introduction
the digital audio age - mpeg audio layer 3 (mp3)
digital audio has been quite a big hit in the 90s, featuring professional
quality homestudios, software synthesizers, digital effects and much more.
but the real breakthrough concerning the way we deal with digital audio has
been achieved by new compression techniques.
in 1994 the
fraunhofer institute for integrated circuits (fraunhofer-iis) in
erlangen, germany introduced a new audio compression based
on a psychoacustic model that offers the highest music quality while
reducing the average file size by factor 10.0.
perceptual audio compression techniques are quite different from traditional
loss-less compression. briefly, perceptual compression throws out the crap
you won´t hear anyway, due to the psychoacustic limitations of the human ear
and brain.
since then, mpeg audio layer 3 (or mp3) has
been flooding the web as the new format for high quality music distribution.
as record companies start selling artist tracks online in mp3 format and
multimedia hardware manufacturers offer walkman style mp3 players for the mobile,
a new chapter in the history of digital audio is being opened that looks both exciting
and promising.
the digital dj age - mj
mp3 compression has also changed the way we handle music as consumers.
since you can easily fit your average 100 cd collection on 10 custom
made mp3 cds or store them on your harddisc, music has become much more
accessible and easier to play with.
quickstart - get the music pumpin
the first time you start mj, the soundcard setup dialog will pop up and two
songs will be loaded and played automatically. now you´re ready for your own mix.
the cross-fader (the scrollbar labeled with "X-FADER") is placed in mid-position by default.
push it hard to the left side and you´ll notice that you´re hearing only deck a. adjust
the volume and then take care of the bpm fader: turn it up and down. you´ll notice that
the playback pitch of the song changes significantly.
load the second mp3 now on the deck labeled b.
watch the bpm detection counter on the left deck and try to match it on the right deck
by adjusting the bpm fader there.
now slowly pull the mix fader to the middle. you should now here two songs playing at
once.
when you observe that both decks are running at the same speed, but slightly out of sync,
just push the the buttons with the arrows below each deck to give the specific song a
slight nudge in the desired direction.
yo. now you´re already in the mix !
setup
minimal system configuration
decoding and mixing two mp3 files at once takes a serious amount
of processor power if it is done right. we suggest the following minimal
system configuration:
- pentium 233mhz mmx or aequivalent processor
- windows 95/98 or windows nt 4.0
- soundcard supported by the system
- 16bit color graphics driver with at least 800x600
installation/deinstallation
click on setup.exe and follow the steps of the installation program.
a d-lusion sound systems folder with a mj icon will be added
in the start bar.
if you might ever want to deinstall mj (although we can't figure
out why you would :)), use the windows install/deinstall option
in the configuration/software menu. everything will be taken care
of then...
soundcard setup
before you can use mj for the first time, you have to check the
soundcard setup. the setup ist located in the window menu. you can obtain it
by clicking on the top left icon of the mj window.
Sound Output
determines the audio driver that mj uses for sound generation. you may have the following choices :
- windows wave mapper
the wave mapper device that windows uses to map audio devices.
use this option if you often change your soundcard driver in windows.
- windows mme soundcard driver
the normal soundcard driver that came with your soundcard.
- directx sound interface
the directX soundcard driver. due to performance reasons you should
use this driver if possible. you can get directX drivers for
your soundcard from the vendor or microsoft.
please make sure that directX is installed on your system before
selecting this option.
Master Stereo
default. choose this option, if you´re soundcard is directly conntected to your
home stereo or boxes.
Master&Monitor 2 x Mono
choose this option if you´ve connected an audio doohicky to your soundcard.
click here for further information about the monitor system.
Frequency
mixing frequency for the mj sound generation.
you will use 44.1kHz to achieve cd quality, unless your
soundcard doesn't support it or you want to torture yourself.
Resolution
the resolution of the generated audio data. usually 16 bit.
Blocksize
the block size determines the size of the output buffer.
if you use a smaller buffer, the time between the movement of a
slider and the actual reaction of the sound generation gets
shorter. unfortunately this highly depends on the soundcard driver
you are using. if the buffer size gets too small, you will hear a
stuttering noise in the sound output. it is best to reduce the
buffer size to the smallest possible size without getting a
stuttering sound. this behaviour is known as "latency" and is typical for
all digital sound applications that have to modify the output in a special way.
preferences
to adjust mj to your needs you can do some fine tuning in the preferences dialog which is located in the system menu.
autosave/load last playlist
if enabled, mj will save the playlist when leaving and reload it the next time you start mj.
recursively add directories
if enabled, mj will browse through all subdirectories and will add all mp3s found there.
docking behaviour
if enabled, moving mj will also move the playlist.
automix time
specify the number of seconds, mj will take if the automix function is enabled.
volume settings/monitor
choose the appropriate volume for the monitor output here.
the audio doohicky
an audio doohicky is nothing more than a channel splitter. it splitters your stereo signal
from your soundcard into two mono signals. now you can attach one signal to your home stereo to
drive the party and the other one to your headphones to monitor your mix and to fine tune
some parameters (e.g. match the tempo of both songs to sync perfectly) before you let your
audience listen your mix.
order it at radioshack : partnumber #274-375B
click here for further information about the monitor system.
mj´s main window
display elements
the main display consists of two areas:
in the upper half of the screen you can see the two mp3 decks.
the lower half of the screen is dedicated to control elements like
volume, position etc.
soundcard setup, about dialog and more can be reached in the window
control by clicking on the icon in the upper left corner of the mj
window.
the following section will explain all elements that are visible in the
mj window:
mp3 decks
the two mp3 decks are located in the upper part of the window.
both can play a 128 bit 44 kHz mp3 file. each deck has the following
controls (text in brackets are keyboard commands for the specified function):
load button
the load button looks like the typical eject button on your cd or tape player.
click here to load a new song into the deck.
time display
displays the remaining time for the file being played in the
upper part of the deck.
bpm display
displays the detected bpm (beats per minute) in the lower part of
the deck. this is quite a useful tool for matching both decks on the same
speed.
Remark: reliable bpm detection is quite a difficult job. the algorithm
used in mj is far from being perfect. we found it to be quite reliable on
house music and other straight beat stuff. but don´t expect it to work
on breakbeat, jungle and trash-metal.
pitch slider (arrow up/down)
each deck has its own pitch slider that alters the speed from 50% to 200%.
by clicking with the right mouse button, the slider automatically jumps back
to 100%.
"+", "-" buttons
these buttons increment (+) or decrement (-) the current pitch of the deck. use these buttons to do some
fine tuning you couldn´t achieve with the pitch slider.
"=" buttons
use this button to set the pitch of the deck to match the bpm settings.
example: deck a and deck b are playing, but by pushing the cross-fader to the right or by
selecting the b-button your audience is listening to the song of deck b. now press the "=" button
on deck a to set the pitch of deck a so that deck a will play with the same beat (bpm) as deck b.
now, all you have to do (supposed the beat detection worked fine) is to nudge deck a forward/backward
in order to synchronize the beats of your songs.
nudge buttons (numeric */numeric /)
the nudge buttons are located below each deck. their purpose is to jump a little
forward or backward in a track that has the right speed, but the wrong offset to eleminate
that nasty double bassdrums.
".", the deck hold button (numeric delete)
this button has the same effect as stopping a turntable with the hand. the deck will slow down and then
stop playing when you click the button with the mouse. as soon as you release the mouse button from its
pressed state, the deck will start to play like before.
equalizer (insert,delete,home,end,pgup,pgdown)
a simple but efficient to use 3-band equalizer.
deck scratching
positioned above the equalizer (the cds). click it and move your mouse to do some scratching with your songs.
play controls
there are several play controls for each deck located in the lower part of the window.
songname
displays the current name of the file being played.
deck volume (numeric +/-)
the vertical slider specifies the volume for each deck. very useful to match different files
to the same volume.
deck punch in (numeric 0)
located directly above the deck volume slider (labelled with a big "P"). press this button to get the specifed
deck into the mix, regardless of the position of the cross-fader.
music controls
probably, these controls look familiar to you since you have seen them on a lot of
audio equipment. they are: previous song from playlist, skip backward, play/pause, skip forward, next song from
playlist.
nothing more to say about.
progress bar
the vertical progress bar below the music controls visualizes the current song position.
you can change the position by dragging the marker or clicking on a specific position.
while loading a file, the marker indicates the decoding position.
crossfader (arrow left/right)
the crossfader between the two decks controls the mixing relation of each deck in
the audio output stream. hard left equals 100% left 0% right, middle equals 50% left 50% right and so on.
playlist
open/close the playlist window
the record button
hit this button to record your mix as one big wave file (.wav) onto your harddisk.
monitor related functions (1/2/3)
these functions will only be useful to you, if you´ve selected the audio doohicky
in the sound setup. but then you have two wave outs. one for
monitoring and one for the crowd. the A/AxB/B switches specify what should be played on your
"crowd" output, eg. if you´ve selected the a button, only the song on deck a will be sent to the "crowd" output,
no matter what you´re doing with the cross-fader.
this is a really important function, since it´s possible to
e.g. match the bpm settings of the other deck or to synchronize the drums of two songs without letting your
audience hear what you´re doing. if you select AxB (which is the default position), the crowd-output will reflect
the state of the x-fader.
on the monitor wave out, there will be always the mixed signal represented by the crossfader.
mj´s playlist
general information
with the playlist you can manage a set of songs to quickly access them within mj. just add songs
with the "Add" or "Add Dir" command or delete them with "Delete" button. "Clear" will
remove all songs from the playlist. the next song to be played is indicated by an arrow.
"Save List" saves the current state of the playlist and "Load List" will load a previously
saved list.
Note: mj loads and saves the playlists in the popular .m3u format for your convenience.
you can drag and drop songs from e.g. the windows explorer onto the playlist to add them.
options
- Loop Playlist
if checked, continues with the first song, if the last one was played.
- Autoload next entry
if this option is checked, mj will automatically load the next song on the end of the current song.
- Clip directory from filename
check this option, if the playlist should display only the filename without directory information.
- AutoMix
select this checkbox, if you would like mj to do take over control of the party. mj then will play the
songs in the playlist one by one, and by using the x-fader there will be no silence between two songs.
you can choose the time mj will take for mixing in the preferences settings in the system menu.
keyboard access
for fast access, all important functions are directly mapped to the keyboard.
the current focused deck is indicated by the red font. you can change the focus permanently by pressing space bar.
by pressing ctrl the opposite deck will be focused as long as you hold the key. the shift keys are used to speed
up the movement of some sliders (e.g. x-fader), just press them in addition to the regular keys.
| function |
key |
| x-fader |
arrow left/right |
| output selector (deck A/AxB/B) |
1, 2, 3 |
| deck pitch |
arrow up/down |
| deck 3-band eq |
ins, del, home, end, pgup, pgdn |
| deck seek |
numeric 4/numeric 6 |
| deck start/stop |
return and numeric 5 |
| deck next/previous track |
numeric 2/numeric 8 |
| deck volume |
numeric +/- |
| deck punch in |
numeric 0 |
| deck hold |
numeric delete |
| deck nudge forward/backward |
numeric */numeric / |
questions & answers
question:
i hear annoying crackling and popping noises when playing
a second song. what´s going on ?
answer:
your machine seems to be a little too slow to run this kind of
highly sophisticated software or the soundcard drivers you are
using have been coded in bangalore. but you can try to correct this
by increasing the buffersize in the mj soundcard setup.
anyway, we would suggest to use DirectX sound drivers since the latency
is far better. you have to install DirectX on your system first though.
question:
my soundcard works perfectly with other programs, but when i start
i get the error "can not open output device". What am i doing wrong ?
answer:
we tried to test the application on a great variety of soundcards and
driver. but some old or very exotic soundcard drivers will just not
work correctly with the program. in this case please get the newest
driver version from your vendor or try to install DirectX.
question:
where the heck is the soundcard setup dialog ?
answer:
it´s well hidden in the windows system menu. click on the icon in
the upper left corner of the mj window and select soundcard setup.
question:
it seems that some files are not played correctly. what´s wrong ?
answer:
the file format is probably wrong. mj only supports mpeg audio layer 3 files
with 128kbit, 44KHz rate.
question:
the bpm detection doesn´t work properly and it jumps significantly in some songs. is this a bug ?
answer:
mj uses a very fast bpm detection routine based on a stochastic model. nevertheless, bpm
detection will not work on all songs. house and techno songs with a clear basedrum will
work best of course.