Problem
External recorder files use a different timecode base than the camera, creating periodic sync drift.
Solution
Root Cause / Diagnostic:
Recording master video to an external HDMI/SDI recorder (Atomos Ninja, Blackmagic Video Assist) while recording internally in camera can result in timecode drift if the HDMI/SDI connection does not pass synchronized LTC timecode. If the external recorder runs on an internal clock while the camera runs on its own internal crystal, clock frequency drift accumulates. Over a 45-minute recording, the two files can drift out of sync by multiple frames.
Actionable Fix:
1. In the camera menu, enable 'HDMI / SDI Timecode Output' and 'HDMI Record Trigger' so the external recorder slaves directly to the camera's master timecode stream.
2. Re-sync existing drifting audio/video tracks using audio waveform alignment or by applying a micro-speed conform (e.g., 99.99% or 100.01% retime) to match duration.
3. Verify frame sync at the head, midpoint, and tail of long recordings by aligning transient slate claps.
Pro Tip:
Feed audio directly into the external video recorder on set; recording dialogue and video into the exact same file hardware buffer eliminates any possibility of external sync drift.
Recording master video to an external HDMI/SDI recorder (Atomos Ninja, Blackmagic Video Assist) while recording internally in camera can result in timecode drift if the HDMI/SDI connection does not pass synchronized LTC timecode. If the external recorder runs on an internal clock while the camera runs on its own internal crystal, clock frequency drift accumulates. Over a 45-minute recording, the two files can drift out of sync by multiple frames.
Actionable Fix:
1. In the camera menu, enable 'HDMI / SDI Timecode Output' and 'HDMI Record Trigger' so the external recorder slaves directly to the camera's master timecode stream.
2. Re-sync existing drifting audio/video tracks using audio waveform alignment or by applying a micro-speed conform (e.g., 99.99% or 100.01% retime) to match duration.
3. Verify frame sync at the head, midpoint, and tail of long recordings by aligning transient slate claps.
Pro Tip:
Feed audio directly into the external video recorder on set; recording dialogue and video into the exact same file hardware buffer eliminates any possibility of external sync drift.