Support

LTC Detective  ·  iOS

This is the support page for LTC Detective, an iOS application that reads SMPTE Linear Timecode (LTC) from any audio input on your iPhone or iPad and displays the decoded timecode along with detailed signal-quality measurements.

Contact

For bug reports, feature requests, or any other questions about the App, please email support@karstlok.nl. Replies usually arrive within two business days.

When reporting a problem, the following information helps a great deal:

• Device model (e.g. iPhone 15 Pro, iPad Pro 11").
• iOS version (Settings › General › About).
• App version and build number (visible at the bottom of Settings › About inside the App).
• Audio input you were using (built-in microphone, USB interface and model, etc.).
• What you expected to happen and what happened instead.

Common questions

The App shows “No signal” even though my source is playing LTC.
Open Settings inside the App and verify that the correct audio input device and channel are selected. If you are using an external audio interface, make sure it is set as a class-compliant device and that the channel carrying LTC is selected. Check that the input level meter on the main screen is showing signal; if the meter is silent, the signal is not reaching the device.

The level meter shows signal but the timecode is not locking.
Look at the signal-quality readouts on the main screen. If Sync Word reads INVALID and Edge Quality is low, the LTC signal is too distorted, too quiet, or has too much noise to decode reliably. Try increasing the input level on your audio interface, shortening cable runs, or removing inline processing.

The Direction readout shows “Forward 1.03×” instead of 1.00×.
This is normal. The App measures the speed of the incoming timecode against your audio interface’s sample clock. A small offset means the LTC source and the audio interface are not running on the same clock, which is common in setups without house sync.

I want to test the App without an external LTC source.
Open Settings, select Loopback (virtual) as the audio device, then tap Play reference LTC loop. The App will generate a clean SMPTE LTC signal internally, which you can decode to verify the App is working correctly.

Does the App run in the background?
No. iOS suspends audio capture when the App is backgrounded. Decoding resumes when you return to the App.

Which audio interfaces are supported?
Any USB-C, Lightning, or Bluetooth audio interface that iOS recognises as a class-compliant input device. You do not need a vendor driver. If iOS lists the device under Settings › Sounds & Haptics or it appears in the App’s audio device list, it will work.

Privacy

The App does not collect, store, transmit, or share any personal data. See the full privacy policy for details.

Open-source notices

LTC Detective uses libltc (LGPL v3) for timecode decoding and the JetBrains Mono, Azeret Mono, and Inter Tight typefaces (SIL Open Font License 1.1). Full attribution and license texts are available inside the App at Settings › Open-source licenses.