Let's say you've decided to videotape an interview with two family members. In order to give yourself some options when you edit, you want to shoot them using two cameras. So how do you capture audio? And how do you synch up the tapes from your two cameras during editing?
Option 1: You can mount a lapel microphone on each subject, run the mics into a mixer, and feed the outputs of the mixer to the audio inputs of each camera. Of course, in order to do this you need a mixer and someone to mix the audio while you're recording. This is probably not something that's going to be possible for most family projects.
Option 2: Most consumer and many prosumer cameras have only one microphone input. When shooting with two cameras, you'll need to run one microphone to each camera. (Note: Unless you're using stereo microphones, the camera will place the audio on only one half of your camera's stereo channel. You'll need to copy the audio over to the other half of the channel during your edit.)
Option 3: You can buy an audio adaptor that contains two audio inputs. The inputs are of the professional XLR type (three-pin). The output of the adaptor is a mini-plug that plugs into the mic input of your camera. The adaptor will allow you to combine the audio from both mics and send the mixed feed to both left and right channels of your camera OR you can choose to keep each microphone isolated on its own channel. This option requires the purchase of an adaptor and some professional cables, though. If you do go with Option 3, remember that you're feeding the output of the microphones to just one camera. However, your second camera will still need to record audio (you'll be using this camera's audio as a reference only - I'll get to this in just a moment) so make sure the onboard microphone contained in the camera is working.
No matter how you record the audio, keep in mind that you're going to need to synch the tapes from the two cameras during your edit. One technique that will help is to record a very recognizable sound on each tape, a sound you can later use to match your tape positions. If you have a clapper, (you know, the small slate with a handle that slaps the top of the slate, used in motion pictures), that'll be just fine. If you don't have a clapper, use your (or your subject's) own two hands. Start both cameras recording, wait a few seconds, and then clap once, as loudly as you can. Do this each time you start recording. You now have audible reference points on each tape.
First of all, you'll need editing software that provides a timeline with a number of video and audio layers. After you digitize your videotapes, you're ready to begin. The first step is to create a "rough edit" during which you synch up all your tapes. Let's say your two-shot is on camera 1. Import tape 1 from camera 1 into video/audio track one. Find your first clap (you'll hear it, of course, but you should also be able to see it clearly on the audio waveform displayed on the audio track) and mark the point with a clip marker. Next, import your close-ups from camera 2. Find the first clap on this tape and then mark it. Finally, line up the two markers.
Now, play the two tapes together on the timeline. If you don't hear any echo, you're right on the money. If you do hear an echo, you may need to shift one of the tapes back or forward by a frame or two. Once the tapes are synched, group them together using your editing software. Grouping guards against accidentally shifting the position of one of the tapes and losing audio synch as a result.
Once the tapes are synched, create another timeline, sequence or project. Use your rough edit as a source and cut and paste segments from your rough cut into the new timeline as you create your final program.