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A comment on Walt: A device for measuring latency of physical sensors and outputs.

Re:Walt: A device for measuring latency of physical sensors ... by javajosh on Tuesday April 05, 2016 @02:25AM (#11428280)
I get that the accelerometer detects the touch, and that one of the photodiodes detects a screen change, and there's another input for the mic as well. But I don't understand the purpose of the laser/laser photodiode. What is that detecting exactly? Also, where does the output of this thing go and how is it encoded? Does it go back to the device you're testing and does that affect latency?
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Re:Walt: A device for measuring latency of physical sensors ... by adlr on Tuesday April 05, 2016 @01:12PM (#11432239)
It's for drag latency: https://github.com/google/walt/blob/master/docs/DragLatency....

It may be counter intuitive, but touch-down latency and drag latency can be very different: on some hardware one may be faster or slower than the other. That's why both are measured.

Note: I worked with Mark to review most of his work on this project.

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