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android / platform / external / walt / 735624bc34a3c9570a0387725868458d5d304c14
commit735624bc34a3c9570a0387725868458d5d304c14[log] [tgz]
authorBob Badour <bbadour@google.com>Wed Mar 25 18:56:52 2020 -0700
committerBob Badour <bbadour@google.com>Wed Mar 25 18:56:52 2020 -0700
treee2a9f9620da01a16a42400ec00ad3df03eea7d0f
parent53c47a96bc0d6129d3dad8219a9a1a793c3da963 [diff]
Remove redundant NOTICE copied from LICENSE.

Identified using the below shell script:

$ find -H . -name LICENSE -type f -print0 | xargs -0 dirname \
  | while read dir; do \
    if [ -f "${dir}/NOTICE" ] \
        && diff "${dir}/LICENSE" "${dir}/NOTICE" >/dev/null; then \
      echo "${dir}/NOTICE"; \
    fi; \
  done

Now that http://r.android.com/r/1235427 and http://r.android.com/r/1238719 are
merged, LICENSE files copied into NOTICE files are no longer needed.

Bug: 67772237
Bug: 68860345

Test: manually built and diffed before and after system image notices
Change-Id: I9ca2f8c0713c2f11b014bf22b2f85c19437be2d6
1 file changed
tree: e2a9f9620da01a16a42400ec00ad3df03eea7d0f
  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. OWNERS
  14. README.google
  15. 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.