x264: Why are b-frames turned off by default?

[pete]

Xvid uses 2 b-frames by default, x264 uses 0. Why? Is there any reason, not to use b-frames?

[Theliel]

by deffault? with x264 you can specify the number b frames with --bframes #. If you don't specific --bframes # in the command line or any gui, x264 won't use any bframes. Bframes are a options, its no sense/logic that when you invoque x264.exe for default and its use bframe.

furthermore, no all profiles support bframes, baseline profile dont support for example, or you simplely dont want use bframe for a faster encoder.

[akupenguin]

Everything is turned off by default. The closest thing to enabling stuff that I might consider would be a set of built-in presets, but I prefer to leave that to front-ends.

[buzzqw]

akupenguin is right, but i think that 5 profile (based on quality/speed tradeoff), and no more , will be gladly accepted

something like --preset fast, good, better, slow ,insane

this preset will set more parameter (like cabac, filter, ref,..)... but user can always override by specifing the value of these parameters

just my 0.02€

BHH

[pete]

Everything is turned off by default.
Then why are there options like:

--no-b-adapt
--no-cabac
--no-deblock
--no-chroma-me
--no-fast-pskip
--no-dct-decimate

???

[Bigmango]

akupenguin is right, but i think that 5 profile (based on quality/speed tradeoff), and no more , will be gladly accepted

something like --preset fast, good, better, slow ,insane

this preset will set more parameter (like cabac, filter, ref,..)... but user can always override by specifing the value of these parameters

just my 0.02€

BHH

/agree 100% , I have been waiting for this for a long time.

I also don't understand why there still is no good x264 gui (with settings as above, and the geeky stuff hidden behind advanced options). I guess this is the difference between good and bad gui design: professional consumer guis and guis made by geeks for geeks.

[Theliel]

Then why are there options like:

--no-b-adapt
--no-cabac
--no-deblock
--no-chroma-me
--no-fast-pskip
--no-dct-decimate

???

I belive that it is because some features were add after other. For example, --no-fast-pskip or --no-dct-decimate. In first time, x264 always used fast pskip, and later, the code was update to one more accuracy and slower so is necesary a new flag.

Other settings are necesary. For example, or you use CAVLC or you use CABAC, but you need use one or other. In this case, I suppouse that in x624 was selected CABAC because its better.

Yes, some features are "by default" but are diferent that use for example 2b frames.

And about a decent GUI for x624... I think that megui are very very complete. what other features do you want see? Megui work with profiles too and you can download a lot of them.

[Warpman]

[...]

And about a decent GUI for x624... I think that megui are very very complete. what other features do you want see? Megui work with profiles too and you can download a lot of them.
offtopic:
sorry but megui is far away from complete, x264 in "early devepment stage" is more mature than megui ever was.

There are >20 bugs on the tracker and nothing seems to get fixed.

Also its crashing for no real reason sometimes... and the startup is slow as hell... (no, .net is no excuse here)

compared to other cli generators, like belight, mkvmergegui or yamb, megui is a bad joke...

[buzzqw]

megui is an open source project you can contribuite with your effort!

also, there are other x264 gui, like staxrip, leiming or automkv

BHH

[Warpman]

sorry but i don't speak c# ;)
so submitting bugs is the only thing i can do... but it's kinda disappointing if there is no improvement at all...

[buzzqw]

and me too...

there isn't much progress... or at least seems.. but must be checked the svn...

megui is a very good program and if correctly used don't have so much bugs...

and with this end of OT :)

BHH

[akupenguin]

Then why are there options like:

--no-b-adapt
--no-cabac
--no-deblock
--no-chroma-me
--no-fast-pskip
--no-dct-decimate


Because those aren't really disabling anything. In each case, there's two alternative algorithms, and you have to pick one of them. The only exception is --no-deblock, because you shouldn't ever disable deblocking (it's only there for my convenience in debugging). Would you be happier if the options were named
--force-max-bframes
--cavlc
--luma-me
--slow-pskip
--simple-decimate
?

[Selur]

The cleanest, not the best, way would be to have e.g. --cavlc and --cabac with no default, but then people would ask for defaults. ;)