Bug?: Celtic Druid 1.1 Build 10 January 2005

[ChronoCross]

ok correct me if I am misunderstanding the way this is supposed to work but if I turn the bvop sensitivity to 30 isn't it supposed to use a significantly greater number of bframes than if the sensitivity is 0? If that's the case then shouldn't the encode gain greater compressability with the expense of quality?

I tested this theory out and came up with an interesting result. The encode actually grew in size by 55MB from the previous test I had ran. Here are my settings

H.263
qpel
GMC
Bvops 2 1.5 1.0
No Packed Bitstream
No Trellis
No Cartoon Mode
Chroma Optimization
B-Vop Sensitivity 30
VHQ 4
Motion Search 6
VHQ for BVOPS
Keyframes every 240 frames
NO Turbo

any idea's why this may be occuring?

[Leak]

Originally posted by ChronoCross
any idea's why this may be occuring?

I'd say it's because when inserting more B-frames the P-frames will also grow, as the difference to the previous P-frame is bigger than without the B-frames - I guess you overdid it, and as a result the size increase of the P-frames was bigger than the bits saved by using B-frames.

np: Zorn - Deconsoled (The City's Collapsing (But Not Tonight))

[ChronoCross]

well that makes sense although if b-frames are directly causing the inflation of the p frames then there really isn't any benefit to increasing the bvop sensitivity in most cases. Anyone got any ideas of what would be a good value to use ( from their own practical testing )? i have tried 10 which produces a 6MB increase in size and 30 which increases it by my previously mentioned 55MB's. Has anyone else dealt with bad results from increasing the sensitivity? Are there any real benefits to lowering the sensitivity to a negative value? Thanks in advance.

Edit: Also I was wondering how the xvid takes the sensitivity into account? is it a percentage or what?

[Sharktooth]

The DEFAULT settings!!!

[Leak]

Originally posted by Sharktooth
The DEFAULT settings!!!
Yep - what he said.

np: Zorn - Nachtbus (The City's Collapsing (But Not Tonight))

[ChronoCross]

lol at this point I wasn't worried about quality/size I just wanted to test all the options of xvid. see what affected what. at this point I'm pretty sure that bvops sensitivity is pretty much useless.

[Didée]

at this point I'm pretty sure that bvops sensitivity is pretty much useless
Did you notice that BVOP sensitivity is a *zone* setting, not a global one? :)

[Selur]

it might also help to modify the overflow settings if one changes the bvop sensitivity,...

[ChronoCross]

Originally posted by Did�e
Did you notice that BVOP sensitivity is a *zone* setting, not a global one? :)

yeah I did. I set it to sone the entire clip. I wanted to see what the results overall were.