DTS to AC3 audio conversion (using MP4Tools on a Mac) issue/problem

[SimonSimon]

Hi guys,

Forgive my ignorance but any help/advice would be appreciated.

I have an MKV file with DTS (6 channel) audio that I want to convert to MP4/M4V with AC3 5.1 audio (as well as an AAC stereo track for devices that can't do surround sound) so it will play on Apple TV 2.

I used the software MP4Tools (previously known as MKVTools) (which is a Mac only app, I believe) to successfully pass through the video into an MP4 container and (seemingly) successfully convert the DTS to AC3.

But when I play the resulting file in Quicktime (the current version as well as Quicktime 7) the converted AC3 5.1 audio has intense static/hissing/crackling/popping (i dont know the correct term).

And when I play the file in iTunes/Apple TV it simply greys out or does not allow me to switch from the stereo audio (which works fine) to the converted AC3 5.1 audio.

This leads me to believe that the audio conversion was not very successful! Yet, when I play the file in VLC both audio streams (including the converted AC3 5.1) seem to play fine.

Any advice?

Is there another Mac app I could try to convert the audio more successfully? Or something technical I don't know about?

Thanks in advance!

[SimonSimon]

Okay, just in case there's another dumbass like me out there who reads this and has the same "problem".

There was actually no problem with the conversion after all.

On my Apple TV 2 I had NOT turned on Dolby in the Audio settings. Since doing that I can select the AC3 audio when the movie is playing. And everything works perfectly.

It's still greyed out (un-selectable) in iTunes, which actually makes sense because my computer is not connected to my surround sound system anyway. The reason I was confused by this is because I remember being able to select the 5.1 audio in iTunes on other video files in the past and it would play the audio fine in stereo, just a little bit quieter in volume than the standard stereo track. But now I'm guessing that an update to iTunes means the option is now greyed out. Which, as I said, makes sense anyway.

As for Quicktime, I'm sure there's a technical explanation for why the audio is horribly distorted when the AC3 5.1 track is selected. I don't know what that explanation is but this isn't important to me either, as I only tried it in Quicktime to test out the success of my file before trying on Apple TV 2.

Anyway, the AC3 5.1 audio works on my Apple TV 2, and that's all I ever wanted. Full marks to MP4Tools

Apologises if I wasted anyone's time