Update libtheora to the 1.1 release.
- Name: Christopher Montgomery (xiphmont), AdamJackson
- Email: firstname.lastname@example.org, email@example.com
- Targeted release: Fedora 12
- Last updated: 2009-07-26
- Percentage of completion: 50%
1.1alpha2 is in rawhide. A release candidate of Theora 1.1 is expected to be released before the end of July.
libtheora 1.1 incorporates a substantially improved encoder, codenamed 'Thusnelda'. Compared to libtheora 1.0, the new encoder can produce comparable quality encodings at a lower bitrate, or better quality at the same bitrate.
Over the last year, Monty has produced a series of detailed reports describing the Thusnelda improvements as they have been developed:
- Improved motion estimation and mode selection
- Rate-distortion optimization
- One-pass DCT tokenization
- Token optimization
- Lambda unification, lambda/qi mapping
- Quantization matrix tuning, forward DCT error reduction
The development of Thusnelda was supported by Red Hat, Wikimedia and Mozilla.
Benefit to Fedora
A lot of positive momentum has been building around open video on the web. With this feature, Fedora becomes more attractive as a platform for producing video content in open formats.
libtheora needs to be updated. All video-encoding applications that support theora will transparently benefit from the improvements in Thusnelda, including all applications that use gstreamer to encode video. Good examples in this category are GUI transcoding apps like transmageddon and arista (see http://lwn.net/Articles/333904/).
Applications that use mplayer or ffmpeg for video encoding will not benefit, since these frameworks come with their own implementations of the Theora format.
How To Test
You don't need any special hardware to test Theora encoding.
Use a video-encoding application to produce Theora-encoded content. Compare the quality with content produced with libtheora 1.0 and notice the improved quality.
The theora-tools package contains a commandline tool, theora_encode, that can be used to create Theora-encoded content.
(More detailed test instructions will be provided when I can get hold of Monty, who is travelling atm)
If libtheora 1.1 turns out to be a catastrophic failure, revert to libtheora 1.0. If libtheora 1.1 is not finalized in time for F12, but the prereleases don't exhibit stability problems, we can just ship the latest available prerelease, which will still give us considerable quality improvements, due to the incremental nature of the improvements that are outlined above.
No specific documentation should be needed, libtheora 1.1 is a transparent replacement for libtheora 1.0.
Fedora 11 comes with libtheora 1.1, including the new 'Thusnelda' encoder.