Howdy, In case anyone is interested, after a bit of a hiatus, I've had the time to return to working on an update for my application - MKVtools. The potentially biggest news for Apple TV users is that I was able to track down a much newer version of mp4box (actually two of them) with the following improvements: Muxing speeds should be improved. AC3 audio can now be muxed into mp4 files. This means that mkv files with avc video and ac3 audio can be converted to mp4 files in minutes with no loss in video quality. The resulting file only plays in VLC unless the extension is changed from .mp4 to .m4v in which case quicktime (w/ perian) and itunes will play the video. Hopefully, this means that the video will also play on Apple TV, however, since I don't have one in my possession, I can't test this, so your mileage may vary. You may have to fall back on AAC stereo encoding. Mp4box can now mux files larger than 2GB. I converted a 3GB HD mkv file to mp4 with video passthru and aac encoding in about 5 minutes on a macbook pro. The downside is that I could only track down an intel binary of mp4box with this capability so though MKVtools is still universal binary, this one feature is intel only, at least for now. If you want to give it a try, the newest beta can be found here. It's fully functional though you'll get an annoying nag screen and you can't queue jobs (sorry!). If you've already registered for older versions of MKVtools, your registration code will work for this version. I'm hoping for feedback regarding the playability of these files on an Apple TV. Also, if needed, MKVtools does some hex editing to change the video track's profile level to 4.1. MKVtools can do this for the most commonly encoded videos, but if you get a "hex not found error" that means that MKVtools couldn't find the hex string to edit. If that's the case, I'd like to hear about it to see if I can expand the profile levels that MKVtools can handle. Cheers and thanks in advance if you are able to supply feedback. P.S. I'm just starting to research the conversion of 5.1 AC3/DTS to 5.1 AAC so if anyone has links to any command line, open source audio tools that have been compiled as static builds for mac, let me know and I'll see if I can incorporate it into MKVtools. P.P.S. My apologies in advance if I don't respond to posts or e-mails promptly. Unfortunately, my other commitments limit my time to this project as sporadic at best, which is evidenced by an old thread I started which died a slow death :-(.