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gerrit-public.fairphone.software / platform / external / walt / 986de24185275a0cf8701fc8199ee704b67228d7
commit986de24185275a0cf8701fc8199ee704b67228d7[log] [tgz]
authorTai Kuo <taikuo@google.com>Thu Jul 30 18:34:59 2020 +0000
committerAutomerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>Thu Jul 30 18:34:59 2020 +0000
tree7336bb04f595404dae6bed38cf0ec0840b3f6521
parent95b54095f0aa6ed9c6e6aca4e1005013245c5042 [diff]
parente58ab75b03450dea476ed92edd35ecf11b013bc4 [diff]
Revert "Convert sync_clock_jni to Android.bp" am: 098c8fb26d am: 9eda51f919 am: e58ab75b03

Original change: https://googleplex-android-review.googlesource.com/c/platform/external/walt/+/11887673

Change-Id: Ibbbb2912fcb53a70e08a310916ab335aab9bf420
tree: 7336bb04f595404dae6bed38cf0ec0840b3f6521
  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.