ffmpeg Timeline editing

Some filters support a generic enable option. For the filters supporting timeline editing, this option can be set to an expression which is evaluated before sending a frame to the filter. If the evaluation is non-zero, the filter will be enabled, otherwise the frame will be sent unchanged to the next filter in the filtergraph.

The expression accepts the following values:

‘t’
timestamp expressed in seconds, NAN if the input timestamp is unknown

‘n’
sequential number of the input frame, starting from 0

‘pos’
the position in the file of the input frame, NAN if unknown; deprecated, do not use

‘w’
‘h’
width and height of the input frame if video

Additionally, these filters support an enable command that can be used to re-define the expression.

Like any other filtering option, the enable option follows the same rules.

For example, to enable a blur filter (smartblur) from 10 seconds to 3 minutes, and a curves filter starting at 3 seconds:

smartblur = enable=‘between(t,10,3*60)’,
curves = enable=‘gte(t,3)’ : preset=cross_process
See ffmpeg -filters to view which filters have timeline support.