VOB Files in DVDA

yirm wrote on 3/30/2003, 2:07 AM
Let's say I create a DVD. But at a later time, I want to add more material to it (not to the same physical DVD, but another one). Well, it turns out that you can import VOB files into DVDA. However, it appears that they will be re-rendered. This means that I have to save all my source files (MP2, WAV, AC3) from the original DVD if I want to add material (or remove material for that matter) to it for a new DVD. Wouldn't it be nice if DVDA recognized that a VOB doesn't need to be rendered? Or maybe there's a lossless (and hopefully quick) way to convert VOBs to MP2s?

-Jeremy

Comments

swattum wrote on 3/30/2003, 9:35 AM
Not sure if you realized this, but when you pull in the VOB to DVDA all you get is the video stream. You can recover the audio stream using something like DVD2AVI.

DVD Decryptor will let you demux the audio and video stream as well (you'll need to do 2 passes on the VOBs though becase DVD Decryptor will only demux one stream at a time), but produces M2V video files which can't be used directly in DVDA - you'll need to run the M2V file thru TMPGEnc and it's MPEG Tools and do a Simple Multiplex without an audio file to get an MPG file that DVDA will use. So unless you really need the MPG file, it's probably easier to use DVD2AVI to simply demux the audio and use that with the VOB in DVDA.

To dexmus the audio with DVD2AVI, open the VOBs, then on the audio pulldown, go to the dolby section and select "demux all tracks" and then on the file pulldown, do a Save Project. You'll end up with an AC3 file and a DVD2AVI project file (which you can delete).
yirm wrote on 3/30/2003, 2:36 PM
That sounds like a lot of work and time. I think it will be better for me to save my source files to a data DVD from now on. But thanks for all that info. SoFo, anything DVDA v2 can do to make this easier for us?

-Jeremy
radcamdvd wrote on 3/30/2003, 8:13 PM
The re-authoring of muxed DVD-Video files is NOT supported by the DVD-Video specifications and therefore there is no standard methodology that would permit such post editing.

Every app on the market today that allows re-editing of muxed VOB's is proprietary to that app.

Sonic Solutions (amongst others) is promoting this ability and indeed, they have built in the function to their software player, however, even they will admit that they are using a non-standard method.

It boils down to what you're looking for. IMHO, DVDA will increase its ability to adhere to the actual DVD-Video specifications because professional video producers and DVD authors will demand wide compatibility for their work product.

If you'd like more information on DVD authoring and production, I strongly recommend two reference books, "DVD Demystified," by Jim Taylor and "DVD Authoring and Production," by Ralph LaBarge.

If however, you're just looking to have some fun and store your home or project movies for a limited audience, then it's likely that you'll find a range of products to fit your needs, including MyDVD.
swattum wrote on 3/30/2003, 10:47 PM
You keep harping on this, and I'm not really understanding why. VOB files appear to be (both from practical experience and the reading I've done) basically an Mpeg2 program stream, with possibly some "extra" information.

As an mpeg2 program stream (as opposed to an elementary stream), the file simply contains multiplexed audio and video. So what's the big deal about using it in various NLE's or DVD authoring utilities assuming that it's not encrypted?

Personally, I find them a bit awkward to work with as they do file splitting at 1GB, but there's nothing special about them that I can see beyond that.

Simply because specifications do not address re-authoring or editing of a muxed stream is not a valid reason for software not to support such an ability. Specifications in this field define how you encode/decode data, not what you can or can't do with that data. Reference models are just that, an example of how something might be built that performs the desired functions of encoding/decoding, they aren't meant to be a straight-jacket prohibiting inovative approaches and features. Just because there is no standard methodology doesn't mean that a software vendor isn't allowed to develop their own means to do something (heck, look around at all of the various utilities floating around that do things that people think need to be done).

If people find a need or desire to include VOB's in their project, and the utility they are using supports the ability to do that, then what's the problem? Clearly the output produced by any authoring program will be (should be) correct regardless of where the source material came from, otherwise the authoring utility wouldn't be compliant to the specs.

Can you point to specific text in the standards that prohibits the inclusion of various source materials in an output program steam? I suspect not. Granted, some source material formats may be more easily used than other formats, but as long as the end result is compliant (which in this case is the job of the authoring utility), who cares where it came from?

--Scott
radcamdvd wrote on 3/31/2003, 8:26 AM
Yes I can and I've given the names of the reference materials that put highly technical engineering specifications into layman’s terms.

The fact is that Video Object Unit (VOBU) construction within Video Object files (VOB) is not and was not designed for direct editing. If you believe that they are merely muxed video and audio streams then it appears obvious that you require a greater understanding of DVD-ROM, DVD-Video and the overall DVD Forum specifications and details of each working group.

VOB files do not exist in a vacuum. While they can be "demuxed" which is essentially a reverse engineering exercise, the ability to re-edit their contents is not.

Perhaps if you had a clearer understanding of the technology you would make better informed assertions.