User selects preset -> API call -> Audio generation (FFmpeg + sox or cloud audio processor) -> Return download URL

"slowed_percent": 30, "reverb_type": "cathedral", "duration_sec": 20

Feature Name: Moon Rise Slowed Reverb Ringtone Tagline: “Wake up to the celestial calm of a moonrise — stretched, softened, and reverberated.”

"job_id": "abc123", "preview_url": "https://cdn.../preview.mp3", "download_url": "https://cdn.../ringtone.m4r", "expires_in": 3600

ffmpeg -i moonrise_original.wav -filter_complex "[0:a]atempo=0.75,aresample=44100,aecho=0.8:0.9:200:0.5[a]" -map "[a]" output_slowed_reverb.mp3 (Better to use sox or rubberband for high-quality slowing + freeverb for reverb)