Looking for a software for easyly solving MKV out of sync issues ?

[guista]

Hi all,

I have a bluray where the video is encoded in VC-1 and the audio in DTS.
Using MeGUI, I successfully converted the video track to h264 and the audio track to AC3.
These conversions generated an out of sync delay of 6 mins of the video over the audio.

I was able to reduce the delay using the "Audio time shift (ms)" feature available in Media Player Classic then stretched the audio with MKVMerge.

Approximately, the first part of my movie still has 1 second out of sync delay whereas the second part is well-synchronized.
For a weird reason, I noticed that the out of sync delay is not linear : at some times, the video is late and at other times, it is ahead.

Anyway, I can easily find out some sync points with MPC.

* Given a list of (audio timestamp, video timestamp) sync points, does someone know a software which could stretch the audio on these given intervals ?

Otherwise, I will have to cut the audio track myself and do the work on some piece of audio which is a very very long job.

Thanks in advance for your help.

PS: is there an "out of sync" FAQ ?

[ChronoCross]

Does your video have a variable frame rate? That seems a bit odd that the audio would go back in forth of being ahead or behind unless it's VFR and you didn't provide the mkv muxer with a timecodes file.

[Emulgator]

what does mediainfo tell about the video source streams and your video encodes ?
6 minutes is suspicious. Unintended PAL/NTSC fps conversion ?

[guista]

Does your video have a variable frame rate? That seems a bit odd that the audio would go back in forth of being ahead or behind unless it's VFR and you didn't provide the mkv muxer with a timecodes file.

Yes it has VFR and no, I did not use a timecodes file. I even did not know that such a file could exist (I am a newbie).

* How do yo generate the timecodes file from the BD source tracks ?

Anyway, I do not want to spend another 15 hours of encoding so I am going to try to write the timecodes file manually by watching the video.


what does mediainfo tell about the video source streams and your video encodes ?
6 minutes is suspicious. Unintended PAL/NTSC fps conversion ?

I already deleted all my BD track's extractions so I do not have the information anymore.
I kept the original 1920*1080 HD resolution but reencoded the movie to 5M.
The only thing I can tell is the input video is VC-1 and I got a perfect H264 video output : video is fluid and picture quality is high. Moreover, I have no interlacing artifacts.

[Selur]

didn't even know vfr was allowed on Blu-ray, but reading (http://forums.plexapp.com/index.php/topic/5389-issue-with-changing-the-framerate-of-m2ts-bd-rips-to-24fps/) it seems like there are a bunch of vfr BDs out there,..

[Inspector.Gadget]

Blu-rays are CFR only. Those people on other forums saying that VFR-encoded Blu-ray titles exist are using unreliable framerate reporting tools and don't actually have any idea what the Blu-ray specs demand. That's not to say that titles on the same disc can't be different frame rates (e.g. 1080p24 main movie and 480i60 extras) but there's no such thing as "VFR Blu-ray" as the term VFR is usually used on Doom9.

[Selur]

Thanks for clearing that up!

[Ghitulescu]

I don't have access to the specs, but BD demystified says that only CFR is allowed on BDs (also fixed-values ie 22fps is not allowed, and coupled to frame sizes), as Inspector.Gadged already said. In fact, except for surveillance cameras and recorders, I am not aware of any industrial standard that endorses VFR. VFR is also often used for screen captures, and of course for material under rule 6, because it saves some space.

[guista]

didn't even know vfr was allowed on Blu-ray, but reading (http://forums.plexapp.com/index.php/topic/5389-issue-with-changing-the-framerate-of-m2ts-bd-rips-to-24fps/) it seems like there are a bunch of vfr BDs out there,..

Please forget my reply about VFR.
I mixed up the frame rate with the bit rate.
Moreover, I was talking about my encoded video output and not my bluray input.

Here are my files (I recovered my original input file and did a mediainfo on it):

Input (VC-1 + AC3) (http://webpollux.free.fr/public/encoding/mymovie_mediainfo_input.txt)

Output (AC3) (http://webpollux.free.fr/public/encoding/mymovie_mediainfo_output_ac3.txt)
Output (h264) (http://webpollux.free.fr/public/encoding/mymovie_mediainfo_output_h264.txt)

In order to get my output files, I encoded them with MeGUI 2008 (profile: "x264: BD9 1080p24 - 720p24").
If you compare the output video duration to the audio duration, you will find the 6 mins delay.
I wrote something wrong in my first post : I left my audio input format unchanged in AC3.
It seems that the frame rate is constant as you said (~ CFR).

* Do you know how to generate the timecodes file from the input file ?

* Can I edit the timecodes file myself ? Is the timecodes file format described somewhere ? (I only found some basic MKVMerge tutorials).

Thanks in advance.