ferraus speed

Change speed and pitch together (varispeed)

Synopsis

ferraus speed <input> [options] [-o <output>]

What it does

Tape-style speed change: --factor 2.0 plays twice as fast, an octave higher, in half the time. Uses windowed-sinc resampling with automatic anti-aliasing. To change only duration or only pitch, use stretch or pitch.

This command is also an fx stage and a pipeline op: ferraus fx in.wav -o out.wav --fx "speed:key=value".

Examples

Faster and higher

ferraus speed loop.wav --factor 1.5 -o fast.wav

Half speed, an octave down

ferraus speed vox.wav --factor 0.5 -o slow.wav

One semitone up and about 6% faster, like tape running fast

ferraus speed song.wav --factor 1.0595 -o song_up.wav

Fix a 45 rpm record that was digitised at 33 1/3 rpm

ferraus speed vinyl_rip.wav --factor 1.35 -o fixed.wav

Options

Global options

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

Exit codes

Common mistakes

• Forgetting that outputs are never overwritten: pass --overwrite or a new -o path when re-running.

For models

• MCP tool: ferraus_speed
• Schema: ferraus schema speed
• Pipeline: { op: speed, args: { ... } } (flag names with _ instead of -)
• fx stage: yes

{"command": "speed", "defaults": {"factor": "1.0"}}