Audio Sync issues with GoT Extras History & Lore

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emilius256
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Audio Sync issues with GoT Extras History & Lore

Post by emilius256 »

Hi,
I'm writing this post for an audio sync issues with GoT Extras History & Lore that don't know if it may be resolved.
History & Lore are many stories, each one is a single episode, each episode play an MPLS with a single M2TS.
But you can also select a "Play All" that play every episode one after the other, in this case it plays an MPLS with multiple M2TS.
This is the MPLS for a single Episode
Single Episode.png
Thisi is the MPLS for Play All
Play All.png
The problem is with Demuxing the Play All MPLS, the audio is slightly getting out of sync.
The extracted Video length is 1:09:04.223 while the extracted Audio length is 1:09:00.064.
I then extracted the same MPLS with the Episode Demuxing option ON.
Checking the length of every extracted audio, I found that each audio is shorter than the video, this causing the audio sync problem episode after episode.
Here an extraction of BDInfo with the length of every chapter (Episode) and the real length of the extracted audio

Code: Select all

Number          Time In         Length BD       Length Extracted Audio   
------          -------         ------          ------     
1               0:00:00.000     0:02:46.416     0:02:46.208
2               0:02:46.416     0:02:44.706     0:02:44.704
3               0:05:31.122     0:02:58.219     0:02:58.208
4               0:08:29.342     0:04:50.540     0:04:50.336
5               0:13:19.882     0:02:50.420     0:02:50.240
6               0:16:10.302     0:02:08.378     0:02:08.224
7               0:18:18.680     0:02:30.400     0:02:30.240
8               0:20:49.081     0:03:27.457     0:03:27.264
9               0:24:16.538     0:02:43.705     0:02:43.552
10              0:27:00.243     0:01:45.188     0:01:44.992
11              0:28:45.431     0:03:21.451     0:03:21.248
12              0:32:06.883     0:02:40.410     0:02:40.256
13              0:34:47.293     0:02:56.426     0:02:56.224
14              0:37:43.719     0:03:11.649     0:03:11.456
15              0:40:55.369     0:02:39.409     0:02:39.232
16              0:43:34.778     0:03:07.020     0:03:06.784
17              0:46:41.798     0:02:58.428     0:02:58.240
18              0:49:40.227     0:03:01.014     0:03:00.832
19              0:52:41.241     0:02:52.922     0:02:52.736
20              0:55:34.164     0:02:10.380     0:02:10.176
21              0:57:44.544     0:01:59.369     0:01:59.168
22              0:59:43.913     0:03:43.473     0:03:43.296
23              1:03:27.386     0:02:33.403     0:02:33.216
24              1:06:00.789     0:03:03.433     0:03:03.232
To "Solve" the problem at the moment I'm encoding the video with the play all MPLS, split by chapter and the mux with the audio extracted using the Episode Demuxing.
But it is a tedious work because are over 100 episodes.
Do you think there may be a possible solution ?
Please let me know if I can help with or you need more information.

Thanks
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Rocky
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Audio Sync issues with GoT Extras History & Lore

Post by Rocky »

Can you give me the disk for testing under fair use? If not, can you link me to where to purchase it?
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emilius256
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Audio Sync issues with GoT Extras History & Lore

Post by emilius256 »

Hi Rocky, thank you for the reply.
Yes no problem, do you need the whole disc or just the disc structure with the problematic mpls and m2ts ?
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Rocky
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Audio Sync issues with GoT Extras History & Lore

Post by Rocky »

I need the whole disk. If you need it I can give you my FTP details.
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emilius256
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Audio Sync issues with GoT Extras History & Lore

Post by emilius256 »

It would be great, thanks.
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Rocky
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Audio Sync issues with GoT Extras History & Lore

Post by Rocky »

PM sent. Thank you.
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Rocky
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Audio Sync issues with GoT Extras History & Lore

Post by Rocky »

Got it, thank you. Investigating...

Are you trying to make a single mux or one for each episode?
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emilius256
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Audio Sync issues with GoT Extras History & Lore

Post by emilius256 »

I'm trying to do a single mux using the MPLS 00322.
With the mux for each episode, with the episode demuxing option enabled, there is no problem, each audio track is shorter than the video but it doesn't matter because it is in sync with the video for every episode.
The problem is only when doing a single mux because the audio is shorter and at the end is out of sync of 4 seconds more or less.

Thanks
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Rocky
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Audio Sync issues with GoT Extras History & Lore

Post by Rocky »

Ouch. This is going to be tricky. This is the first case I've ever seen where there is extra video rather than extra audio per M2TS. My gaps correction assumes extra audio. I'm going to have to give this a big think to see if there is anything that we can do. :scratch:
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Rocky
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Audio Sync issues with GoT Extras History & Lore

Post by Rocky »

OK, I'm going to see if we can just repeat audio frames instead of deleting them. Trying to generate silence for all possible permutations of audio will be difficult.
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emilius256
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Audio Sync issues with GoT Extras History & Lore

Post by emilius256 »

I guess it would have been tricky, and as you said it may be difficult to do it for every kind of audio and without re-encode.
I may try to mux each episode with mkvmerge adding a delay on each audio track, and then merge all of them to see if it stays in sync.
Anyway don't worry too much, as you said, never faced the same kind of problem before, it may not be worth wasting too much time time on it.
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hubblec4
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Audio Sync issues with GoT Extras History & Lore

Post by hubblec4 »

Rocky wrote:
Tue Apr 23, 2024 5:40 pm
Ouch. This is going to be tricky. This is the first case I've ever seen where there is extra video rather than extra audio per M2TS. My gaps correction assumes extra audio.
Hi Rocky

That sounds very exciting.
Because of the other problem "Multi-Edition-MKV", I have delved deeper into the Blu-ray specs and it actually says that the audio should/must be longer.

Would it be OK with you and emilius256 if I also had access to the Blu-ray for testing purposes?
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Rocky
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Audio Sync issues with GoT Extras History & Lore

Post by Rocky »

Please PM/discuss with emilius256 about media availability.

Can you give the spec reference for the claim that audio must be longer? Thank you.
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emilius256
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Audio Sync issues with GoT Extras History & Lore

Post by emilius256 »

With MKVMerge I muxed each episode adding the correct delay, then merged all the episode together to create a single video with chapters.
With this method the audio is in sync with the video, but if the audio track is extracted from the merged file, the delay are zeroed and the audio is again shorter then the video, and is no more in sync.
Anyway is too much work :)
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hubblec4
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Audio Sync issues with GoT Extras History & Lore

Post by hubblec4 »

Rocky wrote:
Wed Apr 24, 2024 8:45 pm
Can you give the spec reference for the claim that audio must be longer? Thank you.
Maybe I'm wrong, or had not correct translated/understand.
I have uploaded the Spec.pdf to your FPT.
The Section about the connection conditions for seamless branching are important.
On page 151 is a "Figure 5-21" which shows the Audio PTS, which is a bit longer than the Video.
Maybe I misinterpret this.
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Rocky
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Audio Sync issues with GoT Extras History & Lore

Post by Rocky »

Well, that's for seamless branching (condition 5). Probably it's not used/appropriate for multiple episodes as they need not be seamless.
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