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android / platform / external / walt / refs/heads/main
commitd4928d8677f5e0636825c845548eac7ee816f4c7[log] [tgz]
authorSadaf Ebrahimi <[email protected]>Wed Dec 18 20:44:29 2024 +0000
committerSadaf Ebrahimi <[email protected]>Wed Dec 18 20:44:29 2024 +0000
tree4423169f99090a786ffb15eca2d3218c50f00fa3
parent223c824cea0a37c8b89f6977ea74170db7b31afc [diff]
Add janitors to the OWNERS file

Test: TreeHugger
Change-Id: I7b88f9a14ec5573aab8a74cb5dfe42dad2f1d666
1 file changed
tree: 4423169f99090a786ffb15eca2d3218c50f00fa3
  1. android/
  2. arduino/
  3. docs/
  4. hardware/
  5. ios/
  6. pywalt/
  7. server/
  8. AUTHORS
  9. CONTRIBUTING.md
  10. CONTRIBUTORS
  11. LICENSE
  12. METADATA
  13. MODULE_LICENSE_APACHE2
  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.