Compression Context

ZIP is a great format—it’s extremely broadly deployed, relatively simple, and supports a wide variety of use-cases pretty well. ZIP is the underlying format beneath Java (.jar) Archives, Office (docx/xlsx/pptx) files, Fiddler (.saz) Session Archive ZIP files, and many more. Even though some features (Unicode filenames, AES encryption, advanced compression engines) aren’t supported by allContinue reading “Compression Context”

Automatically Evaluating Compressibility

Fiddler’s Transformer tab has long been a simple way to examine the use of HTTP compression of web assets, especially as new compression engines (like Zopfli) and compression formats (like Brotli) arose. However, the one-Session-at-a-time design of the Transformer tab means it is cumbersome to use to evaluate the compressibility of an entire page orContinue reading “Automatically Evaluating Compressibility”

Getting Started with Profile Guided Optimization

For the convenience of the Windows developer community, I periodically compile the Zopfli and Brotli compressors from source, building for Win32 and code-signing the binaries (Interested? Get Zopfli.exe and Brotli.exe). After announcing the latest build on Twitter, I got an interesting question in reply: While I try to use the latest compiler (VS2015 U1), I’veContinue reading “Getting Started with Profile Guided Optimization”

Fiddler and Brotli

Regular readers of my blog know how excited I am about Google’s new open compression engine, Brotli. Support is in Firefox 44 Nightly already and is expected for other browsers. Because Brotli is used inside the WOFF2 font format, many clients already have the compression code and just need to expose it in a newContinue reading “Fiddler and Brotli”

WebP–What Isn’t Google Telling Us?

Beyond their awesome work on Zopfli and Brotli, Google has brought their expertise in compression to bear on video and image formats. One of the most interesting of these efforts is WebP, an image format designed to replace the aging JPEG (lossy) and PNG (lossless) image formats. WebP offers more efficient compression mechanisms than bothContinue reading “WebP–What Isn’t Google Telling Us?”