XVID Creating blocks.

[Momo-chan]

Well my problem seems to be that B-Frames in higmotion scenes gets loads of blocks added to them by xvid cause as soon as i turn of bframes i dont get them anywhere.

I tried loads of diffrent stuff to get rid of this problem.

Here is a clip to show you what happens.
bframe-blocking (http://w1.422.comhem.se/~u42236752/bframe_blocking.avi)

Anyone hit this problem before ?
Where frames get blocked and looks like they are corrupted ?
Note: I have two machines they give exact the same result.
---------------------------------------------
Using Koepi binary build 1.0.2

Quant type: H.263
Quarter Pixel: ON
B-VOPs
Max: 2
Quant Ratio: 1.50
Quant Offset: 1.00
Packed Bitstream: OFF
GOV: OFF
-

Motion Search Precision: 6 Ultra High
VHQ MODE: 4 Wide Search
Chroma Motion: ON

Quant Restrictions
1
31
1
31
1
31
---------------------------------------------
Computer setups.

P4 2500 Mhz
1024 (444) ddr ram

and
AMD 2000+
1280 (333) ddr ram
---------------------------------------------
Source:
VBLE made from DVD Source.

[Manao]

Blocks are not corrupted. The codec tries to put a b-frame before a scenechange, which is useless.

To avoid that issue, check 'closed gop' in the codec configuration.

[Momo-chan]

Then its a bug in xvid ?

But for now i should try closed GOV i guess.
So i should do it in packed to ?



Take Care
Momo-chan

[Manao]

Uh, that was fast.

It may be considered as a bug, but it's mainly a check that is not done inside the codec because it shouldn't happen, because if you check closed gop it can't happen.

Best piece of advice I can give you on packed bitstream : go read what crusty's faq (http://www.vslcatena.nl/~ronald/docs/xvidfaq.html#C3k) says about it.

[manono]

I don't know if this will help with your problem or not, but your resolution is no good. 396 is only mod 4. Try 704x400.

[stephanV]

i would use packed bitstream only if you wish to open it in a VFW editor (like VirtualDub)

I would always use closed GOV... i believe i read somewhere that b-frames before a keyframe didnt make much sense. but where? (and why?)

Crusty's FAQ :) (but still... why?)

[Leak]

Originally posted by Momo-chan
Then its a bug in xvid ?

Well, there must be a bug somewhere - VirtualDub crashes when I step past frame 98 using the XviD 1.0.2 VfW decoder...

np: Cujo - Traffic (Adventures In Foam (Disc 1))

[Manao]

The 'why' is simple : firstly, the following frame is a key frame, so it doesn't have motion vectors, so the best mode for b-frames ( direct ) isn't used. Secondly, if it's a scenechange, any information coming from the frame ( mode direct, interpolated, backward ) is totally irrelevant, since the b-frame and the following i-frame are totally unrelated. It leaves us with only one mode - forward - which is exactly what a p-frame would have allowed you to do ( except that with a p-frame you would have also been able to put intra blocks where it was needed ).

Leak : indeed, I didn't check that. FFvfw doesn't crash, but report a broken frame.

[Momo-chan]

Originally posted by manono
I don't know if this will help with your problem or not, but your resolution is no good. 396 is only mod 4. Try 704x400.

Its gimp LB vista originaly dident know exact what res would be best for it is a widescreen format.

And was the first time doing any matterial like that O_o


Take Care
Momo

[lordadmira]

Originally posted by manono
I don't know if this will help with your problem or not, but your resolution is no good. 396 is only mod 4. Try 704x400. 396 is a valid rez for Xvid. It shouldn't cause any problem.

LA

[lordadmira]

Originally posted by Momo-chan
Then its a bug in xvid ?

But for now i should try closed GOV i guess. Maybe. ;) Seriously, I don't know why this is even an option. Closed GOP should *always* be enabled IMHO and I can't think of any situation where u wouldn't want it.

LA

[manono]

It shouldn't cause any problem.

It's less compressible than are mod 16 resolutions, and some vid cards can't play it. I said it may not help with her problem, but using mod 16 resolutions, or at least mod 8 (but I wouldn't) is just good encoding practice.

[Momo-chan]

I want to thank everyone for your awnsers and tips ^_^
*gives out cookies*

Take Care
Momo-chan