External Preview on Desklink not working (slow/laggy) _litz wrote on 8/30/2023, 1:05 PM Anyone got any ideas on why external preview on a DeckLink SDI output is very slow/choppy/laggy? Latest Vegas 21 (and yes, a legal copy), latest Desktop Video drivers from BlackMagic. When I select External Preview, the video output on the SDI is about 10 seconds behind real-time, and sutters and lags badly from there. Back to post