Fallback built-in synthesizer

CMakeLists.txt

@@ -207,6 +207,7 @@ 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)
+check_symbol_exists(sinf math.h HAVE_SINF)
 cmake_pop_check_state()
 
 # ######### General setup ##########

amiga/Makefile

@@ -55,7 +55,7 @@ endif
 	$(CC) -c $(CFLAGS) -o $@ $<
 
 # Objects
-LIB_OBJ= wm_error.o file_io.o lock.o wildmidi_lib.o reverb.o gus_pat.o f_xmidi.o f_mus.o f_hmp.o f_midi.o f_hmi.o mus2mid.o xmi2mid.o internal_midi.o patches.o sample.o sf2.o
+LIB_OBJ= wm_error.o file_io.o lock.o wildmidi_lib.o reverb.o gus_pat.o f_xmidi.o f_mus.o f_hmp.o f_midi.o f_hmi.o mus2mid.o xmi2mid.o internal_midi.o patches.o sample.o sf2.o synth.o
 PLAYER_OBJ= amiga.o wm_tty.o msleep.o getopt_long.o out_none.o out_wave.o out_ahi.o wildmidi.o
 
 # Build targets

amiga/Makefile.vbcc

@@ -34,7 +34,7 @@ endif
 	$(CC) -c $(CFLAGS) -o $@ $<
 
 # Objects
-LIB_OBJ= wm_error.o file_io.o lock.o wildmidi_lib.o reverb.o gus_pat.o f_xmidi.o f_mus.o f_hmp.o f_midi.o f_hmi.o mus2mid.o xmi2mid.o internal_midi.o patches.o sample.o sf2.o
+LIB_OBJ= wm_error.o file_io.o lock.o wildmidi_lib.o reverb.o gus_pat.o f_xmidi.o f_mus.o f_hmp.o f_midi.o f_hmi.o mus2mid.o xmi2mid.o internal_midi.o patches.o sample.o sf2.o synth.o
 PLAYER_OBJ= amiga.o wm_tty.o msleep.o getopt_long.o out_none.o out_wave.o out_ahi.o wildmidi.o
 
 # Build targets

amiga/config.h

@@ -1,4 +1,5 @@
 /* wildmidi config for amigaos variants */
+
 #define WILDMIDI_AMIGA 1
 
 #define WILDMIDI_CFG "wildmidi.cfg"
@@ -20,8 +21,8 @@
 /* #undef HAVE_EXPF */
 /* #undef HAVE_SQRTF */
 /* #undef HAVE_POWF */
+/* #undef HAVE_SINF */
 
 #define WILDMIDI_SF2 1
 
 #define AUDIODRV_AHI 1
-

android/jni/Android.mk

@@ -22,6 +22,7 @@ LOCAL_SRC_FILES := \
 	src/reverb.c \
 	src/sample.c \
 	src/sf2.c \
+	src/synth.c \
 	src/wildmidi_lib.c \
 	src/wm_error.c \
 	src/xmi2mid.c

android/jni/config.h

@@ -64,8 +64,8 @@
 #define HAVE_EXPF 1
 #define HAVE_SQRTF 1
 #define HAVE_POWF 1
+#define HAVE_SINF 1
 
 #define WILDMIDI_SF2 1
 
 /* Define our audio drivers */
-

djgpp/Makefile

@@ -57,7 +57,7 @@ endif
 
 
 # Objects
-LIB_OBJ= wm_error.o file_io.o lock.o wildmidi_lib.o reverb.o gus_pat.o f_xmidi.o f_mus.o f_hmp.o f_midi.o f_hmi.o mus2mid.o xmi2mid.o internal_midi.o patches.o sample.o sf2.o
+LIB_OBJ= wm_error.o file_io.o lock.o wildmidi_lib.o reverb.o gus_pat.o f_xmidi.o f_mus.o f_hmp.o f_midi.o f_hmi.o mus2mid.o xmi2mid.o internal_midi.o patches.o sample.o sf2.o synth.o
 PLAYER_OBJ= wm_tty.o msleep.o getopt_long.o out_none.o dosirq.o dosdma.o dossb.o out_dossb.o out_wave.o wildmidi.o
 
 # Build targets

djgpp/config.h

@@ -19,6 +19,7 @@
 /* #undef HAVE_EXPF */
 /* #undef HAVE_SQRTF */
 /* #undef HAVE_POWF */
+/* #undef HAVE_SINF */
 
 #define WILDMIDI_SF2 1
 

docs/synth_plan.md

@@ -0,0 +1,120 @@
+# Emergency Soundbank — Live Synthesis Fallback
+
+Refs: [issue #121](https://github.com/Mindwerks/wildmidi/issues/121).
+
+Goal: when the user has no `.pat` set and no `.sf2`, WildMIDI still makes
+sound. Not hi‑fi — audible, recognisable GM instruments generated in RAM at
+startup.
+
+## Feasibility: yes
+
+WildMIDI already speaks one internal format: `struct _sample` (see
+[include/sample.h](include/sample.h#L45)). Every loader — GUS, SF2 — ends up
+handing a `_sample` chain to `sample_patch->first_sample` from inside
+[`_WM_load_sample`](src/sample.c#L117). A synthesiser is just another loader
+that never touches disk.
+
+Integration point is one branch in `_WM_load_sample`:
+
+```
+if (guspat = _WM_load_gus_pat(...)) { /* existing */ }
+else if (emergency_bank_enabled)   { guspat = _WM_synth_patch(patchid); }
+```
+
+Trigger: opt-in only — `--emergency` CLI flag, or pass the sentinel
+`"@emergency"` as the config path to `WildMidi_Init()`. Never silent, so a
+missing cfg still surfaces as an error and debugging stays honest.
+No API break; existing users notice nothing.
+
+## Licensing
+
+- `EmergencySoundbank.java` (Gervill / Sun) is **GPL‑2 only** → **cannot lift**. Technique is not copyrightable; a clean reimplementation is fine.
+- `csharpsynthproject` is MIT → compatible, safe to port ideas or code.
+- AKWF single‑cycle waveforms are **public domain (CC0)** → safe to embed as static tables.
+- KissFFT is BSD‑3 → compatible if we want an iFFT approach.
+- Sonivox EAS wavetable (`wt_44khz.c`) is Apache 2.0 → compatible with LGPLv3 (WildMIDI's library license), **not** with LGPLv2. WildMIDI is v3+, so it is usable — but only from library code, not from the GPLv3 player if we want to stay strict.
+
+Any lifted code goes in its own file with its original header preserved and gets called out in `docs/license/`.
+
+## Three approaches, laziest first
+
+### A. Detuned sine + ADSR per program family  *(recommended first cut)*
+
+One sine oscillator, per‑program pitch envelope, per‑program amplitude
+envelope, per‑program brightness (a running average = one‑pole LPF). 128
+programs collapse into ~8 families (piano, organ, guitar, bass, strings,
+brass, reed, lead/pad, plus percussion tables) with a small parameter table.
+
+- ~200 lines of C, no deps.
+- One 1s sample per program → `128 × 44100 × 2 B ≈ 11 MB` worst case; do it lazy per program on first `NoteOn` and it stays under 1 MB in practice.
+- Sound quality: chiptune‑ish. Fine as a "the config is missing" safety net.
+
+### B. Additive (harmonic stack) + noise for percussion
+
+Sum of 4–8 sines with a per‑program harmonic amplitude table, noise burst
+for drums, same ADSR framework as A. Closer to a real timbre; brass and
+strings become distinguishable. csharpsynth's generator is roughly this
+shape and MIT‑licensed — that's the model to crib from.
+
+- ~600 lines of C.
+- Still no FFT dep.
+- Percussion (channel 10) needs its own noise+resonator path — an extra ~100 lines.
+
+### C. Gervill‑style frequency‑domain synthesis
+
+Render weighted Gaussians in the frequency domain, phase‑randomise, iFFT,
+window. This is what `EmergencySoundbank` does and why its output sounds
+plausible. Requires an FFT — pull in KissFFT (BSD, ~1 kLOC, single header +
+single .c).
+
+- ~1200 lines of C + KissFFT.
+- Genuinely usable for casual playback.
+- Only worth doing if A/B prove insufficient.
+
+## CPU cost
+
+All figures are **one‑shot at startup**, or lazy on first use of each
+program. Nothing runs per audio callback — output is a normal `_sample`
+that flows through the existing mixer.
+
+| Approach | Per‑patch synth | 128 patches (upper bound) | Runtime cost after warm‑up |
+|----------|-----------------|---------------------------|----------------------------|
+| A sine+ADSR | ~1 ms | <150 ms | zero |
+| B additive  | ~5–10 ms | ~1 s | zero |
+| C iFFT      | ~10–30 ms (44100‑pt) | ~2–4 s | zero |
+
+Memory: 88 KB per 1s mono patch @ 44.1 kHz. Cap generated length per family
+(pads = 2s, drums = 0.3s, plucks = 0.5s) and total stays around 4–6 MB even
+if every program is touched.
+
+## Difficulty
+
+- **A**: ~half a day. New `src/synth.c` + `include/synth.h`, a
+  128‑entry program table, one branch in `_WM_load_sample`, CLI flag in
+  `src/player/wildmidi.c`, one env‑target/rate mapping using the existing
+  `env_rate[]/env_target[]` machinery.
+- **B**: 2–3 days. Same skeleton as A + a harmonic table per family + a
+  noise+resonator path for drums + real tuning by ear.
+- **C**: 1–2 weeks. Add KissFFT (or write a radix‑2 iFFT — ~120 lines),
+  reproduce the Gaussian‑sum→phase‑rand→iFFT pipeline, tune per family,
+  handle loop‑point selection on non‑decaying tones.
+
+## Recommendation
+
+Ship **A** as `--emergency` in a first pass. It answers issue #121: the
+player never falls silent for lack of patches. If users want it to sound
+good rather than just present, escalate to **B**; skip **C** unless someone
+volunteers.
+
+## Concrete task list for approach A
+
+1. `include/synth.h`, `src/synth.c` — one public function
+   `struct _sample *_WM_synth_patch(uint16_t patchid);` returning a
+   `_sample` chain compatible with the mixer (16‑bit signed, `SAMPLE_LOOP`
+   set on sustained families, envelope in `env_rate[]/env_target[]`).
+2. Program → family table (~30 lines of static data).
+3. Wire fallback into [`_WM_load_sample`](src/sample.c#L117) — one `else if`.
+4. `--emergency` flag in `src/player/wildmidi.c` and matching library
+   sentinel `WM_EMERGENCY_CONFIG`.
+5. `test/` — one MIDI file rendered with `-o` to WAV, byte length asserted
+   non‑zero; that's the "did anything come out" smoke test.

include/config.h.cmake

@@ -52,6 +52,7 @@
 #cmakedefine HAVE_POWF
 #cmakedefine HAVE_EXPF
 #cmakedefine HAVE_SQRTF
+#cmakedefine HAVE_SINF
 
 /* define this if you are running a bigendian system (motorola, sparc, etc) */
 #cmakedefine WORDS_BIGENDIAN 1

include/synth.h

@@ -0,0 +1,33 @@
+/*
+ * synth.h -- Built-in synthesiser: fabricates _sample chains so WildMIDI
+ *            plays even without a GUS patch set or SoundFont.
+ *
+ * Copyright (C) WildMIDI Developers 2026
+ *
+ * This file is part of WildMIDI.
+ *
+ * WildMIDI is free software: you can redistribute and/or modify the player
+ * under the terms of the GNU General Public License and you can redistribute
+ * and/or modify the library under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation, either version 3 of
+ * the licenses, or(at your option) any later version.
+ */
+
+#ifndef __SYNTH_H
+#define __SYNTH_H
+
+#include <stdint.h>
+
+#define WM_EMERGENCY_CONFIG "@emergency"
+
+struct _sample;
+
+/* Fabricate a _sample chain for the given (possibly-drum) patch id.
+   Uses the current _WM_SampleRate. Returns NULL on OOM. */
+extern struct _sample *_WM_synth_patch(uint16_t patchid);
+
+/* Populate _WM_patch[] with 128 tonal + GM drum entries, all with
+   filename==NULL so _WM_load_sample routes them to _WM_synth_patch. */
+extern int _WM_emergency_init_patches(void);
+
+#endif /* __SYNTH_H */

macosx/Makefile

@@ -68,7 +68,7 @@ LDLIBS_EXE+=-L. -l$(LIBNAME)
 
 # Objects
 LIB_OBJ = wm_error.o file_io.o lock.o wildmidi_lib.o reverb.o gus_pat.o
-LIB_OBJ+= f_xmidi.o f_mus.o f_hmp.o f_midi.o f_hmi.o mus2mid.o xmi2mid.o internal_midi.o patches.o sample.o sf2.o
+LIB_OBJ+= f_xmidi.o f_mus.o f_hmp.o f_midi.o f_hmi.o mus2mid.o xmi2mid.o internal_midi.o patches.o sample.o sf2.o synth.o
 PLAYER_OBJ = wm_tty.o msleep.o out_none.o out_wave.o out_coreaudio.o wildmidi.o
 # out_openal.o
 

macosx/config.h

@@ -24,9 +24,9 @@
 #define HAVE_EXPF 1
 #define HAVE_SQRTF 1
 #define HAVE_POWF 1
+#define HAVE_SINF 1
 
 #define WILDMIDI_SF2 1
 
 /* #undef AUDIODRV_OPENAL */
 #define AUDIODRV_COREAUDIO 1
-

mingw/Makefile

@@ -52,7 +52,7 @@ LDLIBS_EXE+=-L. -l$(LIBNAME)
 
 # Objects
 LIB_OBJ = wm_error.o file_io.o lock.o wildmidi_lib.o reverb.o gus_pat.o
-LIB_OBJ+= f_xmidi.o f_mus.o f_hmp.o f_midi.o f_hmi.o mus2mid.o xmi2mid.o internal_midi.o patches.o sample.o sf2.o
+LIB_OBJ+= f_xmidi.o f_mus.o f_hmp.o f_midi.o f_hmi.o mus2mid.o xmi2mid.o internal_midi.o patches.o sample.o sf2.o synth.o
 PLAYER_OBJ = wm_tty.o msleep.o getopt_long.o out_none.o out_wave.o out_win32mm.o wildmidi.o
 # out_openal.o
 

mingw/config.h

@@ -20,9 +20,9 @@
 #define HAVE_EXPF 1
 #define HAVE_SQRTF 1
 #define HAVE_POWF 1
+#define HAVE_SINF 1
 
 #define WILDMIDI_SF2 1
 
 /* #undef AUDIODRV_OPENAL */
 #define AUDIODRV_WINMM 1
-

msvc/common.mak

@@ -11,7 +11,7 @@ PLAYER  = wildmidi.exe
 LIBS_DLL=
 LIBS_PLY= $(IMPNAME) winmm.lib
 
-DLL_OBJ = wm_error.obj file_io.obj lock.obj wildmidi_lib.obj reverb.obj gus_pat.obj f_xmidi.obj f_mus.obj f_hmp.obj f_midi.obj f_hmi.obj mus2mid.obj xmi2mid.obj internal_midi.obj patches.obj sample.obj sf2.obj
+DLL_OBJ = wm_error.obj file_io.obj lock.obj wildmidi_lib.obj reverb.obj gus_pat.obj f_xmidi.obj f_mus.obj f_hmp.obj f_midi.obj f_hmi.obj mus2mid.obj xmi2mid.obj internal_midi.obj patches.obj sample.obj sf2.obj synth.obj
 PLY_OBJ = wm_tty.obj msleep.obj getopt_long.obj out_none.obj out_wave.obj out_win32mm.obj wildmidi.obj
 # out_openal.obj
 
@@ -57,6 +57,8 @@ sample.obj: ..\src\sample.c
 	$(CC) $(DLL_FLAGS) $(INCLUDES) -c -Fo$@ $?
 sf2.obj: ..\src\sf2.c
 	$(CC) $(DLL_FLAGS) $(INCLUDES) -c -Fo$@ $?
+synth.obj: ..\src\synth.c
+	$(CC) $(DLL_FLAGS) $(INCLUDES) -c -Fo$@ $?
 
 # player objects:
 wildmidi.obj: ..\src\player\wildmidi.c

msvc/config.h

@@ -24,10 +24,10 @@
 #define HAVE_EXPF 1
 #define HAVE_SQRTF 1
 #define HAVE_POWF 1
+#define HAVE_SINF 1
 #endif
 
 #define WILDMIDI_SF2 1
 
 /* #undef AUDIODRV_OPENAL */
 #define AUDIODRV_WINMM 1
-

os2/config.h

@@ -18,9 +18,9 @@
 #define HAVE_EXPF 1
 #define HAVE_SQRTF 1
 #define HAVE_POWF 1
+#define HAVE_SINF 1
 #endif
 
 #define WILDMIDI_SF2 1
 
 #define AUDIODRV_OS2DART 1
-

os2/makefile

@@ -38,7 +38,7 @@ BLD_TARGET=$(DLLNAME) $(PLAYER)
 INCPATH=-I"$(%WATCOM)/h/os2" -I"$(%WATCOM)/h"
 INCLUDES=$(INCPATH) -I. -I"../include"
 
-OBJ=wm_error.obj file_io.obj lock.obj wildmidi_lib.obj reverb.obj gus_pat.obj f_xmidi.obj f_mus.obj f_hmp.obj f_midi.obj f_hmi.obj mus2mid.obj xmi2mid.obj internal_midi.obj patches.obj sample.obj sf2.obj
+OBJ=wm_error.obj file_io.obj lock.obj wildmidi_lib.obj reverb.obj gus_pat.obj f_xmidi.obj f_mus.obj f_hmp.obj f_midi.obj f_hmi.obj mus2mid.obj xmi2mid.obj internal_midi.obj patches.obj sample.obj sf2.obj synth.obj
 PLAYER_OBJ=wm_tty.obj msleep.obj getopt_long.obj out_none.obj out_wave.obj out_dart.obj wildmidi.obj
 
 all: $(BLD_TARGET)

os2/makefile.emx

@@ -27,7 +27,7 @@ PLAYER_LIBS+=-lmmpm2
 CFLAGS_LIB= $(CFLAGS) -DWILDMIDI_BUILD
 CFLAGS_EXE= $(CFLAGS)
 
-OBJ=wm_error.o file_io.o lock.o wildmidi_lib.o reverb.o gus_pat.o f_xmidi.o f_mus.o f_hmp.o f_midi.o f_hmi.o mus2mid.o xmi2mid.o internal_midi.o patches.o sample.o sf2.o
+OBJ=wm_error.o file_io.o lock.o wildmidi_lib.o reverb.o gus_pat.o f_xmidi.o f_mus.o f_hmp.o f_midi.o f_hmi.o mus2mid.o xmi2mid.o internal_midi.o patches.o sample.o sf2.o synth.o
 PLAYER_OBJ=wm_tty.o msleep.o getopt_long.o out_none.o out_wave.o out_dart.o wildmidi.o
 
 all: $(LIBSTATIC) $(PLAYER_STATIC)

src/CMakeLists.txt

@@ -14,6 +14,7 @@ SET(wildmidi_library_SRCS
     f_midi.c
     f_hmi.c
     sample.c
+    synth.c
     sf2.c
     mus2mid.c
     xmi2mid.c
@@ -34,6 +35,7 @@ SET(wildmidi_library_HDRS
  ../include/internal_midi.h
  ../include/patches.h
  ../include/sample.h
+ ../include/synth.h
  ../include/sf2.h
  ../include/common.h
  ../include/filenames.h

src/player/wildmidi.c

@@ -264,6 +264,7 @@ static struct option const long_options[] = {
     { "textaslyric", 0, NULL, 'a' },
     { "playfrom", 1, NULL, 'i'},
     { "playto", 1, NULL, 'j'},
+    { "emergency", 0, NULL, 'E' },
     { NULL, 0, NULL, 0 }
 };
 
@@ -300,6 +301,7 @@ static void do_help(void) {
     printf("  -r N  --rate=N      Set sample rate to N samples per second (Hz)\n");
     printf("  -c P  --config=P    Point to your wildmidi.cfg config file name/path\n");
     printf("                      defaults to: %s\n", WILDMIDI_CFG);
+    printf("  -E    --emergency   Use built-in synthesised soundbank (no cfg/sf2 needed)\n");
     printf("  -m V  --mastervol=V Set the master volume (0..127), default is 100\n");
     printf("  -b    --reverb      Enable final output reverb engine\n\n");
 }
@@ -382,7 +384,7 @@ int main(int argc, char **argv) {
 
     do_version();
     while (1) {
-        i = getopt_long(argc, argv, "0vho:tx:g:P:f:lr:c:m:btak:p:ed:nsi:j:", long_options,
+        i = getopt_long(argc, argv, "0vho:tx:g:P:f:lr:c:m:btak:p:ed:nsi:j:E", long_options,
                 &option_index);
         if (i == -1)
             break;
@@ -495,6 +497,10 @@ int main(int argc, char **argv) {
         case 'j':
             play_to = (unsigned long int)(atof(optarg) * (double)rate);
             break;
+        case 'E': /* Emergency built-in soundbank */
+            strncpy(config_file, "@emergency", sizeof(config_file));
+            config_file[sizeof(config_file) - 1] = 0;
+            break;
         default:
             do_syntax();
             return (1);