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android / platform / external / walt / refs/tags/android-cts-10.0_r12
taga15acd09d425d45bb3c77a9b6237804438dc275a
taggerThe Android Open Source Project <initial-contribution@android.com>Wed May 18 15:46:28 2022 -0700
objectbb6a254d9769acc1d022d74977fe5680c2c6218c 
Android CTS 10.0 Release 12 (8504422)
commitbb6a254d9769acc1d022d74977fe5680c2c6218c[log] [tgz]
authorandroid-build-team Robot <android-build-team-robot@google.com>Mon Feb 25 04:11:58 2019 +0000
committerandroid-build-team Robot <android-build-team-robot@google.com>Mon Feb 25 04:11:58 2019 +0000
treec30ac4649286db84b343802e00c4100ad1900759
parent0c112410108569cbff96c8631180fcd4bcc8bd60 [diff]
parent53c47a96bc0d6129d3dad8219a9a1a793c3da963 [diff]
Snap for 5333170 from 53c47a96bc0d6129d3dad8219a9a1a793c3da963 to qt-release

Change-Id: I9987d49120f6a05df6f8c5990958c4291605106b
tree: c30ac4649286db84b343802e00c4100ad1900759
  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.