Problem with out of sync audio

[Dannyboy1985]

Hi guys I have an mkv and it's audio is in sync. Whenever I use tsmuxer to make a bdmv folder or an iso the audio becomes out of sync with the video by a few seconds. Don't known what I'm doing wrong because I've already successfully done about 5 other mkv this way to blu Ray with no sync issues . Thanks.

[Budman1]

There are several reasons, including the type of converter you use, that can alter the sync. Hopefully you just alter the sync during muxing if you can. First you should look at the failed MKV and make sure you do not see any offset in the audio which players use to display correctly but which may not be translated during conversion:


I'm not famliar with TSmuxer much so maybe others can add more help in this area.

[Dannyboy1985]

Ok so you are saying that even tho the mkv plays flawlessly I should check there is no delay in it that the software might be correcting while playing . How do I look at that info you posted for my mkv? Sorry. I just assumed it was after conversion or during that a problem occurred.

[Dannyboy1985]

Sorry for the double post but I think I need mkvtoolnix is that right? Can anyone else she'd some light please. Thanks .

[hello_hello]

Check the MKV for a negative audio delay with MediaInfo (a per Budman1's example). There's no such thing as a negative delay for MKVs so a negative audio delay means there's really a positive video delay. I'd recommend opening the MKV with gMKVExtractGUI, now I think about it. It requires MKVToolnix. You don't have to extract anything, but gMKVExtractGUI will show you both the audio and video delay, which might indicate that's the problem. When it extracts, gMKVExtractGUI assumes there's no video delay so it adjusts the audio delay compensate before writing the delay to the file name.
ie if the audio stream has a 50ms delay and the video stream has a 75ms delay, gMKVExtract will assume the audio delay is only 25ms when it extracts it. I'm sure it shows that delay too in the GUI (ie 25ms for my example), so there's no need to extract the audio to work it out.

Not that I'd have thought any of it should be an issue when remuxing with TSMuxer, but I don't create Bluray compliant files so I wouldn't know. You could remux the MKV with MKVToolNix as another MKV and it wouldn't change the audio sync unless you tell it to.
Even if there's no logical reason for the delay.... and sometimes there doesn't seem to be a reason..... you should be able to open the output with a MediaPlayer, adjust the audio sync until it's right, then use the same delay for the audio when remuxing with TSMuxer. If you don't have a player that'll play the contents of Bluray folders, try remuxing as a TS file for testing. If you open a file with MPC-HC, you can adjust the audio delay while it's playing with the "-" and "+" keys on the numeric keypad. The delay being applied should be shown in MPC-HC's status bar as you adjust it.

Once you think it's about right, you can open the MKV in one player and the TS file in MPC-HC while adjusting the audio. Play the video in both players. The idea is to sync the video so that scene changes are happening at the same time in each player. I can be a bit fiddly to get them to line up sometimes..... you need to be able to stop and resume playback pretty quickly in order to line up the two video... which can take a few attempts to get right. When the videos are synced, adjust the audio delay in MPC-HC. When the two audio streams are in sync they'll sound odd. It's almost impossible to get the perfectly in sync but when it's quite close, to within 10ms or so, you should hear a "phasing" sound. With the videos synced and the audio streams "phasing" you'll know the audio and video sync for each is the same and you can apply the audio delay MPC-HC displays when muxing.
That last parts really only if you're quite fussy. You should be able to work out the required audio delay by adjusting it while you watch the video, but there'll probably be a larger margin of error.

[Dannyboy1985]

Ok heres a screen of gmkv i took and as far as my meagre skills can see every aspect has a 0ms delay.

[hello_hello]

Try setting an appropriate audio delay in TSMuxer when you remux. It can be positive or negative, depending on the direction you need to shift it. If that solves the problem it'll be easier than spending a lot of time trying to work out the cause first, because you're probably still going to have to fix the sync by applying a delay anyway.

Hopefully doing so will sync it again from start to finish. If you can sync the audio at the beginning by applying a delay, but it wanders out slightly as the video progresses..... well..... one problem at a time.....

[Dannyboy1985]

Try setting an appropriate audio delay in TSMuxer when you remux. It can be positive or negative, depending on the direction you need to shift it. If that solves the problem it'll be easier than spending a lot of time trying to work out the cause first, because you're probably still going to have to fix the sync by applying a delay anyway.

Hopefully doing so will sync it again from start to finish. If you can sync the audio at the beginning by applying a delay, but it wanders out slightly as the video progresses..... well..... one problem at a time.....

Thanks man I'll give it a shot tomorrow and report back.