Linux MIDI: A Brief Survey, Part 3

In this installment of my survey of Linux MIDI software, I profile various MIDI utilities, some of which have become indispensable components in my own Linux MIDI studio.

As I already have mentioned, the Old School MIDI studio was more hardware-centric than is today's software-based studio. Sequencers, synthesizers, samplers, MIDI-controllable mixers, MIDI channel routers and MIDI event processors all were available as useful boxes, lending greater flexibility to your studio setup. A common characteristic of most of these devices was the ability to dump the machine's internal settings and states into a type of MIDI message format called system exclusive. Sysex, as it's commonly called, is a way for MIDI equipment manufacturers to accommodate features specific to their designs; that is, sysex code is manufacturer-specific, so the sysex messages that work for a Yamaha synth are meaningless to a Roland synth. Going further, we find that sysex messages are device-specific as well, so the sysex calls to a Yamaha TX81Z are meaningless to my Yamaha TX802.

Sysex is especially important with regards to synthesizers and other "patch"-oriented devices. For example, my Yamaha DMP11 is an 8-channel MIDI controllable mixer with many features, some of which are accessible only by way of sysex commands. More importantly, the only way to back up my custom patches and settings for this mixer is by using sysex.

By using the sysex codes for a device, MIDI programmers are able to write a type of MIDI software known as a synth editor/librarian. Software of this type that attempts to address a variety of machines is known as a universal editor/librarian, and the devices addressed may include machines other than synthesizers. Writing a decent universal editor/librarian is a non-trivial task: the programmer must know the sysex codes for many machines, and he then must devise workable interfaces for each one. Because every synthesizer is a unique device, many interfaces to programs must be included in order to accommodate a wide range of features. These features include typical stages, such as envelope generators and oscillator definitions, as well as less common features, such as microtuning tables and keyboard scaling maps.

Unlike common MIDI messages, a sysex command has a relatively loose construction, based on the following fixed aspects:

  f0	begin sysex
  ..	manufacturer and device IDs
  ..	any number of bytes
  f7	terminate sysex

System exclusive messages typically are represented in hexadecimal notation.

Manufacturer IDs are registered with the MIDI Manufacturers Association. The following example shows a message that prompts my Yamaha TX802 to do what is known as a bulk dump--all internal states and settings are dumped out the machine's MIDI out port :

  f0 43 20 00 f7

where:

  f0  Start sysex command
  43  Yamaha manufacturer ID
  20  Voice memory bulk dump request
  00  Device number
  f7  End sysex command

This message is answered with another sysex message, filled with some number of bytes that represent the patch memory of the machine (all patches). Unlike most other MIDI messages, sysex messages can be any size. This feature is handy for patch editing, but it also can cause a timing problem when you want to insert a lengthy sysex message into a real-time MIDI data stream.

The following sysex example sends a parameter change to the active patch, what Yamaha calls a voice:

  f0 43 10 01 06 00 f7

where:

  f0 Start sysex
  43 Yamaha ID
  10 Device & channel number
  01 Parameter group/subgroup
  06 Parameter number (here, Algorithm Select)
  00 Data (here, algorithm #1)
  f7 End sysex

Thus, this message switches the FM algorithm of the active voice to algorithm 1. Thanks to its size, you are likely to have fewer timing problems when inserting brief parameter changes messages such as this one into a MIDI data stream.

A universal editor/librarian is valuable software if you have any external MIDI equipment, but as I mentioned, writing such software is a non-trivial task. Thankfully, an excellent project is available for Linux MIDI musicians working with hardware synths and other devices: JSynthLib.

JSynthLib is a Java-based universal editor/librarian for Windows, Mac OS X and Linux. The last public release is version 0.18, dated March 2004, but be advised that JSynthLib is an active project; it simply moves slowly. The developers state that JSynthLib should be considered beta software, but I found it to be useful and stable already under Sun's JDK 1.4.

JSynthLib currently supports 30 devices, mostly synthesizers, with more in CVS. Manufacturers represented include Alesis, Korg, Kawai, Roland and Yamaha; check the JSynthLib Web site for the most up-to-date list.

Fortunately for me, I own two synthesizers on the current list, a Yamaha TX802 and a Kawai K4r. The screenshots below show JSynthLib at work with my synths, demonstrating the primary virtue of the universal editor/librarian--organizing the synthesizer's editing capabilities and representing them in a full-screen display. A universal editor/librarian does not give your equipment new capabilities, but it does make it far easier to understand how your synth works, giving you greater control over its capabilities.

Figure 1. JSynthLib and the Yamaha TX802

Figure 2. JSynthLib and the Kawai K4r

This profile is not intended to be a tutorial, so if you want to learn more about JSynthLib and how to use it, download and install it yourself. You need a recent version of Java to use with JSynthLib, but fortunately all this is easy to do. Again, see the JSynthLib Web site for details.