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gerrit-public.fairphone.software / platform / external / walt / cf1f411f8cdaedc921564e087b36579bd9d80f25
commitcf1f411f8cdaedc921564e087b36579bd9d80f25[log] [tgz]
authorGlenn Kasten <gkasten@google.com>Tue Feb 04 10:53:24 2020 -0800
committerGlenn Kasten <gkasten@google.com>Tue Feb 11 14:54:57 2020 -0800
tree2725e363460bdae2c38d68c12e562a75ee03d09f
parent53c47a96bc0d6129d3dad8219a9a1a793c3da963 [diff]
Deprecate OpenSL ES for Android as of API level 30 (R)

Bug: 134958169
Test: try with an NDK r21 canary for both R and earlier, and a pre-21 NDK
Change-Id: Ie0a317debd07230d344218c5874f3060dc3ab85f
1 file changed
tree: 2725e363460bdae2c38d68c12e562a75ee03d09f
  1. android/
  2. arduino/
  3. docs/
  4. hardware/
  5. ios/
  6. pywalt/
  7. server/
  8. AUTHORS
  9. CONTRIBUTING.md
  10. CONTRIBUTORS
  11. LICENSE
  12. MODULE_LICENSE_APACHE2
  13. NOTICE
  14. OWNERS
  15. README.google
  16. README.md
README.md

WALT Latency Timer

DISCLAIMER: This is not an official Google product.

WALT is designed to measure the latency of physical sensors and outputs on phones and computers. It can currently perform the following measurements:

  • Tap latency - time from the moment a finger-like probe touches down (or up) on the screen until the kernel timestamps an ACTION_DOWN (or ACTION_UP) event. This physical contact with the screen is timed using an accelerometer mounted on the probe.
  • Drag latency (scroll).
  • Screen draw latency - using a photodiode that detects whether the screen is black or white.
  • Audio output and microphone latencies.
  • MIDI input and output latencies

The WALT app for Android can be installed from Google Play or downloaded in the releases section; the iOS app must be built from source.

WALT photo

Notes

  • Hardware build instructions can be found in this repository under hardware/.
  • Clock synchronization details are described here.
  • The Android/iOS device and Teensy clocks have a tendency to diverge due to differing clock frequencies. This means they will go out of sync after several minutes. The workaround is to use the app to re-sync the clocks. Some, but not all tests in the app will sync the clocks when starting a measurement.
  • Python code used to communicate with WALT from Linux and ChromeOS can be found here.