At least part of the problem is that 1.0 does not respect the bitrate
settings at all, and also the quality setting varies wildly. So when you
encoded with 1.0, you had double/triple bitrates to what you specified.
For 1.1, the new two-pass thing is what really gets the best results.
Finally, the test clip is not maybe the best as it's relatively soft and
1.0 had the hardest time with anything crisp.

As you can see from your files sizes, there are really no comparable
clips. Ca. 1000 kbps is probably too low for 720p30 video, and all the
1.0 clips use at least 1500kbps instead. I've also understood
constant/average bitrate has problems in one-pass mode especially with
theora so that it's better to use the quality setting, or the two-pass
method only available in 1.1.

Therefore I tried the lowest quality setting with 1.0 which still took
relatively a lot, 1325kbps, for video. I then made comparable but theora
1.1 one-pass (-v 4) and two-pass (-V xxx - here bitrate is used since
it's target for two-pass encoding). I also made a higher bitrate theora
1.0 encoding, still using a quality mode so that quality wouldn't suffer
(not that 1.0 would give much respect to the bitrate setting anyway).
And a comparable 1.1 two-pass encoding with lower bitrate:

http://users.tkk.fi/~tajyrink/theora/clips/ (won't be there forever)

I think the biggest difference is between MVI_0442_theora10_2534kbps.ogv
and MVI_0442_theora11_2348kbps_twopass.ogv - the latter has much less
blockiness/noise and more detail at the same time, quite close to the
original. The 1.0 version with higher bitrate is much worse Also, look
at the gradients with theora10_1325kbps.ogv compared to
MVI_0442_theora11_1279kbps_twopass.ogv and
MVI_0442_theora11_1457kbps.ogv. The 1.1 versions have more detail as
well, though somewhat more luminance noise since the 1.0 is very
smoothed out.

-- 
Please sync libtheora 1.1.0-1 from debian (unstable)
https://bugs.launchpad.net/bugs/436726
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