Timecode Systems: Wave Master Clock for timecode, word clock, & Genlock generator connected to Sound Devices 664 Keeping Your Set in Sync with Timecode, Genlock, and Word Clock Since Genlock clocks the capturing of frames on a camera, it can be used to keep the picture from drifting from the audio over time. This is especially important for 3D two camera rigs. In the HD world, Genlock is still hanging around, but these days it uses a protocol called Tri-Level Sync to clock both the frame rate and line rate. Today, most switchers can compensate for this rather than feeding black burst to every source from a central clock. Genlock was used to keep cameras and other video sources’ frames in sync to avoid nasty artifacts introduced when switching from one source to another. Genlock (which is short for generator locking) originated in the early days of broadcast and video switching systems. This can cause endless headaches in post when you match the audio and video with timecode, and by the end of the clip, the video is noticeably out of sync with the audio. This is especially problematic for productions that require a long roll time (30 minutes plus), such as reality TV or event coverage. The problem you get here is the camera clock is not calibrated to the external sound recorder’s clock, and slowly they will drift apart as you continue to record. Once a camera starts recording, it ignores external timecode and uses its own internal clock to record. Timecode is in fact only metadata to identify how the first frame is labeled for time when the camera begins rolling. Timecode and sync are not the same things. The common assumption is that by feeding timecode to a camera you will keep picture and sound in sync. Is timecode the most important thing to sync picture with sound? Let's explain why it may not be.
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