Revision as of 07:27, 25 April 2007
Final Scratch is a DJ tool created by the Dutch company N2IT with input from Richie Hawtin (aka Plastikman) and John Acquaviva that allows manipulation and playback of digital audio sources using traditional vinyl and turntables. It seeks to cross the divide between the versatility of digital audio and the tactile control of vinyl turntablism.
Concept
Special vinyl records pressed with a digital timecode are played on normal turntables. The timecode signal is interpreted by a computer, connected to the turntables through an interface called the Scratchamp. The signal represents where the stylus is on the record, in which direction it is travelling, and at what speed. This information is interpreted by the computer and used to play back a digital audio file which has been 'mapped' to the turntable.
In practical terms, this means that any audio file can be manipulated as though it were pressed on vinyl. This has a great many advantages for DJs, not least that a laptop computer can often hold tens of thousands of audio files, whilst a record box has a decidedly smaller capacity and is much heavier.
Prerelease
Final Scratch was originally developed for BeOS, and premiered at the Be Developer Conference in 1998.
Versions 1.0-1.5
All versions of Final Scratch 1 use the same Scratchamp, a USB and RCA device in a round plastic shell. The technical specifications of this device have been closely guarded by Stanton as an anti-piracy measure, though some users, unsatisfied with the latency and instability of the system, have alleged the use of faulty Philips sound chips which had already been withdrawn from the market. However, the same chipset was being used in several other USB audio devices manufactured by companies like Griffin and Roland at that time.
FS 1.0 was released for PC only, on a specially modified distribution of Debian Linux. It was relatively primitive but some users found that, if configured correctly, it outperformed all subsequent versions of Final Scratch 1.x.
With version 1.1, Stanton Magnetics began working with Native Instruments on the software side of the product, which became Traktor Final Scratch. As the name suggests, this bore a resemblance to the interface of Traktor, a Native Instruments software DJing product. This version was once again available on Linux, but was also ported to Mac OS X.
The next major revision was version 1.5, which added a Windows XP version and the ability to keep the pitch of the record constant whilst shifting the tempo. The interface changed very little, but some users initially had issues with the Windows Scratchamp drivers.
Version 2
Version 2 added not only a new software engine, but a new Scratchamp as well. This new Scratchamp made 24-bit/96khz digital quality playback and record possible, added an ASIO driver, MIDI in and out, and uses a Firewire interface instead of the previous USB to reduce latency. The version 2 Scratchamp is also compatible with Native Instruments Traktor DJ Studio (starting at version 2.6) to enable vinyl control in that application.
Final Scratch Open
In late 2005, Stanton and Native Instruments ended their working relationship. Stanton still markets the ScratchAmp hardware as part of Final Scratch Open, introduced in early 2007. Stanton claims that the ScratchAmp can now interact with any audio software through ASIO or WDM on Windows, and CoreAudio in Mac OS X. Although all Windows and Mac audio software is ostensibly compatible with Final Scratch Open, there is no dedicated software program for deejaying with the ScratchAmp hardware.
Internal Workings
The internal workings of Final Scratch are quite simple to understand. Multiple open source software libraries have been created to decode the Final Scratch time code. The information here comes from those libraries.
A basic Final Scratch setup consists of five pieces of equipment.
- A computer running a compatible software, usually Native Instrument's Traktor
- The ScratchAmp
- Two turntables or two CD decks made for DJ'ing
- Two time coded vinyl records or time coded cd's
- An audio DJ mixer.
Vinyl/CD Time Code
Analog/Digital Code
The most complex piece of the Final Scratch setup is the code pressed onto the vinyl. A 1200 Hertz amplitude modulated sine wave is pressed into the left and right channels with a phase difference of 90 degrees. Each channel holds one of the two bit streams required for the time code. In one cycle of either wave form, two bits are stored: one on the positive voltage peak and one on the negative voltage valley. The relative amplitudes of these peaks represent either a binary one or zero. A relatively high amplitude on either peak represents a one, a relatively low amplitude represents a zero. In each channel is a separate bitstream, the left channel is not identical to the right (disregarding the phase difference).
Finding Position
The time codes themselves consist of 40 individual bits, or 20 cycles on each channel's waveform. On the right channel the bit sequence of 0, 0, 0, 1 represents the start sequence for a single time code. Those four bits along with the four corresponding bits on the left channel and the next 16 bits on each channel can be decoded as an integer position value which represents where the needle is on the record.
Finding Speed
The speed at which the record is spinning can be found by comparing the frequency of the waveform being read off of the record to the true frequency of the wave form on the record at normal speed. This difference represents the speed at which the record is turning.
Finding Direction
The direction which the record is spinning at any given time can be found using the phase difference between the waves on the two channels. This procedure is the same as that used to determine the direction a ball mouse is moving.
ScratchAmp
With Stantons move to make Final Scratch Open, they decided to use the ScratchAmp for it's real purpose. The ScratchAmp is really nothing more then a firewire audio device. It has four phono/line level inputs to read the timecode from the record or the cd along with four line level outputs to feed into the audio DJ mixer. If Stanton wished to take their product further, they could, instead of using the ScratchAmp for input and output they could use a PCI or PCMCIA sound device that has the same number of outputs.
Issues regarding time code errors
Because a single time code is made up of 40 consecutive bits, read errors can cause a timecode to be unreadable even if a single bit is misread. A bit that has become unreadable due to a scratch can make an entire 40 bit long time code permanently unreadable. Dust can have a similar affect on the time code. The time code implements very little error checking, an attribute strong in a number of other vinyl control systems.