Specifications

converter 1.5

2000 - 2005 urr Sound Technologies Inc.
20
software installation and configuration
To ‘install’ converter, simply create a directory (folder) somewhere on your computer’s hard drive, and
copy all the files contained in the converter .zip archive to that folder. Or alternatively, create a self-
bootable converter floppy disk using the floppy boot disk image creator included in the converter .zip
archive, or copy the files to your own bootable blank 1.44MB 3½” floppy disk (for information on both
procedures, see the appendix on creating a bootable floppy).
Before running converter, the file
hardware.cfg
should be examined to ensure the settings are
appropriate for your particular soundcard. This can be loaded using any text editor – in Windows you
can use Notepad, or under DOS you could use Edit. Make sure not to change the layout of the file
(don’t delete any lines, even blank ones). The parameter to be adjusted is just below the listing of
options, and is not
notnot
not preceded by a ‘#’ sign.
The first parameter
allows you to select the soundcard and what core input mode you want to use
depending on your system’s soundcard (audio input or midi input for most of the soundcards, and the
additional option of simultaneous audio and midi input for users with an additional MPU-401 card).
The second parameter
only affects audio input, and allows you to define the size of the audio buffer.
This determines both the response time for audio to midi conversion, as well as the quantity of midi
data generated from the audio input (in continuous controller mode). Since each buffer of data is
converted into a single amplitude value, the smaller the buffer size, the greater number of times it is
converted per second, with lower latency – and conversely, the larger the buffer size, the fewer number
of times it is converted, with greater latency. The smallest buffer size you can use is determined by your
computer’s processing speed; smaller buffer sizes result in significantly more instructions per second
and I/O functions that the computer must complete in order to avoid losing audio samples, and will
have an impact on the speed of the overall system. The side effect of using a very small buffer is that
the software will actually trace individual cycles of lower-frequency waveforms, resulting in midi
continuous controller streams that oscillate at a very fast rate, much like an LFO on a synthesizer. This
ability has been preserved for those wishing to experiment with these types of oscillations as control
signals. To avoid this type of effect, try using an input buffer size of 80 bytes or greater –
experimentation is key. In general, a buffer size below 80 (and certainly below 64) bytes is unnecessary.
For most applications, the default buffer setting of 80 is fine, and gives you a low latency of ~3
milliseconds.
Note also that with a buffer size less than 72 bytes, gameport input is automatically disabled – refer to
the gameport system overview for further details.
The third and fourth parameters
are to define the hardware settings (interrupt (IRQ) and base port
address) for those using a Roland or generic UART-mode MPU-401 for midi input in mode 0, or midi
input & output in one of converter’s dual cards input modes. For the SoundBlaster Pro & MPU401 MIDI
output mode (mode 8), only the base address of your MPU-401 interface is needed – the IRQ for the
MPU-401 is not used by converter in this particular mode. For modes 0, 9, 10, and 11, both the base
address and IRQ values are needed for your particular MPU-401 interface. The numbers for the base
address and IRQ used by your MPU-401 can be found in the resources tab of its driver under Windows
9x (if you are using Windows 9x) and just entered here. The factory default for an MPU-401 is base
address 330 at IRQ 2/9.
If using a dual card mode for converter, it is best if the interrupt assigned to the MPU-401 interface
being used for midi input is lower than the interrupt assigned to the card performing audio input. For
further information, see the section in this manual entitled “dual cards for simultaneous audio and midi
input”.