Zep
29th December 2003, 11:52
I just did my first test of Beta 3 after loading the defaults to get a fresh good start
then my few changes etc... but the encode was way undersized. Ok no big deal
i thought, i will do it again and set b-frames to Q=2 instead of default Q=4 and encode
again. Same file size. way under. Hmmm....
So i decide to turn on debug stats window and run it again and watch. Pass one
was fine. All frames as expected were
i=2
p=2
b=2 (4 on default setting when I loaded defaults and did it again later)
b=2 (4 on default setting when I loaded defaults and did it again later)
Pass two was not fine. All frames were coming in around Q= 4 to Q=9 with most at
around Q=7. Bit rate was also way under what nic's calc was saying. 1720kb is what
the calc said for the final size i was inputing but only 860kb was being used during the
pass 2 encode and of course that lead to undersized file. I'm not talking a little undersized
here I'm talking it was about half the size it should have been and the bit rates above
back that up.
So I'm trying to figure out just how Xvid is using that first pass file which is so far off
from what is actually done in 2nd pass. Why is this? I thought Xvid used the numbers from
the first pass but it appears Xvid (at least beta 3 I never ran into this problem before) is not
even in the same ballpark.
Can someone explain how Xvid uses the first pass numbers and why are the second
numbers are so far away from the first pass numbers? What could be the problem?
Is there a way to get Xvid to save the 2nd pass stats? The first pass stats are useless to me
because they are not what is actually being done in the 2nd pass. i really want to see
what the final frame Q's are.
The thing that makes me go hmmm... the most is that the file is way undersized so we
know there is plenty of bits to be used but Xvid will not use them and sticks to the
Q=4 to Q=9 range seemly disregarding the first pass big time.
Thoughts?
NOTE: 2.4Ghz P4 running XP. Re install of Xvid did not help.
then my few changes etc... but the encode was way undersized. Ok no big deal
i thought, i will do it again and set b-frames to Q=2 instead of default Q=4 and encode
again. Same file size. way under. Hmmm....
So i decide to turn on debug stats window and run it again and watch. Pass one
was fine. All frames as expected were
i=2
p=2
b=2 (4 on default setting when I loaded defaults and did it again later)
b=2 (4 on default setting when I loaded defaults and did it again later)
Pass two was not fine. All frames were coming in around Q= 4 to Q=9 with most at
around Q=7. Bit rate was also way under what nic's calc was saying. 1720kb is what
the calc said for the final size i was inputing but only 860kb was being used during the
pass 2 encode and of course that lead to undersized file. I'm not talking a little undersized
here I'm talking it was about half the size it should have been and the bit rates above
back that up.
So I'm trying to figure out just how Xvid is using that first pass file which is so far off
from what is actually done in 2nd pass. Why is this? I thought Xvid used the numbers from
the first pass but it appears Xvid (at least beta 3 I never ran into this problem before) is not
even in the same ballpark.
Can someone explain how Xvid uses the first pass numbers and why are the second
numbers are so far away from the first pass numbers? What could be the problem?
Is there a way to get Xvid to save the 2nd pass stats? The first pass stats are useless to me
because they are not what is actually being done in the 2nd pass. i really want to see
what the final frame Q's are.
The thing that makes me go hmmm... the most is that the file is way undersized so we
know there is plenty of bits to be used but Xvid will not use them and sticks to the
Q=4 to Q=9 range seemly disregarding the first pass big time.
Thoughts?
NOTE: 2.4Ghz P4 running XP. Re install of Xvid did not help.