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List:       theora-dev
Subject:    [theora-dev] Theora file size
From:       dvdkhlng () gmx ! de (David Kuehling)
Date:       2006-10-10 4:54:49
Message-ID: 87lkno8jz1.fsf () snail ! Pool
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>>>>> "Unga" == Unga  <unga888@yahoo.com> writes:

> Hi I was surprised with size of Theora files and thought of feedback.

> Following 1minute duration Theora and Xvid files were made from a y4m
> file. The resolution is 1280x720:

> 1. Xvid 17MB 2. Ogg/Theora Q7 31MB 3. Ogg/Theora Q8 38MB 4. Ogg/Theora
> Q9 49MB 5. Ogg/Theora Q10 61MB

I just ran my own test on a 1 minute video of 1280x720 using theora
SVN.  

/usr/local/src/xiph-cvs/theora/examples/encoder_example  \
  -o movie.ogg -v 7 stream.yuv

Result: 37344631 bytes

Then I set:

  ti.keyframe_frequency=3*64;
  ti.keyframe_frequency_force=4*64;
  ti.sharpness=2;

Result: 31377957 bytes

Viewing the resulting video, there's still some noticable noise (which
might be typical for HDTV content?).  So I also tried to tune the noise
sensitivity: 

  ti.keyframe_frequency=3*64;
  ti.keyframe_frequency_force=4*64;
  ti.sharpness=2;
  ti.noise_sensitivity=6;

Result: 28579140 bytes

I also perceive the resulting quality as better now.  Maybe a result of
noise suppression?  If I now encode with these settings at quality 5
(which I usually use for all the stuff I encode), I get:

Result: 18219860 bytes

I can't see any "bad" artefacts like blockiness etc., so for me this
quality would be ok.  But actually I don't have XviD installed to
compare to.

regards,

David
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