RE: Try time (decode) and size for null glyf/loca xform vs regular vs woff1

Thank you Rod!
The results are impressive, considering both memory and decompression time decreases compared to widely used WOFF 1.0 I hope that wide adoption of WOFF2 will be a fast and easy process.

Cheers,
Vlad


From: Roderick Sheeter [mailto:rsheeter@google.com]
Sent: Thursday, May 19, 2016 12:00 PM
To: WebFonts WG
Subject: Try time (decode) and size for null glyf/loca xform vs regular vs woff1

As requested in https://www.w3.org/Fonts/WG/track/actions/186 I ran a variety of compress/decompress scenarios over the Google Fonts collection.

Main findings are:

 * WOFF2 decompression uses less memory than woff, more than brotli standalone.

 * WOFF2 decompression was faster than WOFF at min, median, and average but has a higher standard deviation and max.

 * Applying brotli (using the "bro" utility; https://github.com/google/brotli/blob/master/tools/bro.cc) directly to a font (to simulate use via Accept-Encoding: br) resulted in a file that was larger than a transformed woff2 but fastest to decompress.

 * WOFF2 decompression is slightly faster when there are no transforms. The most significant improvement is lower standard deviation and worst-case time.

The brotli codebase is probably the most carefully optimized of the implementations I compared. WOFF2 without transform could likely be sped up, though some work is hard to dodge without violating the spec. For example, "the decoder MUST recalculate the checkSum value for each decoded table."

Summary and raw results can be seen in https://docs.google.com/spreadsheets/d/1_ZYTFaG6_NJy7n_t-RpPDXCAZIKDP_1SXiJQz0o8QMg/edit#gid=367643030.


Cheers, Rod S.