Just a curiosity about the VOB container.

[Talayero]

Hello,

I'm wondering why when you compile just a video stream, a m2v, without any audio or subpictures at all, the resulting VOB is rather bigger than the m2v.

For instance, if I compile a 4000 MB m2v the resulting VOB has 4093 MB.
93 MB are not a few MBs. Anyway I suppose that this difference of size is a normal thing, because the container must always be bigger than the content. But couldn't the people who created the DVD format make a container that would use a little better the space? It's not that easy, I know.

Well, may be someone has a good explanation for all that.

Thanks in advance

[guns1inger]

You are talking about 2%, so in the larger scheme of things that it not a huge overhead. Even disks that have no menu have a menu structure associated with them. It is a simple, autoplay menu, but it exists none-the-less. You also have space for nav points (chapters) etc. That all stored in the overhead area.

I would be curious to see if this is relative to the size of the video, or a constant amount.

[borax]

From my experience it is mostly mux overhead. This has several effects:
1. Pack headers are added at each 2kB to get the "Vobunits"
2. Navigation packs which are added into the stream
-> These two should be rather constant (depend on the filesize only) and are VOB specific
2. Sync info (even if no audio or sub is there). This is added to the GOPs
-> Depend more or less on the duration of the video in seconds (or number of GOPs). Should be the same as if an elementary stream is muxed to a system stream (m2v->mpg).