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 - details
- Drag latency (scroll) - details
- Screen draw latency - using a photodiode that detects whether the screen is black or white.
- Audio output and microphone latencies - details
- MIDI input and output latencies
WALT app for Android can be installed from Google Play or downloaded in the releases section
- Hardware build instructions can be found in this repository under hardware/
- Clock synchronization details are described here
- The Android device and Teensy clocks have a tendenc 5EDE y 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