MIDIField Guide
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Clock & latency tester

Is your clock steady, and how long does a message take to come back? Measure the tempo and jitter of an incoming MIDI clock, drive a device with clock from the browser, and time round trips through a cable or virtual loopback.

Background Timing & SyncTransports
Libraries RealtimeUtilities

Devices

Web MIDI
Not connected. You can still try the simulated clock below.

Incoming clock

F8 × 24 per quarter

Send MIDI clock from a drum machine, DAW or sequencer. The tester measures tempo and how evenly the clocks arrive.

Interval deviation from the mean (ms), last 384 clocks
Jitter histogram (ms)

Send clock

FA · F8 … · FC

Drive a device from the browser to check that it follows. Clocks are scheduled ahead with Web MIDI timestamps.

Round-trip latency

out → device/cable → in

Connect an output back to an input: a MIDI cable from OUT to IN on your interface, a device with MIDI Thru, or a virtual loopback port (the IAC Driver on macOS, loopMIDI on Windows). The tester sends numbered probes and times their return.

Round-trip time histogram (ms)

Reading the numbers

Times come from Web MIDI event timestamps, so they include the operating system's MIDI stack and the browser, not just the cable. At 120 BPM clocks arrive every 20.83 ms; a 5-pin DIN cable needs 0.32 ms to carry one clock byte and 0.96 ms for a three-byte message. Jitter under a millisecond is typical for USB MIDI; numbers well above that point to a busy computer, a long chain of devices, or a struggling interface. Use the results to compare setups on the same machine rather than as absolute truth.