Creative Workflow Hacks

We’ve been doing HD work at Primal Screen for a few years now. Both for delivery to fledgling HD Networks like Animania and as an acquisition format for live and studio shoots. Like any endavor there has been a bit of a learning curve. My biggest takeaway that I’d like to share is to treat your acquisition and delivery formats differently.

When I was putting together a spec for our HD rig circa 2003 I knew I wanted to deliver on HDCAM and I figured I’d also use HDCAM and HDCAM tape as an acquisition format for our green screen captures etc.. I was never really happy with the results however. After doing a bit of research I started to see what I was up against. Once the signal is recorded to tape some pretty major compression is introduced. We go from a 1920 x 1080 4:2:2 signal from the single-link HD-SDI and once we hit the tape it is compressed into an 8-bit 3:1:1 color space before being DCT compressed aprox. 6:1. The frame size is also nudged from 1440 x 1080 and then stretched back out to 1920 wide. yuck.

In all honesty, the image looks pretty nice for delivery. Since cable and satellite companies will introduce yet another round of MPEG 2 or H264-MPEG 4 compression. This is the best your image is going to look in it’s final form, but what we are interested in as image makers is how we can manipulate and process our image. Here is where it falls short.

So if you can shoot in a studio it makes a lot of sense to capture directly off the single-link HD-SDI to a 10bit 4:2:2 stream. Or even better, shoot…

HDCAM SR. HDCAM SR is capable of recording in 4:4:4 1080p RGB over a dual-link HDSDI. Dual link HDSDI is a fatter data pipe necessary to carry the approximately 237Mbps video signal. I’ve been really impressed with the results. Colors pop. No Interlacing with 1920×1080 30fps frames. 4:4:4 color space. This is more like it. We’re using a Kona 3 from AJA, but there are similar product offerings from Decklink. We are using a 8port E-SATA raid and a Quad G5 over dual-link HDSDI and then moving selects to our Apple XRaids via an internal LAN for processing. We also have an HDCAM SR tape as a safety with much less compression if we need to recapture. I’m a happy camper and it looks like my HD visions are finally starting to play out how I’d hoped.

So bottom line, if you can afford to put it in the budget, HDCAM SR is a no brainer win for HD acquisition.

• Some additional resources:
• The great HD For Indies site is your one-stop-shop for the latest in hardware, format info and news for HD production.This post particularly covers the issues above in detail.
• Alex Lindsay gives a great demo of 1080p 4:4:4, 4:2:2, and 4:1:1 color space and gives the case for high-quality acquisition even for broadband delivery.