How do I calculate the size of the converting video?

[s_joy09]

Hi!
I have recently started to use VirtualDub and when I convert a video with Xvid as the compression codec I either get the converted one to be smaller or larger then the actual one.My question is how can I determine the size of the output video, I mean how do I calculate it ?
I hope there is a way !

Thanks for listening.

[manono]

You use a bitrate calculator, either the one built into XviD or perhaps the one here at videohelp:

https://www.videohelp.com/tools/VideoHelp_Bitrate_calculator

https://www.videohelp.com/calc.htm

[s_joy09]

Yeah!
Understood the bit calculation bit but suppose I am using VirtualDub, then where am I required to put the calculated bit rate to get my desired size on the video.

Let me put it this way-

I have a video file whose run time is 45 minutes and 16 seconds, and the size is 351MB. The audio is no good so I had converted an audio file ac3 whose size is 75 MB now I want to add the audio to the video using the Two Pass method for Xvid. But I don't want the saved file to be any larger than the original one, well give or take a few MB's.

How am I to go about ?

One more thing when taking the first pass can I use the 'Video analysis pass' option in the file menu rather than 'Save as Avi' and then take my second pass. Will it work this way too.

thanks & T.C.

[manono]

How am I to go about ?

At the risk of repeating myself, you use a bitrate calculator. I use the one in GKnot. You fill in the length of the video, the size of the audio, and the final size (in red), and it spits out the bitrate (in blue). Then you stick that number into the bitrate part of the XviD Configuration panel. Here are pics:

[filmboss80]

In VirtualDub, when you select Video>Compression, you will get a window that will list the codecs available. On the right side of that same window is a button that says "Configure." First, select your Xvid codec from the list on the left, then hit the configure button to calculate bitrate and do your settings. I would also convert the audio to mp3 instead of ac3. Mp3 works better with Xvid, while ac3 works better with MPEG-2.