• Apple Final Cut Pro Legacy

  Compressor Question

  Posted by Derek Natzke on July 10, 2006 at 3:24 pm

  I have heard the term Constant Bit Rate. Is that the same as “One Pass”? (I am using Compressor 2). My next question is, what bit rate is safe to use for CBR to get the best compression and lets say there is a lot of motion in the spot. I have heard a bit rate of 8 is safe.
  Are there any added advanteges to using VBR? I heard it takes longer. Is the compression really any better?

  Thank you for your time,
  Derek

  Bill Kelly replied 19 years, 10 months ago 2 Members · 1 Reply
• 1 Reply

• 

  Bill Kelly

  July 10, 2006 at 4:01 pm

  1. Yes, Constant Bit Rate is the same as One Pass. The video is encoded at a constant bit rate during the one pass. One Pass VBR is NOT a constant bit rate. VBR stands for Variable Bit Rate.

  2. The general rule of thumb is that if your project is an hour or less, encode at a constant bit rate of about 6.5 or 6.7. Some older DVD players start to act funky when the bit rate is 7 or more, so it pays to err on the side of caution. You don’t really notice much of a difference, if any, between something encoded at 6.7 and something encoded higher.
  If your project is more than an hour, encode with Two Pass VBR. One the first pass, Compressor analyzes your movie and determines when it can best use a low bit rate (for example when you fade to black, it doesn’t require as much information to be encoded as when you have a scene with a lot of colors and motion.) and when it needs to use a high bit rate. On the second pass, it encodes based on the information it gathered on the first pass, making best use of it. Make sure to set your maximum bit rate at about 6.7 when you encode using VBR, or the aformentioned playback problem may occur if the bit rate goes over 7.

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