VirtualDub & Blackmagic Decklink: Capture NTSC

Post by **^rooker** » Mon May 14, 2012 11:17 am

We've been using the Blackmagic Decklink SDI cards for over 2 years, happily capturing PAL (720x576 @25fps).
Now I wanted to switch in order to record NTSC, but there are a few things that need to be changed in order to do so:

1) A real NTSC replayer (not one that will convert from NTSC to PAL)
2) A video A/D converter which can handle NTSC input
3) Change the Decklink to do "NTSC- 8bit 4:2:2 YUV"
4) Check that VirtualDub has the correct capture size (720x486 @29.97fps)

In our case we've used a Leitch DPS575, as well as a Focus MC-2E: Both can be switched between PAL/NTSC. The Leitch doesn't label it "PAL" or "NTSC", but lists it as "line standard" with the options 525(=NTSC) and 625(=PAL).

The Blackmagic/Decklink settings in the control panel don't offer the control over the video format. The required menu can be accessed from within VirtualDub (in capture mode) with:

Video > Capture filter > Video format

There you can select between different NTSC/PAL options. Regular 8-bit NTSC/PAL is:

NTSC - 8 bit 4:2:2 YUV
PAL - 8bit 4:2:2 YUV

If the changes are applied correctly, you can (and should) verify the framerate:

Capture > Settings > Frame rate

For PAL this field will contain the value: "25.0000", and after you've changed the Decklink's input, this will automatically be switched to "29.9700".