Comments

musicvid10 wrote on 11/26/2008, 9:31 AM
Two-pass rendering is a VBR option only. Compression look-ahead is not needed for CBR.

Two-pass rendering can give you a better picture where there is action / motion or tight detail in your movie, but I rarely use it because it takes a lot of extra time to render.

For setting your average / max bitrates sensibly, do a search on this forum. There is lots of good advice around here.
blink3times wrote on 11/26/2008, 10:00 AM
"Also, do you prefer Variable Bit Rate or Constant Bit Rate?"

It depends on whether or not your concerned about disks space. Most of the time when working with HDV (which has a bit rate of 25M) I use CBR (28M) because it's a faster render. But cbr can be a bit wasteful with the bits. 2 pass vbr on the other hand can distribute bits in a more efficient manor so it's better if you're concerned about disk space... but it's also a longer render time.

I had similar questions and here's the thread... some good info here:

http://www.sonycreativesoftware.com/forums/ShowMessage.asp?ForumID=4&MessageID=625100
Terry Esslinger wrote on 11/26/2008, 10:07 AM
It would seem to me that if your program is short enough that using a high constant bit rate would be the way to go (8,000,000). But as the program gets longer the file gets bigger and a way to limit the file size is to lower the bit rate. As you lower a CBR the quality degenerates. But if you could use a variable bit rate (VBR) and use higer rate where there is more action (motion) and thus more information is needed and a lower bit rate where very little action is taking place, the quality degradation would be much less.. A two pass VBR is like a 'smart' VBR. It looks ahead (actually reads the material twice) so that it knows where it can make the changes and how much it needs to change so that it can save the bits it would normally use in low motion areas and use them in high motion areas. This double read is why it takes longer.
WARNING: I am in no way an expert in this matter and I could be totally off-base, but thats the way I read it.
John_Cline wrote on 11/26/2008, 11:33 AM
Terry, that is an accurate description of the reasoning behind 2-pass VBR.