Jaytrax

The MIDI module

The MIDI module is the place to turn Jaytrax into a full featured professional synthesizer.

Connecting your gear

Jaytrax supports MIDI in 2 distinct ways: You can first of all use any MIDI compatible attached keyboard to enter notes into Jaytrax. If you haven't got a MIDI keyboard, you can also use the keyboard of the computer to act as a MIDI-'keyboard'. Secondly: you can let Jaytrax behave as a stand alone synthesizer that responds to incoming MIDI messages. This second feature can be setup in this screen. In order to let Jaytrax respond to the messages intented for itself some things have to be configured. First of all one has to select the MIDI device to which Jaytrax shopuld respond. Thios can be selected with the dropdown list called 'Select main MIDI input device'. You can have multiple MIDI cards installed on your computer and this selector decides onto which card we are hooked. The 'MIDI activity' led just underneath twinkles when MIDI activity is registered. Even MIDI messqges not meant for Jaytrax is registered. After selecting the MIDI device we now need to configure the MIDI channels Jaytrax should respond to. There are 16 available MIDI channels and since there can be more than one MIDI device hooked up we have to select to which MIDI channel Jaytrax must respond. On the screen are the 16 channels displayed in rows. Everyone of the channels can be actived with the 'Acitve' checkbox. When activated, Jaytrax will try and interpret incoming MIDI messages for that channel. The 'Instrument' dropdown list selects which instrument should be heared when Jaytrax receives 'Note-on' MIDI messages on that channel. If the 'Pgm Chng' checkbox is selected, Jaytrax will interpret the incoming 'Program change' MIDI messages and change the currently selected instrument on that channel if possible. If the 'Ctrl-Chng' checkbox is selected, Jaytrax will process the incoming 'Control Change' MIDI messages. More hereover later. The 'Nr of Channels' box selects the number of allocated Jaytrax sound reproduction channels for the MIDI channel. Jaytrax has a maximum of 16 sound channels playing simultaneously so choose them wisely. Last but not least, the 'Delay Amount' selects how much Echo the sounds on that MIDI channel should have. With the 'Delay Time' box you can specify at how big an interval the echo effect should occur. The amount is given in samnples per second. This means that if you set it to 44100, the echo time will be exactly 1 second. The 'Sound Amplification' is the amount (percentagewise) the sound will be amplified before it is send to the speakers.

Control changes

Just like in the pattern editor, Jaytrax supports the manipulation of instrument parameters through MIDI messages. This is done through 'Control Change' MIDI messages. Control changes are used to send data other than note data through MIDI. The Control Change messages Jaytrax responds to are the following: Message 123 - 127 All Notes Off. When Jaytrax receives this, all sound is stopped. Control Change 16 is used in the same manner as the Script number in the pattern editor. Just like you could select a script in the pattern editor, you can select one with Control Change 16. After selecting the script you can execute the script with a value by sending a Control Change nr 17 or 18 with the corresponding value. The difference between using Control Change message 17 or 18 is it's scope. Since MIDI messages are limited to 7 bits (is 0-128) data and Jaytrax needs 8 bits (0-256) you have to select the mapping method used. If you use Control change nr 17 the value is not converted and just used. When using Control Change 18 however the value is doubled before it is used. This way the 0-128 value is converted to the 0-256 value.

An example might by enlightening. Say we want to change the main volume to 200 of the currently playing instrument. We now from the pattern editor that the 'CHNG MASTER VOL' controller script is nr 4. So first of all we send a Control Change MIDI message nr 16 (from the MIDI sequencer you are using) with parameter 4. Then we send a Control Change MIDI message nr 18 with parameter 100. The value 100 is doubled by Jaytrax before it is used and so in effect the volume is changed to 200. To know how you can send Control Change messages from your MIDI sequencer please refer to the Help guide from your program.

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