DSLR Dual-System Audio: The 99.9% Solution
What is dual-system audio?Dual-system audio is one name for the technique of recording audio and video on separate devices, and then combining them in post-production. Since the quality of built-in mics and audio systems of cameras are generally not nearly as good as the video, dual-system is a convenient way to get high-quality sound. It is particularly effective for video coming from a DSLR like the wildly popular Canon 5D Mark II.The price to pay for these benefits is a small one: you need to synchronize the audio and video in post-production. This can be done manually or automatically using our PluralEyes product.The problem with Final Cut ProMany non-traditional cameras shoot video at 30 fps instead of the more usual (in some parts of the world) NTSC rate of 29.97 frames per second (fps). If you are using Final Cut Pro with such video there is one quirk that you need to be aware of. This has been discussed in recent blog postings (see, for example the comment at 9:45 of the Zacuto video here). The quirk has come to be known as the 99.9% problem: when audio is combined with 30 fps video, the audio speed (sometimes) needs to be adjusted by the NTSC factor of 99.9% (actually 1000/1001).Fortunately there is a simple fix for this: use an Easy Setup for 30 fps. Details below, but first some background.BackgroundVideo from a DSLR and other still cameras is typically recorded with a frame rate of 30 fps. If you do a lot of work with NTSC video, your default settings in Final Cut might be something like HDV 1080p30 which has a framerate of 29.97 fps. When you work with 30 fps material, you might expect that ensuring that the sequence frame rate is 30 (and not 29.97) would be enough to make things work. But what happens is that when you add an audio track to the timeline, Final Cut retains some memory of the NTSC settings and applies an NTSC adjustment to the playback speed of the audio. This seems like a bug to me--I can't imagine any situation where I would want it to