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android / platform / external / walt / cab7a88e3380469c9255f05148bf6d81ba9446a9
commitcab7a88e3380469c9255f05148bf6d81ba9446a9[log] [tgz]
authorXin Li <[email protected]>Sat Sep 07 03:17:11 2024 +0000
committerAutomerger Merge Worker <[email protected]>Sat Sep 07 03:17:11 2024 +0000
tree2d2abb3883e3d49daa405ba6ca7315492e41c0d8
parent01d392b914fde9e220d60a958430d55181ade402 [diff]
parent41e2472a820433c0b656897ffba290dadcbd8af1 [diff]
[automerger skipped] Merge 24Q3 to AOSP main am: 41e2472a82 -s ours

am skip reason: Merged-In Id55979b34f94b9d6819a9e3054aa3a37ac8b44e4 with SHA-1 37e94ff4ff is already in history

Original change: https://android-review.googlesource.com/c/platform/external/walt/+/3258574

Change-Id: I64d906d5a0587476989652d0c62579dac2785158
Signed-off-by: Automerger Merge Worker <[email protected]>
tree: 2d2abb3883e3d49daa405ba6ca7315492e41c0d8
  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.