bg-musiclisted

# bg-music Background music makes a podcast clip feel like a TikTok, not a recording. This skill picks a random mp3 from the local `./songs/` library, loops it to match the clip's length, and mixes it under the speaker with a hard volume attenuation. No ducking sidechain — the bed is just quiet enough to live underneath broadcast-leveled speech. ## Invoke ``` .claude/skills/bg-music/bg-music.sh <input> <out> [category=ALL SONGS] [volume=0.17] [fade=0.6] ``` - `input` — finished, loudnorm'd mp4 - `out` — output mp4 with music mixed in - `category` — subfolder of `./songs/` to pick from (e.g. `Energetic`, `Story`, `Inspiring`). Defaults to `ALL SONGS`, which recurses across every mood folder under `./songs/`. - `volume` — linear gain for the bg track, default `0.17`. Lower for more speech-forward clips. - `fade` — seconds of fade-in so the bed ramps up instead of blasting at `t=0` (it would otherwise be exposed under the speech-free title card). Default `0.6`. ## How - Picks a random `.mp3`/`.MP3`/`.wav` from `$SHORTS_ROOT/songs/<category>/`. - Loops it with `-stream_loop -1` so any track length covers the clip. - `amix` with `duration=first` so output matches the video duration exactly. - Bg volume hard-set; output limited with `alimiter=limit=0.97` to avoid clip. - Video is stream-copied. ## Caveats - Re-encodes audio only. - Idempotent via `<out>.bgmeta` (input mtime + category + volume + fade + chosen track basename). - The chosen track is logged to stderr so you ca