Audio sync issues.

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Bipolarbear
Posts: 23
Joined: Mon Oct 23, 2017 2:42 pm

Audio sync issues.

Post by Bipolarbear » Wed Jun 13, 2018 2:24 pm

This is a general question, not about any specific rip I've done. When you guys encounter a/V sync issues using "same as source" with CFR, what do you usually try first or what seems to work best for you in most cases? This only happens occasionally, probably less than 5% of the time, and frequently it's not the entire video, just sections of it. Sometimes just switching the container to MKV fixes it, for reasons I really don't understand. Sometimes I try doubling the frame rate, but I'm looking for some more informed suggestions. Thanks in advance.

mduell
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Re: Audio sync issues.

Post by mduell » Wed Jun 13, 2018 3:22 pm

First thing I do is look at the activity log to see what actually happened.

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JohnAStebbins
HandBrake Team
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Joined: Sat Feb 09, 2008 7:21 pm

Re: Audio sync issues.

Post by JohnAStebbins » Wed Jun 13, 2018 3:24 pm

Have you tried playing the same file with multiple players (that don't rely on the same possibly broken demux library)? Often these kinds of problems are problems with the player and the only solutions are to use a different player or fiddle with the encoding until you find something your player likes.

It could of coarse be that 5% of your source videos that you are encoding are just broken in some way. But of coarse there is no way for us to know this without seen an activity log for one of these out of sync files.

Bipolarbear
Posts: 23
Joined: Mon Oct 23, 2017 2:42 pm

Re: Audio sync issues.

Post by Bipolarbear » Wed Jun 13, 2018 3:34 pm

I will post the log. But this is not an isolated incident and I doubt the log will reveal much because we are only talking about a portion of the video. And since these are standard settings I use all the time and this only happens occasionally, I think we can safely assume the variation is in the source material itself. John, multiple players are involved, from WMP to VLC, to WDTV and the native player in my Samsung TV. In in this particular case, changing the CFR to 29.9 seems to have solved this issue. That confuses me since HB identified the native frame rate as 23.976. I'm really just trying to understand this.

http://www.jpages.net/714-The%20Critic. ... -48-14.txt

Bipolarbear
Posts: 23
Joined: Mon Oct 23, 2017 2:42 pm

Re: Audio sync issues.

Post by Bipolarbear » Wed Jun 13, 2018 4:02 pm

It seems as if the source material frame rate is actually variable and increasing the CFR allows it to pick up the variations that land between the cracks of the constant 23.976 frame rate.

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JohnAStebbins
HandBrake Team
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Re: Audio sync issues.

Post by JohnAStebbins » Wed Jun 13, 2018 5:55 pm

That encode log looks completely normal and shouldn't result in loss of A/V sync. If you are seeing sync issues from that encode, either your player has a problem or HandBrake does.

DVDs with 23.976 fps content are inherently variable framerate. The DVD spec only permits 29.97 fps. To achieve 23.976, they use field repeat flags in the video stream to extend the duration of some frames. Some frames will have a duration that is too long and some are too short, but they average to 23.976. HandBrake does it's best to output the original expected 23.976 framerate without the the jitter in frame durations, even when you specify variable framerate in the settings.

In your log, you'll see some of these:

Code: Select all

[08:36:45] 651.129578s: Film -> Video
[08:36:45] 651.246338s: Video -> Film
These are spots in the stream where the cadence of the frames varies from the normal 23.976 film cadence. These are pretty much always cut points between scenes in the movie. The number in front of the message (e.g. 651.129578s) indicates how many seconds into the video this occurs. In your log these cadence variations are all very short duration indicating they are almost certainly all cut points and the normal film cadence picks right back up immediately.

Bipolarbear
Posts: 23
Joined: Mon Oct 23, 2017 2:42 pm

Re: Audio sync issues.

Post by Bipolarbear » Wed Jun 13, 2018 6:28 pm

Thank you. But the very intermittent nature of these issues, coupled with several different players, leads me to believe it's the source. I guess what I'll do is try a constant 29.97 FR for a bit and see if that yields better consistency. That is the frame rate I used years ago when I first started ripping, using Win X DVD, which is not even a patch on HB. Thanks again.

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