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Author Topic: VC1 - playback and audio sync issues  (Read 1573 times)

steelman1991

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VC1 - playback and audio sync issues
« on: July 02, 2014, 09:03:21 am »

Hi folks

Been battling audio sync issues for some considerable time now - initially I thought with all bluray rips - to mkv. The files have been ripped using in the main MakeMKV, though I also tried ripping them using individual components (eac3to and mkvmerge) in case MakeMKV was adding something to the ripping process (it wasn't).

I tried all manner of possible solutions (bitstream, decoded in player utilizing videoclock) however, nothing resolved the issue. Some further testing this week identified that the sync issues only manifested themselves in VC1 encoded material (mpeg4 and mpeg2 encoded material, played back without issue)

My current system consists of

Windows 7
i5 3570K @ 3.40Ghz
ATI HD 7850 graphics card
4GB RAM

feeding an Anthem MRX300 and Panasonic 65VT30 plasma.

Has anyone else encountered this weird phenomenon, or perhaps explain why this would be restircted to VC1 - its not a random file, I can faithfully reproduce the sync issues in all VC1 encoded media.
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Matt

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Re: VC1 - playback and audio sync issues
« Reply #1 on: July 02, 2014, 09:19:21 am »

You can adjust the sync in Options > Video > Advanced > A/V sync correction.  It's global, so you'd have to fix it for the files in question then fix it back for normal files.
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Matt Ashland, JRiver Media Center

steelman1991

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Re: VC1 - playback and audio sync issues
« Reply #2 on: July 02, 2014, 09:46:46 am »

You can adjust the sync in Options > Video > Advanced > A/V sync correction.  It's global, so you'd have to fix it for the files in question then fix it back for normal files.

Firstly - nice to see you back Matt

Sorry forgot to say the sync issue is only introduced when playing back the VC1 encoded files at 23.976 framerate - all other framerates (50 and 60) and encoded files (AVC, mpeg2), sync perfectly.

Appreciate that there is the sync correction option, but not quite sure how to carry out your instruction - surely after setting it globally, then when I revert back all files will lose the correction previously set, or is there a tag that can be set/unset? As I said the sync issue isn't a fps issue, but rather the encoded video that seems to be the issue.

Any ideas why I would only be seeing this on VC1 encoded files

Thanks
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Hendrik

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Re: VC1 - playback and audio sync issues
« Reply #3 on: July 02, 2014, 09:57:36 am »

Try RO Standard and try toggling hardware accelerated decoding. VC-1 can be kinda stubborn on that front.
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steelman1991

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Re: VC1 - playback and audio sync issues
« Reply #4 on: July 02, 2014, 10:22:12 am »

Stubborn - its been driving me round the twist.  :D

Was already using RO Standard, toggled HA and also switched off videoclock. Whatever it was the combination of these seems to have slightly improved the situation - though I will have to test some other files to confirm.

Any reason Hendrik why VC1 is more stubborn than AVC and is there any other cpu/gpu combination which would allow the use of madVR as renderer with those particular files - yet retaining correct audio sync.

Thanks again
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Hendrik

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Re: VC1 - playback and audio sync issues
« Reply #5 on: July 02, 2014, 10:43:51 am »

Using Windows 8.1 can actually help with VC-1 playback, as we leverage the Microsoft decoder, which was greatly improved in Windows 8/8.1.

As an alternative, Hardware Decoding is better supported on NVIDIA cards.
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steelman1991

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Re: VC1 - playback and audio sync issues
« Reply #6 on: July 02, 2014, 10:56:55 am »

Using Windows 8.1 can actually help with VC-1 playback, as we leverage the Microsoft decoder, which was greatly improved in Windows 8/8.1.

As an alternative, Hardware Decoding is better supported on NVIDIA cards.

Thought you might have gone down the NVidia route lol. You know what's coming next - recommend a card, please. Might just go down the upgrade route, if I'm likely to see improvement. The only thing that puts me off the 8.1 upgrade is the loss of WMC and I'm not sure I'm willing to stump up to get it (I know its not needed, but it was always nice to have).

Thanks again for the advice - much appreciated.
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