Help with calculating bitrates when converting from Xvid?

[digital_frog]

Wondering if someone can help with this bc I'm a bit confused.

First off I use tmpgenc to convert xvids/divxs to vcd/svcd/dvd. Typically the source files are between 700-1100 kb/s and resolutions vary (.e.g. 576x304, 352x288 etc etc). What I want to ask is what determines whether an divx/xvid avi is worth making into vcd/svcd or dvd? Bitrate or resolution?

For example, a xvid file that is 576x304 @ 800 kbps, is it worth making it into an svcd? Or am I just wasting bitrate that won't improve the end file? It would be very useful is someone could post a rough guide on converting xvid/divx bitrates to help decide, for example:

600-800 kb/s xvid should be converted to vcd @ 1150
800-1100 kb/s xvid should be converted to svcd @2520
? - ? kb/s xvid should be converted to dvd @ 6000 kbps etc

Thanks in advance for any replies.

DF

[bugster]

There is absolutley no reliable way of correlating divx/xvid bitrates with mpeg-1 or mpeg-2 bitrates.

As to wether a particular file is worth converting to (S)VCD or DVD, only you can really decide as its your time and effort we are talking about.

As a rough guide, for a 100 min movie, if it is 1 CD's worth of XVID (700Mb) , VCD will be OK, it may be worth SVCD. If the same movie is two CD (1400Mb) it may well be worth DVD, if it was well encoded and is not an all action type movie. An all action, special effects type movie needs 3 CD's to get close to DVD quality.

But thats just my opinion.

[feenix]

Difficult one because it can also depend on where you obtained your source(xvid) from.

For example, if you have a downloaded 800kbps file it may be nowhere near as good as a file you've encoded yourself at the same bitrate from a decent source.

Also it can depend on the movie - a 'talking heads' type of film with very little action requires a lower bitrate to keep good quality. Whereas a high action movie or movies with lots of running water scenes will require more bitrate to preserve quality.

One thing I will say is that an Xvid/divx encoded properly at a reasonable bitrate will be much better that a VCD.

Doesn't really answer your question but just some other things to consider.

Perhaps you have to judge yourself by watching the xvid and if you think that quality wise it's pretty damned good then go for the format you think will do it justice.