The teensy_latency_test measures audio output latency using an additional Teensy board with microphone by playing audio, triggering a timer on the Teensy board, and stopping once the Teensy board records audio. Compared to loopback_latency, we can get output latency results that are not affected by input latency.

Some commands

Serial port loopback latency

teensy_latency_test -s

Plug in 3.5mm heaset or speaker to teensy and toggle teensy playback on/off from host through serial port by

teensy_latency_test -t

Speaker output latency test (ALSA path)

teensy_latency_test -a hw:0,0

Speaker output latency test (CRAS path)

teensy_latency_test -c

In the current SerialLoopBack/ code the measure output latency and set_level command is missing. But we can add that back easily from the teensy side.