bitrate calculaor formula

[dimaj]

Hello everybody!

I am pretty much a newbie to divx and it's been my experience that the bitrate calculators are not very accurate.
So, i wanted to make my own. The problem is that i don't know a formula, which is uded to find out the bitrate to make a file x mb big. So, could anyone help me out by giving this formula?
Also, what is the main difference in bitrate between Divx 4.xx and Divx 5 Pro?

thank you very much,

dimaj

[benderman]

Most bitratecalculators are very accurate. The only problem is that the most codecs normaly produce a few MB more or less than they should. The difference with the codecs depends on the way they interpret a KB. In DivX3.11 1KB is 1024Byte, in DivX4.xx KB is 1000Byte and I don't know what the other codecs use.

If you want to make a calc on your own the formula is very simple:

filesize[in kilobyte]*8 / time [in seconds] = bitrate [in kbps]

That's really simple, isn't it? The resulting bitrate includes the video- and audio-bitrate.

[dimaj]

seems easy

thank you very much for your reply!

So, what you are saying that if I want to encode with DivX 4.xx and my desired filesize is: 600MB, I should enterpret 1MB as 1000Bytes?
and have a formula:
600*1000*8/(# of secs)=result

correct?

and what 8 stand for in this formula?

thank you very much

dimaj

[benderman]

1 Megabyte=1024 Kilobyte
1 Kilobyte = 8 Kilobit

The problem is the calculating from kilobyte to (kilo)bit. 1 kilobit is 1000 bit while 1 kilobyte is 8*1024=8192 bit and NOT 8000 bit. That differs from codec to codec.The formula is correct for DivX3.11 but if you use DivX4.xx you must multiplicate the result with 1024/1000.