Digital Clapperboard

On a film set every clip needs a name before it is shot. Which scene is this, which angle, how many times have we tried it? A clapperboard, or slate, answers by showing those details to the camera for a moment at the start of each take. The clap itself gives the editor a marker for syncing sound that was recorded separately. This page puts the whole slate on a phone or tablet, with the clap, the beep and a running timecode.

The fields

Production is the title of the project. Roll is the card or reel, for example A007. Scene is the scene number, with a letter if the scene has several set-ups, such as 12B. Take counts attempts at that shot. Director and Camera name the people or the camera unit. Date comes from the device. All fields are editable; the text is kept in the browser so the slate is ready next time. The take number can also be changed with the Next take and Take 1 buttons.

A worked example

Press Sample to fill a slate for production “Harbour Lights”, roll A007, scene 12B, take 3, director M. Rivera, camera A, at 25 frames per second. The panel shows those fields in large type, today’s date and a timecode that counts hours, minutes, seconds and frames of the day, for instance 23:04:09:03 at 25 fps, where the last number runs from 0 to 24. Press Clap, or Space: the top stick comes down, the screen flashes white for a moment, the beep sounds and the take changes from 3 to 4.

How the clap syncs sound

Cameras and external recorders each keep their own clock, so a track recorded on a separate recorder starts at a slightly different moment from the video. If a clap is visible on camera and audible on both recorders, the editor lines up the frame where the sticks close, or here the white flash, with the spike in the audio waveform. After that the two stay together for the length of the clip. The beep is a short 1000 Hz click, which is easy to see on a waveform.

Timecode

The timecode on the slate is the time of day on your device, shown as hours, minutes, seconds and frames at the rate you choose. It is helpful to read the time of a take but it is not locked to the camera’s clock, so it does not replace a timecode generator. For multi-camera shoots, hold the same device in front of every camera, or use a hardware timecode source.

Using it on set

Hold the screen close to the lens, with the fields in focus, and say the details aloud for the audio recorder: “Harbour Lights, scene twelve B, take three”. Clap, then take your hand away before the action starts. Turn the brightness of the device up outdoors, use Full screen to fill the display, and keep the device awake. The white flash is bright, so avoid pointing it at people’s eyes at close range.

Edge cases

A frame rate with decimals, such as 23.976, is accepted, and the frame counter never goes above the whole number below the rounded-up rate, so at 23.976 it counts 0 to 23. Browsers may need a first tap or key press before they allow sound, so interact with the page once before the first take. The flash lasts 90 milliseconds. It is a single flash, but if anyone on set is sensitive to bright flashes, switch the beep off and rely on the sticks, or keep the screen angled away from faces. The date uses your device’s local calendar day, in the same time zone as the timecode.

Limits

It is a slate, not a sync device: no genlock, no jam-sync, no LTC audio output. The beep is a simple generated tone. Nothing is recorded or sent.

Related tools

• Chroma Key Screen provides a green backdrop for the same shoot.
• Video Cutter & Trimmer trims takes to the part you need.
• Voice Recorder records the separate audio to sync.
• Mic Test checks the microphone level before rolling.