Welcome to Doom9's Forum, THE in-place to be for everyone interested in DVD conversion.

Before you start posting please read the forum rules. By posting to this forum you agree to abide by the rules.

 

Go Back   Doom9's Forum > Video Encoding > MPEG-4 AVC / H.264

Reply
 
Thread Tools Search this Thread Display Modes
Old 26th October 2009, 21:57   #1  |  Link
Forteen88
Herr
 
Join Date: Apr 2009
Location: North Europe
Posts: 416
b-pyramid modes quality-difference?

About how much quality-difference is it between the b-pyramid modes (normal and strict)? Is 'normal'-mode like going from me-umh to me-tesa (almost placebo quality-difference), or is it bigger change?
I guess it depends on which source also.
EDIT: Ok, thanks DS! I guess it's more quality-difference than going from me-umh to me-tesa then

Last edited by Forteen88; 26th October 2009 at 22:08.
Forteen88 is offline   Reply With Quote
Old 26th October 2009, 22:00   #2  |  Link
Dark Shikari
x264 developer
 
Dark Shikari's Avatar
 
Join Date: Sep 2005
Posts: 8,689
Strict is always worse than normal and should never be used unless you absolutely need it.
Dark Shikari is offline   Reply With Quote
Old 27th October 2009, 18:40   #3  |  Link
shon3i
BluRay Maniac
 
shon3i's Avatar
 
Join Date: Dec 2005
Posts: 2,426
What is averge gain in percent of quality with normal b-pyramid? i think than strict have no sense then if not have at least of 80% power as normal mode.
shon3i is offline   Reply With Quote
Old 27th October 2009, 22:48   #4  |  Link
juGGaKNot
Registered User
 
juGGaKNot's Avatar
 
Join Date: Feb 2008
Posts: 733
strict is for blu-ray, normal is for the rest, what are you asking ?
__________________
Quote:
Originally Posted by Dark Shikari View Post
If they can beat x264 in visual quality on ordinary test clips without postprocessing, I'll eat my hat.
juGGaKNot is offline   Reply With Quote
Old 28th October 2009, 09:55   #5  |  Link
egrimisu
Registered User
 
egrimisu's Avatar
 
Join Date: Jan 2008
Location: Romania - neighbor of Dracula
Posts: 327
Quote:
Originally Posted by juGGaKNot View Post
strict is for blu-ray, normal is for the rest, what are you asking ?
does MB-tree work with b-pyramid? if no what to chose MB tree or b-pyramid normal?
__________________
I7 920 @ 3.60GHz + Thermalright Ultra 120 Extreme
Asus P6T Deluxe, 6GB Corsair XMS3 1600MHZ 8-8-8-24
2x1TB Samsung + 1x500GB Samsung,
Corsair 520W, Thermaltake Soprano DX
GeForge GTX280
egrimisu is offline   Reply With Quote
Old 28th October 2009, 10:19   #6  |  Link
nm
Registered User
 
Join Date: Mar 2005
Location: Finland
Posts: 2,643
Quote:
Originally Posted by egrimisu View Post
does MB-tree work with b-pyramid?
Not yet, but maybe soon.

Quote:
if no what to chose MB tree or b-pyramid normal?
MB-tree. Use presets if you don't know what you're doing.
nm is offline   Reply With Quote
Old 28th October 2009, 13:49   #7  |  Link
juGGaKNot
Registered User
 
juGGaKNot's Avatar
 
Join Date: Feb 2008
Posts: 733
It will soon, ask dark when, i see 0.5 lower qp with mb-tree than with b-pyramid normal on my source.
__________________
Quote:
Originally Posted by Dark Shikari View Post
If they can beat x264 in visual quality on ordinary test clips without postprocessing, I'll eat my hat.
juGGaKNot is offline   Reply With Quote
Old 28th October 2009, 15:57   #8  |  Link
RainyDog
Registered User
 
Join Date: May 2009
Posts: 176
Quote:
Originally Posted by juGGaKNot View Post
It will soon, ask dark when, i see 0.5 lower qp with mb-tree than with b-pyramid normal on my source.
Juggaknot, is that qcomp=0.5 or 0.5 less than the standard setting (qcomp=0.1)? Just curious as I preferred a lower qcomp value with mbtree on my tests as well (all film sources). I found the bitrate distribution was far too aggressive otherwise, sometimes with double the peaks of no-mbtree and in turn half as many, or even less than that, bits in dark/still scenes that clearly needed more.
RainyDog is offline   Reply With Quote
Old 28th October 2009, 16:54   #9  |  Link
juGGaKNot
Registered User
 
juGGaKNot's Avatar
 
Join Date: Feb 2008
Posts: 733
Quote:
Originally Posted by RainyDog View Post
Juggaknot, is that qcomp=0.5 or 0.5 less than the standard setting (qcomp=0.1)? Just curious as I preferred a lower qcomp value with mbtree on my tests as well (all film sources). I found the bitrate distribution was far too aggressive otherwise, sometimes with double the peaks of no-mbtree and in turn half as many, or even less than that, bits in dark/still scenes that clearly needed more.
not qcomp, qp, as in average qp ( or final ratefactor smaller by 0.5 )

default is 0.6

BTW Raising qcomp lowers MB-tree strength

so less qcomp = more mbtree
__________________
Quote:
Originally Posted by Dark Shikari View Post
If they can beat x264 in visual quality on ordinary test clips without postprocessing, I'll eat my hat.

Last edited by juGGaKNot; 28th October 2009 at 17:00.
juGGaKNot is offline   Reply With Quote
Old 28th October 2009, 17:44   #10  |  Link
RainyDog
Registered User
 
Join Date: May 2009
Posts: 176
Quote:
Originally Posted by juGGaKNot View Post
not qcomp, qp, as in average qp ( or final ratefactor smaller by 0.5 )

default is 0.6

BTW Raising qcomp lowers MB-tree strength

so less qcomp = more mbtree
Ok, cheers for clarifying. Yeah, I was aware that less qcomp=more mbtree and visa versa. But from all my tests, I found that lower qcomp led to less 'aggressive' bitrate distribution using mbtree, if that's the right word. Which led to compression balanced more akin to no-mbtree, at least for my sources (Blu-Ray, film). Though I don't claim to know whether it would even be possible, I still think it'd be ideal to have an mbtree rate control that was independent of qcomp...
RainyDog is offline   Reply With Quote
Old 28th October 2009, 20:29   #11  |  Link
shon3i
BluRay Maniac
 
shon3i's Avatar
 
Join Date: Dec 2005
Posts: 2,426
Quote:
Originally Posted by juGGaKNot View Post
strict is for blu-ray, normal is for the rest, what are you asking ?
I ask, what is point of B-pyramid strict then if incrase of quality is almots zero, or half of normal mode or anything?
shon3i is offline   Reply With Quote
Old 28th October 2009, 20:37   #12  |  Link
LoRd_MuldeR
Software Developer
 
LoRd_MuldeR's Avatar
 
Join Date: Jun 2005
Location: Last House on Slunk Street
Posts: 13,073
B-Pyramid enabled will compress more efficient than B-Pyramid disabled. This applies to both modes, "normal" and "strict". But "normal" mode is even better than "strict" mode.

So if you can't use "normal" mode (e.g. BluRay compatibility is required) then it's still better to use "strict" mode than nothing. Otherwise you'd prefer "normal" mode

However it should be noted that at the moment MB-Tree RC will completely disable B-Pyramid anyway, no matter what mode you select. Unless you disable MB-Tree, of course.

Therefore this topic will become more important once MB-Tree starts supporting B-Pyramid...
__________________
There was of course no way of knowing whether you were being watched at any given moment.
How often, or on what system, the Thought Police plugged in on any individual wire was guesswork.



Last edited by LoRd_MuldeR; 28th October 2009 at 20:41.
LoRd_MuldeR is offline   Reply With Quote
Old 28th October 2009, 20:54   #13  |  Link
Dark Shikari
x264 developer
 
Dark Shikari's Avatar
 
Join Date: Sep 2005
Posts: 8,689
Quote:
Originally Posted by LoRd_MuldeR View Post
B-Pyramid enabled will compress more efficient than B-Pyramid disabled. This applies to both modes, "normal" and "strict". But "normal" mode is even better than "strict" mode.
Not necessarily true. Though I can't say for sure until I write MB-tree support for B-pyramid and do some optimizing of the quantizer offsets, it's possible that strict will be worse than none in some cases.
Dark Shikari is offline   Reply With Quote
Old 28th October 2009, 20:55   #14  |  Link
LoRd_MuldeR
Software Developer
 
LoRd_MuldeR's Avatar
 
Join Date: Jun 2005
Location: Last House on Slunk Street
Posts: 13,073
Quote:
Originally Posted by Dark Shikari View Post
Not necessarily true. Though I can't say for sure until I write MB-tree support for B-pyramid and do some optimizing of the quantizer offsets, it's possible that strict will be worse than none in some cases.
Good to know. Even more reason to stick with "normal", if possible
__________________
There was of course no way of knowing whether you were being watched at any given moment.
How often, or on what system, the Thought Police plugged in on any individual wire was guesswork.


LoRd_MuldeR is offline   Reply With Quote
Old 28th October 2009, 22:55   #15  |  Link
RainyDog
Registered User
 
Join Date: May 2009
Posts: 176
Is b-pyramid normal any better/more efficient than the old b-pyramid?
RainyDog is offline   Reply With Quote
Old 28th October 2009, 23:09   #16  |  Link
LoRd_MuldeR
Software Developer
 
LoRd_MuldeR's Avatar
 
Join Date: Jun 2005
Location: Last House on Slunk Street
Posts: 13,073
Quote:
Originally Posted by RainyDog View Post
Is b-pyramid normal any better/more efficient than the old b-pyramid?
The "normal" B-Pyramid in current x264 is like to the "old" B-Pyramid, but spec compliant. Only "strict" mode is really new.
__________________
There was of course no way of knowing whether you were being watched at any given moment.
How often, or on what system, the Thought Police plugged in on any individual wire was guesswork.



Last edited by LoRd_MuldeR; 28th October 2009 at 23:13.
LoRd_MuldeR is offline   Reply With Quote
Old 28th October 2009, 23:12   #17  |  Link
Dark Shikari
x264 developer
 
Dark Shikari's Avatar
 
Join Date: Sep 2005
Posts: 8,689
Quote:
Originally Posted by LoRd_MuldeR View Post
The "normal" B-Pyramid in current x264 is identical to the "old" B-Pyramid.
No it isn't. It's worse than the old pyramid (albeit spec-compliant). It's probably only marginally worse though, nothing that seriously matters.
Dark Shikari is offline   Reply With Quote
Old 28th October 2009, 23:16   #18  |  Link
LoRd_MuldeR
Software Developer
 
LoRd_MuldeR's Avatar
 
Join Date: Jun 2005
Location: Last House on Slunk Street
Posts: 13,073
Quote:
Originally Posted by Dark Shikari View Post
No it isn't. It's worse than the old pyramid (albeit spec-compliant). It's probably only marginally worse though, nothing that seriously matters.
Argh, he's replying faster than I can edit
__________________
There was of course no way of knowing whether you were being watched at any given moment.
How often, or on what system, the Thought Police plugged in on any individual wire was guesswork.


LoRd_MuldeR is offline   Reply With Quote
Old 29th October 2009, 00:18   #19  |  Link
Trahald
Wewkiee
 
Trahald's Avatar
 
Join Date: Feb 2002
Location: kashyyyk
Posts: 2,270
Quote:
Originally Posted by LoRd_MuldeR View Post
The "normal" B-Pyramid in current x264 is like to the "old" B-Pyramid, but spec compliant. Only "strict" mode is really new.
'Spec Compliance' involves making sure there is a spot in the dpb for possible delayed display time of a b-frame.

That part of normal involves removing frames from the dpb which leaves less references hurting quality. Normal only does it when it absolutely must (which is not every minigop especially when badapt == 1/2 is used.) But often enough to hurt quality a bit

Strict maintains h264 spec compliance by doing the following. After its bframes refer to it, bref is removed to maintain hierarchy (blu-ray requirement), then the frame with the lowest poc for spec compliance (even when there are no delayed frames that gop since its 'strict' )
__________________
...yeah...but...why on earth would I compare apples with apples?
Trahald is offline   Reply With Quote
Old 5th November 2009, 17:49   #20  |  Link
benwaggoner
Moderator
 
Join Date: Jan 2006
Location: Portland, OR
Posts: 3,064
Do we have any sense about the general relative value of B-pyramid versus MB-Tree? Since they're exclusive choices for the moment, any sense on what the appropriate choice would be.

Anime/animation/motion graphics clearly get a huge MB-tree win and so that should be a slam dunk, but what about film/video? Any cases where we're better off with B-pyramid?
__________________
Ben Waggoner
Principal Video Specialist, Amazon Prime Video

My Compression Book
benwaggoner is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +1. The time now is 03:42.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, vBulletin Solutions Inc.