avi to vob size comparison

[thai1]

Hi guys,

I understand that .avi files ripped from DVD that are then converted back to .vob are going to be lesser quality than the original, but my question is what should the .vob file size be compared to the .avi?

I am looking to fit multiple movies on a DVD but don't want to compromise the quality any more than it already is.

Am i right in thinking that there is nothing to be lost by assuming a 1:1 ratio, or should the .vob file be larger? If so, by how much?

As an example, I have some 840mb avi files and would like to fit 5 on a DVD.

Thanks

[manono]

Hello,

Am i right in thinking that there is nothing to be lost by assuming a 1:1 ratio, or should the .vob file be larger?

The VOB file should be larger - much larger. The usual rule of thumb is that they should use 3-4 times the bitrate of the AVI. MPEG-2 doesn't compress as well as does MPEG-4. Also, compare the number of pixels of your AVIs (heigth x width) with that of DVD resolution (720 x 480/576).

As an example, I have some 840mb avi files and would like to fit 5 on a DVD.

Forget it, unless you don't care at all about the final quality. You said you do care, so maybe you'll be able to fit a couple.

[guns1inger]

If you want to fit 5 movie length avi files on a DVD, burn them as data and play them back on a suitable player.

For DVD Video you can get

90 - 120 minutes at good - reasonable quality
120 - 180 minutes at average quality (assuming good source. Average to low using downloaded avi files)

180 - 240 at average quality if you use half-D1.

More than that and you will be dropping back to VCD quality or worse.

Simply rule - one movie per disc for DVD Video if quality means anything at all to you.

[thai1]

Thanks guys,

As you can tell, I am new to this.

So if I check the kbps in Gspot I should expect to see an average of x3 or x4 when encoding with FAVC.

I only have a Sony 4:3 29 inch non-digital TV, so haven't noticed poor quality when I have tried 5 movies before (I use half-D1) - although that could be my failing eye sight (age! )

I was prompted to ask because I encoded the 5 I mentioned before then checked the .vob files with VLC and the quality was less than usual, poor enough for VLC not to fill the screen, so I didn't burn. I then tried just 3, with the same results, which surprised me. I did burn those and as they are 16:9 movies they look OK on my TV, being a thin strip!, but others have digital widescreen...........

Maybe if their eyes are as bad as mine they won't notice either

[jagabo]

I was prompted to ask because I encoded the 5 I mentioned before then checked the .vob files with VLC and the quality was less than usual, poor enough for VLC not to fill the screen, so I didn't burn.

Not filling the screen has nothing to do with the quality of the MPEG compression.

[thai1]

I meant that the .vob when viewed with VLC was so poor that it resized smaller than a full screen. I could see a marked difference in quality to the .avi file.

Thanks for helping me to learn.

[jagabo]

VLC's default behavior is to show a video at it's storage resolution adjusted for the indicated display aspect ratio (DAR). It makes no judgement of the quality of the video. If you encode something at half D1 resolution with a 4:3 DAR setting it will display 4:3.

You can use GSpot to get detailed information about your MPG/VOB files.

If you just want to watch your AVI files (presumably Divx or Xvid) on TV get a Divx certified DVD player. You won't have to convert to movie DVD specs. Just burn the AVI files on ISO data discs.