Demuxed AC3 Track Out of Sync After Muxing

[Shinji-kun]

In DGIndex I exported a project file using the audio option to demux all streams. The info in the AC3 file's title said "delay 0 ms". However when I mux the AC3 track with the video in MKVMergeGUI the audio is noticeably out of sync. I tried using the audio option "demux AC3 to WAV" (as I heard that demuxing to WAV actually applies the delay specified in the title) and saving the .d2v file again but I did not even get a WAV file in the location were the d2v was saved. I tried using BeLight to transcode the AC3 file to vorbis and aac but still got the same audio/video sync issues when I played the muxed MKV.

So how can I:

- Make DgIndex actually decode the audio track to WAV when saving the d2v?

- Fix the audio sync in some other way?

Note: The video file is NOT VFR.

[Usedocne]

Try seeing if MediaInfo can spot an audio delay. Or maybe try opening your video in either Avidemux or VirtualDub, then saving your audio as WAV, and see if that bypasses any delay.

[Shinji-kun]

I'd rather not do that unless nothing else works. Why isn't DGIndex just demuxing the AC3 to WAV in the first place?

[7ekno]

Cell blanking copy protection?

7

[Hagbard23]

Shinji - you're thinking too complex. This is just "every-day business". Try to check the delay in some Video-Front End like Virtual Dub and stor it with the correct delay value.

Do not recode it to wav first and such crap - that's far to complex.

I've had 100eds of DVDs where the DGIndex reported delay was wrong, and i had to set it manually inside Virtual Dub. The only thing which was reporting delay relatively sure was "Media Info". But you never can rely on that.

€dit: Okay - not 100eds...probably a dozen or more are correct ;) ...

[Shinji-kun]

I opened the VOB in vdub and exported the audio as WAV and got the same problem. There was no delay info for the audio under "file Information" either. Can someone just describe exactly how to demux the audio stream to WAV in DGIndex? Or maybe suggest a better option than all the others.

[Usedocne]

I had a similar problem a few years back. Turned out to be caused by a bad rip. Video length was shorter than the audio length, because of corrupt video frames being dropped (not decoded).

[Inspector.Gadget]

DGIndex is RARELY wrong about audio delay. Odds are you have either a bad rip or an initial cell made up of black frames - what happens if you make your project after moving the left-hand timeline marker in DGIndex to the first frame with movie content?

[manono]

DGIndex is RARELY wrong about audio delay. Odds are you have either a bad rip or an initial cell made up of black frames - what happens if you make your project after moving the left-hand timeline marker in DGIndex to the first frame with movie content?
Bingo. Blame an improper decrypt rather than DGIndex.

- Fix the audio sync in some other way?
Figure out the amount of the delay and get rid of it entirely using DelayCut.

[Shinji-kun]

Yes there is a few seconds of black before the intro. What about decoding to WAV with DGIndex? Will this not fix the delay from the start?

[Inspector.Gadget]

Not necessarily, because DGIndex is sometimes unable to calculate accurate delay in such a case (consider neuron2's past responses when asked about wild delay values). Use the trim method I described above, and learn about it in more detail from the DGIndex manual.