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Opendivx digest, Vol 1 #12 - 13 msgs



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Today's Topics:

   1. Re: Re: [Opendivx] Some ideas (Gunter Ohrner)
   2. Re: Re: [Opendivx] Some ideas (John Funnell)
   3. Re: Re: [Opendivx] Some ideas (Gunter Ohrner)
   4. ThreadSafe in OpenDivX (c0redumb)
   5. The .divx file format (Thomas Hargrove)
   6. .divx file format without messed up line wrapping.  Ignore the previous message. (Thomas Hargrove)
   7. Re: Reusability (Thomas Hargrove)
   8. Re: Reusability (Nick Feamster)
   9. Re: Reusability (ridaas syncprodz.com)
  10. Re: wavelets (John Funnell)
  11. documentation, mpeg4 divx etc... (ridaas syncprodz.com)
  12. Re: Reusability (prakash)
  13. Re: wavelets (ridaas syncprodz.com)

--__--__--

Message: 1
From: Gunter Ohrner <[email protected]>
Reply-To: [email protected]
Organization: RWTH Aachen
To: "OpenDivX Mailingliste" <[email protected]>
Subject: Re: Re: [Opendivx] Some ideas
Date: Wed, 31 Jan 2001 19:36:34 +0100

Am Mittwoch, 31. Januar 2001 14:22 schrieben Sie:
> compiler from intel on linux [rumoured] or someone to write intel2gas for
> inlined asm.  All new sample code from Intel etc. is always supplied in
> the intel syntax.
In fact intel2gas *does* support inline asm conversion although it's not 
perfect.

Greetinx,

  Gunter Ohrner

-- 
+-+-+-+-+-+-+-+-+-+-+-+- http://www.scheibenwelt.de -+-+-+-+-+-+-+-+-+-+-+-+
"Letztes Jahr haben wir ihn erwischt, aber er schüttelte ganz plötzlich den 
Kopf und entkam, wärend wir versuchten, [Korporal] Nobby auszugraben." 
(Hauptmann Karotte von der Stadtwache in Ankh-Morpork über den unter 
Schuppenbefall leidenden Dunnelgurt "Schneetreiben" Schuppert) (Terry 
Pratchett * Fliegende Fetzen - ein Scheibenweltroman)
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--__--__--

Message: 2
From: "John Funnell" <[email protected]>
To: <[email protected]>,
	"OpenDivX Mailingliste" <[email protected]>
Subject: Re: Re: [Opendivx] Some ideas
Date: Wed, 31 Jan 2001 18:36:15 -0000

> In fact intel2gas *does* support inline asm conversion although it's not 
> perfect.

Question is:  does it work on the opendivx sources?



--__--__--

Message: 3
From: Gunter Ohrner <[email protected]>
Reply-To: [email protected]
Organization: RWTH Aachen
To: "OpenDivX Mailingliste" <[email protected]>
Subject: Re: Re: [Opendivx] Some ideas
Date: Wed, 31 Jan 2001 20:31:55 +0100

Am Mittwoch, 31. Januar 2001 19:36 schrieben Sie:
> > In fact intel2gas *does* support inline asm conversion although it's
> > not perfect.
> Question is:  does it work on the opendivx sources?
It does, more or less. Just try it and/or read my following posting to the 
ML: [Opendivx] inline assembly and gcc

Greetinx,

  Gunter Ohrner

-- 
+-+-+-+-+-+-+-+-+-+-+-+- http://www.scheibenwelt.de -+-+-+-+-+-+-+-+-+-+-+-+
The only way housework could be done in this place was with a shovel or, 
for preference, a match.        -- (Terry Pratchett, Witches Abroad)
+-+-+-+-+-+-+-+-+-+-+-+-+- http://www.lspace.org +-+-+-+-+-+-+-+-+-+-+-+-+-+


--__--__--

Message: 4
From: "c0redumb" <[email protected]>
To: <[email protected]>
Date: Wed, 31 Jan 2001 12:01:31 -0800
Subject: [Opendivx] ThreadSafe in OpenDivX

Hi,

I think maybe I can inject some thoughts here on the multi-instance and
thread safe issues.

When the encore was first put together, I was thinking about thread safe,
because Windows might generate multiple instances of a driver. That's why I
use handles for calles to encore() to distinguish the calling thread.
However, the code now is not 100% global-free, because we have some legacy
code from MoMuSys. I would like to see the code to be free of global (maybe
it is just my personal taste).

I do agree with Nick that ensuring thread safe is more an application level
issue, and encore is just an encoding module. But I think Stefan's concern
has its reason. If I can write the encore careful enough without much
penalty on performance for getting rid of globals (I think I can), I would
do it to make things simpler for the application builders.

Adam


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--__--__--

Message: 5
From: "Thomas Hargrove" <[email protected]>
To: <[email protected]>
Date: Wed, 31 Jan 2001 20:41:46 -0800
Subject: [Opendivx] The .divx file format

When is work on the new .divx file format going to begin?   I have been
thinking recently
that a new file extension would greatly help the success of the divx
standard.

The first time I downloaded a large (300 MB) divx file, I threw it away
because I could not
play it.  I am sure this happens all the time.  If there had been a diferent
extension, I would
have searched for a player.

I understand that keeping the .avi format lets you use all the existing
windows video software,
but there are some options to deal with this:

    1) Create a program to (mass) convert .avi to .divx and vice versa
without recompression.
        (Maybe throw in .qt as well).  If you needed to edit a divx file in
a non-compatible
        software package, you could convert it, edit it, and convert it
back.

    2) Create a Direct Show .divx splitter.  From what I understand, Divx
currently looks like
        this:

        [File Source] ------- [ AVI Splitter ] ------ [ DivX
Decompressor ] --- [Render Filter]
                                                    |
                                            [Audio Decompressor] ----
 Audio Device ]

        If we replaced the AVI splitter, we would no longer need to use the
AVI file format.  With
        a new splitter in place, it would be trivial to add .divx support to
any DirectShow program.

    3) Convince people to add native .divx support to their programs.
VirtualDub would be
        easy, but big ones like premiere would be hard.

I can see three big advantages of the new format:

    1) People would not think that the file was a broken avi.

    2) If the new file format was designed with streaming in mind, someone
could start an open
        source streaming .divx server.  This could compete against streaming
.WMV .ASF .RM
        and .QT.

    3) No more 2GB file size limit.  :)

--Tom





--__--__--

Message: 6
From: "Thomas Hargrove" <[email protected]>
To: <[email protected]>
Date: Wed, 31 Jan 2001 21:21:38 -0800
Subject: [Opendivx] .divx file format without messed up line wrapping.  Ignore the previous message.

When is work on the new .divx file format going to begin?   I have been
thinking recently that a new file extension would greatly help the success
of the divx standard.

The first time I downloaded a large (300 MB) divx file, I threw it away
because I could not play it.  I am sure this happens all the time.  If there
had been a diferent extension, I would have searched for a player.

I understand that keeping the .avi format lets you use all the existing
windows video software, but there are some options to deal with this:

    1) Create a program to (mass) convert .avi to .divx and vice versa
without recompression. (Maybe throw in .qt as well).  If you needed to edit
a divx file in  a non-compatible software package, you could convert it,
edit it, and convert it back.

    2) Create a Direct Show .divx splitter.  From what I understand, Divx
currently looks like this:

[File Source]
         |
[ AVI Splitter ] ------ [Audio Decompressor]
         |
[ DivX Decompressor ]
         |
[Render Filter]

        If we replaced the AVI splitter, we would no longer need to use the
AVI file format.  With a new splitter in place, it would be trivial to add
.divx support to any DirectShow program.

    3) Convince people to add native .divx support to their programs.
VirtualDub would be easy, but big ones like premiere would be hard.

I can see three big advantages of the new format:

    1) People would not think that the file was a broken avi.

    2) If the new file format was designed with streaming in mind, someone
could start an open source streaming .divx server.  This could compete
against streaming .WMV .ASF .RM and .QT.

    3) No more 2GB file size limit.  :)

--Tom




_______________________________________________
Opendivx mailing list
[email protected]
http://lists.projectmayo.com/mailman/listinfo/opendivx




--__--__--

Message: 7
From: "Thomas Hargrove" <[email protected]>
To: "Nick Feamster" <[email protected]>
Cc: <[email protected]>
Subject: Re: [Opendivx] Reusability
Date: Wed, 31 Jan 2001 22:50:47 -0800

I was under the impression that MPEG4 uses DWT instead of DCT.  (The W
stands for wavelet).

Am I wrong?

--Tom

----- Original Message -----
From: "Nick Feamster" <[email protected]>
To: "prakash" <[email protected]>
Cc: <[email protected]>
Sent: Wednesday, January 31, 2001 8:08 AM
Subject: Re: [Opendivx] Reusability


> The motion estimation done in MPEG-4 is similar to that done in MPEG-2.
> Both use block matching and motion estimation on 16x16 blocks, with an
> option to have 4 motion vectors per block.  I am not sure if the DCT
> coefficients are the same though...
>
> Nick
>
> On Wed, 31 Jan 2001, prakash wrote:
>
> > Hello all,
> > Is it possible to reuse the motion vectors/dct from other mpeg standards
> > here? How different are the motion vectors here when compared to mpeg-2?
> >
> > with regards
> > Prakash
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > _______________________________________________
> > Opendivx mailing list
> > [email protected]
> > http://lists.projectmayo.com/mailman/listinfo/opendivx
> >
>
>
> _______________________________________________
> Opendivx mailing list
> [email protected]
> http://lists.projectmayo.com/mailman/listinfo/opendivx
>



--__--__--

Message: 8
Date: Thu, 1 Feb 2001 01:45:53 -0500 (EST)
From: Nick Feamster <[email protected]>
To: Thomas Hargrove <[email protected]>
Cc: <[email protected]>
Subject: Re: [Opendivx] Reusability

The last time I looked at the standard, it used a DCT.

On Wed, 31 Jan 2001, Thomas Hargrove wrote:

> I was under the impression that MPEG4 uses DWT instead of DCT.  (The W
> stands for wavelet).
>
> Am I wrong?
>
> --Tom
>
> ----- Original Message -----
> From: "Nick Feamster" <[email protected]>
> To: "prakash" <[email protected]>
> Cc: <[email protected]>
> Sent: Wednesday, January 31, 2001 8:08 AM
> Subject: Re: [Opendivx] Reusability
>
>
> > The motion estimation done in MPEG-4 is similar to that done in MPEG-2.
> > Both use block matching and motion estimation on 16x16 blocks, with an
> > option to have 4 motion vectors per block.  I am not sure if the DCT
> > coefficients are the same though...
> >
> > Nick
> >
> > On Wed, 31 Jan 2001, prakash wrote:
> >
> > > Hello all,
> > > Is it possible to reuse the motion vectors/dct from other mpeg standards
> > > here? How different are the motion vectors here when compared to mpeg-2?
> > >
> > > with regards
> > > Prakash
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > _______________________________________________
> > > Opendivx mailing list
> > > [email protected]
> > > http://lists.projectmayo.com/mailman/listinfo/opendivx
> > >
> >
> >
> > _______________________________________________
> > Opendivx mailing list
> > [email protected]
> > http://lists.projectmayo.com/mailman/listinfo/opendivx
> >
>



--__--__--

Message: 9
Reply-To: [email protected]
From: "ridaas syncprodz.com" <[email protected]>
Subject: Re: [Opendivx] Reusability
Date: Thu, 01 Feb 2001 01:10:24 -0800
To: [email protected], [email protected]
Cc: [email protected]


wavelet is very good for still images, it will be the major point of the =
coming jpeg2000 standard.

for mpeg4 they (mpeg group) talked about putting wavelet but they saw the=
 added complexity will not increse the performance since with video wavel=
et and dct works quite the same.

federico
_________________________________________________________________________=
__
Visit http://www.visto.com/info, your free web-based communications cente=
r.
Visto.com. Life on the Dot.



--__--__--

Message: 10
From: "John Funnell" <[email protected]>
To: <[email protected]>, <[email protected]>,
	<[email protected]>
Cc: <[email protected]>
Subject: Re: [Opendivx] wavelets
Date: Thu, 1 Feb 2001 09:46:45 -0000

Federico,

Do you know if there were studies done to prove that wavelets would not be
better than dct?  And has the situation changed now - are there new wavelet
(or perhaps matching pursuits) schemes that could outperform dct?

In fact, it could be said that the dct scheme we have is wavelet based!  The
definition of a wavelet actually encompasses dct basis functions.

So, DivX uses wavelet compression ;-)

Tell me if you agree/disagree!

John


----- Original Message -----
From: ridaas syncprodz.com <[email protected]>
To: <[email protected]>; <[email protected]>
Cc: <[email protected]>
Sent: Thursday, February 01, 2001 9:10 AM
Subject: Re: [Opendivx] Reusability



wavelet is very good for still images, it will be the major point of the
coming jpeg2000 standard.

for mpeg4 they (mpeg group) talked about putting wavelet but they saw the
added complexity will not increse the performance since with video wavelet
and dct works quite the same.

federico
___________________________________________________________________________
Visit http://www.visto.com/info, your free web-based communications center.
Visto.com. Life on the Dot.


_______________________________________________
Opendivx mailing list
[email protected]
http://lists.projectmayo.com/mailman/listinfo/opendivx



--__--__--

Message: 11
Reply-To: [email protected]
From: "ridaas syncprodz.com" <[email protected]>
Date: Thu, 01 Feb 2001 02:06:55 -0800
To: [email protected]
Subject: [Opendivx] documentation, mpeg4 divx etc...

i would love to make a page on the web with updated links to any document=
ation related to mpeg4 and divx that can be useful to anyone want to ente=
r the field of video-coding.
i tried to look around but didn't found any good docs or tutorial on this=
=2E
i think it's good to have some coding documentation for the people who wi=
ll implement the opendivx stuff but it woiuld be nice to have references =
for people who already know about coding in general but maybe lack knowle=
dge about video.
expecially some docs about putting the things in a right contest (where d=
ivx come from, which are the liasons with mpeg4 standard, which are the d=
ifference, where we are moving..)

anybody know good urls already?

federico
---
http://www.syncprodz.com=20
(free mp3 since 1997)
_________________________________________________________________________=
__
Visit http://www.visto.com/info, your free web-based communications cente=
r.
Visto.com. Life on the Dot.



--__--__--

Message: 12
Date: Thu, 1 Feb 2001 14:29:48 +0200 (EET)
From: prakash <[email protected]>
To: Thomas Hargrove <[email protected]>
Cc: Nick Feamster <[email protected]>,
	<[email protected]>
Subject: Re: [Opendivx] Reusability

Looking through the encore code, dwt is not implemented for encoding the
texture. I think i did not phrase the question properly. The idea here is
to do a real time transcoding from MPEG-2 to MPEG-4 without complete
decoding. The idea is to resue the motion vectors and dct co-efficients as
much as possible. Since the implementation of encore works completely with
vops(foreground/background detection, scene change detection, ...etc), I
am still wondering how to go about this. Any suggestions would be quite
helpful.

with regards
Prakash













On Wed, 31 Jan 2001, Thomas Hargrove wrote:

> I was under the impression that MPEG4 uses DWT instead of DCT.  (The W
> stands for wavelet).
>
> Am I wrong?
>
> --Tom
>
> ----- Original Message -----
> From: "Nick Feamster" <[email protected]>
> To: "prakash" <[email protected]>
> Cc: <[email protected]>
> Sent: Wednesday, January 31, 2001 8:08 AM
> Subject: Re: [Opendivx] Reusability
>
>
> > The motion estimation done in MPEG-4 is similar to that done in MPEG-2.
> > Both use block matching and motion estimation on 16x16 blocks, with an
> > option to have 4 motion vectors per block.  I am not sure if the DCT
> > coefficients are the same though...
> >
> > Nick
> >
> > On Wed, 31 Jan 2001, prakash wrote:
> >
> > > Hello all,
> > > Is it possible to reuse the motion vectors/dct from other mpeg standards
> > > here? How different are the motion vectors here when compared to mpeg-2?
> > >
> > > with regards
> > > Prakash
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > _______________________________________________
> > > Opendivx mailing list
> > > [email protected]
> > > http://lists.projectmayo.com/mailman/listinfo/opendivx
> > >
> >
> >
> > _______________________________________________
> > Opendivx mailing list
> > [email protected]
> > http://lists.projectmayo.com/mailman/listinfo/opendivx
> >
>
>
> _______________________________________________
> Opendivx mailing list
> [email protected]
> http://lists.projectmayo.com/mailman/listinfo/opendivx
>



--__--__--

Message: 13
Reply-To: [email protected]
From: "ridaas syncprodz.com" <[email protected]>
Subject: Re: [Opendivx] wavelets
Date: Thu, 01 Feb 2001 05:30:17 -0800
To: [email protected], [email protected],
	[email protected]
Cc: [email protected]

i have very few knowledge about video coding since my proper job is more =
focused on transport-layer of mpeg standard (the so called mpeg2-TS).
i am not sure if mpeg4 standard talk or not about wavelets, maybe is poss=
ible than more then one coding techinique is allowed.
what i know is this:

-wavelet is based on subband coding, the wavelet transform scheme combine=
 transform coding with subband coding

-wavelet is supposed to be very good for I-frame coding (same as jpeg cod=
ing) and for low-bitrate videos (12-48kbps) the I-frame coding takes abou=
t 40-70% of the bit used in the stream, this means that for very low bitr=
ate you save a lot respect typical dct.

-wavelet is supposed to be more cpu intensive, i checked some article and=
 it seems the coder (on a dsp implementation) has 50% less framerate.

-the problem with video and wavelet-based coding scheme is find a mechani=
sm to exploit the temporal redundancies and here i found 3 proposals:
1) extensions of the 2-D wavelet-based scheme to 3-D subband coding (3-D =
SBC)
2) use of a multiresolutional motion compensation (MRMC) in the wavelet d=
omain
3) so-called overlapped block motion compensation

now don't ask me details cause i am not in this things at all :(

good references can be found (where i found them, but there are lotsa of =
article cited there) in this article:
"Very low bit-rate video coding using wavelet-based techniques" by D.Marp=
e H.Cycon (IEEE Transactions on circuits and system for video technology =
vol.9 feb 1999)

i will check this wavelet things and mpeg4 and divx code (if i can manage=
 it) and will try to post my 2 cents when i will know more :)

federico
ps: i thought divx was the microsoft hacked mpeg4 encoder btw..:)
-------------------------------------
http://www.syncprodz.com=20
------(mp3 since 1997)-------





-----Original Message-----
From:    John Funnell [email protected]
Sent:    Thu, 1 Feb 2001 09:46:45 -0000
To:      [email protected], [email protected], [email protected]
CC:      [email protected]
Subject: Re: [Opendivx] wavelets


Federico,

Do you know if there were studies done to prove that wavelets would not b=
e
better than dct?  And has the situation changed now - are there new wavel=
et
(or perhaps matching pursuits) schemes that could outperform dct?

In fact, it could be said that the dct scheme we have is wavelet based!  =
The
definition of a wavelet actually encompasses dct basis functions.

So, DivX uses wavelet compression ;-)

Tell me if you agree/disagree!

John


----- Original Message -----
From: ridaas syncprodz.com <[email protected]>
To: <[email protected]>; <[email protected]>
Cc: <[email protected]>
Sent: Thursday, February 01, 2001 9:10 AM
Subject: Re: [Opendivx] Reusability



wavelet is very good for still images, it will be the major point of the
coming jpeg2000 standard.

for mpeg4 they (mpeg group) talked about putting wavelet but they saw the
added complexity will not increse the performance since with video wavele=
t
and dct works quite the same.

federico
_________________________________________________________________________=
__
Visit http://www.visto.com/info, your free web-based communications cente=
r.
Visto.com. Life on the Dot.


_______________________________________________
Opendivx mailing list
[email protected]
http://lists.projectmayo.com/mailman/listinfo/opendivx


_______________________________________________
Opendivx mailing list
[email protected]
http://lists.projectmayo.com/mailman/listinfo/opendivx



_________________________________________________________________________=
__
Visit http://www.visto.com/info, your free web-based communications cente=
r.
Visto.com. Life on the Dot.




--__--__--

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