FFmpeg Document 33-timeline editing

33 Time Line editing

Some filters support the general enable options. For filters that support timeline editing, this option can be set to an expression that determines whether the frame is sent to the filter by evaluating the previous situation. If the expression evaluates to a value other than 0, the filter is used or the filter is skipped (that is, the frame is sent directly to the next filter in the filter chain)

The following values can appear in an expression:

• ' t '

  Timestamp, per second. If the input timestamp is unknownNAN

• N

  Enter the ordinal of the frame, counting from 0

• ' POS '

  Enter the offset position of the frame in the file, if unknownNAN

• ' W '

• ' H '

  Video input frame width and height

In addition, these filter enable option States can also be used for expressions.

Similar to other options, this enable option has the same rules.

For example, to allow a blur (blur) filter () in 10 seconds to 3 minutes smartblur , and then curves the filter after 3 seconds:

smartblur = enable=‘between(t,10,3*60)‘,curves    = enable=‘gte(t,3)‘ : preset=cross_process

FFmpeg Document 33-timeline editing