Speed multiplier. 2.0 = double speed, 0.5 = half speed. Video: 0.25–4.0 (setpts). Audio: 0.5–2.0 per atempo pass (chained for extremes).
Optional
Extra output options e.g. ['-preset', 'ultrafast']
Speed multiplier. 2.0 = double speed, 0.5 = half speed. Video: 0.25–4.0 (setpts). Audio: 0.5–2.0 per atempo pass (chained for extremes).