Cutting middle of AC3 losslessly

[alleycat]

Hi all,

I'm trying to sync a DVD track to a webrip. The DVD contains three extra frames during once scene in the middle of the movie, what's the best way to cut the audio? 

I've tried Womble, which can usually do it losslessly but for some reason, even if I select a reference for the audio and match it, it still insists on re-encoding the entire audio file. 

I've also tried delaycut, but can only see the options of cutting the file at the beginning or end, not the middle. I'm using the latest version - do I have to make two files with delay cut (one before the cut and one after the cut) and then join them? 

Finally there is eac3to, however same problem, I'm fine with cutting the beginning and end of files, but can't see any way in the help guide to cut out the middle. 

I'm sure it's simple and I'm just having a moment!

Thanks

[deleted user]

Idk if there's a better way but yeah, I'd do it by doing two cuts. Beginning, and end, and join.

[zoidberg]

eac3to can definitely remove or loop audio within a track losslessly (ie no transcoding) using the -edit command. Obviously the frames of AC-3 are larger than other formats (32ms) so you will have to do some detective work to make sure you get the edit point and duration bang on

[pipefan413]

Aye, split it, chop it, join it back together again. This is what I was doing with stuff like Near Dark DVD audio. You can literally just concat the bits back together at the end if you want, since there's no global header, just the frame headers. Just make sure you're converting back and forth accurately, as @zoidberg says. 48 kHz DVD AC-3 is 1536 samples per frame so 1536/48000 = 0.032 sec => 32 ms.

You can, in fact, do the entire thing in a hex editor, if you're a masochist. (*Waves* hi)

[viktorlovisa]

Doing two cuts works.

[alleycat]

Sorry for the delay everyone, thanks to all who replied I did the two cuts and join option, all works fine. Cheers