OptionalstartOptionalendEnd time: seconds or 'HH:MM:SS[.mmm]'
OptionaldurationDuration from start (alternative to end)
OptionalcopyWhen true (default): stream-copy — instant, no quality loss, may be off by a keyframe. When false: re-encode with libx264/aac — frame-accurate but slower.
OptionalvideoOptionalaudioOptionalbinary
Start time: seconds or 'HH:MM:SS[.mmm]'