Sorry to be pedantic, but what is 'the General Midi 1 soundfont'?

Usually, a 'soundfont' is a file of digital data (like .wav or mp4 data) to be used to create the sound of instruments. There is certainly not ONE of such a file, I'm sure there are a number, of varying size and quality, some free, some costing money. I use one called 'Timbres of Heaven' and it's quite good. I've heard some pretty poor ones as well.

There are certainly files providing sounds for GM instruments (i.e. GM1, or just GM). There are other files with extended facilities, but maybe not as far as full GM2, as GM2 is a LOT bigger than GM

The list of instruments for GM is pretty standard, so you can find 'the list'. I have seen lists for GM2, but these tend to vary (somewhat) between manufacturers so I'm not certain that GM2 is as 'standard' as is GM (1). Standard enough for most purposes, I guess. But not 100%??

Coming back to 'soundfont' files, if there are any complete enough to be worthy of the name, they may not be 'standard' enough to count??

Geoff

General midi 1: https://www.midi.org/specifications-old/item/gm-level-1-sound-set

Hi,
I thought I might be able to help clear this up... General Midi System Level 1 and General Midi System Level 2 do not define specific sounds, It defines a set of shared features that can be used to describe a sound as well as standard patch's or program numbers for where that sound should go.
From the GM1 Spec document
[code type=markup]
General MIDI Sound Generator Requirements
Synthesis/Playback Technology (Sound Source Type):
• Up to the manufacturer.
Number of Voices:
• A minimum of:
1) 24 fully dynamically allocated voices available simultaneously for both melodic and
percussive sounds; or:
2) 16 dynamically allocated voices for melody plus 8 for percussion.
MIDI Channels Supported:
• All 16 MIDI channels.
• Each channel can play a variable number of voices (polyphony).
• Each channel can play a different instrument (timbre).
• Key-based Percussion is always on channel 10.
Instruments:
• A minimum of 128 presets for Instruments (MIDI program numbers), conforming to
the "GM Sound Set" (see Table 2)
• A minimum of 47 preset percussion sounds conforming to the "GM Percussion Map"
(see Table 3)"
[/code]

So basically you must include 128 sounds that conform to the GM Sound Set. but these sounds can be generated in any number of ways. Windows 10 by default comes with a GM1/2 and Roland GS Sound Set Synth which (supposedly) uses wave table synthesis. Microsoft Documentation

--TLDR--
Probably the best example i can give is WAY back in high school i got the PC/Windows version of Final Fantasy 7. (i promise this will make sense). FF7 made use of SystemMidi (or Playstation MIDI if on console) for background music. On the PC though i had routed the actual midi from my sound-card to a Yamaha GM Synth . Both the System Midi and The Yamaha were "General Midi" compliant... but the Yamaha sounded a thousand times better because it used a Sampled synthases rather than whatever the Sound blaster 16 used.

I know I'm very late to the party, but technically the sf2 soundfont format can't support General MIDI 2's 128 extra melodic instrument patches. For General midi 2, banks must be selected with a 7-bit MSB (cc0) and a 7-bit LSB (cc32).

For GM2's melodic instruments, the MSB is set to 121 and the LSB is set to select the appropriate bank variant (Usually a number between 0-9).

Example: Midi program 81 (80 in 0 based numbering) Square lead can be set to these patches for GM2

Bank MSB is 121

Bank LSB:

0 = Square lead (GM1 patch)

1 = Square wave

2 = Sine wave

So GM2 adds 2 extra sounds for program 81.

For GM2's drums, The MSB is set to 120 to select a drumkit. This is used to allow Channel 11 (10 in 0 based numbering) to be set as a percussion channel.

In Soundfonts of the sf2 extension, only banks from 0-127 are allowed (selected with the MSB cc0) and bank 128 is reserved for drums. This means that Soundfonts cannot natively support general Midi 2's melodic instrument patches. it can support the GM2's drumkits and the extra notes such as hi Q and sleigh bells for example. In the format, it is told to ignore banks higher than 128 but maintain them in the file.