| commit | c4457f1a6c3b969dcfc4d7f673aa5c35b62ada90 | [log] [tgz] |
|---|---|---|
| author | Linux Build Service Account <lnxbuild@localhost> | Wed Jan 26 00:41:51 2022 -0800 |
| committer | Linux Build Service Account <lnxbuild@localhost> | Wed Jan 26 00:41:51 2022 -0800 |
| tree | ee43c6b47d9f36bdabb1b33437d56e46091c22de | |
| parent | f0e78166bf686c03d7f30903d89ea51df50d067f [diff] | |
| parent | 3be621cc9a88ef90e8b5f14f93baacbe6b0d0d4b [diff] |
Merge 3be621cc9a88ef90e8b5f14f93baacbe6b0d0d4b on remote branch Change-Id: I2f9827ab16bf35e09c5417370a7b40394b4e62c5
tree: ee43c6b47d9f36bdabb1b33437d56e46091c22de
- android/
- arduino/
- docs/
- hardware/
- ios/
- pywalt/
- server/
- AUTHORS
- CONTRIBUTING.md
- CONTRIBUTORS
- LICENSE
- METADATA
- 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.