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Since I have been blogging about syncing considerations, this blog is just a reminder that when recording audio directly to camera with on-board microphones can have a sync offset already inherent in the recording. This will go further out of sync as the subject, or source of audio moves away from the camera. The farther away you go, the more of a sync offset is introduced. At some point it becomes moot, as you will no longer be able to see what should be in sync the farther out it goes. If you are using this audio track as a reference track to sync with tools like PluralEyes, then you need to keep this offset in mind. This is where 1/4 frame syncing comes in handy as offsets are not always one frame in duration, nor fall on frame boundaries. Related blogs on syncing are here and here.
The screenshot above shows the results from a quick test I did with the Blackmagic Cinema Camera recording ProRes at 1920×1080. The screen grab is from the timeline with three distances as logged on the clip names; 5 FFET, 10 FEET, and 20 FEET. I used the iPad MovieSlate application that flashes the screen orange with a beep making it easy to see and hear. Clicking it will either prompt to download the full size image, or open in an other window/tab.
I added frame boundaries in a graphics program to make it easier to see. The last clip in the timeline (20 FEET) shows two frames of orange. That is actually a blend frame and based on “blend” I put the sync location where you see the dotted green line. This camera has an inherent “audio ahead of picture” by 1/4 frame. Then, as the subject moves farther back, the sync offset get larger; 1/4 frame every 5 feet. This is a case where you would want to resync on 1/4 frame boundaries if possible for tightest sync possible. In a timeline you could slip clips before sending to PluralEyes to ensure even better sync when the results are returned.