app.py

"""
Hugging Face Space entry point for SoulX-Singer.
Downloads pretrained models from the Hub if needed, then launches the Gradio app.
"""
import os
import sys
from pathlib import Path

# Set matplotlib backend before any imports that might use it (required for headless environments)
import matplotlib
matplotlib.use('Agg')  # Use non-interactive backend

# Import spaces for ZeroGPU support (if available)
try:
    import spaces
except ImportError:
    # spaces module not available (not running on HF Spaces or not ZeroGPU)
    spaces = None

ROOT = Path(__file__).resolve().parent
PRETRAINED_DIR = ROOT / "pretrained_models"
MODEL_DIR_SVS = PRETRAINED_DIR / "SoulX-Singer"
MODEL_DIR_PREPROCESS = PRETRAINED_DIR / "SoulX-Singer-Preprocess"


def ensure_pretrained_models():
    """Download SoulX-Singer and Preprocess models from Hugging Face Hub if not present."""
    if (MODEL_DIR_SVS / "model.pt").exists() and MODEL_DIR_PREPROCESS.exists():
        print("Pretrained models already present, skipping download.", flush=True)
        return

    try:
        from huggingface_hub import snapshot_download
    except ImportError:
        print(
            "huggingface_hub not installed. Install with: pip install huggingface_hub",
            file=sys.stderr,
            flush=True,
        )
        raise

    PRETRAINED_DIR.mkdir(parents=True, exist_ok=True)

    if not (MODEL_DIR_SVS / "model.pt").exists():
        print("Downloading SoulX-Singer model...", flush=True)
        snapshot_download(
            repo_id="Soul-AILab/SoulX-Singer",
            local_dir=str(MODEL_DIR_SVS),
            local_dir_use_symlinks=False,
        )
        print("SoulX-Singer model ready.", flush=True)

    if not MODEL_DIR_PREPROCESS.exists():
        print("Downloading SoulX-Singer-Preprocess models...", flush=True)
        snapshot_download(
            repo_id="Soul-AILab/SoulX-Singer-Preprocess",
            local_dir=str(MODEL_DIR_PREPROCESS),
            local_dir_use_symlinks=False,
        )
        print("SoulX-Singer-Preprocess models ready.", flush=True)


@spaces.GPU() if spaces is not None else lambda f: f
def initialize_gpu():
    """Initialize GPU for ZeroGPU. This function must be called at startup."""
    # This function is called at startup to initialize ZeroGPU
    # The actual model loading happens lazily in webui.py
    import torch
    if torch.cuda.is_available():
        print(f"GPU initialized: {torch.cuda.get_device_name(0)}", flush=True)
    else:
        print("GPU not available, using CPU", flush=True)
    return True


if __name__ == "__main__":
    os.chdir(ROOT)
    ensure_pretrained_models()

    # Initialize GPU for ZeroGPU (must be called before importing webui)
    if spaces is not None:
        initialize_gpu()

    from webui import render_interface

    page = render_interface()
    page.queue()
    page.launch(
        server_name="0.0.0.0",
        server_port=int(os.environ.get("PORT", "7860")),
    )