Technical Aspects of Shooting to Sync Playback:
Non lip sync sequences for Music Videos are relatively easy. Since the images do not require frame to frame alignment with the music and lyrics, the filmmaker is pretty much free to do whatever they want. Footage can be shot at any frame rate (overcranked for slow motion, undercranked for accelerated motion, stop-frame, etc.) Sync playback of the music during shooting is not a requirement, although many filmmakers prefer to listen to some sort of rough playback track (also referred to as a tempo track) to guide them in terms of shot length (for eventual cutting to the beat) and pacing of camera moves (to match the mood or pace of the music).
However, when we are shooting a Performance sequence for a music video, then strict adherence to sync playback rules must apply.
When we record sync dialog for a movie, it is critical that the recorded audio be able to match the played back (video or projected) picture frame for frame, or else the actors will appear to be out of sync. Being off by even a fraction of one percent is enough to ruin a scene. That is why professional motion picture cameras run at speeds carefully regulated by crystal controlled motors and the production audio recorders rely on complex sync and/or timecode systems to completely eliminate any speed variance (wow & flutter). Both the film camera and the audio recorder capture the scene in REAL TIME so that they can be aligned later during editing and played back with accurate lip sync.
The traditional clapstick slate (or modern timecode) is used to line up the respective audio track with its matching picture.
Of course, if audio is originally recorded simultaneously on the videotape, as in a video camcorder, then lip sync is guaranteed since we do not need to concern ourselves with matching up the track from an audio recorder with that from the camcorder.
When we shoot a music video, the audio is NOT recorded live on the set, but is instead PLAYED BACK for the musicians to pantomime in lip sync to. It is sort of like recording live dialog, but in reverse. The audio track must be able to match the camera track frame for frame, or else the lips will be out of sync. This requires a camera with crystal controlled speed, and an audio playback system completely devoid of any wow & flutter. If the audio does not play back at precise speed every single take, then the musicians will be pantomiming to a song that may be several beats off tempo from the actual recording (the actual song that appears in the finished music video).
To do sync playback, you will need a recorder or playback device that is capable of speed accurate playback every time. That means a reliable digital recorder or laptop device. In addition, we need some way to record a signal onto the camera to allow us to know what section of the music was playing while we were filming.
Here is how we do it in the professional world…
The first step is to obtain a copy of the final music selection that the artists will be performing to in the music video and create an EDIT MASTER. That means making a digital copy of the music that has SMPTE timecode added to it. The timecode should run at 29.97 NonDropFrame rate for standard video or DVD, and 23.976 for HD.In addition to the frame rate, pay attention to the sampling rates being used. Digital recorders rely upon the sampling rate for playback speed more than the timecode, which is used for syncing back to picture later on.
It is strongly recommended to check with the POST PRODUCTION SUPERVISOR regarding what settings to use, as the digital editing workflow is continually evolving with each new release of software.
This piece of music will become the master soundtrack that we will edit our music video images to.
Multiple copies of the EDIT MASTER (with matching timecode) will be produced for us to playback in the field during production. Format will match the type of audio device that we will be using for sync playback. These copies are called PLAYBACK DUPES.
In the event that we are using a non-timecode digital recorder for playback, the PLAYBACK DUPE will be mixed down to mono, so that the file will have music on the left track and SMPTE timecode on the right.
Out on the set, the Director will call for the camera to roll first, and then call for the Playback. As the music begins playing, we need some means to identify the musical section for the camera. This is professionally done by means of the timecode that was pre-recorded alongside the music. A timecode slate is used to display the running timecode for the camera to photograph. This provides a match frame for the video editor to use in order to align picture with the appropriate point in the master song.
After shooting a brief amount of the timecode slate, the Director is free to call for Action.
