I have over 100 MKVs and I'm converting them to M4V using Subler. I got a couple of problems though. 1. When a video's got more than one audio track, after the conversion my Apple TV3 will play all audio tracks at the same time. I need to hold down the Select button on my Apple TV and chose a track in order to just listen to that one. How can I fix this? 2. I've seen all these movies several times, so I know they are perfectly fine. But when converting the file (I convert the DTS or AC3 audio to AAC) some audio tracks seem to acquire some delay. It's pretty weird and random, can't really tell what's causing this. Any ideas on how to fix it? All I can think of is keep going and at the end just find out how much delay each track has and then correct it with the offset setting, but of corse if you guys know of a simpler solution I'd thank you eternally. Thanks! P.S: What is the Optimize option exactly?