Neowin.net

Thanks Ultima who got this alert through the vorbis mailing list.

We're gearing up to the next full release of the Vorbis codec; I've just tagged a release candidate in SVN in order to encourage wider testing toward final 1.1 release.

This release includes the following updates:

1. Adoption of AoTuV and other tuning work by Vorbis developers outside of Xiph into the mainline codebase
2. New bitrate management code
3. bugfixes. more details in Read More

Download: Ogg Vorbis 1.1 Public Release Candidate 1 (Encoder) | Dll's
News source: hydrogenaudio.org

In more detail:

1) Adoption of AoTuV tunings
The AoTuV encoder substantially improves the basic tunings of the 1.0.1 encoder for 32,44.1 and 48 kbps input samples. This 1.1 release merges the AoTuV tunings into the mainline Xiph codebase along with other tuning tweaks. The AoTuV tunings are unchanged from the AoTuV encoder with the following exceptions:

a) bugfix to AoTuV code section 'M1'; after discussion with Aoyumi, we agree that the second tuning case both triggered relatively seldomly and did not produce the intended results when it did trigger.
The predominating first case ('partial masking') is now used for all samples. This should address some minor pure tone instability issues in the AoTuV encoder.

b) Changes to book construction, training, and on-the-fly adjustment to allow the AoTuV tunings to work properly with bitrate management.

c) AoTuV introduced quality ranges down to -2; the 1.1 Xiph libvorbisenc implements the same modes but maps them down to -1 as in previous Xiph releases. The bitrate of quality -1 in 1.1 is similar to quality -1 in 1.0.1 but the quality of the output is improved.

2) New bitrate management code
After use case analysis, I concluded that the 'sliding window' approach to bitrate bounding and management in previous encoders was not usefully more featureful than the more standard 'bit reservoir' approach used in the rest of the industry. In addition, the bit reservoir approach uses substantially less memory in the encoder. For these reasons, the 1.1 libvorbisenc moves to implementing bitrate bounding and management by using a bit reservoir.

The bit reservoir is also conceptually easier to understand; the encoder has a fixed bucket size for 'slop space' in encoding. When a frame is smaller than the desired rate, the unused bits go into the reservoir so that they may be used by future frames. When a frame is larger than target bitrate, it draws 'banked' bits out of the
reservoir. Encoding is managed so that the reservoir never goes negative or fills beyond a fixed limit.

The 1.1 libvorbisenc allows setting the fixed reservoir size (in bits, defaulting to two seconds worth of requested bitrate) and 'hoarding' behavior (whether the encoder tends to keep the bit reservoir more full or more empty) as well as the other encoding heuristics available through the API of 1.0.1.

3) Bugfixes
See SVN for a more details; I'll collect a list for the full release.

There are vorbisenc API additions to handle the new bit reservoir configuration; I will describe those in more detail tomorrow. The binary API is undisturbed; deprecated calls are are all mapped to the new infrastructure. I *believe* oggenc is already updated to the new API.