How to fix a (specific) audio delay? (80ms over and over)

[Fañch]

Hi everyone,

Here's the issue I have for some time now:

I want to encode in mp4s DVDs I ripped, and all of them end up after the encoding process with a specific audio delay. Delay which I want to get rid of eventually.

Here's the steps I follow:

- I rip the DVD,
- I get the VIDEO_TS folder in which I find the .vob files I use for encoding,
- I encode using AVIDEMUX 2.5.6 (2-pass encoding, no delay option ticked, same output) ; H264/AAC codecs in a mp4 container,
- Checking the resulting file, MediaInfo reveals the following: "Delay relative to video: 80ms".

Should I tick the delay box and take off 80ms and encode again, it doesn't change the resulting delay anyway.

Looking back with MediaInfo at the different .vob files I have, most of them have a delay mentioned in the audio - like this one for instance:

VTS_02_1.VOB: no delay
VTS_02_2.VOB: -448ms
VTS_02_3.VOB: -560ms
VTS_02_4.VOB: -496ms

I'm not a specialist but I suppose this delay is somewhat normal as I tend to find it on most .vobs I get after ripping.

Should I encode from one single .vob only (with MediaInfo not mentioning any delay in the latter) or one single .mpeg made out of all .vob(s), 80ms delay is still appearing in the resulting file.

This situation makes me wonder if the issue is not coming from my own software. But I did try out other versions of Avidemux (2.5.6.0, 2.6.0, 2.6.1 - all three in both 32/64-bit - plus portable version) and it would either crash (the latest versions, presumably because of the 2-pass encoding) or end up with the mentioned delay.

This leads me to 2 questions:

- Does anyone know where this audio delay to video could come from? (the ripping? Some Avidemux's option not properly set? Some MediaInfo bug?? [which I doubt])

- Does anyone know how to fix this delay? (Should I edit the .vobs in some specific software or something? Or demux the audio, resynch it somewhere else before remuxing it in? That one sounds pretty painful if it must be done for every ripped file)

Thanks a bunch if you guys can help me see clearer on this matter.

P.S. I checked with PGCDemux, which finds "A/V Delay: none" in my .ifos.

Note that I do see a delay when playing the .mpeg or the .vob(s) in VLC, but I don't when playing it in AVIDEMUX.

Anybody knows what is going on ..??

Thank you

[Jan Gruuthuse]

Avidemux is not intended as player. It is more a quick and dirty guidance in to the video.

[Fañch]

Should your answer give me me any clue on how to solve the delay..?

[Jan Gruuthuse]

- no It did not provide a clue to solution. Try this:
Join vob manually in avidemux 2.5.6, answer no when avidemux asks to join for you. Use copy for both video and audio using mpeg-ps (a+v) and save as big with extension .vob
Now with avidemux 2.6.1 latest build: load the newly saved .vob video and re-encode to H264/AAC codecs with mp4v2 muxer.

[Fañch]

Join vob manually in avidemux 2.5.6, answer no when avidemux asks to join for you. Use copy for both video and audio using mpeg-ps (a+v) and save as big with extension .vob

There's two different audios in the DVD and when I join the vobs manually - ie. one after another - the audio tracks get mixed up between vobs, even when I specify which audio track I want to keep as main.
Thus I decided to use (again) VOB2MPG to change the vobs into a single mpg. I then get the audio track I want and MediaInfo doesn't show any delay anymore.

Now with avidemux 2.6.1 latest build: load the newly saved .vob video and re-encode to H264/AAC codecs with mp4v2 muxer.

Again an issue.
Using Avidemux 2.6.1 latest build (8321) 64-bit, and changing my file extension from .mpg to .vob, here's what I get:

-> 2-pass encoding impossible (H264 won't let me encode in 2 passes, while other codecs will).
-> 1-pass encoding : OK and the resulting file is synched (according to MediaInfo) and seems synched indeed in various players (except WMP).

N.B.: The "swith-off computer when job is done" option doesn't even work when ticked on this version.

I feel like it's too much of a pain to encode further on with Avidemux really. This audio delay bug was pointed out already back in 2007 (!) and it meant back then to re-synch the whole in VirtualDub (meaning another encoding process that lowens the quality): http://www.avidemux.org/smf/index.php?topic=2948.0

I can understand the problem when the DVD itself suffers from such a delay (though it's supposingly quite rare), but when it's coming from the encoder itself, that's just too bad.

Thanks Jan for your help anyway, appreciated.

[Fañch]

In case you encode in .mkvs, then MVKmerge fixes the audio delay just fine without any re-encoding process.
Perfie!