I need offset (some silence) in the start of file, so I tried:
./ffmpeg -itsoffset 100 -i 3.mp3 offset_test.mp3
But it doesn't work.
How to add offset to audio file with ffmpeg?
For formats without timestamps, you'll need to add silence, as @Brad mentioned.
ffmpeg -i 3.mp3 -af adelay=100000|100000 delayed.mp3
The adelay takes delay in milliseconds per channel, separated by |
.