Linked by lemur2 on Wed 9th Mar 2011 00:18 UTC
The WebM project Blog has announced an update release of the VP8 Codec SDK codenamed the "Bali" release. The Bali release was focused on making the encoder faster while continuing to improve its video quality.
RE: 13.7% improvement, not 12.8%
by lemur2 on Wed 9th Mar 2011 22:22 UTC in reply to "13.7% improvement, not 12.8%"

Member since:
2007-02-17

Bogus algorithm for computing improvement in the article: total improvement is multiplicative, not additive If the improvement from base to A is M% and from A to B is N%, then we need to convert to improvement- factors to do the computation. A's improvement factor is 1 + M/100, and B's factor is 1 + N/100, so the total improvement factor is (1 + M/100)*(1 + N/100). Converting that to percentages gives an incremental improvement of 100*(1 + M/100)*(1 + N/100) - 1), or M + N + M*N/100 If I read the individual numbers M,N correctly, that gives a 13.7% improvement, not 12.8%.

A (Aylesbury) is (1+M%) * base
B (Bali) is (1+N%) * A

So, B is (1+N%) * (1+M%) * base

Bali: "Best" mode average quality improved 6.1% over Aylesbury using the SSIM metric.
Aylesbury: "Best" mode average quality improved 6.3% over launch release using the SSIM metric.

Total improvement from launch release to Bali release = 1.061 * 1.063 = 1.127843. I rounded this out to 12.8%.