hi guys
I'm trying to add silence at the start of ac3 file, however I can't make it sync with video even though the time lenght is exactly the same with video (video also have 5 seconds header added to it by tmpgmpegeditor), but my five seconds audio added to it doesn't work, either tried by joining 5 second audio encoded same as original or five seconds delay using ac3delay.

please help me. thanks