URN Save Audio with Lyrics

ComfyUI's core Save Audio writes a file and forgets everything about it. Which is fine right up until the moment you generate a song with lyrics you spent an hour on and the only record of those lyrics is a text widget in a workflow JSON you'll never open again.

URN Save Audio with Lyrics writes FLAC or MP3 with the lyrics, artist, title and album embedded in the file's real metadata - the same fields any player, tagger or DJ app can read. It's the other half of the round-trip with URN Load Audio.

How it works

FLAC is written losslessly via soundfile. MP3 is encoded by calling ffmpeg as a subprocess at 320 kbps with libmp3lame - meaning ffmpeg has to be on PATH, and the node raises a clear error if it isn't rather than writing a broken file.

Then the metadata goes in with mutagen, and the mapping is worth knowing because it's what makes the round-trip work:

• MP3 - lyrics to ID3 USLT, artist to TPE1, title to TIT2, album to TALB, written as ID3v2.3 for broad player compatibility.
• FLAC - lyrics to the Vorbis Comment LYRICS field, artist/title/album to the matching Vorbis Comments.

The node is an output node, so it runs on every queued workflow rather than being satisfied from cache - that's deliberate, since a save node that silently skips is worse than a slow one.

Inputs and outputs

• audio - the AUDIO you want written. Loader, trim, mixer, whatever.
• lyrics - required STRING. This is the point of the node; connect Transcript_Out from URN Audio Lyrics, or an accepted URN Text Edit string.
• format - flac (default) or mp3.
• save_location - a relative folder created under ComfyUI/output/ (the default is audio, and music/finished works the way you'd hope), or an absolute path like D:\Music\Exports.
• filename - the base name, user-controlled. The extension for the selected format is appended automatically, and if you type an extension yourself it gets replaced to match format.
• artist, title, album - optional strings, wired from URN Load Audio or URN Audio Lyrics.

Outputs are audio (passthrough, so you can keep going in the graph) and saved_path - the full path of what was written, returned newline-separated when a batch produced several files.

Install

cd ComfyUI/custom_nodes
git clone https://github.com/Clivey1234/Comfyui_URN_AudioTools

Then either run install.bat on Windows, or install the pack's requirements.txt with ComfyUI's Python environment - this node needs soundfile and mutagen, and MP3 export additionally needs ffmpeg available on PATH. FLAC export works without ffmpeg; that's your fallback if you're on a box where you can't install it.

ComfyUI Manager: search Comfyui_URN_AudioTools.

Common issues

MP3 export fails with an ffmpeg error. ffmpeg isn't on PATH as far as ComfyUI's process can see it. Either install it or switch format to flac - FLAC is lossless anyway, and the lyrics embed just as well.

Every file is called audio.flac. You left the filename widget at its default. It's a text box, not a prefix pattern - and the pack removed the old behaviour of copying the source filename, so nothing is auto-named for you any more. Type a name, or drive it from a string node.

A batch overwrote itself. A single audio payload with a batch of waveforms produces name.flac, name_001.flac, name_002.flac and so on, so that's handled. Two separate queue runs with the same filename will happily overwrite each other though - nothing warns you.

The lyrics look wrong when a player shows them. Some players only read synced (timed) lyrics and ignore the plain USLT frame. The lyrics are in the file; the player is being fussy. Check with a tag editor, or load the file back with URN Load Audio and read Embedded_Lyrics.