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Old 13th August 2005, 20:36   #16  |  Link
DeathTheSheep
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To find out what bitrate to use, start out by asking yourself what the maximum should be. For instance, if I wanted to encode The Matrix 3, I'd probably set aside 2 CDs to acheive the maximum quality. Then use a bitrate calculator (like the one in xvid).

But, if you wanted a more exact bitrate based on quality, try to take a sample of the source (make it a fairly large) and encode it with your desired QP. With the resulting file, perform this calculation:

{ (# of MB in file x 1024) / (# of seconds in file) } x 8 = (Average Bitrate)

This will give you an average bitrate for the quality you desired.

An example: I take out 10 minutes of a cool scene in the middle and encode it with a quantizer of 22, 26, and 28. I find that the file with the quantizer of 26 fits my liking, so I apply my formula to it. With the resulting bitrate, I encode the entire movie in 2-Pass mode with the "High Speed, High Quality" mode above.

Of course, if you knew your target size (ex: you wanted to fit your content fit to two CDs), use the following formula:

( {(target MB x 1024) / (# of seconds in video)} x 8 ) - (audio bitrate) = (bitrate needed)

Cheers.
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