I was recently asked to edit footage filmed using a dual system setup (video and audio recorded to two seperate devices). Recording audio seperately from video is one of the best ways to increase production value, but only if it is done properly. Based on the material I was asked to edit, I realized some people may know what is needed for dual system recording, but don't know what steps to take for their efforts to be effective. With that in mind, here is a quick guide on how to run a dual system shoot. Getting the best quality is a discussion best left for another post, this is simply a Dual System Recording for Dummies Guide if you will.
The most important thing to remember when using dual systems is that you need to record a visual AND audio cue in order to sync audio and video in post production. We've all seen behind the scenes footage were a crew member calls out the scene and take number, and proceeds to slam the gate on the clapper. This way the editor has visual data to connect to audio data. In the footage I was given, a clapper was clearly labeled, and used properly, only no one on set called out the scene or take number, meaning the audio files have no discernable information. They only have a clap, and the line reading, making it nearly impossible to match them to the video.
Another key step is making sure your camera and audio recorders, are recording audio at the same bit rates. If your camera records audio at 44.1bits, and your audio recorder records at 48bits, you will get what is called drifting in post production. Drifting is when your audio and video are in sync at the beginning of a take and drift out of sync by the end of it. this is because your audio and video are playing back at two different rates. The numbers above were just examples, as these numbers will vary based on the equipment your using. For more information, refer to the owners manual for your gear.
These are essential steps to follow. If they are ignored, you could have the best quality audio and video imaginable, but they will be nearly useless, as syncing them up in post production will be near impossible.