Compatibility/Telemetry

Measuring web compatibility

This page tracks the telemetry measurements that the Web Compat team is tracking. See Telemetry for more information.

Bug 1109958 will serve as the meta tracking bug for all telemetry probes.

Possible telemetry probes

CSS

• `display: table` with `max-width: 100%` on children.

HTTP

• WAP (WML or XHTMLMP) content sent to Fennec and Firefox OS users (see Bug 941241)
• `Server:` name
• Redirection sequences
• Wrong mimetypes for images
• Wrong mimetypes for JSON

JS/DOM

• (When Possible) identify the js lib used against a DB of the latest versions of JS libs. (to understand the use of legacy code)
• Identify, count how many times `navigator.userAgent` is used on the Web and a couple of other related thing.
• WebKitCSSMatrix usage See https://bugzilla.mozilla.org/show_bug.cgi?id=717722

Video

• requestFullScreen vs requestFullscreen. See https://bugzilla.mozilla.org/show_bug.cgi?id=743198#c5
• Ads before video and transition to video
• EME required
• List of video providers (stats for understanding if we need to focus our contacts actions toward some specific people)
• List of JS libraries used for video players
• Flash-only video (perhaps already covered in 1108668)
• Media formats (ogg, mp4, h264, m3u8/HLS)
• Media MIME types
  • HTMLMediaElement.canPlayType()
  • MediaSource.isSupportedType()
  • MediaSource.addSourceBuffer(DOMString type)
• Video dimensions
• Compressed video sample sizes
• Frame drops
• Hardware or software decoders
• Playing videos concurrently
• Audio speaker configuration e.g. mono, stereo, 5.1
• H264
  • H.264 AVC profile info (profile/flags/level)
  • FRext in SPS

Related information

h264 rec: http://www.itu.int/rec/T-REC-H.264-201402-I/en