Why is a VOB almost half the size of the parent MPEG-2 file?

[regular8mm]

Proof. I knew there was something up.
A DVD made of Hi-8mm video captured and a backup coded into MPEG-2 files were used to copy from. The same video file was taken from the DVD and from the data dvd backup of MPEG-2 files that went in to make it. The VOB is 69.8 MB while the Mpg is 120 MB.
Now, the mpeg-2 files are 640 x 480 with 44K/16/s while the vob is 704 x 480 with 48K stereo even though it is smaller.
Would someone explain what is happening please?
Nero 6 is being used.
Thanks.

[pyrohydra]

640x480 is not a DVD-compliant resolution, and as such your authoring application re-encoded your MPEG to make it DVD compliant, and from the looks of it did so using a much lower bitrate than the original. 44.1KHz audio is also not DVD compliant, so your authoring program resampled it to 48KHz.

Look at the resulting video - if the quality of it is acceptable to you, you can leave it as-is. Otherwise, you have 3 options:

1) Increase the encoding bitrate that your authoring app uses (you didn't specify which Authroing app you're using).

2) Re-encode your MPEG to a DVD-compliant resolution with a 3rd party tool such as TMPGENc.

3) Recapture from your source to a DVD-compliant resolution.

edit: I somehow managed to typo the word "authoring" three different times in this post. I also typoed it while typing it here. Perhaps I woke up too early this morning...

edit: make that FIVE times...

[regular8mm]

Like I said, Nero 6, nero vision express, was used to author it.

A test was made this morning using the captured avi; one version was encoded directly by Nero, the other was encoded by TMPGEnc first then put into Nero where it was encoded to DVD, authored too, with the other one. They are 105 and 104 MB each when done. Same thing. Look alikes.

I know that 640 and 44k and not DVD. Analog Hi-8mm video is the source. Nero takes care of enlarging and up sampling for me.

Another test was made by capturing in 720. That squashed and streched the image. 640 works better. Nero will change the files either way, avi or mpg.

Where would I look for the bit rate it encodes at? I'll keep my eyes open. Quality did suffer a bit especially on very small figures.

[teegee420]

Like I said, Nero 6, nero vision express, was used to author it.

Your first mistake. Use Nero to burn only. Use dedicated programs for encoding and authoring.

[lordsmurf]

Nero is not a video program, not for quality anyway.

[CrustyCurmudgeon]

Aw, come on, LS. Nero 6 Ultra is $70. And with the latest releases, it's gotten pretty usable. For someone just getting into making home movie DVD/VCDs it's pretty handy and quick. Sure you can find better slide show creating, audio mixing, video editing, dvd authoring and burning programs, but all in one package for so little money? I don't think so.

It's a good value for beginners.

[coldfire]

Another test was made by capturing in 720. That squashed and streched the image.

You definitely should capture in 720*480 and if you look at the captured picture on your VGA monitor it will appear squashed but this is absolutely normal !
(NTSC DVD are always 720*480 pixels whatever their display aspect ratio is )

[ZippyP.]

NTSC DVD are always 720*480 pixels

NTSC DVD resolution can also be 352x240, 352x480 and 704x480. So not always.

[regular8mm]

I am VERY happy with this program now. It changes my 640 analog video into 704 DVD with absolutly NO artifacts. I've never had it so good. Another program couldn't look any better, at least I don't think I could see any difference. I CAN see a difference between the quality settings and that is what I was asking about.
In NVE2 at the bottom is "more" then "Default Video Options" then "DVD-Video (VR)" and in there is "Transcoding Quality" "Quality Setting". Quality Setting is set to Automatic by default. THAT is what made the compression occure on my MPEG-2 files.
Last night I changed the Quality Setting to High Quality instead. Only half as much MPEG-2 files now would fit onto one DVD. It took 6 hours to transcode an image file.
You know, you have to name where to save the image file AFTER it is encoded and before the machine will turn off? I mean, I had to get up and name the file before it would stop. That is stupid programming It offers you the option of shutting down when done but not before you need to name where to save the nrg file!!!
The quality was and is superb.
Captures to 720 are crap from Analog 640.
I am thankful for all your replies, but, other than the hint about bit rates, I've answered my own questions and fielded some wrong responces.
A DVD was made showing 640 captures vers 720 captures. I still have it on a RW disk if you want to see the VOB files. Try it yourself before you tell me to just use 720. It doesn't work properly with analog 640 source material!
There is even a "Custom" setting for quality where all the different numbers may be entered manually in small incriments.
I don't know why you all are so down on Nero, No I'm not as experienced as youall are but my results have been just fantastic with it.
Could you tell and show me/us just what can be better, using other programs?
Keep in mind that I do not have a digital movie camera but rather a Hi-8mm analog video camera that captures in 640 x 480 with 44k/16/s. Nero effortlessly ups those to 704 and 48k. I cannot capture in 704 and the 720 captures distort the image too much.

[CrustyCurmudgeon]

Originally, like about 8 months ago, NeroVision Express had a lot of bugs and crashed a lot, or insisted on transcoding everything. Ahead Software has been continually working on improvements since then and I think now it's a good beginner/home video program. I don't think the fellows on here have tried the latest releases and are still remembering their bad experiences from last fall.

[teegee420]

I don't think that's it at all. The fact is that you can find more robust features in dedicated programs. If NVE works for you, that's great. It's just not for me....and a lot of other people here.

[regular8mm]

It still does transcode everything.

NO, wait, NERO does NOT transcode everything. There was a file of mine that breezed through the transcoding at 4x fast forward and I never knew why; it didn't even stay black for half of the time during 2 pass vbr. I thought it was because of the way it had been transfered from film. Not so.
It was because I had accidently encoded it in TMPGEnc to a DVD NTSC template; the 640 avi file was changed to 720 x 480 and 48K audio. Nero likes it and does NOT reincode it; that is why it was passed over and goes through the DVD making process in fast speed.
This morning I took a new 640 avi capture and used the TMPGEnc wizard NTSC DVD setting. The file was accepted by Nero and was NOT transcoded during a burn to image file; it acted just like the other fast file.
Phew, I learned a lot today

After more tests it was determined that Transcoding is suspended only for files that were made using the Wizard in TMPGEnc. If I made them manually it didn't work. THose files were transcoded. ???