app.py

import gradio as gr
import numpy as np
import librosa
import soundfile as sf
from pedalboard import Pedalboard, Reverb, Gain

def slow_reverb(audio, speed=0.8, reverb_mix=0.5, decay=3.0, pre_delay=0.0, damping=0.5):
    # Load audio
    y, sr = librosa.load(audio, sr=None, mono=True)
    
    # Slow down
    y_slow = librosa.effects.time_stretch(y, rate=speed)
    
    # Apply reverb using Pedalboard
    board = Pedalboard([
        Reverb(
            room_size=decay/10,  # Convert seconds to 0-1 scale (0.3 for decay=3.0)
            wet_level=reverb_mix,
            dry_level=1-reverb_mix,
            damping=damping
        )
    ])
    
    # Process audio
    y_reverb = board(y_slow, sr)
    
    # Save to temp file for Gradio
    sf.write("output.wav", y_reverb, sr)
    return "output.wav"

iface = gr.Interface(
    fn=slow_reverb,
    inputs=[
        gr.Audio(type="filepath", label="Input Audio"),
        gr.Slider(0.5, 1.0, value=0.8, label="Playback Speed"),
        gr.Slider(0, 1, value=0.5, label="Reverb Mix"),
        gr.Slider(0.1, 10.0, value=3.0, label="Decay Time (s)"),
        gr.Slider(0.0, 0.2, value=0.0, label="Pre-delay (s)"),  # Still shown but unused
        gr.Slider(0.0, 1.0, value=0.5, label="Damping (high-frequency roll-off)")
    ],
    outputs=gr.Audio(type="filepath", label="Processed Audio"),
    title="Slow + Reverb Audio Processor",
    description="Upload an audio file and control slow-down and reverb parameters. Note: Pre-delay is currently not implemented.",
    live=False
)

if __name__ == "__main__":
    iface.launch()