Tutorial: Mastering Dual-System Audio for DSLR Production

Hearing is Believing

You're probably wondering how the audio sounds coming from camera compared to the recorder. So you can hear for yourself, I did a few test files for comparison. I plugged a simple lav mic into the Zoom H1 and recorded a short sound test in wav format. I then plugged the same mic directly into the GH2 and recorded another sound test. Upon ingest into the computer I found the 2 files to be fairly close in quality regarding background noise and quality. Here are the 2 files directly from the camera and the Zoom H1.

Note: The GH2 file was trimmed and saved as a wav file. Originally it was in mts format. You will notice the actual direct mic into the GH2 is slightly cleaner than the feed off the recorder.

However, I wanted to clean up the audio to remove any his from both sources. After using an Audio Restore filter (similar to Sound Soap or other well known noise removal filters) I noticed that the audio from the GH2 was degraded a little more because the original file from the GH2 records audio in a compressed format. The cleaned up audio from the Zoom H1 sounded cleaner and had less detectable compression artifacts. The difference is small but noticable if you need to tweak your audio much.

In many cases, that direct feed into the GH2 will be acceptable, but there will be other times where higher-quality audio is needed. It's those circumstances where the audio from the H1 will be your choice. Here are those same files cleaned up with the Audio Restore filter.

The beauty of recording directly to the H1 and also feeding the headphone jack to the GH2 is that you have a sync track that matches easily between the camera and external recorder. This makes syncing files manually much easier.

Syncing in Post

Now that you have video footage from multiple cameras and 3-5 different audio files from your recorders, how do you sync all those files on the timeline? You can do it manually, which becomes fairly time-consuming, or you can use a great little utility from Singular Software called PluralEyes. With Plural Eyes you simply drop your files on the timeline (try to get them in chronological order as best possible) and launch PluralEyes. Press the Sync button, and a few minutes later you have a timeline with your video and audio files linked on your timeline. Of course, larger projects will take longer than smaller projects. Plural Eyes is available for all the popular NLE applications, including FCP X. PluralEyes 3 is available in beta now. Watch www.singularsoftware.com for updates.

As you can see there are a few small challenges added to the workflow for audio acquisition using DLSR-type cameras because of the need for external off-camera audio and the lack of professional XLR inputs like those commonly found on pro camcorders. Overall, the quality of your audio will improve because the recorders can create wav files as opposed to the compressed files of HD video formats. Even with the few extra steps needed, the reward is much more cinematic-looking footage and even better audio than you had before. That sounds like a win-win situation to me.