Add sf2 (soundfont) support to wildmidi

CMakeLists.txt

@@ -12,10 +12,12 @@ SET(VERSION 2.1.0)
 # Find Macros
 SET(CMAKE_MODULE_PATH ${PROJECT_SOURCE_DIR}/cmake)
 
+INCLUDE(CMakePushCheckState)
 INCLUDE(CMakeDependentOption)
 INCLUDE(CheckCCompilerFlag)
 INCLUDE(CheckCSourceCompiles)
 INCLUDE(CheckIncludeFile)
+INCLUDE(CheckSymbolExists)
 INCLUDE(GNUInstallDirs)
 INCLUDE(TestBigEndian)
 
@@ -66,6 +68,8 @@ OPTION(WANT_OPENAL "Include OpenAL (Cross Platform) support" OFF)
 
 OPTION(WANT_DEVTEST "Build WildMIDI DevTest file to check files" OFF)
 
+OPTION(WANT_SF2 "SoundFont2 (SF2) support via TinySoundFont" ON)
+
 CMAKE_DEPENDENT_OPTION(WANT_MP_BUILD "Build with Multiple Processes (/MP)" OFF "WIN32;MSVC" OFF)
 CMAKE_DEPENDENT_OPTION(WANT_OSX_DEPLOYMENT "OSX Deployment" OFF "APPLE" OFF)
 
@@ -189,6 +193,7 @@ CHECK_INCLUDE_FILE(inttypes.h HAVE_INTTYPES_H)
 TEST_BIG_ENDIAN(WORDS_BIGENDIAN)
 
 # UNIX-like environments
+cmake_push_check_state()
 IF (UNIX AND NOT APPLE)
     # find our math lib
     FIND_LIBRARY(M_LIBRARY m)
@@ -197,10 +202,16 @@ IF (UNIX AND NOT APPLE)
         SET(M_LIBRARY "")
         SET(PKG_PRIVATELIBS "")
     ELSE()
+        LIST(APPEND CMAKE_REQUIRED_LIBRARIES m)
         SET(PKG_PRIVATELIBS "-lm")
     ENDIF()
 ENDIF()
 
+check_symbol_exists(powf math.h HAVE_POWF)
+check_symbol_exists(expf math.h HAVE_EXPF)
+check_symbol_exists(sqrtf math.h HAVE_SQRTF)
+cmake_pop_check_state()
+
 # ######### General setup ##########
 INCLUDE_DIRECTORIES(BEFORE "${PROJECT_SOURCE_DIR}/include" "${PROJECT_BINARY_DIR}/include")
 IF (NOT HAVE_STDINT_H) # AND NOT HAVE_INTTYPES_H
@@ -299,6 +310,12 @@ IF(WANT_PLAYER OR WANT_PLAYERSTATIC)
     MESSAGE(STATUS "Enabled audio output backends: ${ENABLED_OUTPUT}")
 ENDIF()
 
+IF (WANT_SF2)
+    SET(TINYSOUNDFONT_DIR "${PROJECT_SOURCE_DIR}/extern/TinySoundFont")
+    INCLUDE_DIRECTORIES(SYSTEM "${TINYSOUNDFONT_DIR}")
+    SET(WILDMIDI_SF2 1)
+ENDIF()
+
 # Setup up our config file
 CONFIGURE_FILE("${PROJECT_SOURCE_DIR}/include/config.h.cmake" "${PROJECT_BINARY_DIR}/include/config.h")
 

docs/SF2.md

@@ -0,0 +1,67 @@
+# SoundFont2 (SF2) Support
+
+Implementation plan and design notes for [issue #8](https://github.com/Mindwerks/wildmidi/issues/8).
+
+## Approach
+
+WildMIDI gains SF2 rendering via [TinySoundFont](https://github.com/schellingb/TinySoundFont)
+(`tsf.h`, MIT licensed, single-header, pure C), fetched at configure time with CMake
+`FetchContent` and pinned to a known-good commit.
+
+The key insight: WildMIDI's format parsers (MID, XMI, MUS, HMP, HMI) already convert
+everything into a single time-stamped event list (`struct _event`), and the renderer is
+just the stage that consumes that list. SF2 support swaps the *rendering* stage while
+keeping every parser, the timing engine, and the public API untouched. No other MIDI
+library renders XMI/MUS/HMP/HMI through SoundFonts — this is WildMIDI's niche.
+
+TinySoundFont's common criticism — "you must do your own MIDI parsing" — is exactly
+what makes it the right fit here: its `tsf_channel_*` API maps 1:1 onto WildMIDI's
+already-decoded event types.
+
+## How it works
+
+1. **Loading** — `WildMidi_Init()` / `WildMidi_InitVIO()` sniff the config file for the
+   RIFF/`sfbk` magic (not the file extension). An `.sf2` file given directly as the
+   "config file" is loaded through the existing VIO buffer callbacks into one global
+   `tsf*` instance. Additionally, the timidity.cfg parser understands a
+   `soundfont <file>` directive (relative paths resolved against the config dir, same
+   as `source`), so `/etc/timidity/fluidr3_gm.cfg` works as-is.
+2. **Per-song synth** — each opened midi (`struct _mdi`) gets its own `tsf_copy()` of
+   the global instance (sample data shared, voices private), created in `_WM_initMDI()`
+   and freed in `_WM_freeMDI()`. Concurrent handles stay safe.
+3. **Rendering** — `WM_GetOutput_SF2()` mirrors the scheduling loop of
+   `WM_GetOutput_Linear()`. Every event still runs its normal `do_event` (tempo, lyrics,
+   channel state; GUS note-ons no-op safely since no GUS patches are loaded) and is
+   additionally translated to the corresponding `tsf_channel_*` call. Audio is rendered
+   by `tsf_render_short()` into the 32-bit mix buffer, so `WM_MO_REVERB` and the rest of
+   the output pipeline behave exactly like the GUS path.
+4. **Release tails** — when the event list ends, rendering continues while
+   `tsf_active_voice_count() > 0`, so SF2 release envelopes aren't clipped at
+   end-of-song.
+
+## Event translation
+
+| WildMIDI event | TSF call |
+|---|---|
+| note on/off | `tsf_channel_note_on` / `_off` |
+| patch change | `tsf_channel_set_presetnumber(..., isdrum)` |
+| pitch wheel | `tsf_channel_set_pitchwheel` |
+| all controllers (bank, volume, pan, expression, hold, RPN/NRPN, sound/notes off, …) | `tsf_channel_midi_control` (TSF implements the full CC map) |
+| Roland drum-track sysex | `tsf_channel_set_bank_preset(ch, 128, 0)` |
+
+Channel 9 defaults to bank 128 (drums) at synth creation, per GM convention.
+
+## Build
+
+* `WANT_SF2` CMake option, default `ON`. No network dependency: TinySoundFont is
+  vendored at `extern/TinySoundFont/` (MIT licensed, compatible with LGPLv3
+  linking). Refresh by replacing `tsf.h` with a newer upstream revision.
+
+## Non-goals (first pass)
+
+* Mixing GUS patches and SF2 in one config — if a soundfont is loaded it takes over
+  rendering entirely.
+* SF3 (ogg-compressed) soundfonts — one `#define TSF_SF3` + stb_vorbis away if wanted.
+* timidity per-soundfont options (`amp=`, `order=`, `remove`) — parsed token is the
+  filename only.
+* `WildMidi_MasterVolume()` does not affect the SF2 path yet (TSF has its own gain).

extern/TinySoundFont/LICENSE

@@ -0,0 +1,19 @@
+Copyright (C) 2017-2023 Bernhard Schelling (Based on SFZero, Copyright (C) 2012 Steve Folta, https://github.com/stevefolta/SFZero)
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+of the Software, and to permit persons to whom the Software is furnished to do
+so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

extern/TinySoundFont/README.md

@@ -0,0 +1,11 @@
+# TinySoundFont
+
+Vendored copy of [TinySoundFont](https://github.com/schellingb/TinySoundFont)
+at commit `fbc913531b85f5707f49115110bb86b1cd583885` (2025-07-19), used by
+`src/sf2.c` when built with `-DWANT_SF2=ON`.
+
+MIT licensed — see `LICENSE`.
+
+To refresh, replace `tsf.h` and `LICENSE` with a newer upstream revision. Only
+`tsf.h` is compiled; the rest of the upstream repo (examples, tools) is not
+needed.