Lip Sync Problem (xVID audio/video not in sync)

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JXBlack

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Post Sun Apr 05, 2009 3:42 pm

Lip Sync Problem (xVID audio/video not in sync)

I occasionally have an XivD file that my LG Recorder/Player refuses to play. I have found that running them thru AutoGK solves the problem. Sometimes, however, I lose Lip Sync by doing this. Is it possible for Media Coder to help me? I have never used Media Coder and would appreciate some help.

Thank You
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mixer

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Post Tue Apr 07, 2009 11:52 am

Re: Lip Sync Problem

You could use MediaCoder to change a fixed sync problem....that is a sync or delay that is the same through the entire clip. To do that you would use MediaCoders time "Delay" function and delay (or advance the audio). Doing this would require a re-encoding which may make your video look worse.
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JXBlack

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Post Tue Apr 07, 2009 7:48 pm

Re: Lip Sync Problem (xVID audio/video not in sync)

Thank you for your reply.
While I am unable to play the file on my LG Recorder/Player the file plays without any Lip Sync problems on my computer. When I run it thru Auto GK to limit the screen width to 640 pxl it loses lip sync. I would like to try running the original file thru Media Coder but I can't see how to even start.

Can you please give me instructions on how to do this?

Thanks again.
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ladycoder

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Post Wed Apr 08, 2009 4:16 am

Re: Lip Sync Problem (xVID audio/video not in sync)

Most players limit the width to 720 pixels wide, so you would resize to 720xH (keeping the aspect ratio) and copy audio.

also check in MPEG4Modifier to see if these files have square pixels, packed bit streams, B-frames,QPEL, GMC.

The first 2 can be fixed without recoding using MPEG4Modifier. AutoGk just has a setting to make it more compatible with certain players, which basically uses no custom matrices,no B-frames QPEL,GMC.
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davea0511

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Post Wed Apr 08, 2009 4:58 am

Re: Lip Sync Problem (xVID audio/video not in sync)

I believe avidemux can do this. Just load the file, check shift audio (it's right there on the main screen), and type in a number (in milliseconds, most likely it will be in increments of 250). You can preview the result by clicking the play button. When it is in sync, select the right container from the dropdown on the mainscreen, and select "copy" in the audio and the video drop-down boxes. Then click the save button. It will not re-encode so it goes pretty fast and you will not lose quality.
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JXBlack

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Post Fri Apr 10, 2009 7:08 pm

Re: Lip Sync Problem (xVID audio/video not in sync)

Ref: Ladycoder

Thank You for your reply.

Is MPEG4Modifier a program?
How do I check "if these files have square pixels, packed bit streams, B-frames,QPEL, GM"

Ref: dave0511

Thank You for your reply.

If I unpack the bitstream I get picture gut no sound on Preview.
If I don't unpack then I don't get either picture or sound.

Is their a tutorial that explains what all these various controlls do?


Thanks again
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ladycoder

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Post Sat Apr 11, 2009 4:44 am

Re: Lip Sync Problem (xVID audio/video not in sync)

Sorry I didn't have a link for MPEG4Modifier. I assume you found it online.

With regard to standalones:
QPEL and GMC are encoding options that most players won't play.
Custom Matrices can create sharper video, but some players do not like them either, and there are many different ones.
Packed Bitstream is a setting some claim makes smoother playback, but some players cannot tolerate.
B-frames are used to increase compression as they are smaller than I- and P-frames.

Square Pixels means the actual dimensions of the file, WxH detemine the aspect ratio. The aspect ratio in the avi header is rarely used to override the WXH for playback, but some players can only play those with square pixels, not just Custom 1:1, either.

The Modifier can be used to unpack and change to square pixels, and the info tells you if the other things are present.

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