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Venturing into HD post production - TvTechnology

Venturing into HD post production

If your budget has room for a modern high-end digital camcorder or VTR, then an HDTV purchase is in your range. With digital TV transmission nearly a
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If your budget has room for a modern high-end digital camcorder or VTR, then an HDTV purchase is in your range.

With digital TV transmission nearly a fact of life, many stations and facilities have to decide whether or not to tackle HD television production and post. The major professional VTR manufacturers are adding products that offer the ability to play SD and HD formats in the same deck. If your budget has room for a modern high-end digital camcorder or VTR, then an HDTV purchase is in your range. Century III, a post production company at Universal Studios in Florida, is an example of a facility that has integrated HDTV into its workflow.

We were in the market for a Digital Betacam field package, and for almost equal cost, Sony's 1080i HDCam 700A model camera made more sense. At first, we downconverted to SD straight from the camera's transport but soon added an HDW-500 1080i studio VTR. Though the VTR was an additional expense caused solely by HD, it has allowed us to keep the camera packages working more frequently. We can source directly from the HD camera tapes into any of our linear and nonlinear edit suites without the extra burden of downconversion. So current workflow is the same as shooting any SD format, with the added benefit of a superior camera image and format protection for the future.

If you are shooting HD, but plan to post in SD for NTSC or PAL distribution, there are several things you should consider. First is aspect ratio. Since HD natively shoots in 16×9, you will compose with both 16×9 and 4×3 framing in mind. In post, you will have to decide which framing you will use. The 16×9 HD footage can be converted to 16×9 SD (an anamorphic image in a 4×3 frame), a letterboxed or a cropped 4×3 image. Keeping the 16×9 squeezed image lets you retain all the image information, but then you have to decide how your final master will be used. This may mean creating several separate masters — letterbox, “pan-and-scan” 4×3 and the anamorphic version. Graphics will have to be composed and edited for each of these versions.

HD cameras are far sharper and have more natural resolution than their SD counterparts. This resolution looks very pleasing and filmic in HD but may seem soft in the SD conversion. If your end result is to be NTSC, you may wish to run with more enhancement than you'd like for HD. Consider a separate outboard downconverter with image enhancement adjustments. The cameras can be “painted” to create many different looks. This can be stunning in the right hands, but terrible in the wrong hands. Shooting for a “safer” look will often render an image that is somewhat flat, necessitating more color correction in post.

After a couple of years of shooting HD footage, Century III has now moved into HD post. Our SD editing has almost completely changed over to Avid-based suites, complemented by one Digital Betacam linear suite. HD will follow the same path, because it keeps the investment and maintenance costs in VTRs down, while adding far greater versatility. This is truly the first year in which you can build a nonlinear-based HD edit suite for about the same cost as a high-end SD nonlinear suite or a low-end component digital linear suite.

If you are designing an HD suite, here are some things to consider. Which signals do you have to deal with? The dominant HD formats are either 1080i or 720p with frame rates of 24, 25, 30, 50 and/or 60. A broadcaster won't have to deal with all of these, but a post facility might. Remember, in HD you can go 23.96 or 24 and 29.97 or 30, so be careful. A domestic broadcaster will probably be mainly concerned with either 720p/60 or 1080i/30, so don't overpurchase. Fortunately it's all mainly done in software. Do you want your system to function for SD work as well? If so, it will stay busy and you will get the best return. Do you want to work in the compressed native format of your HD system? All modern HD VTRs use compression but output their signal to a switcher or NLE as full bandwidth HD. If your NLE can utilize the native codec of your in-house recording format, you will be able to squeeze more HD media onto your drives. Typically uncompressed HD video consumes hard drive space at about 8GB per minute.

All of these considerations have implications for which peripherals you purchase. Take sync as an example. Most NLEs working with 29.97 material (1080i) will function locked to NTSC black burst or sync for reference. Many require a new tri-level sync generator to work with 24p material. What about your scopes and video monitors? Many NLEs will give you a converted SD monitor signal, but that doesn't truly represent what the material looks like in HD. Professional HD video monitors are fairly expensive. A good substitute is the use of a high quality SVGA monitor for your HD image. Miranda and AJA Video, among others, make HD-to-SVGA signal converters for this application. These CRTs, and flat panel screens, are available in wide-screen (16×9) versions. True HD waveforms and vectorscopes also are a good idea, but you might wish to consider some of the on-screen displays, like those from Videotek, which convert the HD signals along with audio displays into a VGA signal. Add a standard computer CRT and you're done.

A big advantage with nonlinear HD suites is that they are generally SGI, PC or Mac-based, meaning that they will network nicely with existing graphics workstations. Rendering is a real factor in finishing HD projects (almost no effects can be completed with real-time processing), so spreading the load becomes very beneficial. If your graphics/effects department already uses After Effects, Commotion, Combustion, Maya, Softimage or others, they are already equipped to produce graphics, animation and/or effects for HD. You can send them materials from your system over the network (usually as a sequential frames or a QuickTime movie), let them add their work and then import the rendered files back into the NLE, all over the existing network. 100-T is fine, but fatter is better!

The last consideration is workflow. HD post is largely the same as SD post, except that because many effects work requires rendering, you will wish to go back to offline/online editing procedures. This will let you work quickly at low cost to rough in the show and then spend time in the HD suite tweaking the effects. Unfortunately, if you are using most of the popular standard definition NLEs for offline editing, your effects information won't come across too well. It works better within the same “family” of products. To improve this, most HD manufacturers are offering draft or offline modes on their HD systems. You also could cut on a lower-cost version of the same system during the offline editing phase in order to guarantee direct interchange. For instance you can rough-cut a show on a low-cost version of Apple's Final Cut Pro and then post the online using a Cinewave HD system, which is driven by the same Final Cut Pro software. Effect metadata is then virtually identical.

Like everyone else, Century III has been struggling with all these issues. We have posted a few HD projects with Pinnacle's Cinewave HD system to put it through its paces. This is giving us an idea of how best to finalize purchases for our HD nonlinear suite. Meanwhile we also are looking long and hard at some of the others so we'll be ready in the next month or so to make our final commitment to the system that is right for our clients. HD demand isn't terribly high right now, but like so many things, the floodgates will soon open and we had all better be ready.

Chris Fischer is a visual effects editor at Century III in Orlando, FL.