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[OpenDivX] OpenDivX Encoder -> OpenDivX Daily Fourms Digest

Topic:		Does DivX have B frames?
Author:		Adia
Posted:		 2001-03-22 01:05

Thank you very much!
Could you tell me the detail about bit rate control method which
OpenDivX employs?
Does I-Frames always use constant quantizer 8?
Is P-Frames's quantizer related to forward n P-Frames's MADs and
quantize parameters, even allocated bits number? The current P-frame
don't care about forward I-frame's allocated bits number, is it right?
Your help will be appreciated.

Topic:		Encoder progress?
Author:		wanton
Posted:		 2001-03-22 07:26
What's the progress of fixing problems that doom9 pointed out in his
page (artifacts if there is a lot of motion changes) and progress of
following too: Bitrate control to at least as good as original DivX and
2pass encoding support? I really like to know when these updates are

Topic:		New Codec On The Block (SBC)
Author:		wanton
Posted:		 2001-03-22 11:09
Just saw Smart Bitrate Control sample. Looked really amazing quality no
visible artifacts even with lot of motion. And it handle that matrix
lobby explosion scene really good that had been used to test codecs at
doom9 page. I heard that SBC is 2 pass encoding method.

Just wanted to add something. SBC sample i saw looked better than most
(or maybe any) SVCD that i've seen or done and i hope they release
encoder to public soon. I also saw sample from ledeng of baggar vance
encoded with SBC and it looked really good too. VCDVAULT seems to have
real winner here [ This message was edited by: wanton on 2001-03-22
11:13 ]

Topic:		OpenDivX Variable Bitrate Encoding
Author:		AnonyMS
Posted:		 2001-03-22 11:18
The movie group VCDVaULT has developed one of the world's first VBR
Mpeg4 encoders using the DivX 3.11 alpha codec. You can read about it
here at <a href="http://www.vcdvault.net"; target="_blank"

vV found out that the only differences between Low-Motion DivX and
Fast-Motion DivX were compression factors. (something like a range of
(2-4 for low motion and 5-16 for High Motion) They also figured that by
manipulating this internal variable they could make the low motion codec
act like the fast motion codec, or even start acting like the low motion
codec again. Their encoder is also fairly interesting. It is a two pass
VBR system, with scene based keyframe insertion, true VBR control based
upon a motion curve and stats generated in a first pass.. Among other
things that vV figured out was the fact that crispness/sharpness of the
Mpeg4 codec is also useful to modulate based upon motion because of
properties that it exhibits at certain bitrates (An unsharp filter is
applied to make the image easier to compress with certain sharpness
settings). The encoder also has its own unique motion detection
algorithm used for motion based modulation of the compression factor...

All of this info they gleaned from disassembly of the existing codecs
and reading the assembly source code.

The encoder is not released yet, but it should be soon.

Anonymous vV Programmer[ This message was edited by: AnonyMS on
2001-03-22 11:19 ]

Topic:		New Codec On The Block (SBC)
Author:		AnonyMS
Posted:		 2001-03-22 11:24
It isn't a codec. Its an encoder. Through disassembly of the existing
DivX 3.11 codecs, we found that there were many internal codec variables
that could be manipulated in ways never ever thought of before. We found
that you can change the compression factor of the MS codecs on the fly,
in essence, morphing the low motion to high motion, and back again, with
no side effects.. We implemented a motion based two pass truly VBR
system in our encoder.. with a bunch of other spiffy features. Read the
VBR OpenDivX thread for some more info I posted.

It will be released soon, under GPL of course. Eventually we might turn
our attention to OpenDivX development.. although we don't know how much
of this 'content control' idea we want to support.

Anonymous vV Programmer

Topic:		New Codec On The Block (SBC)
Author:		wanton
Posted:		 2001-03-22 11:26
Kick's ass  Great work guys 

Topic:		jorel1
Author:		daxgk
Posted:		 2001-03-22 19:50

sorry if this is a stupid question, but is there any way to convert a
DivX encoded movie file to Quicktime?  

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