Grass Valley ADVC-300 - Manual (Page 21)

21
No.8 Video Sync Mode setting
Allows you to select whether to enable the PLL (phase-locked loop)
control or not. This switch is effective only for DV inputs.
OFF: External Sync ON: Internal Sync
If set to [OFF: External Sync], the ADVC-300 synchronize the frame
and subcarrier period of analog video to be output with the pulses of
the incoming DV stream. If set to [ON: Internal Sync], the ADVC-300
uses its internal circuit to determine the frame period of the analog
video to be output.