What's the difference between MPEG and VOB files?

[dbjames]

OK, here's the question. I have captured movies etc as MPEG files. they look OK, play OK, no sync problems. A few frames were lost during capture from VHS, but otherwise they seem 100% OK.
I use Pinnancle Studios to create the VOB files prior to burning a DVD. Apparently the MPEG source goes through some sort of rendering/compiling process to end up as the VOB files which go on the DVD.
However, with a lot of movies the VOB files have out-of-sync audio. It is not consistent - some times simply re-running the render/compile step will solve the problem, sometimes a re-run will make it worse and sometime make it better but still not correct.
So - I need to understand what this render/compile process is and how then to solve the sync problem.
Q : what is the difference between the MPEG input and the VOB output of "render/compile" ???
(as in MPEG=OK, VOB=out-of-sync)

[dbjames]

and I guess, 2nd Question:
can I edit these VOB files to re-sync the audio?
and, if yes, will editing individual VOB files destroy the integrity of everything in the VIDEO_TS folder?

[guns1inger]

An mpeg programme stream contains video and audio that has been encoded in a compliant manner. Elementary stream means that the video and audio are in seperate files. Mpeg is a container format, so it may contain more than one audio stream, and the video may be encoded using mpeg-1 or mpeg-II compression.

VOB is also a container format. It may contain DVD compliant mpeg video, one or more audio tracks encoded as either PCM, AC3, mpeg1-layer2 or DTS, subpictures used in menus or subtitles, and navigation data associated with chapter stops etc. A single VOB may contain several titles or titlesets, including the menus.

I would suggest that either the dropped frames or the authoring process (ot both) is causing your problem. Can you give more detail about the sync problem.

Does it start out in sync and drift out over time ?
Does it start in sync, then abruptly jump out of sync when frames are dropped ?
Does is start out of sync and remain out of sync the whole way ?

Each of these problems requires a different solution, so we need to know exactly what is happening before giving a complete answer.

[guns1inger]

I have just read your other post, and what I said there stands here as well. Until you can get a clean transfer of material into your PC, without dropped frames, you will not get good, predictable results. regardless of the quality of the pinnacle software (and I have my suspicions there as well), unless you can gaurantee your source material, you can't point the finger at anything else.

[dbjames]

OK, thanks for the info.
Let's try to go through this with a real example and one which is causing me the grief at the moment.
- I capture a 2 hour movie from VHS to MPEG using Dazzle AVC and Pinnacle. The capture drops frames all through the 2 hours. This is usual, I've never been able to capture any VHS source without dropping frames even with a 2GHz laptop. However, dropped frames don't equal bad DVDs. 90% of my DVDs are OK, even though I had dropped frames during each capture.

- 2 hours is too big for one 4.7GB DVD so I cut the MPEG in half with VideoReDo

- the first 1 hour MPEG compiles nicely to DVD, there is a tiny fractional loss of sync but barely noticeable

- the second hour won't render/compile without loss of sync. This second 1 hour MPEG produces 4 VOB files. The first file is in sync at the beginning, but by the end of the fourth VOB the sync loss is about 2 seconds

- there is no obvious jerk in playback where loss of sync occurs. It appears to be gradual.

- I've made many re-runs, and it was almost correct on one occasion. The other occasions, and using different PCs/Laptops, gives different, random, results

- Pinnacle Studios support consistently say the problem is with my PC during the render/compile step and that I should close down all tasks and ensure there is no other disk activity during this processing

I'd be happy with a "dropped frames on capture" conclusion if it wasn't for the fact that I get perfectly good DVDs most of the time and these good DVDs came from captures that dropped significantly more frames than this particular movie (described above). Also, one half of the movie comes out OK, when frame drop was consistent all through the capture. If the first 1 hour of MPEG had the same amount of frame drop on capture as the second 1 hour MPEG, why the difference in the resultant VOBs/DVDs?

PS the comment in the other forum about "800 dropped frames" was NOT for the movie in this example.

Any help appreciated !!

[ZippyP.]

You might want to read this: http://www.digitalfaq.com/dvdguides/capture/droppedframes.htm

[dbjames]

Lots of help here, but I'm still lost.

If frame drop on capture can cause audio sync problems, why is my MPEG file apparently perfect?
If I could simply copy the captured MPEG to a DVD all my troubles would be over.

It's MPEG to VOB where it all goes wrong.

Sorry if I'm being stupid here, but I'm lost.

(On the other hand, I could completely forget the DVD bit and simply re-play these occasional problem movies only on my PC? Defeats the whole point though....)

[lordsmurf]

MPEG is not a "container format". That would be AVI or Quicktime. MPEG is a video standard.

MPEG is the video format, and both audio and video are available. Video has 2 options (a 3rd too, MPEG-4, but not really). Audio has several layers available (like MP2, MP3). Generally, you see 1 audio paired with 1 video.

VOB is a DVD-Video part. VOB files contain a portion of the audio and video (in 1GB chunks) along with some navigation data (chapters) and extras (subtitles, multi audio, etc). Nothing is converted. VOB is also a "container format" too, if you want to think of it that way.

Your problem is the source is bad. The PTS is messed up, or one of the streams is damaged. I use Womble MPEG Video Wizard to fix MPEG files extracted from the VOB, as Panasonic has a crap AC3 encoder that makes invalid and flawed AC3 files. I let the software convert to MP2 audio, and it realigns PTS in the process.

Your authoring software is rejecting half-quality MPEG files (something that is a problem, just you cannot see or hear it, it's technical issues). And then your MPEG editor is not doing a good job of editing problem files. You need to save the MPEG, use Womble MPEG Video Wizard, and then author in something else, not Pinnacle.

[dbjames]

Can't say I'm any farther forward in relief of ignorance of this topic.

Let's try one more question to see if any answer puts me out of my misery -

If this problem is due to a corrupt MPEG source file, caused by dropping frames during capture from VHS - then (simple question) why does this MPEG file play OK? If there was something wrong with it, why don't I see a problem in playback using Real or Media Player?

As I said before, if I could simply put my MPEG file onto a DVD disk without all this VOB creation render/compile stuff, my life would be bliss.

[dbjames]

Well, there's a thing !
Just downloaded the trial version of Womble Video Wizard and gave it my MPEG file as input.
Guess what? It created a perfect VIDEO_TS folder full of pefect in-sync VOB files.

All I've got to do now is to find another piece of software to actually burn the DVD ! Pinnacle Studios refuses to accept the VIDEO_TS files created by Womble, so I'm going to have to burn the video another way.

Anyway - audio sync problem solved. Still can't see what it had to do with dropped frames on capture, but at least this forum pointed me towards Womble ! Thanks for that.

[guns1inger]

One success doesn't prove the problem is solved, but hopefully it is a good sign.

[ZippyP.]

All I've got to do now is to find another piece of software to actually burn the DVD !

Read on: https://www.videohelp.com/guides.php?howtoselect=3;25#3;25

[geowharton]

Your problem is the source is bad. The PTS is messed up, or one of the streams is damaged. I use Womble MPEG Video Wizard to fix MPEG files extracted from the VOB, as Panasonic has a crap AC3 encoder that makes invalid and flawed AC3 files. I let the software convert to MP2 audio, and it realigns PTS in the process.

What's a PTS?

[jameshgross]

A simple Google search would have revieled that:

PTS is the Program Time Stamp and states when a certain stream starts.

Do a little research!

[tmh]

My guess is the problem was Pinnicle created the problem. I assume it renders the already compliant mpeg file and screws it up. No need to use pinnicle at all as it's all set for authoring - no encoding needed or wanted. Just use an authoring program like TMPEenc DVD Author or one of the free ones. Then burn with nero or whatever.

[Guest34343]

A simple Google search would have revieled that:

PTS is the Program Time Stamp and states when a certain stream starts.

Do a little research!

Wrong!

It's the Presentation Time Stamp. It specifies when an audio or video access unit is to be displayed. It has nothing to do with the start of the stream.

[jameshgross]

Well we better inform DOOM9 that they have the wrong def.

http://www.doom9.org/index.html?/dvd-structure.htm

[Guest34343]

Well we better inform DOOM9 that they have the wrong def.

The only thing wrong there is using the word "Program".

If you detect and report *only the first* PTS of a stream, then yes, that does represent the starting time of the stream relative to the PCR. But that's just a specific application of the general concept of PTS, which is to signal the presentation time of audio and video access units, as I stated.

You can verify my claim here:

http://neuron2.net/library/mpeg2/iso13818-1.pdf

[jameshgross]

I think we have a case of calling a fish a flonder or a halibat.

I bow to your superior knowledge of fish.

[Guest34343]

No, we have a technical inaccuracy stated by you that I have corrected.

[Guest34343]

[deleted] somehow double posted

[DarrellS]

All I've got to do now is to find another piece of software to actually burn the DVD !

No need to use pinnicle at all as it's all set for authoring - no encoding needed or wanted. Just use an authoring program like TMPEenc DVD Author or one of the free ones. Then burn with nero or whatever.

The free option would be to open the VIDEO_TS folder with DVD Shrink, use Full Disc Back Up, and choose Create ISO and Burn With DVD Decrypter.