theora - Sep 2009 - I'm almost very impressed with theora 1.1 beta 3

Firstly I have to say that having just tried out theora 1.1 beta 3 the
improvement over the previous 1.0 is amazing. In my very subjective view
it looks like the same quality for about half the bitrate and that's
amazingly impressive. The results have for the most part been excellent
and my congratulations to all concerned for there very hard work.

There is (for me) only one serious problem remaining. As Monty points
out in http://web.mit.edu/xiphmont/Public/theora/demo.html there is an
issue with flat colour surfaces and gentle gradients. This is most
annoying! For example, a video I was encoding the other day has a floor
area that's pretty much just a plain polished black. When watching this
there was very noticeable blocking artefacts on the floor that because
of their nature proved very distracting.

Is there any work going on in this area? It seems that even upping the
bitrate significantly fails to solve this problem. Or are there any
tweaks I can perform to help?

Many thanks and keep up the good work!

Jim.

Yeah, I've seen this too.  It's pretty obvious in this example:

http://people.mozilla.org/~blizzard/videos/grid_vfx_concepttest/Grid_VFX_ConceptTest_1080.ogv

In the blue of the clouds behind the castle during the opening disney logo.

But, yeah, I'm seeing impressive results with 1.1 for sure.  Bitrates 
are way down and quality at the same bitrate is much higher.  It's 
shaping up to be a good release.

--Chris

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On 09/16/2009 09:59 PM, Jim Darby wrote:
> Firstly I have to say that having just tried out theora 1.1 beta 3
> the improvement over the previous 1.0 is amazing. In my very
> subjective view it looks like the same quality for about half the
> bitrate and that's amazingly impressive. The results have for the
> most part been excellent and my congratulations to all concerned
> for there very hard work.
>
> There is (for me) only one serious problem remaining. As Monty
> points out in http://web.mit.edu/xiphmont/Public/theora/demo.html
> there is an issue with flat colour surfaces and gentle gradients.
> This is most annoying! For example, a video I was encoding the
> other day has a floor area that's pretty much just a plain polished
> black. When watching this there was very noticeable blocking
> artefacts on the floor that because of their nature proved very
> distracting.
>
> Is there any work going on in this area? It seems that even upping
> the bitrate significantly fails to solve this problem. Or are there
> any tweaks I can perform to help?
>
> Many thanks and keep up the good work!
>
> Jim.
Jim,

I've noticed the same thing myself, and it is quite distracting.  The
improvements in the high-frequency portions of a frame are phenomenal,
to say the least, but as you've pointed-out, in the more smooth areas,
blocking becomes quite obvious.

This, along with general encoder & decoder performance, are two areas
which, if improved, would make Theora quite competitive with MPEG4 ASP
and even H.264/AVC (at least in some areas).  In my informal (soon to
be formal, hopefully) testing, I found clips where Theora actually
exceeded the performance of H.264 (via the libx264 encoder in FFmpeg).

It's amazing, really.  Most other codecs would require a new,
incompatible version of a codec to get the kinds of improvements that
Theora has seen.  Kudos to the devs, really.  I wish them all the best
in their continued pursuit of a truly free (as in freedom) video codec.

- -- 
      Basil Mohamed Gohar
abu_hurayrah at hidayahonline.org
http://www.basilgohar.com/blog
basilgohar on irc.freenode.net
GPG Key Fingerprint:  5AF4B362
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On 9/16/2009 9:26 AM, Gregory Maxwell wrote:
> On Wed, Sep 16, 2009 at 12:09 PM, Christopher Blizzard
> <blizzard at mozilla.com>  wrote:
>    
>> Yeah, I've seen this too.  It's pretty obvious in this example:
>>
>>
http://people.mozilla.org/~blizzard/videos/grid_vfx_concepttest/Grid_VFX_ConceptTest_1080.ogv
>>
>> In the blue of the clouds behind the castle during the opening disney
logo.
>>
>> But, yeah, I'm seeing impressive results with 1.1 for sure. 
Bitrates
>> are way down and quality at the same bitrate is much higher.  It's
>> shaping up to be a good release.
>>      
> Is that the right example file? it's encoded using "Vendor:
Xiph.Org
> libTheora I 20081020 3 2 1"
>    
Argh, sorry, here's the right url:

http://people.mozilla.org/~blizzard/videos/grid_vfx_concepttest/Grid_VFX_ConceptTest_1080_thesnulda.ogv

Has similar problems.

The original .mov is in that directory:

http://people.mozilla.org/~blizzard/videos/grid_vfx_concepttest/

--Chris