How to convert AC3 to Flac and apply a delay?

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http://askubuntu.com – I have a MKV video file. The audio track is ac3. I extracted the AC3 and now want to convert it to Flac. But I need to add a delay/offset of 150ms. The offset should be permanent; the actual duration of the resulting Flac should be 150ms longer than the Ac3 input. What is the command line to do this? Thank you in advance. (HowTos)