Add Stable Audio 3 Small-SFX to sound effects tab, with model toggle and save-to-library

Runs entirely on CPU (no VRAM contention with ComfyUI), and sounds
noticeably better than MOSS-SoundEffect per listening test, so it is now
the default model. Toggle keeps MOSS-SoundEffect available as a fallback.
Saved clips land in the-service-station/sfx_library/ on disk, no db/
metadata system per explicit scope.

Co-Authored-By: Claude Sonnet 5 <[email protected]>

sfx-stable-audio-3/generate.py

@@ -0,0 +1,32 @@
+"""
+Stable Audio 3 Small-SFX CLI: generate a sound effect/ambience clip from a
+text description. Runs on CPU by design - this checkpoint is the
+"lightweight, no GPU required" model in Stable Audio 3's lineup, so it
+never contends with ComfyUI/other models for VRAM (unlike generate_sfx.py's
+MOSS-SoundEffect, which needs the 3090 and ComfyUI's memory freed first).
+"""
+
+import argparse
+
+import torchaudio
+from stable_audio_3 import StableAudioModel
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser(description="Stable Audio 3 Small-SFX text-to-sound-effect")
+    parser.add_argument("--text", required=True, help="Description of the sound effect/ambience")
+    parser.add_argument("--output", required=True, help="Output wav path")
+    parser.add_argument("--duration", type=float, default=10.0, help="Clip duration in seconds (max 120)")
+    parser.add_argument("--seed", type=int, default=-1, help="Random seed, or -1 for random")
+    args = parser.parse_args()
+
+    model = StableAudioModel.from_pretrained("small-sfx", device="cpu")
+    sample_rate = model.model.sample_rate
+
+    audio = model.generate(prompt=args.text, duration=args.duration, seed=args.seed)
+    torchaudio.save(args.output, audio[0].cpu(), sample_rate)
+    print(f"[INFO] Saved {args.output}")
+
+
+if __name__ == "__main__":
+    main()

webui/app.py

@@ -28,6 +28,7 @@ import glob
 import json
 import os
 import re
+import shutil
 import subprocess
 import tempfile
 import time
@@ -51,6 +52,16 @@ TTS_PYTHON = TTS_DIR / ".venv" / "bin" / "python3"
 TTS_GENERATE = TTS_DIR / "generate.py"
 TTS_GENERATE_SFX = TTS_DIR / "generate_sfx.py"
 
+# Stable Audio 3 Small-SFX - a separate isolated venv/repo, not the tts/ one.
+# Runs on CPU by design (the model's own "lightweight, no GPU" tier), so it
+# never needs ComfyUI's VRAM freed first, unlike MOSS-SoundEffect below.
+SFX_SA3_DIR = REPO_ROOT / "sfx-stable-audio-3"
+SFX_SA3_PYTHON = SFX_SA3_DIR / ".venv" / "bin" / "python3"
+SFX_SA3_GENERATE = SFX_SA3_DIR / "generate.py"
+
+SFX_MODEL_SA3 = "Stable Audio 3 (Small-SFX)"
+SFX_MODEL_MOSS = "MOSS-SoundEffect"
+
 MODEL_BASE = "Base (full quality)"
 MODEL_FLASH = "Flash (fast draft, 4-step)"
 
@@ -59,6 +70,10 @@ MODEL_FLASH = "Flash (fast draft, 4-step)"
 SERVICE_STATION_DIR = Path(os.environ.get("SERVICE_STATION_REPO", "/root/projects/the-service-station"))
 SS_VOICES_DIR = SERVICE_STATION_DIR / "voices"
 
+# Saved sound effects just live on disk here - no metadata/db, per Steve's
+# "just on disk FOR NOW is fine".
+SFX_LIBRARY_DIR = SERVICE_STATION_DIR / "sfx_library"
+
 WORKDIR = Path(tempfile.mkdtemp(prefix="audio-demo-webui-"))
 
 # AuK's Emotion task has exactly this vocabulary (vendor/AuK/docs/COOKBOOK.md
@@ -419,22 +434,37 @@ def generate_speech(reference: str, text: str, language: str):
     return str(out_path), transcript
 
 
-def generate_sound_effect(description: str):
+def generate_sound_effect(description: str, model_choice: str, duration: float):
-    """MOSS-SoundEffect - text-only ambience/SFX generation, no reference
+    """Text-only ambience/SFX generation, no reference audio or character
-    audio or character voice involved (different generation primitive from
+    voice involved (different generation primitive from the AuK/MOSS-TTS
-    the AuK/MOSS-TTS voice-cloning flow above, so it's a standalone section
+    voice-cloning flow above, so it's a standalone section rather than
-    rather than wired into that pipeline's history/reference state).
+    wired into that pipeline's history/reference state).
+    Two model backends: Stable Audio 3 Small-SFX (own venv, CPU-only, no
+    ComfyUI VRAM contention, `duration` matters) and MOSS-SoundEffect (tts/
+    venv, needs the GPU + ComfyUI's memory freed first, length is implicit
+    in its own generation rather than a parameter).
     No whisper verification here - there's no speech content to check."""
     if not description or not description.strip():
         raise gr.Error("Enter a description of the sound effect/ambience.")
 
-    _free_comfyui_memory()
     out_path = WORKDIR / f"sfx_{int(time.time())}.wav"
+
+    if model_choice == SFX_MODEL_SA3:
+        _run(
+            [
+                str(SFX_SA3_PYTHON), str(SFX_SA3_GENERATE),
+                "--text", description.strip(),
+                "--output", str(out_path),
+                "--duration", str(duration),
+            ],
+            cwd=SFX_SA3_DIR,
+        )
+    else:
+        _free_comfyui_memory()
         env = None
         if TTS_LD_LIBRARY_PATH:
             env = os.environ.copy()
             env["LD_LIBRARY_PATH"] = TTS_LD_LIBRARY_PATH
-
         _run(
             [str(TTS_PYTHON), str(TTS_GENERATE_SFX), "--text", description.strip(), "--output", str(out_path)],
             cwd=TTS_DIR,
@@ -443,6 +473,19 @@ def generate_sound_effect(description: str):
     return str(out_path)
 
 
+def save_sound_effect_to_library(audio_path: str, description: str) -> str:
+    """Copy the current clip into SFX_LIBRARY_DIR so it survives past
+    WORKDIR (a tempdir, wiped on restart). On-disk only, no metadata/db -
+    per Steve's "just on disk FOR NOW is fine"."""
+    if not audio_path:
+        raise gr.Error("Generate a sound effect first.")
+    SFX_LIBRARY_DIR.mkdir(parents=True, exist_ok=True)
+    slug = _slugify(description or "") or "sfx"
+    dest = SFX_LIBRARY_DIR / f"{slug}_{int(time.time())}.wav"
+    shutil.copy2(audio_path, dest)
+    return f"Saved to {dest}"
+
+
 # ---------------------------------------------------------------------------
 # Characters (the-service-station cast)
 # ---------------------------------------------------------------------------
@@ -846,11 +889,16 @@ with gr.Blocks(title="Audio-demo pipeline studio") as demo:
             )
         with gr.Tab("Sound Effects"):
             gr.Markdown(
-                "# Sound effects (MOSS-SoundEffect)\n"
+                "# Sound effects\n"
                 "Text-only ambience/SFX generation - a separate model from the "
                 "voice pipeline in Pipeline Studio, no reference audio or "
                 "character voice involved."
             )
+            sfx_model = gr.Radio(
+                choices=[SFX_MODEL_SA3, SFX_MODEL_MOSS],
+                value=SFX_MODEL_SA3,
+                label="Model",
+            )
             sfx_description = gr.Textbox(
                 label="Description",
                 placeholder=(
@@ -859,9 +907,25 @@ with gr.Blocks(title="Audio-demo pipeline studio") as demo:
                 ),
                 lines=2,
             )
+            sfx_duration = gr.Slider(
+                minimum=1, maximum=60, value=10, step=1,
+                label="Duration (seconds) - Stable Audio 3 only",
+            )
             sfx_btn = gr.Button("Generate sound effect", variant="primary")
             sfx_audio = gr.Audio(label="Generated sound effect", type="filepath")
-            sfx_btn.click(generate_sound_effect, inputs=[sfx_description], outputs=[sfx_audio])
+            with gr.Row():
+                sfx_save_btn = gr.Button("Save to library")
+                sfx_save_status = gr.Markdown()
+            sfx_btn.click(
+                generate_sound_effect,
+                inputs=[sfx_description, sfx_model, sfx_duration],
+                outputs=[sfx_audio],
+            )
+            sfx_save_btn.click(
+                save_sound_effect_to_library,
+                inputs=[sfx_audio, sfx_description],
+                outputs=[sfx_save_status],
+            )
 
         with gr.Tab("Characters"):
             gr.Markdown(