pad { length[@position(=)] }
Length is the amount of
silence to insert and position the position in the input audio
stream at which to insert it. Any number of lengths and positions
may be specified, provided that a specified position is
not less that the previous one, and any time specification may
be used for them. Position is optional for the first and last
lengths specified and if omitted correspond to the beginning and
the end of the audio respectively. For example,
pad 1.5 1.5 |
adds 1.5 seconds of silence padding at each end of the audio, whilst
pad 4000s@3:00 |
inserts 4000 samples of silence 3 minutes into the audio. If silence is wanted only at the end of the audio, specify either the end position or specify a zero-length pad at the start.
See also delay for an effect that can add silence at the beginning of the audio on a channel-by-channel basis.