How to fix out of sync audio track?

[Bsmooth]

I'm putting all my blurays on hard drive. I'm older so I always use subtitles, but some of the vocal audio tracks are near impossible to hear. On the more quiet ones I am actually redoing the audio tracks using Audacity. Trouble is sometime and I don't know why yet it gets out of sync with the video.
The way I do it is; seperate the audio track using MkvToolInc, then adjust in Audacity. Put it back in by using MKVToolInc, and everything is usually fine.
I have found a workaround by watching the movie with VLCMedia Player and in tools there is a resync option where its adjustable. Then I find the amount usually in ms and then in Audacity, add or take away the amount of time and it usually works... after a few tries.
Would anyone have any idea what would cause the delay while I adjust in Audacity or with the add or remove option using MKVToolInc?
Its driving me crazy.

[cholla]

I believe you mean you use MKVtoolnix.
In it there is this setting you could try:
"Timestamps and default duration
Delay (in ms):"
You can use -(negative) also depending on which direction the "out of sync is".
This corrects the video sync as far as I can tell.
You can use VLC to determine the setting in ms.
In VLC use the hotkeys k & j for this.

Can I assume you are working with ,MKV files after using MKVtoolnix?
This is an unusual fix for some problems with .MKV files & it has fixed an out of sync problem sometimes.
I do not know why.
Multiplex the file as is with MKVtoolnix.
Then "Chapterize" the file with MKV-Chapterizer-v2.4.
Uncheck overwrite old files. That way you keep the old file as is.
And get a new file also.

[Bsmooth]

Sorry yes MKVtoolnix is correct. I tried that delay feature in it, but it just immediately goes to 100% finished without doing anything. Yes using MKV files. Weird problem indeed

[cholla]

I will have to give mkvtoolnix a try on an .mkv to see if it immediately goes to 100% finished without doing anything.
I have not use the delay feature much if any.

You could give the MKV-Chapterizer-v2.4 a try.
At worst it just won't help.

[Bsmooth]

What I would really like to do is find out why its happening in the first place.

[ProWo]

What I would really like to do is find out why its happening in the first place.

Use mediainfo to see the original delay. Note it and mux the new created audiostreams with the same delay.


[Attachment 88387 - Click to enlarge]

[cholla]

Use mediainfo to see the original delay. Note it and mux the new created audiostreams with the same delay.

What MediaInfo reports should be the "delay" already in the a/v file.
Some formats do not show this.
Audio can be either lead or lag so delay can be positive or negative.

I use both VLC & MPC-BE to check the audio or video sync.

[videoAI]

try clever FFmpeg-GUI

[Bsmooth]

I have mediainfo, didn't even think of that ! Great info I'll look into it and let you know. Does anyone else have the issue with soft vocals> Otherwise I wouldn't have this problem in the first place. I have to say they really do a lousy job with vocals in movies.
You'd think with those cool in the ear devices they have for bands and musicians, that they could come up with some better mics in movies. I realize they are different but they still both have audio in common.

[cholla]

A lot of movies have "soft vocals"(dialog).
They also seem to have much louder music that drowns out the dialog.
Some amps have a dialog setting where the dialog can be turned up.
This helps some but not as much as it should.

I did this short video using mkvtoolnix.
I added both audio lag & audio lead.
The original had already been synced with audio lead(negative delay).

[ProWo]

I have mediainfo, didn't even think of that ! Great info I'll look into it and let you know. Does anyone else have the issue with soft vocals> Otherwise I wouldn't have this problem in the first place. I have to say they really do a lousy job with vocals in movies.
You'd think with those cool in the ear devices they have for bands and musicians, that they could come up with some better mics in movies. I realize they are different but they still both have audio in common.

You can use clever FFmpeg-GUI.
Load your video, click main page, click encode audio stream.
Click on extra, then on volume detection.


[Attachment 88398 - Click to enlarge]

Wait until is finished.
You'll get a message of the gain found. Click OK.
On the left click on Audio filter.
On the top you see the found gain in dB.


[Attachment 88399 - Click to enlarge]

Remember the value and cancel the field.
Check the clevernorm filter and enter the remembered value. Click OK.
Select your encoder and the bitrate, then click encode.
If finished, click on multiplex.
The new created audiostream is shown in green. Deselect the old audiostream on the left; all other streams should be selected.


[Attachment 88400 - Click to enlarge]

Set your container and click multiplex. Done.
Listen at your new video and report, if the vocals are better for you.

[Bsmooth]

I've tried twice to get that program to work, with no luck, plus all the warnings I keep getting. Appreciate the help but no joy with Clever FFmpeg-GUI.

[hello_hello]

For the record, MediaInfo only reports an audio delay relative to the video. It doesn't tell you whether the video track also has a delay. For example, if the video track had a delay of 50ms, MediaInfo would report an audio delay of -50ms, assuming there's not also an audio delay.

To check for certain whether there's a video delay, you can open MKVs with gMKVExtractGUI.
Here's what it'd look like if the video track had a 41ms delay and the audio track had a 16ms delay. MediaInfo would report an audio delay of -25ms. That would also indicate there is a video delay, as MKV tracks can't have negative delays (applying one when muxing would cause MKVToolNix to truncate an appropriate amount from the beginning of the track instead).


[Attachment 88412 - Click to enlarge]

No video delay and a 16ms audio delay.


[Attachment 88413 - Click to enlarge]

[Bsmooth]

Thats the thing though. So far every single issue I have had problems with was a case where I needed to take away part of an audio track to fix the issue. Basically I go into Audacity and snip say .30 ms out and that fixes the problem. Its the cause I'm looking for. I think I might know what it is.
Since I don't use a surround system, a lot of blurays have a 5.1 audio track, which I am in Audacity changing to a two channel stereo track. That could be whats causing the delay, though I'm not sure.
I already use MKVToolNix, so I would also need to download gMKVExtractGUI, and this is a separate program?

[cholla]

Try keeping the track 5.1 when doing the snip with Audacity
The media player or other device you use to play should convert 5.1 to 2 track if that is what you have.

For the gMKVExtractGUI. I did not have it so I downloaded it.
It has "Auto locate" for the MKVtoolnix program.
I put the files in gMKVExtractGUI in the MKVToolnix folder & that also worked.

MKV tracks can't have negative delays (applying one when muxing would cause MKVToolNix to truncate an appropriate amount from the beginning of the track instead).

I checked the videos I posted in AVIDemux.(The delays were added with MKVtoolnix)
It did truncate from the beginning as you posted but added the same amount to the end.
I guess if the beginning is affected by this.
For example it cuts a really important scene. If not anything less than a second should not make much difference.
Even more so when MKVtoolnix keeps the correct length of the video,

[Bsmooth]

I'll try keeping the 5.1, and give that a go. I hope I get to see, and hear those results soon.

[hello_hello]

Thats the thing though. So far every single issue I have had problems with was a case where I needed to take away part of an audio track to fix the issue. Basically I go into Audacity and snip say .30 ms out and that fixes the problem

.30ms or 30ms?
Where do you need to remove it from? The beginning or somewhere else? Which codec are you using for the audio?

By the way, if MKVToolNix goes to 100% straight away without muxing, its probably because of an error. The delay (positive or negative) must be specified in ms, but only as an integer.

For example, this in the delay field would delay the selected track by negative half a second:
-500
While this would result in an error:
-500ms

[hello_hello]

cholla,

gMKVExtractGUI can be configured to write more than one delay to the output file name when extracting (by default it writes the delay relative to the video). Try clicking the Options button and changing the text in the audio track section to this:

{FilenameNoExt}_track{TrackNumber}_[{Language}]_ActualDelay_{Delay}_DELAY {EffectiveDelay}ms

When you use gMKVExtractGUI to extract the audio, the file name will look something like this (using your original sample, first renamed as Pity.mkv):

Pity_track2_[eng]_ActualDelay_0_DELAY -33ms.ac3

There's no audio delay, so the video must have a positive delay of 33ms. It can be handy to know, because if you re-encode the video it's delay will be lost, so you'd remux the audio with the encoded video using a -33ms audio delay.
If you don't re-encode or extract the video and simply add the new audio to the existing MKV, the video will still have a delay of 33ms, so you'd mux the replacement audio without applying any delay.

Having said all that though, for the example above I'd probably remux the original MKV first, while applying a -33ms delay to every stream, making the video delay zero. Then after the audio is extracted there can't be any ambiguity as to what the audio delay should be.

When you mux audio with MKVToolNix, it automatically applies the DELAY value in the file name by default, assuming there is one.

[Bsmooth]

Sorry 30 ms not .30. Always take it from the beginning. As far as audio codec, I think its AAC.

[cholla]

@ hello_hello,
I played around with the file as you suggested.
I believe you worked with the "Pity the Cowboy (lag positive delay).mkv " example instead of the "original"
I applied the -533 to only the Video track with mkvtoolnix.
Then extracted the Audio track with gMKVExtractGUI per you instructions.
Then I remuxed them with mkvtoolnix with a blank Delay.
There is an 11ms difference in the length of the video track & Audio track now but the sync is better.
This is the newly created file: