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android / platform / external / walt / 31105a838fb4cc8e04f88f773831877cbb862231
commit31105a838fb4cc8e04f88f773831877cbb862231[log] [tgz]
authorTai Kuo <taikuo@google.com>Sun Sep 13 12:42:14 2020 +0000
committerAutomerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>Sun Sep 13 12:42:14 2020 +0000
tree00e0f9517f22f9f9fc95aa6a242a072f9b188f09
parent8e130cdec6b7a0b53a2d2bcf1e67c3aabedc0b59 [diff]
parent0f9c951bf56d46a537ca69585543f70eb622823d [diff]
[automerger skipped] Deprecate OpenSL ES for Android as of API level 30 (R) am: 484fb8a77d am: 56db2d6fa9 -s ours am: ff4f624a41 -s ours am: 0f9c951bf5 -s ours

am skip reason: Change-Id Ie0a317debd07230d344218c5874f3060dc3ab85f with SHA-1 484fb8a77d is in history

Original change: https://googleplex-android-review.googlesource.com/c/platform/external/walt/+/11926619

Change-Id: I6c9f425c6893703168db78bf7cc967ed3b0b34f2
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.