ferraus concat

Join files end to end, optionally with crossfades or gaps

Synopsis

ferraus concat <inputs...> [options] [-o <output>]

Joins the inputs in the order given. --crossfade overlaps the end of each file with the start of the next (each overlap shortens the result by the crossfade length); --gap inserts silence instead. With --match on (the default) every input is resampled and remixed to the first file's sample rate and channel count.

Examples

Join three files back to back

ferraus concat intro.wav body.wav outro.wav -o episode.wav

DJ-style 3-second equal-power crossfade; b.mp3 is converted to a.flac's format

ferraus concat a.flac b.mp3 --crossfade 3s -o mix.flac

Join every take with a second of silence between them

ferraus concat take*.wav --gap 1s -o all_takes.wav

Options

Flag	Type	Default	Meaning
`--crossfade`	time	`0ms`	Overlap (duration) between consecutive files, e.g. 2s
`--crossfade-curve`	equal-power \| linear	`equal-power`	Crossfade shape: equal-power keeps perceived loudness constant through the overlap
`--gap`	time	`0ms`	Silence (duration) inserted between files
`--match`	on\|off	`on`	Resample and remix inputs to the first file's sample rate and channels; off fails on a mismatch

Global options

Every command also accepts the global options (-o, --json, --dry-run, --overwrite, --progress, ...). See Global options.

Exit codes

Code	Meaning
0	Success
1	Processing failed
2	Usage or parameter error
3	Input missing or unreadable
4	Unsupported format or codec
8	Cancelled
70	Internal error (bug)

Common mistakes

Forgetting that outputs are never overwritten: pass --overwrite or a new -o path when re-running.
Beat-based times (4b, 1/4) need a tempo: pass --bpm or write 4b@120.

For models

MCP tool: ferraus_concat
Schema: ferraus schema concat
Pipeline: { op: concat, args: { ... } } (flag names with _ instead of -)
fx stage: no

{"command": "concat", "defaults": {"crossfade": "0ms", "crossfade_curve": "equal-power", "gap": "0ms", "match": "on"}}