The Coolness of B-Frames

[DeathTheSheep]

My final word:

at lower bitrates B-frames are much better at increasing quality

False!

The results are a lot better with lower quant than those obtained with a higher B-framed quant at the same filesize...(In terms of blocking and overall quality)

True as rain, baby.

[Manao]

But will you quit falling always to the same (wrong) conclusion ? You're judging something with the wrong tools, so the results are expected.

[DeathTheSheep]

Wrong tools? ...

Oh, that explains it...

I knew B-frames were too crappy to be true in my tests...*sigh*

So how can I go about finding the right tools? I'm curious now...

[bond]

to get correct deblocking on b-frames you have to do the following:

1) avi -> raw with mpeg4ip's avi2raw tool
2) raw -> mp4 with mpeg4ip's mp4creator tool (make sure to use the latest version (~1 day old))
3) decode with nero's dshow .mp4 parser and decoder

Originally posted by SeeMoreDigital
All the samples are Mpeg4/AVC (VideoSoft H.264 Codec 2 to be more precise).

nope they have been encoded with x264 (only the fourcc has been changed to VSSH)

[dragongodz]

quote:"at lower bitrates B-frames are much better at increasing quality"

False!

no not false at all. try an easy experiment. make 2 encodes with xvid with full framerate and a reasonable frame size(lets say atleast 352x288/240) and set a smallish target size(something that should average around 400kbs would be good). do 1 with Bframes and 1 without, THEN you may see Bframes do actually work.

I knew B-frames were too crappy to be true in my tests...*sigh*

your test ,as has been already said by many, is the problem. at the ridiculously low bitrate nothing looks good and there is not enough detail left for motion vectors to make any sane decisions, Bframes OR Pframes, Bframes just get screwed up worse in this example.

The main advantage of the b-frames is not the detail gain, but the better motion handling imo

and the better detail preservation gained from the better motion handling ?

there are still problematic blocks, but i think it's just due to the immature b-frame ME in x264

yes i already said Bframes are the least mature part of x264 and in another thread akupenguin reccomended only using 1 Bframe for the time being because of it. so saying Bframe as a whole are bad or whatever is plain wrong of course, which i dont think DeathTheSheep is ever going to understand. so i wont bother again here, i have better things to do than waste time convincing 1 person they dont know what they are talking about.

[DeathTheSheep]

Bframes are the least mature part of x264

True. I confess. I'm starting to see things clearly (glaucoma clearin' up, heh, lol).

akupenguin reccomended only using 1 Bframe for the time being because of it

...Although I did only use one in my higher bitrate tests, still, yeah, I get the picture.

so saying Bframe as a whole are bad or whatever is plain wrong of course...

Well, I never actually said that they were bad as a whole. But yeah, I did complain about the blocksing and all that, so I suppose. NERO has a good deblocking postfilter, which bond explained how to use (and fairly well, too!).

is plain wrong of course

...

Eheh, beleive it or not (likely not, but who beleives sheep these dayz?), I'm truly not the only person who thinks that. Many folks I know who are partially involved in video encoding push against B-frames.

which i dont think DeathTheSheep is ever going to understand

Hey, I understand now! Ease off, man! I'm second person here, too... <[ sweat bead ]> Eheh...

PS
Although I'd recommend dragongodz read the thread a bit more thoroughly... I suppose you'd see that I didn't just test at ridiculously low bitrates. I did one at "near Bearable" quality, too (to my eyes, heh, which means quantizer ~30, which is recommended for x264.)

Originally posted by DeathTheSheep
Although I'd recommend dragongodz read the thread a bit more thoroughly... I suppose you'd see that I didn't just test at ridiculously low bitrates. I did one at near perfect quality, too (to my eyes, heh, which means quantizer ~30, which is recommended for x264.)

If that's considered "perfect quality" you are again having a case of glaucoma or you are just plain blind. Even that quant 30 encode looks pretty blocky with or without b-frames. The difference being that the p-frame is being deblocked while the b-frame is not, but even with the smoothing the blocking is still quite apparent in the p-frame. If the b frame was being deblocked I'd be willing to bet that they would look almost the same. Besides comparing a P frame to a B frame is a pretty meaningless comparison considering the conditions (the p-frame is not only a lower quant but is being deblocked) which would be like comparing an I frame to a P frame and saying that P frames suck cause they don't look as good as the I frame (again a ridiculous conclusion considering the comparison).

[DeathTheSheep]

Heh, sure. To each his own, as becomes apparent in this thread... lol

Yeah, even I can admit it's far from perfect...I just tried to get something that you guys would consider "bareable" or even "watchable for short periods of time without headaches" heh. Yeah, I admit, it's pretty far from perfect. I'll edit that out! Ya gotta love computers...

I hereby place a request to moderate the "glaucoma" forum.

[Shinigami-Sama]

Originally posted by Dhampir
Here is where the samples are. They are quite hideous to watch whether they have b-frames or not.

I'm ging to agre with sheep ehre
the b frames do look like crap
but I also have very sensitves eyes
even though I had shitty glases 0_o
anyways
but hte problem is hte bitrate is to low for acurate b-frame vectors
so hte de/edncoder doesn't know what hte hell do with b-frames
and it kinda can't increase the quants anymore because you seem to have hith te limit
also
with b-frames I can only read about 1/2 hte subs
and your audio blows even for that small a file size
I wonder what happened htere
but a certain plant help glacoma sheep
maybe you wer useing a bit to much medicine when encoding/watching these eh sheep?

Originally posted by Shingami-Sama
I'm ging to agre with sheep ehre
the b frames do look like crap

But the P and I frames look like crap as well.

[Shinigami-Sama]

but with that being said
it means the b-frames will look worse
seeing as how they;re hte more or les byproduct of hte p and i frames
there isn;t enough data left to justify useing b-frames at that low of a bitrate

[SeeMoreDigital]

I think this thread has run its course and should be closed now... It's doing more harm than good!

Both RadicalEd and Skal have pointed out why the original posters B-VOP comments are based on flawed assumptions!

In essence... DeathTheSheep's B-frames look poor because his I and P "reference" frames were poor to begin with!

[Elias]

Originally posted by DeathTheSheep
Yeah, I've heard all the hype. I see it written about in posts all the time. Never a day does pass without questions pertaining in some form or another to B-Frames ("When are B-Frames gunna be enabled for AVC?!!!!"). But now I must ask, what the heck is up with B-frames anyway?

I heard they are a form of bidirectional frame encoding/rendering. At this, I scratched my head long and hard and almost pulled a "pancake bunny." So what?!

B-Frames are complicated, they take long to encode, they are BLOCKY as HECK, and they increase filesize. Need I upload a sample with and without B-Frames fer y'all to see? Why don't people stick to the IPPPPPPPIPIPPPPPPPPPP... method? Complexity? If so, I don't see it.

So what is all this B-Frame craziness? What use to they serve? Or are they only useful at collosal bitrates (yeah, I'm livin the >56kbps road)? NeeheeharharharHAR.... No, seriously,
Inform Da Sheep Afore He A-Kills Hisself...BAAAa

Wow, was that English? I'm impressed, you should become a literature writer. As for B-Frames, they're good. The image becomes somewhat softer, as (opposed to sharper) but you loose lots of macroblocks. So, conclusion is to not use B-Frames with higher bitrates. Only with low bitrates is it to be used. Besides, it degrades the compatibility for the MPEG-4 file. I've completely stopped using B-Frames.

[Tommy Carrot]

Originally posted by Elias
As for B-Frames, they're good. The image becomes somewhat softer, as (opposed to sharper) but you loose lots of macroblocks. So, conclusion is to not use B-Frames with higher bitrates. Only with low bitrates is it to be used.

In my opinion b-frames are always beneficial, except when the codec reaches the maximum quality (but this is only problem with mpeg ASP, as AVC becomes saturated at MUCH higher bitrate), and - as DeathTheSheep's example showed - at ridiculously low bitrates, where the reference frames are already useless. The softening effect is not necessary, it's quite the opposite, the bitrate saving of b-frames helps to preserve even more details.

[Elias]

Originally posted by Tommy Carrot
In my opinion b-frames are always beneficial, except when the codec reaches the maximum quality (but this is only problem with mpeg ASP, as AVC becomes saturated at MUCH higher bitrate), and - as DeathTheSheep's example showed - at ridiculously low bitrates, where the reference frames are already useless.

When I said low bitrates, I meant like 1024 kbit/s etc. using very very very low bitrates... it doesn't matter what you use, it will look shitty either way. Honestly, I don't see the point with B-Frames at bitrates such as 3 mbit and up. It'll only make the video not playable on some DVD standalones and... well, Quicktime Who cares about Quicktime anyway. Hehe, seriously though, there are lots of software players that can't handle B-Frames/GMC etc.

[yaz]

Originally posted by Elias
... seriously though, there are lots of software players that can't handle B-Frames/GMC etc.

wouv ... just point me only one anyway, handling b-frames is not a player issue when sw environment is considerded but a codec one. hw players are another part of this prob, of course.

however (just my simpleton approach) why do u think so many ppl of brilliant minds & skills would put so much effort on implementing b-(s-, n-)frames in their codecs if it(they) were such useless a/o harmful as u state ? ever thought of that ?

the bests
y

[Elias]

Originally posted by yaz
wouv ... just point me only one

Philips MPEG-4 Player.

Originally posted by yaz
however (just my simpleton approach) why do u think so many ppl of brilliant minds & skills would put so much effort on implementing b-(s-, n-)frames in their codecs if it(they) were such useless a/o harmful as u state ? ever thought of that ?

Originally posted by Elias
As for B-Frames, they're good. The image becomes somewhat softer, as (opposed to sharper) but you loose lots of macroblocks.

I said it was good, not harmful. I rest my case.

Originally posted by Elias
[B]Philips MPEG-4 Player.

I have the DVP-642 and it handles my XviD encodes with 2 consecutive b-frames just fine.

[Elias]

Originally posted by KaiserS
I have the DVP-642 and it handles my XviD encodes with 2 consecutive b-frames just fine.

I was talking about the software player.

Originally posted by Elias
I was talking about the software player.

Oh, my bad.