bitrate calculaor formula

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  • dimaj
    Junior Member
    Junior Member
    • Feb 2002
    • 7

    bitrate calculaor formula

    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
    Digital Video Specialist
    Digital Video Specialist
    • Nov 2001
    • 770

    #2
    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.
    don't trust in guides

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    • dimaj
      Junior Member
      Junior Member
      • Feb 2002
      • 7

      #3
      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

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      • benderman
        Digital Video Specialist
        Digital Video Specialist
        • Nov 2001
        • 770

        #4
        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.
        don't trust in guides

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