Or lack thereof.

1. 5.1 or 4.0 surround sound output.  Make 5.1 or 4.0 wave
files with the "-Ow" option or ac3 files with the "-Od"
option.  Make AC3 files (pseudo-Dolby Digital).

2. Use samples from (a) GUS patches, (b) extended GUS patches,
(c) AWE Soundfonts, and (d) SFZ patches.  The configuration file
syntax lets you use them in combination and mix them up any way
you want.  Gt implements velocity layers and stereo instruments
in soundfont instruments, extended GUS patches, and SFZ
patches.  Soundfonts can be loaded in toto or by bank and
preset.

3. Included utility programs for (a) extracting extended
GUS patches from soundfonts (unsf), (b) deriving GUS patches
from SFZ patches (sfz2pat), (b) displaying info about extended
GUS patches (patinfo), (c) creating stereo patches from mono
patches (patcat), (d) constructing config files for Soundfonts
(sf2cfg).  A simple midi file disassember is also included.

4. Spruced up on-screen help with "gt -h".  Now it shows
what the default config file is and any patch set options
you've set up in the config file with "if" statements.

5. Play lists of all the midi files in a directory are
constructed automatically for a single directory named
on the command line, or for the current directory, if
no file or directory arguments are given.

6. Alsa sound driver only -- I removed all the other sound
drivers.  I don't know how to get multichannel sound using
other drivers.

7. Linux systems only -- I removed support for compiling on
other systems.  It might still compile on another Unix
system -- I don't know.

8. The ncurses and Dumb terminal interfaces only -- I removed
all the other user interfaces.

9. No filters for effects.  Instead, doubling up notes is
used to produce pseudo-reverb and -chorus.

10. Controlled use of memory: gt will keep its use of memory
for patches within bounds that you set.  In playing a list
of midi files, it keeps track of which patches haven't been
used recently, and discards them as necessary to keep within
its alloted memory.  In loading large soundfonts, the files
are memory mapped to load patches more efficiently (on little
endian systems), unless this would exceed allowed memory, in
which case patches are loaded the slow way.  The permissible
amount of memory is 250 megs by default and can be set with
the "-r" option from the command line or in the main config
file.  Gt reports on how much memory it used after playing
each midi.

11. Clipping reports: In trimming down its output samples to
fit into 16 bit words (typically what you use), some samples
have to be clipped back to fit.  Gt counts the number of
times it has to do this and reports, as a guide to how much
amplification you can afford to use without excessive
distortion.  You can lower amplification sufficiently to avoid
all clipping, but then the music loses some life.

12. Eric Welsh studied the relation between XG and GS/GM
conventions for intrument banks and instrument numbering, and
included "map" statements in the config files he prepared for
his "eawpats".  These "map" statements are read and interpreted
by Timidity++.  Gt's config file reader does not understand
"map" statements; however, I've incorporated Eric's XG mapping
directly into gt's code.  So "map" statements are not required,
and Eric's XG mappings work whether or not you use the "eawpats".