ComfyUI Extension: Save MP3

Save MP3 node for ComfyUI

<img width="366" height="245" alt="image" src="https://github.com/user-attachments/assets/6fdae56c-6f65-4581-8af8-1b9e15d5b892" />

Simple, flexible MP3 saver with bitrate options and handy path/filename templates.

Features

• Audio input: accepts common formats used by audio nodes
• File path: ComfyUI output subfolder or absolute path (any drive)
• Filename prefix
• Bitrate mode: variable, constant, average
• Quality: low, medium, high (mapped per mode)
• Outputs: AUDIO and STRING (bitrate info summary), output node compatible (can terminate a graph)

Installation

1. Go to the custom_nodes/ directory in ComfyUI.
2. Clone or copy the comfyui-save-mp3 folder:

   git clone https://github.com/Dehypnotic/comfyui-save-mp3.git
   

3. Restart ComfyUI.

Optional backends (no system install required)

• Auto-download ffmpeg: pip install imageio-ffmpeg (first run caches a static ffmpeg)
• Drop-in ffmpeg: place ffmpeg/ffmpeg.exe in a bin/ folder next to the node
• Or install lameenc: pip install lameenc

Backend preference: uses ffmpeg when available; otherwise falls back to lameenc.

Bitrate/quality mapping

• Variable (VBR): high → -q:a 0 (~245 kbps), medium → -q:a 4 (~165 kbps), low → -q:a 7 (~100 kbps)
• Constant (CBR): high → 320k, medium → 192k, low → 128k
• Average (ABR): high → 256k, medium → 192k, low → 160k (uses -abr 1)

Path and filename templates Placeholders supported in file_path and filename_prefix:

• [time(%Y-%m-%d)] → formatted time (strftime)
• [date] → YYYY-MM-DD
• [datetime] → YYYY-MM-DD_HH-MM-SS
• [unix] → epoch seconds
• [guid] / [uuid] → random UUID4 hex
• [model] → tries extra_pnginfo keys: model, checkpoint, ckpt_name, model_name; else unknown
• [env(NAME)] → environment variable NAME

Examples

• audio/[time(%Y-%m-%d)]
• runs/[model]/[datetime]
• D:/Exports/[env(USERNAME)]/[guid]

Security and external save paths (ComfyUI Manager compliant)

• By default, saving is allowed under ComfyUI’s output/ directory.
• To allow external locations (e.g., other drives), create a local JSON file next to this node named save_mp3_allowed_paths.json with:

  { "allowed_roots": ["D:/AudioExports", "E:/TeamShare/Audio"] }
  

Alternatively (advanced): you can set the environment variable SAVE_MP3_ALLOWED_PATHS to point to the JSON file. This is optional — for most users it’s enough to place the JSON file next to the node or in one of the global ComfyUI locations listed below.

• You can also place the file globally under your ComfyUI root:
  • <ComfyUI>/save_mp3_allowed_paths.json
  • <ComfyUI>/config/save_mp3_allowed_paths.json
  • <ComfyUI>/user/save_mp3_allowed_paths.json
  • <ComfyUI>/user/config/save_mp3_allowed_paths.json
• The node refuses writes outside output/ unless the path is under one of the whitelisted roots. Edit this file offline and restart ComfyUI.

Notes

• On Windows, prefer %H-%M-%S instead of %H:%M:%S in strftime patterns.
• If neither ffmpeg nor lameenc is available, the node raises a clear error with install hints.

Addendum: whitelist behavior and safety

• Recommended location for save_mp3_allowed_paths.json is under the ComfyUI root (e.g., ComfyUI/config/) so it survives node updates.
• Loader lookup order: env var → global ComfyUI locations → node folder.
• A node‑local file is used only if it defines at least one allowed root; empty example files are ignored.
• Lines starting with # are treated as comments in the JSON file.
• An allowed root permits saving in that folder and all subfolders; whitelist a deeper path to restrict more tightly.