
Revisiting Daala Technology Demos - espadrine
https://people.xiph.org/~jm/daala/revisiting/
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Johnny_Brahms
So, I am very much not a video codec developer, so I feel I have to ask: in
the comparison I can see a difference, but I have a hard time discerning
whether one or the other is better. Maybe not when there are very visible
artifacts, but say comparing Daala and HEVC.

Apart from obvious artefacts, what are we looking for?

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lambda
As it says, at this point it's getting pretty subjective, and so you'll need a
blinded subjective test to really judge which one is better:

    
    
      The improvement in quality compared to the previous 
      status update is quite obvious. Daala is now much better 
      than both WebP and JPEG (libjpeg-turbo is the most 
      commonly used JPEG encoder). As for Daala vs BPG/HEVC, 
      the artifacts are obviously different and hard to judge 
      from just four images. Opinions are likely to vary based 
      on the viewer and the input image. At this point, what 
      we'd really need is a full subjective test. Fortunately, 
      this is exactly what is going to take place shortly, as 
      Daala has been submitted as a candidate for the Image 
      Compression Grand Challenge at ICIP 2016. The results 
      should be available in September. In the mean time, you 
      can read the paper we will be presenting.
    

What I generally do is toggle between three images, the original, Daala, and
HEVC, and focus on a different area each time. There is always some obvious
distortion from the original, so I try to determine for each area I'm focusing
on, which one is closer to the original perceptually. It is a subjective
process, but if you make this evaluation for each area of the image, count up
your judgements over the whole image, do that over multiple images, and have
multiple people all do that and combine their results, you can come up with a
reasonable evaluation of the quality.

~~~
FullyFunctional
One good example is the hair on the forehead of the "woman" image. IMO, Daala
does better than BPG here, but obviously overall there's no clear overall
winner (but JPEG is a clear looser :)

Very excited to see another Daala update. I look forward to a competivite
alternative to HEVC.

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vanderZwan
The stills are great, but I really would like to compare what these codecs
look like for actual video. Motion changes a lot.

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MrZeus
True, some ready-made video comparisons would be nice, but the codec is being
actively developed as we speak, so they'd be out of date pretty quickly (the
bitstream format isn't even frozen yet).

However, the Daala code is open-source, so people are free to generate their
own comparisons using whichever codecs they like on whatever video snippets
they have.

The Daala code is available via Git
([https://git.xiph.org/?p=daala.git;a=summary](https://git.xiph.org/?p=daala.git;a=summary)
and [https://github.com/xiph/daala/](https://github.com/xiph/daala/)) and
there are even some test video sequences one can compare with at
[https://media.xiph.org/video/derf/](https://media.xiph.org/video/derf/).

