app.py

import sys

sys.stdout.reconfigure(line_buffering=True)

try:
    import spaces
except ImportError:
    # keep @spaces.GPU usable as a no-op; ZeroGPU requires this exact name.
    class spaces:
        class GPU:
            def __init__(self, func=None, duration=60):
                self.func = func

            def __call__(self, *args, **kwargs):
                if self.func is not None:
                    return self.func(*args, **kwargs)
                func = args[0]
                return func

import threading

import audiotools
import gradio as gr
import torch
from pyharp import ModelCard, build_endpoint, save_audio

from audiocraft.data.audio_utils import normalize_audio
from audiocraft.models import MusicGen

DEVICE = "cuda" if torch.cuda.is_available() else "cpu"
CHECKPOINT_REPO = "Cyan0731/MusiConGen"

model = None
model_ready = False   # has model been moved onto the GPU yet?
model_loading = True
model_error = None


def load_model():
    """Download + construct on CPU only. ZeroGPU only intercepts CUDA calls 
    made inside @spaces.GPU decorated call."""
    global model, model_loading, model_error
    try:
        model = MusicGen.get_pretrained(CHECKPOINT_REPO, device="cpu")
        print("Model loaded (CPU).")
    except Exception as e:
        model_error = str(e)
        print(f"Load error: {e}")
    finally:
        model_loading = False


threading.Thread(target=load_model, daemon=True).start()


model_card = ModelCard(
    name="MusiConGen",
    description=(
        "Text-to-music generation with rhythm and chord control. Generates a "
        "music clip from a text description, a chord progression, and a "
        "tempo/time signature."
    ),
    author="Yun-Han Lan, Wen-Yi Hsiao, Hao-Chung Cheng, Yi-Hsuan Yang",
    tags=["music generation", "text-to-music"],
)


@spaces.GPU(duration=120)
@torch.inference_mode()
def process_fn(description, chords, bpm, meter, duration, conditioning_strength):
    """Generate a music clip conditioned on text, chords, and rhythm."""
    global model, model_ready
    if model_loading:
        raise gr.Error("Model is still loading, please wait a moment and try again.")
    if model is None:
        raise gr.Error(f"Model failed to load: {model_error}")
    if not model_ready:
        model = MusicGen.get_pretrained(CHECKPOINT_REPO, device=DEVICE)
        model_ready = True

    model.set_generation_params(
        duration=duration,
        extend_stride=duration // 2,
        cfg_coef=conditioning_strength,
    )
    wav = model.generate_with_chords_and_beats([description], [chords], [bpm], [meter])

    wav = normalize_audio(wav[0].cpu(), strategy="loudness", loudness_compressor=True, sample_rate=model.sample_rate)
    signal = audiotools.AudioSignal(wav, sample_rate=model.sample_rate)
    return save_audio(signal)


with gr.Blocks() as demo:
    input_components = [
        gr.Textbox(
            label="Description",
            value="A laid-back blues shuffle with a relaxed tempo, warm guitar tones, and a comfortable groove. Instruments: electric guitar, bass, drums.",
            info="Text description of the music to generate.",
        ),
        gr.Textbox(
            label="Chord Progression",
            value="C G A:min F",
            info="Space-separated chord symbols, one per bar, repeating to fill the duration (e.g. 'C G A:min F'). Syntax: root note plus optional ':quality', e.g. C, A:min, D:min7.",
        ),
        gr.Number(
            label="Tempo (BPM)", value=120, minimum=40, maximum=240,
            info="Tempo in beats per minute (default: 120, per repo demo script).",
        ),
        gr.Number(
            label="Time Signature (beats per bar)", value=4, minimum=2, maximum=12,
            info="Numerator of the time signature (default: 4, per repo demo script).",
        ),
        gr.Slider(
            minimum=5, maximum=30, step=1, value=30, label="Duration (seconds)",
            info="Length of the generated clip (default/max: 30s, the model's trained segment length, per repo config segment_duration=30).",
        ),
        gr.Slider(
            minimum=0.0, maximum=10.0, step=0.5, value=3.0, label="Conditioning Strength",
            info="How strongly generation follows the description/chords/rhythm vs. sounding more free (default: 3.0, per paper guidance scale γ).",
        ),
    ]
    output_components = [
        gr.Audio(type="filepath", label="Generated Music").set_info("Generated music, 32kHz."),
    ]

    build_endpoint(
        model_card=model_card,
        input_components=input_components,
        output_components=output_components,
        process_fn=process_fn,
    )

demo.queue().launch(pwa=True)