gerrit-public.fairphone.software / platform / external / walt / 66b2c2057b3a0c6af79bc49ae358531c135f93e5
| commit | 66b2c2057b3a0c6af79bc49ae358531c135f93e5 | [log] [tgz] |
|---|---|---|
| author | Xin Li <delphij@google.com> | Fri Apr 10 03:12:49 2020 +0000 |
| committer | Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com> | Fri Apr 10 03:12:49 2020 +0000 |
| tree | 11af8e90dc3ca95b5850b8d5734e7cc2da37ba03 | |
| parent | 2e1d8eaca5b604d62bde90925c53ff1137e6a3ce [diff] | |
| parent | 53874e9928f332525656a08de8f0091c5c6fcbbe [diff] |
[automerger skipped] DO NOT MERGE - Empty merge qt-qpr1-dev-plus-aosp into stag-aosp-master am: 53874e9928 -s ours am skip reason: subject contains skip directive Change-Id: Id0a3e2fea99ed69780696858ce6ed6b55f8df184
tree: 11af8e90dc3ca95b5850b8d5734e7cc2da37ba03
- android/
- arduino/
- docs/
- hardware/
- ios/
- pywalt/
- server/
- AUTHORS
- CONTRIBUTING.md
- CONTRIBUTORS
- LICENSE
- MODULE_LICENSE_APACHE2
- OWNERS
- README.google
- README.md
README.md
WALT Latency Timer
DISCLAIMER: This is not an official Google product.
- Post about WALT on Android Developers Blog
- Instructional videos showing how to use WALT
- Detailed usage instructions
- Mailing list - walt-discuss
- Low-traffic mailing list for major announcements walt-announce
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.
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.