The miracle of film and television is a result of a perceptual phenomenon known as "persistence of vision."

When pictures are flashed in front of the eyes at a certain rate, they appear to have motion. In reality, a movie is merely 24 pictures flashing on a screen each second. This frame rate convinces our minds that what we are seeing is actual motion. But there is no motion to the pictures; they're just a series of still images.

The illusion that persistence of vision creates is kicked into virtual reality when sound is incorporated. An actor on screen might appear to be stabbing another actor with a butcher's knife, but of course, he's probably using a fake knife and not coming remotely close to the other actor. When the sound of the inside of a watermelon being bludgeoned is played in sync with the stabbing images, the audience is thrust into a realism that will make them squirm in their seats or even look away from the screen. The illusion is now complete. They are convinced that what they hear is a result of what they see.

When the dialog of a scene is played in sync with the images on the screen, the audience associates the two forms of media, sound and picture, as being one source. They believe that what they hear is coming directly from the screen. Most movie patrons (including my dad) are unaware that there are speakers behind the screen. The rnoment the sound and picture appear out of sync, the audience is immediately taken out of the fantasy world of storytelling and realize they are being subjected to the technology Older martial arts films are a classic case of out-of-sync dialog. The words move, but the dialog is delayed.

There are two methods of recording sound tor picture: single system and double system.


A single system consists of a camera that records both sound and picture simultaneously. Sound sync is achieved as the image is recorded. Therefore, the camera serves as the audio recorder. The audio controls on the camera are impossible to manage during a shot, so with a single system setup, the sound mixer uses his equipment as a remote control of the camera's audio inputs. Once the mixer and camera are calibrated (i.e., inputs selections, channel levels, etc.), the sound mixer controls the sound recorded by the camera. It is common practice to place a piece of gaffer tape over audio controls on a camera that might get bumped or accidentally moved. Some newer camera manufacturers have solved this problem by adding plastic shields that allow you to see the controls without moving them. If the knobs are too dark to see in low lighting environments (often the case in production) you can place thin strips of glow-in-the-dark tape on them for orientation.

It is important to understand that the camera can be the audio recorder. While this isn't possible with film cameras (outside of Super 16mm), modern digital film cameras offer audio recording. Most ENG production is shot single system. A backup recorder can be used if the camera's audio is poorly recorded or the wireless hop experiences hits and drops.

Backup recorders are also used to record audio for transcribing. These transcription recorders do not need to provide superior audio, just a reference so that a transcription service can transcribe the interview or producĀ­ tion content. Producers use these transcriptions during the editing process as a way of quickly finding sound bites for the piece. A handheld recorder, like the Zoom H4n, can be used for transcription recorders, but do not have timecode capability. One solution is to record audio to channel 1 and timecode to channel 2.


In a double system, the picture is captured with a camera and the sound is captured on an audio recorder. The audio recorder functions independently of the camera. \X/ith a single system, one button on the camera is used to record both sound and picture. In a double system, the recording process requires both the camera and recorder to be rolling. The picture and sound are synced together later during postproduction.

Modern-day digital film cameras, such as the Red One, are capable of recording audio, but are usually shot double system. The audio capabilities of these cameras are simply inferior to stand-alone recorders. However, you can send an audio signal to these cameras via a wireless hop, to be used for reference. Obviously, a hardwire cable will give the best results, but even a wireless signal, dropouts and all, can be useful for on-set playback and provide dailies that are already in sync. This can be a time-and-money saver tor independent films. Be sure to have a harness or mount for the wireless receivers that are going to the camera to allow the camera crew to work freely without getting tangled up with your cables. Also, send reference tone during each camera setup to ensure the audio received by the wireless receiver is properly sent to the camera.

Avoid using the camera mic as a "reference" track in a double system. Instead, send a signal from the mixer or recorder to the camera, The distance from the talent to the boom mic will be different than the distance from the talent and the camera mic. This greater distance can cause a delay in the camera mic, which may create problems when syncing audio in post without timecode or a slate marker.


Double system setups require the use of a clapboard in order to sync the audio to picture efficiently. A standard protocol is followed for each take. This protocol provides information for both the camera and audio recorder.

At the beginning of each take, the following call will be made:

1st AD: "Roll Sound"

Sound Mixer: "Speed"

1st AD: "Roll Camera"

Camera Operator: "Rolling" or "Camera Speed"

lst AD: "Marker"

2nd AC: "Scene 1, Take 1, Marker"

The 2nd AC then closes the clapboard sticks to create an audible clap for a sync point.

Alternate terms might be used and different crewmembers might make these calls. The important thing to realize is the protocol. Sound will roll their media first and then audibly confirm their roll by saying "Speed" to let the crew know that their equipment is recording. Sound media is cheaper than film stock, so it makes sense to let sound roll first to save the cost of film. Camera will then roll film and confirm this roll audibly by saying "Rolling" or "Camera speed." Avoid hand signals such as "thumbs up" or simply nodding your head. Do not assume that someone is watching you or that they somehow realize that you are rolling. The production "will wait for you to say "Speed" before continuing, so make sLlre that you say "Speed" nice and loud. If you say "Speed" and there is a long pause, you might confirm they heard you by saying "Sound Speed" a second time.

When the scene is marked, be sure to have the clapboard held close enough to the microphone so that theclapboard's sticks are heard when they close. In some cases, the clapboard might be held away from the talent for framing reasons. In this case, the boom operator should point the mic toward the clapboard to hear the sticks. If you are only using lavs or plant mics, try to have the clapboard as close as possible to those mics. This might include standing next to an actor wearing a hidden lav.

Slating a scene inside a car near the plant mics

It is imperative that the camera sees the information on the clapboard along with the sticks when they come together. This includes scene/take information and timecode (if using a timecode slate). In some situations, slating the shot might be difficult or impossible. For example, if the camera starts with an extreme close-up of an actor's eye and then slowly pulls out, the shot can be complicated to position and focus fc)r a clapboard. If this is the case, you can "tail slate" the shot. This means that the slate happens at the end or "tail" of the shot. It is standard procedure to hold the clapboard upside down to indicate that the shot is being tail slated. Be prepared to preempt a "cut" call from the director so that the shot can be slated. Remind the director (who will probably begin the cut call with a paused "And ... cut!") to tail slate by calling out "Tail Slate." If the shot is cut before a tail slate is called, be sure to note "No Slate" on the sound report.

In cases where it is difficult or impossible for front- or tail-slate sticks to be heard by the microphone, you can have the actors mark the take by saying the scene and take number and then clap their hands. This is a crude solution, but it works. Be sure to have the talent clap their hands so that both of their hands are seen coming together by the camera. (There is a funny behind-the-scenes clip on the Home Alone DVD that shows actor Daniel Stern inside a van with fellow actor Joe Pesci. Since the clapboard was held outside of the van, Stern had to use handclaps to mark the scenes, often at the expense of Pesci's ears.)

"Second Sticks" refers to a shot that was slated, but the clap sticks were out of frame or not clearly seen by the camera. To avoid confusion in post, it is standard procedure to call "Second Sticks" before the clapboard is clapped for the second time. Always note "Seconds Sticks" on the sound report. If this is not noted, the editor might sync to the wrong marker.

Slating is a standard procedure in double system productions. If you are not able to slate each take, be it a lack of crew or lack of time, you can always manually sync up the takes using the waveforms. Keep in mind: this will cost you extra time in post.


Each system presents its own set of assets and liabilities. Here's a look at the most significant:

Sittgle System Pros

The setup is much easier. One device records both sound and picture. Sync is achieved during the recording process, which saves time in postproduction.

Single System Cons

Cameras are manufactured to produce great images, not necessarily great sound. Nearly all cameras have substandard audio compared to low-priced, handheld recorders. The sound mixer must be tethered to the camera. If the tether is a wireless hop, the audio can suffer from hits and dropouts.

Double System Pros

A double system setup will always offer superior sound. The sound mixer operates independently of the camera, which gives the camera operator greater freedom. The audio can be properly monitored and adjusted from a single location.

Double System Cons

The setup is more complicated. Two separate systems are involved. Sound and picture will need to be synced together in postproduction.


Mic to Camera

Mic to Mixer to Camera

Mic to Mixer to Camera and Backup/Transcription Recorder

Mic to Mixer to Multiple Cameras

Mic to Mixer to Multiple Cameras and Backup/Transcription Recorder
Mic to Mixer to Satellite Truck with Return Feed for IFB and RTS/Clearcom


Mic to Mixer to Recorder

Mic to Mixer to Recorder and Camera (camera audio is used for reference)*

Mic to Multitrack Recorder

Mic to Multitrack Recorder and Camera (camera audio is used for reference) *

*Note: Sending audio to camera in a double system can provide a reference track for dailies or instant sync for quicker editing. The audio can be replaced with the recorder's audio in postproduction, but may need to be re-synced manually if the camera was not fed the same timecode from the recorder.