mkv -> m4v with AC3 soundtrack problem

[jamesmac]

Hi,

I'm trying to convert an MKV file that contains an AC3 soundtrack to an m4v with the same soundtrack. I've confirmed that the source soundtrack is fine and is decoded correctly by my amp. I've been able to convert many DVD's using Handbrake to m4v that contain the AC3 track, so I know it can work.

I've used the following settings:

- MP4 H264 setting for the output
- Video Codec H264 - (tried ffmpeg & x264)
- Audio Codec - tried both .AC3 and passthrough

The problem is that the resulting file only contains an ACC stereo soundtrack.

I read somewhere that an MP4 file shouldn't contain an AC3 soundtrack. Is this the reason I'm having trouble? If it is, is there a way for FFMPEGx to create an M4V file with the AC3 track?

I want to be able to do this so I can use Front Row. My iMac is set up with Quicktime 7.4.5 and Perian and so this all works really well. MKV's are a bit painful for Front Row...

Thanks for any suggestions!

James

[Case]

I read somewhere that an MP4 file shouldn't contain an AC3 soundtrack. Is this the reason I'm having trouble? If it is, is there a way for FFMPEGx to create an M4V file with the AC3 track?

As the HandBrake guide will tell you, it is highly non-standard to put an AC3 stream in an .mp4 container. That is why ffmpegX forces AAC audio for .mp4. The current version of ffmpegX won't allow AC3 in .mp4. Besides HandBrake, there is also VisualHub that knows the trick, and the latter should take MKV as input.

[jamesmac]

Thanks - I actually read about the .mp4/ac3 thing on the Perian website. I managed to find (thanks to gbooker from Perian!) a really easy way around the issue. I open the .mkv in Quicktime Player, let it load, then choose File > Save as... and save the .mkv as a .mov file. The .mkv container is stripped away replaced with a .mov - no transcoding required! The result is a Front Row friendly .mov file that plays the ac3 soundtrack perfectly. Very cool.

James