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  #1  
03-19-2010, 11:41 AM
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Iím trying to synch audio to several videos with Womble, pasting a higher-quality copy of the soundtrack over the video and muting the video (as I describe here). One particular video is not keeping in synch; it will line up at the beginning, but fall quickly out of synch as the video progresses.

Why would this happen? Is there anything I can try to correct it? Iíve done dozens of exports like this (including two from this same DVD) and never before had a problem. Iíve even done a couple since without incident, so I know itís not Womble. Thanks!
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  #2  
03-19-2010, 11:56 AM
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MPEG-VCR or MPEG Video Wizard?
How long is the video?
What is the source? (retail DVD, homemade DVD). If homemade, how was it made?

I've run into this issue with discs made on Panasonic DVD recorders. The AC3 stream is either not compliant, or is somehow otherwise unstable. The solution is to trim off 1 frame of audio+video at the beginning, and then re-encode the audio to MP2 (MPEG Layer II). If you're using the latest "DVD" version, it may be possible to also encode to a new different-bitrate AC3 (go one notch higher in bitrate).

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  #3  
03-19-2010, 01:04 PM
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It's MPEG Video Wizard. The video is only about two minutes long, as are the other two successful exports from this same DVD (same title too, with no chapter breaks). And it's a homemade DVD, created with iMovie/iDVD on a Mac Pro.

By trimming off, you're referring to the video stream only, right? On the source DVD, this particular video is positioned between the other two. Editing has already been done to the video timeline to remove the segments before and after.
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  #4  
03-19-2010, 05:17 PM
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Just a few ideas --

Are you sure you don't have any duplicated frames of audio? Sometime I run across this and when I isolate the audio track at the position where it goes out of sync, there are duplicated audio frames (you'll hear a slight stutter). I've run into this same issue especially on Sony DVD recorders.

The easiest way to identify where a video goes out of synch is to unmute both and listen to them at the same time as the timeline is running. If they are perfectly in synch at the beginning, you won't hear an "echo" that you'll hear if it's off in either direction (one frame to the left, one frame to the right or more)

Also, there is a "bug" in Womble (or more likely my computer itself) that pop up sometimes, where the audio will seemingly "drift" out of synch, but if I just grab the audio track and "drag" it to the left (doesn't actually do anything in your timeline cause the audio track is flush against the previous clips audio) then it will sound back in synch again. It's normally only a problem on longer clips, but just thought I'd throw that out there.
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  #5  
03-25-2010, 07:04 PM
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@robjv1
I've never heard of the audio drift bug in Womble MPEG Video Wizard -- I thought that was isolated to 2+ hours in certain older versions of MPEG-VCR only? Confirm, if you would.

@Reading Bug
It may be bad/inferior authoring on the part of the Apple iMovie software. I wonder if there is a sync delay at the head of the video. Open the extract MPEG file in VirtualDub -- use the version on this site, found in the editing subforum. It will often report audio sync errors, or you can preview it to see if there is a delay (meaning there is an offset). Offsets are VERY common on commercial DVDs.

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  #6  
03-27-2010, 06:35 PM
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Do you have a direct link, Admin? I can't find Virtual Dub anywhere.
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  #7  
03-27-2010, 06:42 PM
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VirtualDub download (with filters and plugins preinstalled) at http://www.digitalfaq.com/forum/show...aldub+download

Also:
- You can always manually find the latest version of VirtualDub at http://www.virtualdub.org
- And then the filter archives are at http://www.thedeemon.com/VirtualDubFilters/
.... although not all filters and plugins are in the archive. I also DO NOT suggest installing the bloated "filter pack" on that site -- lots of unneeded crap in there.

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  #8  
04-01-2010, 01:02 PM
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Thanks Admin. I've previewed the MPEG with Virtual Dub and there is indeed a synch error.

What is so strange is that this particular video is sandwiched between two others. They're all part of the one (and only) title on the source disc, containing no chapter breaks. I've done my editing to these other two videos with no problems. How can this middle one be so troublesome? What can I do to correct this?
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  #9  
04-02-2010, 01:40 AM
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You have to locate the sync loss areas, and then split the MPEG into multiple MPEG files. Then you have to re-sync the audio. I do that task in
  • VirtualDub when filtering/editing, and exporting back out to an intermediary for later editing/encoding,
  • Adobe Premiere, when I'm doing editing, or
  • Womble MPEG Video Wizard DVD, when I don't need fancy editing, and I need/want to work in the MPEG domain.
So the tool you use really depends on the project. Womble MVW would probably do the trick. Start with 15 frames one way (or 12 if PAL), and then if it gets worse, try 15 the other way. Just drag one frame at a time, and look for a good place to spot the sync, be it instant sound effects (explosions, drums, etc), or vocals (people talking quickly -- not slowly!)

It's a huge pain in the ass, and it takes a good bit of time.

For a perfect example of "commercial release" crap audio sync, look at the 1998 DVD release of Conan the Destroyer. You'll notice the voice is a few frames too slow, and the foley (sound effects) is a few frames too fast. The video quality is butchered too, with noise on the image edges, and the aspect slightly squished.

When I tried to re-sync the disc and fix the errors, I ran into a glitch at a badly-set layer break, which causd the exact problem you're having. The layer break affected the MPEG file embedded in the VOB set, further offsetting it by 5 frames. You don't notice this when the disc is played, but it happens once the files are extracted.

I don't understand layer breaks intimately enough to know what happened, or why it still plays fine embedded in the VOB set, but I've seen this many times in past years. It's not that common, but still common enough to be noticed.

The Conan was a personal/hobby project. Luckily, a friend told me a better release was made in Australia, so I may get that one.

Some of our projects are re-edits/re-authors for clients (studios, corps, etc), and we see a good bit of these, often because the client gave up and just sent it to us for repair. In most cases, they want to replace footage, re-arrange, delete outdated content, fix older editing/authoring errors, or simply add more to a disc. But these sync errors make otherwise easy tasks long and tiring work.

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  #10  
04-03-2010, 09:13 PM
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Thanks Admin. I haven't yet attempted anything as I'm still trying to picture how this would be done.

I'm concerned about two points. One, 15 frames - or even 30 frames - seems like a very short length to be determining whether something is in synch or not. Of course if I work with something longer, I risk the audio drifting.

The other, bigger issue: Womble doesn't recognize the audio stream on the source MPEG. It just plays back static. So it will be extremely difficult to synchronize short clips as you describe. It was indeed quite a hassle to line up new soundtracks over the other two videos from this DVD, and they didn't have synch errors at all.

Do you have any advice for attempting this under these conditions with Womble? Would you recommend VirtualDub instead?

Or, is there another program that might work around this synch issue? The source DVD plays back without incident, and I'm still a little confused as to why this is happening at all. Especially when the other two videos in this stream, front and back, are fine...
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  #11  
04-04-2010, 12:17 AM
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Quote:
Womble doesn't recognize the audio stream on the source MPEG. It just plays back static.
None of this sounds right. That's just can't be.

Womble recognizes all standard homemade MPEG sources: AC3, MPEG audio, PCM WAV.

Homemade DVD is almost always AC3, MPEG Layer II (MP2) or PCM WAV audio. If you have the right tools, DTS is an option, but unlikely. Retail is generally AC3, but you see some DTS and WAV. MP2 is not NTSC MPEG standard, so you'll never see it used retail. (Even PAL doesn't seem to use MPEG audio either, although it's part of the PAL DVD specs.)

You're going to need to figure out what the audio codec is. Use Gspot to analyze it.

Have you accidentally installed a codec pack on your system? NEVER INSTALL A CODEC PACK! It causes major damage to how a system can understand audio and video formats -- it makes a huge mess of things, so many conflicts tend to happen.

Quote:
One, 15 frames - or even 30 frames - seems like a very short length to be determining whether something is in synch or not.
I think you'd be surprised how big a quarter-second difference can be visually, when watching audio/video sync.

Quote:
Would you recommend VirtualDub instead?
VirtualDub is not an editor with independent audio/video abilities, so it's probably not the right tool.

Womble MPEG Video Wizard can edit MPEG files. The newer "DVD" version (MPEG Video Wizard DVD) is suggested. More on Womble versions at: http://www.digitalfaq.com/forum/show...-vcr-1880.html

The best way to edit AVI is with something like Premiere or Vegas (or Final Cut Pro on Mac), however that would always require a full re-encode of the video.

Quote:
I'm still a little confused as to why this is happening at all. Especially when the other two videos in this stream, front and back, are fine...
You cannot compare the authored DVD with the unauthored sources. It's not necessarily 100% the same, excluding video and audio quality, of course. Note that "quality" does not include sync.


However...

You may need to back up more steps, and then let's start at the beginning.

If Womble is unable to play the audio, then maybe you have not ripped it correctly. Maybe it's trying to play several audio streams at the same time. You need to demux it with a complex demux. Use the TMPGEnc Plus MPEG Tools (under File > MPEG Tools) to do a non-simple "regular" demux on the source VOB file.

Also be sure you ripped the file as one big VOB, and have not tried to manually join VOB files in an editor -- that never works well.

Guides for ripping at:

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  #12  
04-04-2010, 07:30 PM
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Ok, I've gone back to the beginning with a Gspot scan (a program I hadn't used before - nice little tool!)

I popped in the DVD and just scanned the single VOB straight off the disc. It appears there is a single, linear PCM stream found. I've attached a JPEG for reference.

The computer I do my editing on is a dedicated offline machine. Virtually nothing is installed on the computer without my doing it manually and knowingly, so it's doubtful any codec pack has made its way there. But thanks for that info

To clear up a few things...
- This six-minute DVD only has a single VOB file, so nothing is joined.
- The only thing I've done to this file is rip it to my HD and convert it to MPEG with VOB2MPG. Womble plays back static whether it's the MPEG or the VOB.
- VirtualDub does not experience static with this disc.
- This project involves numerous homemade DVDs. Most (but curiously not all) also have this static problem. Some were created on the same computer (with the same Apple software) that produced this problem disc, while others were burned by other people on other computers.
- Womble continues to work flawlessly with other DVDs, video files and audio files.


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File Type: jpg DVD_scan.jpg (68.6 KB, 1 downloads)
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  #13  
04-05-2010, 01:26 AM
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Mac, you say? I bet it's an AIFF based PCM audio, instead of a WAV one. That might explain the Womble static/noise playback.

I like VOB2MPG, but you'll want to use DVD Decrypter on this disc, and extract via IFO mode. Then open the VOB in TMPGEnc, and demux with a non-simple demux using the MPEG Tools. That will give you the M2V video and the AIFF PCM audio file. TMPGEnc may insist on using the WAV extension, so rename it.

Then you'll have to convert with an editor. Do you have Goldwave, Audacity, SoundForge, or something else? Audacity is freeware. I don't have to work with AIFF much anymore (and when I do, I'm usually on OS9 or OS X, not Windows), so I'm not readily aware of what works and what does not. Will take a bit of trial and error to see which programs open AIFF and can re-save as WAV.

If you want to upload that 361MB file, I can provide temporary FTP credentials, since you're a Premium Member, to a special uploads folder. I can look at it.

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  #14  
04-06-2010, 07:29 PM
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Thanks Admin. I'd love to upload the full file and get your evaluation before I consider doing what you recommend
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  #15  
04-11-2010, 12:45 PM
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Thread bumped?
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  #16  
04-28-2010, 07:45 AM
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PM'd you the FTP details, still don't see the file there.
Let me know via post or PM if you're still wanting to FTP submit the test for my review.

Thanks.

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  #17  
04-29-2010, 05:27 AM
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Got the uploaded VOB file.
It's just bad editing by whoever made the retail source (or sent the broadcast, or cut the master). It might be bad timing between cameras, as the camera cut each time. I've seen this many times on conversion/restore work I get from studios -- cameras are not in sync 100%, so the edited final version is off. You see drum hits perfect in one angle, but the next is almost an echo effect, a/v not in sync. The cuts can be so small sometimes that it's just not cost effective (no ROI) to fix. I'd suggest this be the case here, too.

There's nothing you can do, aside from cut the video into many little clips, and then offset the audio by about 5-10 frames each time you see the issue.

Since it's socket puppets, it's not like they have lips to sync to. That may even be why is was messed up AND why it wasn't fixed at a much earlier mastering/editing stage, long before you got it.

Sometimes audio delays from the recording system are responsible for this, too.

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  #18  
04-29-2010, 06:27 PM
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Thanks again for your help, Admin.

I don't think it could be a camera issue, as the same one was used for all three videos. All three were shot with a basic digital camcorder (with live sound), imported into iMovie, the CD track was layed over the live audio and then fades were applied. That's all.

I suppose it could be either iMovie importing sloppily, or iDVD not getting the burn right. The kicker is that all three were produced, imported and edited in the exact same way, so they should have the same issues (or lack thereof) across the disc.

I'm not sure what I'm going to do, if anything. It seems too tough (and arduous) to deal with. I guess I'm just thankful the other two are fine.
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  #19  
06-13-2010, 02:29 PM
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I'm now having a very similar problem with a retail MPEG. It had serious synch issues (about 15 frames in difference), which I corrected with MPEG Video Wizard's MBS Scanner. It's now synched perfectly.

When I try to introduce a new audio track from a CD (the exact same recording) it presents major delays. It might stay for thirty seconds or so, but if I go any further into the video (about four and a half minutes total) it's delayed big time.

How can this happen? The audio stream is now fine and is of the same content as the CD track. Is there a program that can possibly adjust my CD track to match the pacing of the video? That's the only thing I can think of trying next. Really at a loss. Thanks!
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  #20  
06-13-2010, 02:32 PM
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P.S. Admin, PLEASE change the reply limitations. It took me three times longer to compose my above post because the little box wasn't checked off first. I lost my edits twice!
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