preface

hier kommt marcs geschwafel...

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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 wonīt 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.

blabla dj mixing etc....





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 youīre ready for your own mix. !!!!!!!!!!!!!!!!hirt gehts weiter !!!!!!!!











features

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:



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.

output device
determines the audio driver that mj uses for sound generation.

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 it is 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.

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.

buffersize
the buffer 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.




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 every element that is 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:

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 donīt expect it to work on breakbeat, jungle and trash-metal.

pitch slider
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%.

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.

nudge buttons
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.

crossfader
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.



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
the vertical slider specifies the volume for each deck. very useful to match different files to the same volume.

music controls
probably, these controls look familiar to you since you have seen them on a lot of audio equipment. they are: skip back, play, stop, skip forward. 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.











questions & answers

question: i hear annoying crackling and popping noises when playing a second song. whatīs 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: itīs well hidden in the windows system menu. click on the icon in the upper left corner of the mj window and select soundcard setup.