Last modified: 2014-06-02 11:32:48 UTC
The video transcoding infrastructure creates Theora versions of uploaded videos in various resolutions and bitrates. Currently version 0.27 of the ffmpeg2theora transcoding tool is used which uses the Theora 1.1 encoder. Current versions of ffmpeg2theora (0.29) usually include the Theora 1.2 encoder (e.g., http://v2v.cc/~j/ffmpeg2theora/ffmpeg2theora-0.29.linux64.bin). This often creates much nicer looking videos. Example: Original File: https://commons.wikimedia.org/wiki/File%3ALutra_lutra_grooming.ogv Wikipedia 360p transcode created ffmpeg2theora 0.27 and Theora 1.1: http://maikmerten.de/theora-test/Lutra_lutra_grooming.ogv.360p.ogv 360p transcode with ffmpeg2theora 0.29 and Theora 1.2: http://maikmerten.de/theora-test/Lutra_lutra_grooming.ogv.ogv The change is quite noticeable on the water. The updated ffmpeg2theora version expects the same commandline arguments and should be a drop-in replacement.
If I'm not mistaken we're currently using the Ubuntu distro package of ffmpeg2theora; might have to backport the package or something if there's not a handy one available with the right versions linked in.
Quick note per discussion on IRC with Xiph folks: The 1.2 Theora branch apparently has some unresolved regressions with fades in the middle of content, so we should probably run some more tests for comparison to make sure we're happy with the tradeoffs. But it looks like it's probably a big improvement in many cases. See http://people.xiph.org/~xiphmont/demo/theora/demo9.html for some background and samples -- the improvement on the 'dirty window effect' is particularly striking.
After some testing I can confirm that Theora 1.2 has some regressions I was not aware of regarding scene changes. This can be very visible. It appears that Theora 1.1 is the more reliable choice for the time being, which is desirable for automated transcodes.
So is this request a WONTFIX as per comment 3 (and we'd update the Theora encoder simply when upgrading the machines to a newer distribution version which might include a more recent Theora encoder)? I don't want "at some future point we update a package as we upgrade the distro shipping that package update anyway" tickets in Bugzilla (if I got it all correctly). :)
I think WONTFIX is suitable here, as there's no action to be taken here. (Later this may be a "free"/"automatic" upgrade once the new encoder is stable enough quality-wise to enter Ubuntu upstream.)
Alright, thanks :)
