Please explain this to me (lengths of video that an fit on a DVD media)

[perfection]

I have a movie in avi format (compressed using Xvid codec) which i wished to convert to a DVD format. The running length of the movie is 2 hrs 20 minutes. while converting the movie iI chose the option of fitting 60 minutes per 4.5 GB DVD. At the end of the conversion i has three DVD folders ready for burning. Agreed! (this was expected)

If i has chosen 120 minutes (standard play) video per DVD i would have landed up with 2 DVDs for this movie. If i wished i could ave put the entire converted movie onto a single DVD too

My question is considering my dvd standard is PAL 25 fps 620 x 576 and a constant VBR of 6000 kbps how and more importantly why do these conversions take up an increasing amount of space if i choose 60 minutes, 120 minutes or 180 minutes ? I mean where is the extra space being taken up?? In other words what and where is the sacrifice being made in each case and ideally what should be done? What is getting sqeezed knowing that the bitrate is fixed??

Would i get a better quality DVD in case one where i chose to write only 60 minutes of video per 4.5 GB DVD? and the noticeably worse quality in the last case or is it a case of overdrive anyways??

[bacardi/avt]

VBR of 6000 kbps

That is NOT constant bitrate it is Variable Bite Rate=VBR.

That is why

[SLK001]

Analogy:

You have a 4 by 4 inch piece of paper. You want to paint a picture of your dog.

Low bitrates - you are allowed to paint your dog using only 32 dots.

Slightly higher bitrate - you are allowed to paint your dog using 96 dots.

Even higher bitrate - you can paint your dog using 192 dots.

Really good bitrate - you can paint your dog using 1024 dots.

Now assuming that you store your painting using 8 bits per dot, you can see that as your bitrate increases, your required storage also increases.

Also, just what crappy encoder are you using? You should be able to put 140 minutes on a DVD with very good quality. Just reserve ~4,100MBytes for your video (and 4,100M x 8 bits / seconds = 3.9Mbps). Use the 3.9Mbps as your target bitrate.

[jman98]

SLK001 - The people who ask this question have easy to use tools that isolate them from the process of encoding. These tools often have preset limits. I've heard of some that will refuse to let people put more than 2 hours on a single layer DVD. Looks like the original poster has one that only allows 1 hour.

perfection - If you encode it yourself and choose the right bitrate, you can get more than 2 hours on a single layer DVD. You can even get 6 hours or more with the correct (low) bit rate, but as a general rule, I would not recommend putting more than 3 hours of video on a single layer DVD unless lower quality is acceptable.

[guns1inger]

Have a look at FAVC. Amongst it's many tricks and great encoder (HCenc) is it's ability to use Half-D1 and VCD resolutions when encoding and authoring. Use DVD to put up to three hours of reasonable quality on a single layer disc. If yu need to put more than this on a disc, you can use Half-D1 and put 4 - 5 hours on a disc. If you use VCD resolution you will get VHS-ish quality, but you can fit 7 - 7.5 hours on a disc.

[redwudz]

And to throw something in that wasn't really mentioned; If you started with a average 700MB Xvid off the net, you won't see much difference converting that to a 1.5GB DVD file or three 4GB DVD files. The quality has already been destroyed most times by the Xvid encode and the amateur encoder settings.

BTW, just to clarify, what software are you using for Xvid to DVD conversion?

And if you want to see what bitrates are used or needed for a specific encoder output filesize and running time, look into a bitrate calculator: https://www.videohelp.com/tools/sections/bitrate-calculators