gerrit-public.fairphone.software / platform / external / walt / 53c47a96bc0d6129d3dad8219a9a1a793c3da963
| commit | 53c47a96bc0d6129d3dad8219a9a1a793c3da963 | [log] [tgz] |
|---|---|---|
| author | Xin Li <delphij@google.com> | Sun Feb 24 02:27:11 2019 -0800 |
| committer | android-build-merger <android-build-merger@google.com> | Sun Feb 24 02:27:11 2019 -0800 |
| tree | c30ac4649286db84b343802e00c4100ad1900759 | |
| parent | b1e527855f02cb8e91bfa725e6685c979a5b0936 [diff] | |
| parent | 16e42bb744a7eb83fe95f4a781494e9826800c51 [diff] |
[automerger skipped] DO NOT MERGE - Merge pi-dev@5234907 into stage-aosp-master am: 16e42bb744 -s ours am skip reason: subject contains skip directive Change-Id: I38d4ced5bc1fa3b820c5743fd046da95d3d5c9b5
tree: c30ac4649286db84b343802e00c4100ad1900759
- android/
- arduino/
- docs/
- hardware/
- ios/
- pywalt/
- server/
- AUTHORS
- CONTRIBUTING.md
- CONTRIBUTORS
- LICENSE
- MODULE_LICENSE_APACHE2
- NOTICE
- 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.