gerrit-public.fairphone.software / platform / external / walt / 2ff9309bca425769ba220c8abff716b2f712b861
| commit | 2ff9309bca425769ba220c8abff716b2f712b861 | [log] [tgz] |
|---|---|---|
| author | Linux Build Service Account <lnxbuild@localhost> | Tue Feb 16 21:02:31 2021 -0800 |
| committer | Linux Build Service Account <lnxbuild@localhost> | Tue Feb 16 21:02:31 2021 -0800 |
| tree | 00e0f9517f22f9f9fc95aa6a242a072f9b188f09 | |
| parent | 32cdbc5dc02735c3c6f41f8a325f457ccd124c8f [diff] | |
| parent | a1792408ce74a96375c62769ed0a10d879336634 [diff] |
Merge a1792408ce74a96375c62769ed0a10d879336634 on remote branch Change-Id: I5f6c3ecf254767e6f7d3c75ac957561b21482cb5
tree: 00e0f9517f22f9f9fc95aa6a242a072f9b188f09
- 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.