is it good to use B-frames above 2000kbit/s ?

[dihelson]

Hello, friends,

Since I use almost 2 or 3 CDs for my Xvid, which tends to above 2000kbit/s, I would like to know if it's a good idea to use B-frames at all. Or to disable it by putting -1. Would I have a better quality?
Sometimes my xvid files are a bit undersized, for instance, I try to make it for 3 CDs, and get a 1600Mb file size...With disabling B-frames should I get a big file AND BETTER quality ?
And what about quarterpel ? is it good to use around 2000Kbit/s also?
Since I saw in Snowbeach guide, quarterpel is best for low bitrates...

Thanks in advance,
Dihelson

[Sigmatador]

Well, on a movie, i don't think bframe 1/100/0/0 is going to hurt the quality ^^, but on anime yes you can disable it at this bitrate.

[Asmodian]

I don't like B-frames on high bit rate encodes because of the slight flicker due to the quant fluctuations if the ratio and offset are set high enough to significantly effect the size. Of course B-frames are not a good idea if you are getting undersized files except maybe at 1/0 and then they don't change very much.
I don't know if B-frames are good at 1/0 it seems like they should but I decided not to use them for easy of playback (now somewhat theoretical problem because I use matroska too...).
Does anyone know anything about B-frames at 1/0?

I have read here, though I forgot who wrote it, that the I/P decision was better in the new (I/P/B capable) 'one' so you could try a max B-frame setting of 0 instead of -1.

[sysKin]

Originally posted by Asmodian
I don't like B-frames on high bit rate encodes because of the slight flicker due to the quant fluctuations [...]The filckering is caused by ffdshow's postprocessing. The video itself is perfectly flicker free :)

Radek

[V-tec]

IMHO, the good use of b-frames doesn't depend so much on the bitrate but by the compressibility of the source and by the compression that I want to do, (1, 2 or more CD).
There are some movies, for example Matrix, The EYE... that you can compress for 2 CD @ 608*xxx pixels with quantizer = 2 without B-f and the final size is 1.1 gb (the bitrate is more or less 1100Kbps..) and looks perfect.

They are instead other films that is so bright and fast that if don't use the b-frames, also at high bitrates don't give exceptional results...

I generally make some tests of compressibility with and without b-frames, and if it comes out that compressibility is too low I use b-frames.

[mf]

Originally posted by sysKin
The filckering is caused by ffdshow's postprocessing. The video itself is perfectly flicker free :)

Radek
Actually it's the ffdshow mplayer postprocessing. I got annoyed at this way back and now since use Nic's (in ffdshow) instead.

[dihelson]

Originally posted by mf
Actually it's the ffdshow mplayer postprocessing. I got annoyed at this way back and now since use Nic's (in ffdshow) instead.

FFDSHOW also caused me serious problems in playback, after putting subtitles the film runs skipping...
I then ununstalled FFDSHOW, and solved my problem.

Dihelson

[trodas]

I nevee ever used this feature and never ever had a major issue with FFD show filters. Well, there are some missing things and one problem with IDCT (simple IDCT cause some color shifts into DivX4,5 and Xvid movies, while Xvid IDCT not, but tend to make bars into DivX3 movies. And there is not automatical IDCT change depending on movie - yet), but so far, i never run wrong with FFD show.
And i never ever used ANY postprocessing.

In fact, the second and LAST for me - missing thing into FFD show is, that it should be albe to disable default deblocking - this is possible to do with deleting one *.ax file into DivX and then the picture looks like miracle - much nicer and sharper and cleaner - unfortunately it can't be resized, so that's why it get blurred a little, to do not show jagged edges on resize.
But this is ofcourse wrong approach.
Its better to allow BSplayer to change resolution to the resolution of movie, that blur & resize (thus blur even more!) the movie...

Well, one have to enable doublescan for this.
No clue what the doublescan is? Check there:
http://trodas.mujhost.cz/doublescan/