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gerrit-public.fairphone.software / platform / external / walt / 96290295779178916d2eeb533ec2397f3ebe6ee7
commit96290295779178916d2eeb533ec2397f3ebe6ee7[log] [tgz]
authorAutomerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>Thu Jul 30 19:18:26 2020 +0000
committerAutomerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>Thu Jul 30 19:18:26 2020 +0000
tree00e0f9517f22f9f9fc95aa6a242a072f9b188f09
parent8facfd5fab486dbd0b4d500c480e88285dcda074 [diff]
parent2c7107e507a99a5ba061131e0387ca4d7c7f22f4 [diff]
[automerger skipped] Merge changes from topic "am-ade31d6990834be4b754e817590f547b" into rvc-d1-dev-plus-aosp am: 2c7107e507 -s ours

am skip reason: Change-Id I166eb01a5da30caacf113712b158d5c7dd999d97 with SHA-1 54e55736cd is in history

Original change: https://googleplex-android-review.googlesource.com/c/platform/external/walt/+/11926622

Change-Id: Id00b8aca352261223d93b8a1a4a3748f7e3f1ef9
tree: 00e0f9517f22f9f9fc95aa6a242a072f9b188f09
  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.