[XviD-devel] BUG: real n-vops with b-frames combination b0rks

[bond]

for a long time xvid didnt insert real n-vops into the video stream when
b-frames have been enabled (be it packed bitstream or not). since 1.1 this
has been changed
you can get xvid to insert real n-vops by increasing the framedropratio
option (maximum is a value of 100)

i made various tests with the framedropratio option and i noticed that in
the case xvid inserts real n-vops together with b-frames things are not
correct because of four reasons:
1) the amount of real n-vops is different whether i use packed bitstream or
whether i dont (counting of course only the real n-vops, not the fake ones
caused by packed bitstream)
2) the second problem is that the frametypes should be exactly the same no
matter if packed bitstream is used or not, but when getting xvid to insert
real n-vops this isnt true anymore, as the frametypes differ between using
packed and not using it, altough all other settings are the same
3) the third problem is that when getting xvid to insert real n-vops the
targeted bitrate isnt hit at all anymore in 2pass.
4) apart from that the final bitrate isnt hit it also differs clearly
between the stream using packed bitstream and the stream not using (target
bitrate was 700kbps, the packed stream had 800kbps, the not packed one had
850kbps)

all these problems are not the case if xvid does NOT insert real n-vops in
the stream, which tells me that this new feature of combining real n-vops
with b-frames does not work correctly

i hope this can either be fixed or reverted to the old stage, where
inserting real n-vops was simply disabled when using b-frames

thx


ps: i am obviously not counting the fake n-vops here inserted by packed
bitstream. i am talking about real n-vops