D'Groove (Digital Groove) is the world's first digital haptic force feedback
turntable system. It controls the playback rate and position of digital
music (MP3's, WAVs, CDs, etc) using a physical turntable controller that
plugs into a computer. It also uses "haptic" force feedback
to provide information about the music to the DJ through the sense of
touch.
D'Groove was designed and created by Timothy for his Master's Degree
at the University of British Columbia in Vancouver, Canada.
The Components
D'Groove consists of 3 physical components that work with specially
designed software to control the playback of music.
The Turntable Platter:
The turntable platter is the focal point of the interface. It operates
much like a conventional turntable, rotating to produce playback
in the music. The lines on the platter facilitate a unique visual
beat matching aid described in the feature section below. Each revolution
plays back exactly one bar of music (or 4 beats).
The platter also provides various haptic force feedback effects when
the system is switched into one of the many haptic modes. The platter
consists of a specialized high torque haptic motor with a record
and platter connected to the top. Sensors are connected to the motor
so we can calculate the position and velocity of the platter as
it spins. The computer can also control the motor, producing automatic
scratching or other neat haptic tricks.
The Q-Slider: The
Q-Slider is used to replace the function of the conventional needle
and needle arm. It provides random access to various parts of the
songs (like picking up and dropping the needle on a new part of
the record) and it gives visual temporal feedback on the current
position in the song.
The slider consists of a motorized track and a touch sensitive knob.
The track represents the length of the song and as the song plays,
the knob travels along the track much like a progress bar. The DJ
can squeeze the knob (activating the touch sensor), effectivly lifting
the virtual needle off the virtual record. Then the DJ can move
the knob along the track, finally letting go to play a different
section of the song. The Q-Slider moves in bar-increments so moving
the slider one increment ahead, moves the playback to the next bar
of music.
As the DJ is moving the knob, haptic force feedback is used, allowing
the DJ to "feel" the type of music at any given point
in the song. Areas of high musical intensity feel like pushing through
thick mud whereas "breaks" or areas of lower musical intensity
feel much easier to push through.
The Pitch Slider:
The Pitch Slider works much like a pitch slider found on a conventional
turntable. Moving the slider up causes the platter to rotate faster,
increasing the pitch and tempo of the music. Likewise, moving the
slider down, lowers the pitch and tempo of the music.
Unlike conventional pitch sliders, our Pitch Slider supports an
infiinite range of pitch/tempo adjustment. A switch on the top of
the device allows the DJ to turn it on or off. If the DJ increases
the slider to the top and wants to increase the pitch/tempo further,
he or she can switch the device off, reset the slider to the bottom,
switch the device on away, and continue increasing the slider upwards.
Unique Features of D'Groove
Visual Beatmatching Aid
The lines drawn on D'Groove's turntable platter produce a powerful beatmatching
aid. We assume that all songs played on D'Groove will have a constant
tempo and will follow a 4/4 musical timing structure. We impose a rule
that one revolution of turntable playback is exactly one bar of music
(i.e. 4 beats). The red line on the platter represents the current point
in the music. When it revolves around to 12 o'clock (direct north),
the music is at the beginning of a bar (beat 1 of 4). When it revolves
to 3 o'clock (direct east) the music is playing the 2nd beat of a 4
beat bar. Likewise, beat 3 is at 6 o'clock and beat 4 is at 9 o'clock.
When it revolves back to 12 o'clock, the music is playing the first
beat of the next bar. The below figure demonstrates this concept.
If we had 4 D'Groove turntables and they were all spinning at the same
velocity, we would know that their tempos were the same. To see that
they were in phase, we would note the red lines on each turntable in
relation to each other. In the below figure we can see that
turntables 1 and 2 are perfectly beatmatched, turntable 3 is half a
beat ahead of turnable 1 and turnable 4 is one beat ahead of turntable
1.
Playback Distance Mapping Adjustment
D'Groove is able to break the rule assigned in the visual beatmatching
aid (described above), allowing any amount of music to playback during
any amount of turntable movement. It is possible to make an entire song
play with one revolution or make the song thousands of revolutions.
This is useful, as an example, for scratch DJs who want to determine
how much movement of the turntable produces a certain sound. The common
"frreeessshh" sample could be mapped to just a few millimetres
of movements or spanned out for several revolutions. The green section
in the figure below shows how a certain sound sample could be mapped
to various distances on the turntable.
Infinite Pitch/Tempo Adjustment
As mentioned above, D'Groove's pitch slider allows the DJ to alter the
pitch and tempo of a song to ± anything. It can even play songs
backwards. Combining this with the distance mapping adjustment (mentioned
above), the DJ could reverse the direction of the turntable but still
allow the music to play in a forward direction (which might be useful
for left-handed DJs).
Motion Recording
D'Groove can record the physical motions of the turntable and then play
them back. This motion could be mapped to a different piece of music
so you can try a scratch out on one song and then see how it sounds
with another song. In the future, you may also be able to download the
scratch sets of your favorite DJs and study them.
Intelligent Turntable
In the D'Groove system, the turntable has two way communication with
the computer system that drives the application. This means that the
turntable "talks" to the computer and the computer "talks"
to the turntable. Thus, the turntable can be controlled from the computer
and can be given certain information about the music it is controlling.
Thus we can make the turntable act in various ways depending on what
is needed in terms of the music. By making a smarter turntable, we can
make smarter music.
The Haptic Spring Mode
The turntable platter can be placed in Spring Mode, causing it to spring
back and forth when moved by hand. The red line on the platter fixes
on a selected home position and stays there. Any scratch movements will
cause the platter to bounce back and forth (like a spring) until it
settles at it's home position. The parameters of the spring can be adjusted
to produce tight fast bouncing or slow sloppy bouncing. This is useful
for new scratch tricks including the helicopter scratch - where the
turntable bounces wildly across it's home position, never quite settling
down.
The Haptic Bumps-for-Beats Mode
The turntable platter can be placed in Bumps-for-Beats mode, causing
it to produce a haptic bump for every beat. Using resistance, it is
possible to produce the illusion (for the sense of touch) of pushing
the turntable platter up and down a hill. This is a type of haptic bump
and it can be configured in terms of size and duration. We place one
of these bumps at every quarter turn (utilizing the one revolution plays
one bar rule discussed in the visual beatmatching aid), thus they indictate
a beat in the song. This is useful for beat juggling as you can feel
your way around the music instead of looking at markers on the record.
It is also fun for scratching as you can throw the platter up a hill
and have it fall back into your awaiting hand - this is called the dribble
scratch because it's like dribbling a basketball.
The Haptic Resistance and Beat-Hills Mode
In these modes, we produce haptic force feedback based in the wave form
of the music we're playing. We use the wave form to generate a force
file and then use that to produce resistance (on the turntable and Q-slider)
or hills (on just the turntable).
The result in resistance mode is that moving the turntable or Q-slider
in musically instense moments is hard and moving them during breaks
or musically relaxed moments is easier. In beat-hills mode, the turntable
feels like you're pushing uphill when you hit a patch of musical intensity
and feels like you're falling downhill when you hit a break. This
mode is useful for navigating through the song and is also fun for
producing new scratch tricks and effects.
Features of Digital Music
Access to Massive Music Selection
There is an immense amount of music available in a digital format. CDs
and MP3s are cheaper than vinyl and last longer. They maintain their
auditory quality with each play and are much easier to transport (you
can carry over 1000 songs on a laptop)..
Visualization of Music
When using vinyl, a DJ can gain knowledge about the music from looking
at the grooves of the track. In a digital format, we can not only look
at virtual grooves, we can color code various parts of the track, provide
valuable timing information, display frequency/time graphs and study
a Fourier analysis of a sound. We can provide a much better and more
useful visualization of the music when analysing it in digital format.
Beatmatching Aid in Software
Software exists that can analyse the beat structure of a song and determine
it's tempo (even if it is not constant). This information is useful
for beatmatching two songs so that they can be mixed into a single musical
output. It should be noted that beatmatching is often thought be one
of the fun challenges in DJing so any aids that are provided should
be optional.
Digital Sound Effects
Without having to purchase a separate effects unit, a DJ could add sound
effects such as distortion, reverb, delay, wah and many others to his/her
music. This is as simple as using a plugin to alter the sound.
Speed/Tempo Control
The speed or tempo of a track could be altered independently from the
pitch. In most turntables, DJs have the option of altering this to only
±8% of the preset speed. In this case, the pitch is also affected.
In a digital format, this parameter could be altered to allow the DJ
to have a much wider range of speeds while maintaining a certain amount
of precision.
Pitch Control
The pitch of a track can be altered independently from the speed or
tempo. In most turntables, DJs have the option of altering this to only
±8% of the preset pitch. In this case, the speed or tempo is
also affected. In a digital format, this parameter can be altered to
allow the DJ to have a much wider range of pitches.
Sampling
Also, without the addition of an extra unit, the DJ could create and
use samples taken from the digital music. This common technique involves
taking smaller sound bites (samples) and placing them in a track or
looping them to create a backbone for a track. This can be done quite
easily and precisely in a digital format. You could record any sound
on your computer and then start scratching it or adding it to a mix.
Digital Scratching
By monitoring the speed of the platter and/or "a specially encoded"
record on the platter, we can implement scratching sounds as done in
the analog world. The same feeling as found when using a traditional
turntable can be maintained. A physical model of a needle scrubbing
vinyl can be used to faithfully reproduce the sound of scratching. We
can even replace that model with a different physical model (example:
glass on brick) to produce new scratch sounds.
Inner workings of D'Groove
D'Groove is a complete standalone turntable system. The output of the
computer (audio) needs to be sent to a DJ mixer and the DJ controls D'Groove
much like one would control a conventional turntable. In our first prototype,
a special hardware card is needed inside the computer to communitcate
with the external components. Every millisecond we calculate the velocity
of the turntable, send it a haptic command and alter the playback of the
music accordingly. The average latency between adjustment of the turntable
and affected auditory response is approximatly 6 milliseconds. D'Groove
is currenty a "proof-of-concept" prototype. It has been displayed
in public performance and tested with real DJs. We have shown that our
ideas are useful and are expanding the boundaries of DJing.
D'Groove Video
The Feature Video from youTube. When watching, note how the red line on the turntable platter hits 12, 3, 6 and 9 o'clock as the beat plays.
Here's
a short video demonstrating some of D'Groove's featues. Note the position
of the red line in reference to the music. It shows the current beat
of the song and one revolution plays 1 bar or 4 beats of music
A phamplet
that was made to pass out at conferences. Print it on both sides of
a page and fold into three sections along the lines. It's a quick
reference on D'Groove's features.
The turntable platter is the focal point of the interface. It operates
much like a conventional turntable, rotating to produce playback
in the music. The lines on the platter facilitate a unique visual
beat matching aid described in the feature section below. Each revolution
plays back exactly one bar of music (or 4 beats).
The
Q-Slider is used to replace the function of the conventional needle
and needle arm. It provides random access to various parts of the
songs (like picking up and dropping the needle on a new part of
the record) and it gives visual temporal feedback on the current
position in the song.
The Pitch Slider works much like a pitch slider found on a conventional
turntable. Moving the slider up causes the platter to rotate faster,
increasing the pitch and tempo of the music. Likewise, moving the
slider down, lowers the pitch and tempo of the music.
