Google open sources WALT Latency Timer to help Android developers make snappier apps

Google releases internal testing tool for audio and touch response timings to developers


Google has publicly posted its in-house tool for testing touch and audio latency commands for Chromebook and Android products. The WALT Latency Timer is a descendant of Quickstep, originally meant for measuring the response time on a track-pad. The tool uses an external clock along with the timestamps of events pulled from the internal clock of the device, to give a precise breakdown of the time taken for the device to process an input and output.

Instructions posted on the Android Developers Blog allows developers to download the source code of the software as well as instructions for building the DIY device. The cost for making the device is less than $50, and uses a microcontroller board, photo diodes, accelerometers and lasers to measure the latency. A partial build can be made that measures only audio or only touch response times.

Every input action has its own method of measurement. Tap latency can be measured using a pen like device with an accelerometer to measure the time between a tapping event and a response from the device. The drag latency or scroll latency is measured using a laser mounted above the touchscreen or trackpad. The latency is calculated by corresponding the timings of laser events with the device events. Screen draw latency uses a photodiode to check if the screen is black or white. Audio latency is detected by comparing the time when the device decides to output a tone till the audio line voltage crosses a specified threshold.

Source code and other resources are available on the GitHub project page. Instructions to build the devices are also posted, and can be easily modified as per requirement. The Google Play store also has the WALT Latency Timer app.


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