What does CMT do? The major components and their functions are:
Required Hardware and Software
CMT runs on:
The entire CMU MIDI Toolkit occupies 5 to 10MB of disk space, although this could be trimmed considerably by not compiling all the examples.
Other Details
CMT is distributed by Roger B. Dannenberg,
Computer Science Department, Carnegie Mellon University, Pittsburgh, PA,
15213-3890, USA. We hope that users will contribute new software to the
system and enhance the existing software in various ways. We will encourage
this by helping to integrate and document new software and by distributing
software updates to CMT users.
Installing CMT
Software installation procedures are described in the file named
README on the distribution disk.
With the computer powered off, install your (hardware) MIDI interface. Connect your keyboard MIDI OUT to the interface MIDI IN. Connect the interface MIDI OUT to your keyboard MIDI IN. Hardware procedures should be described in the documentation with your interface. This manual does not discuss hardware installation.
MIDI THRU is likely to cause some confusion at some point, so please read this and the next paragraph carefully. MIDI THRU means that MIDI IN data is copied to MIDI OUT. For example, an MPU-401 interface normally implements MIDI THRU when CMT is not running. Some synthesizers cannot handle having output data returned to their input, so you may have to disconnect one of the MIDI cables to avoid the adverse effects of MIDI THRU. On the other hand, if you connect your computer's MIDI OUT to a sound module, you may depend upon MIDI THRU to route MIDI from your keyboard to your sound module.
In the current releases (but check for documentation updates),
So, to use a SoundBlaster or other UART-mode MIDI interface, place the following in your autoexec.bat file:
This procedure allows you to use the SoundBlaster MIDI interface only. You need an adapter cable to convert from the small sound card connector to MIDI connectors (see your sound card manual for details). Unfortunately, this procedure does not support the use of the synthesis capabilities of your sound card.
Within your main CMT directory you will find four main folders (with
names greater than two letters) and a bunch of folders with one- and
two-letter names.
The main folders are:
The one- and two-letter directories are the details for individual
platforms, i.e. a compiler and/or operating system; you can delete the ones you don't need. (Also, by the way,
you can delete the makefiles for platforms you don't use from the
individual library and applications directories.)
Within /app there are folders for specific applications and several
general directories:
Macintosh users may not be familiar with command lines. Since the toolkit
developed from a command-line interface, parameters called options can be passed to
programs by typing them on the command line. On the Macintosh, a dialog box
appears when a program is started, prompting for a command line.
If you install and compile CMT, you will find that compiled programs are
left in the same directory as the source (C) code. You may wish to copy
these to a single directory such as
DOS IRQ and Base Address
The CMU MIDI Toolkit currently supports only Roland MPU-401 compatible interfaces on PC compatible computers. These interfaces are now available from several manufacturers. Usually, these interfaces are used on interrupt 2 at base address 33016, and this is where CMU MIDI Toolkit programs expect to find an interface. If the interface is not there, CMT will search interrupt levels and addresses for an MPU-401, but there is no absolutely safe way to do this. In the process of searching, CMT writes to various I/O locations, and if non-MPU-401 hardware responds to the write, a device may be reset and/or your machine may crash. To avoid the search when your interface is not at the default
interrupt level and location, you can set two environment variables, MPUIRQ and MPUBASE. For example, to specify an IRQ level 6 and base address 36016, place the following in your autoexec.bat file:
set MPUIRQ=6
set MPUBASE=360
Be sure the values of these environment variables correspond to the actual hardware. Consult your MIDI interface hardware documentation to determine the proper values.
Other Interface for PCs
In addition to Roland MPU-401 interfaces, there are many options for MIDI on PCs. Some interfaces are MPU-401 compatible, and may require no changes (or at most putting the IRQ number and base address in the environment as described in the previous section). Other interfaces, including Rev. 4.xx Sound Blasters from Creative Labs, claim to be MPU-401 compatible but only support the MPU-401 UART mode. This can be handled easily as described in the next section (``SoundBlaster and MPU Compatible Interfaces''). Another possibility is that you have an earlier version of Sound Blaster, a Voyetra VP11, or a Keytronics MIDIator. These all require recompilation of CMT, and the full process is described in Appendix ``Non-MPU-401 MIDI Interfaces''.
SoundBlaster and MPU Compatible Interfaces
If you have an "MPU Compatible" MIDI interface, it may be compatible only with UART mode. If so, we have bad news and good news. The bad news is that CMT uses the ``intelligent'' mode to determine whether or not you actually have an MPU-401 installed in your system, and this will fail if your MIDI interface supports UART mode only. The good news is that you can set the MPUUART environment variable to disable the code that checks for an MPU-401. More good news is that CMT uses UART mode for everything else.
set MPUUART=1
and reboot. If you set MPUUART, then you must have the proper MPUIRQ and MPUBASE settings (see the previous section). CMT will not check these settings and will not operate if they are incorrect.
Files and Naming
Different operating systems use different naming conventions and terminology for files and directories or folders. This manual will use the slash character (``/'') to separate directory names and will use the term directory to mean a Macintosh folder. For Macintosh users,
app/util/step
means the step program in the folder util, which is within the folder app. All directory paths are assumed to start in the directory in which the toolkit is installed. For DOS users, substitute ``\'' for ``/'' in paths.
bin. A set of compiled programs
is included with the release.
Command Help
Typing "?"
to any toolkit program will cause it to display the complete set of command
line options. Any command line option may be abbreviated with a single
letter if no other options start with the same letter.
Software Structure
For programmers intending to write new applications, the shear volume of
code in CMT may be a bit overwhelming. This section gives a brief overview
of the software, which is covered in greater detail in Chapters
``Programming in C'' through ``Advanced Moxc Features'', ``System Details'', and
Appendix ``The MIDI Interface''.
Support Modules
In order to maintain portability, CMT is based on a number of support modules:
midifns.c provides an interface to MIDI input and
output.
userio.c provides system-independent functions to print text, read user type-in, test for input ready, and open files.
cmdline.c provides a standard way to read and parse command lines.
cleanup.c provides a way to register functions that
perform cleanup operations such as removing interrupt handlers, closing
windows and files, and freeing memory. An EXIT function
automatically invokes the cleanup operations.
mem.c provides fast constant-time allocation and
freeing of small blocks of memory.
Moxc
The programs Step, MM, Exget, Exput, and Tuning are built directly on this
foundation, but most MIDI programs in CMT are based on a programming system
called Moxc. Moxc depends upon the support modules listed above, and Moxc
is in turn implemented in three modules:
timebase.c provides a data structure, call_type, that holds a function pointer, a set of parameters for the function, and a time at which to call the function. A timebase_type is a structure that holds a sorted queue of call_type's and maintains a mapping from real time to virtual time, which can run faster or slower than real time.
moxc.c implements cause, which schedules a function to be called in the future. Moxc manages a set of timebases and also parses MIDI input and ASCII (console) keyboard input, calling application-specific handlers when input arrives.
moxcmain.c is a default main program. It is intended to be linked with application-specific handlers to implement an interactive MIDI program.
Sequences
Sequences are built on top of Moxc and account for a large fraction of the CMT code. The important modules are:
seq.c implements the seq_type data structure, with operations for creating empty sequences, inserting events, playing sequences, and deallocating sequences.
seqread.c is the Adagio score language parser.
seqmread.c is the standard MIDI file reader, it translates the contents of a standard MIDI file into a seq_type. It relies on midifile.c to parse the MIDI file, and tempomap.c to convert beat number and tempo information into absolute real time in milliseconds needed for seq_type.
seqwrite.c writes a sequence as an Adagio file.
seqmwrite.c writes a sequence as a standard MIDI file.
Applications
Some applications build upon both the seq_type structure and Moxc. These include Adagio, Cornucopia, and Conduct, described at the beginning of this chapter and more fully in chapters of their own. There are also a few small demonstration and test programs in app/test.
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