Question: Who would be interested in low-cost uncompressed HD capture and post, if such a thing were possible?
Answer: Indie filmmakers concerned with best results in transferring small-format HD to HDCAM for festival circuit projection or, better yet, blowup to 35mm.

By D. W. Leitner

Well, such a thing is now possible. Ushered in by a new acronym, HDMI, which, if unknown to you at the moment, will soon become as familiar as USB or FireWire.

First, some background. And fasten your seat belts — we’re about to hit bumpy air called disruptive technology. Several stretches of it, in fact.

When Canon introduced its XL H1 HDV camcorder last year, one of its selling points was the inclusion of a professional connection for uncompressed HD called HD-SDI. HD-SDI stands for High Definition Serial Digital Interface, and it uses a single BNC bayonet connector. The idea behind HD-SDI is that instead of three cables, which analog HD uses, a single cable serves as a pipeline for the torrent of data that is uncompressed HD. That Canon provided such a costly high-end spigot for uncompressed HD on a mere HDV camcorder was groundbreaking, and consequently so was the XL H1’s price tag, $9,000. Twice the street price of a Sony Z1.

The XL H1 was the first and only HDV camcorder to feature an HD-SDI output until Canon recently announced its new, more compact XH G1 ($7,000), due out in October. But all HD-SDI outputs are not created equal. At minimum, an HD-SDI signal must contain uncompressed video data. Optionally, it can also carry audio and timecode — eliminating two more cables — if these are first “embedded” in the HD-SDI data stream. While the XL H1’s HD-SDI output did not contain audio and timecode — necessitating extra cabling and concerns about sync — the good news is that the new XH G1 does indeed embed audio and timecode.

Now, if you think about it, digital audio and timecode embedded in a digital video signal is commonplace in the low-end realm of FireWire. So what’s the big deal with uncompressed HD? Ginormous bandwidth, that’s what. Where DV and HDV use data rates of 25 Mbps (megabits per second), HD-SDI provides for 1.485 Gbps — that’s gigabits per second, almost 60 times the data rate of DV and HDV! Therein lies the daunting challenge of capturing and editing uncompressed HD.

Miraculously however, another path to uncompressed HD has opened up, and, equally amazing, it’s a low-cost solution from the world of consumer video called HDMI, (high-definition multimedia interface).

HDMI is, in effect, an update of the common DVI (digital visual interface) connection used since 1999 to digitally connect computer displays to computers. DVI looks like your typical rear-of-computer multi-pin connector, with screws at either end to fasten it. It was created by an industry consortium to make it easy for consumers to connect pixel-based digital displays like LCD screens. To be able to display digital images using digital signals was a big step forward, because unlike analog CRTs, in which line resolution and brightness are subject to vagaries of electron beam scatter, electromagnetic distortion and phosphor decay, digital displays like LCDs, plasmas and DLP projectors create individual pixel brightnesses based on levels that are digitally encoded and therefore perfectly reproducible.

Like HDMI, DVI too was designed from the outset to support display of HD, up to 1080p and 3.7 Gbps, but what was missing was audio. In 2002 Sony, Panasonic, Philips, Thomson, Toshiba and others joined to create a smaller, single-cable standard with a flat, consumer-friendly USB-like plug that would carry HD, eight channels of audio and standardized control signals (consumer electronic control) for devices like DVD players and cable/satellite set-top boxes, the market for which HDMI was intended. The latest iteration of the HDMI standard — version 1.3, ratified in June — hiked data rates to a stratospheric 10.2 Gbps, bit depths to 16 per color, and introduced a new mini-HDMI connector for camcorders.

If you’d like to see this cute mini-HDMI connector up close and personal, simply pick up the latest miniature HD consumer camcorder from Sony, the HDR-SR1. Notice I didn’t say HDV camcorder. It isn’t. Read on.

Most of us were stunned a year ago when Sony introduced a tiny single-CMOS HDV camcorder called the A1 that produced images rivaling the larger Z1. The A1 was a professionalized version of a $2,000 consumer camcorder, the HDR-HC1. Months later, in February, Sony replaced the HDR-HC1 with the HDR-HC3, $300 cheaper and 26 percent smaller. With a notable innovation: a mini-HDMI connector.

In July Sony announced two more single-CMOS camcorders (due in October): the HDR-SR1 ($1,500), virtually identical to the HDR-HC3 but three ounces heavier due to substitution of an internal 30 GB hard disk instead of a MiniDV drive, and a sister model, the HDR-UX1 ($1,400), which substitutes a DVD drive to write to inexpensive 3-inch (8 cm) DVD-R’s (2.6 GB each). In addition to mini-HDMI connectors, these tapeless camcorders sport new logos — “AVCHD” and “Full HD 1080.”

AVCHD (advanced video codec high definition) is a new disc/disk-based consumer format announced last summer that outperforms the tape-based HDV format. While AVCHD employs the same MPEG-2 transport stream as HDV, it uses the MPEG-4 AVC compression popularized as H.264 by Apple Computer and others and often described as two times as efficient as MPEG-2 compression. Since AVCHD’s data rate is about 24 Mbps, similar to HDV’s, that means, roughly speaking, double the potential image quality.

AVCHD’s specific qualitative advantages over HDV are: (1) support for 24P, (2) a full 1920 x 1080 pixels instead of HDV’s undersampled 1440 x 1080 (HDCAM also undersamples horizontal resolution at 1440) and (3) uncompressed audio, either linear PCM or Dolby Digital AC3. Like HDV, AVCHD’s color sampling is 4:2:0 and 8 bits/color, with support for both 1080i and 720p formats as well as standard-definition formats of 480/60i (NTSC) and 576/50i (PAL).

In other words, the HDMI signal coming from Sony’s latest inexpensive single-CMOS consumer camcorders, whether HDR-SR1 or HDR-UX1, contains full-blown 1920 x 1080 uncompressed HD and multitrack audio, because that’s what these little guys handle internally in their digital signal processing (DSP) circuitry. That’s what the new logo “Full HD 1080” means. Who says we don’t live in an age of miracles? (What’s more, in the case of the HDR-SR1 and HDR-UX1, audio is Dolby Digital 5.1 Surround!)

Some, in fact, have likened the debut of HDMI to the coming of FireWire 10 years ago, but that’s stretching things. FireWire was designed as a hot-swappable, high-bandwidth replacement for SCSI that could carry power and enable device-to-device communication. HDMI, by comparison, is just an output for uncompressed digital HD signals intended for viewing purposes. Nothing less, nothing more.

Unless you happen to think outside the box. Which is what Matrox did earlier this year when they introduced their MXO DVI-to-audio/video output adapter box ($1,000). Matrox understood the frustration of Final Cut Pro users who edited HDV in real time, only to stand by for hours on end, if not days (no exaggeration), while a struggling Apple G5 rendered FCP’s timeline contents into an unbroken long-GOP MPEG-2 file for HDV playback.

Matrox figured, Why not convert the DVI signal sent to the Apple Cinema Display for real-time timeline playback into a real-time uncompressed HD-SDI signal? (Remember, like HDMI, DVI is uncompressed but lacks audio, so MXO must digitize audio from the G5’s analog stereo miniphono jack and embed the result in the HD-SDI stream it creates.) Did this approach catch on? Last month at the International Broadcasting Convention in Amsterdam, Matrox reported over a thousand MXO units sold in the first 60 days of production.

As detailed above, HDMI does indeed contain audio. So last month Blackmagic Design, renowned for affordable capture and playback cards like its popular DeckLink series, announced the world’s first HDMI editing card, named Intensity, priced at a mere $250. Founder Grant Petty calls Intensity “a product we have always dreamed of making.”

If you guessed that Intensity uses HDMI to capture uncompressed HD directly from camcorders into computers, laptops and disk arrays, you’re right. In a nutshell, it works with either Mac OS X (PCI Express) or Windows XP systems and is compatible with Final Cut Pro as well as Photoshop, After Effects and Premiere Pro. In fact, Blackmagic says any QuickTime or DirectShow-based software can be used with Intensity.

If the steep climb in disk capacity needed to capture and store uncompressed HD is a deal-breaker for you, Intensity can instead employ one of several mild compressions, including Panasonic’s 100 Mbps DVCPROHD (whose codec is embedded in QuickTime) or, in the case of Windows XP, Blackmagic’s new JPEG-based compression. Lossier standards like M-JPEG, DV and HDV itself are also supported.

On its Web site, Blackmagic says that HDMI makes possible “direct-from-CCD recording” by “capturing direct and bypassing the HDV compression chip, for high-quality video, captured direct from the CCD.” Putting aside the fact that all of the camcorders cited above are CMOS, not CCD, I’m not too sure about this “direct-from-CCD” business. CCDs and CMOSs are analog sensors, which means that analog-to-digital conversion must take place, as well as pixel interpolation (in the case of pixel-shifting, for instance), then encoding of RGB samples into component video YCrBr signals (the digital equivalent of YUV). Plus, there’s gamma correction, edge enhancement, low-pass filtering, white balancing, etc. Hardly “direct-from-CCD.” In other words, what you’re getting from a camcorder via HDMI is the processed HD signal one step before it hits the HDV or AVCHD codec.

There’s yet another new Sony CMOS camcorder featuring the new mini-HDMI connector — this time HDV — which must be prominently mentioned in this discussion of HDMI’s potential, because for many indie filmmakers, this camcorder will prove the most significant development of all. In September, Sony announced the HVR-V1U, a deeply innovative 3-CMOS HDV camcorder about the size of a PD150, with true 24P and a modest $4,800 list.

The “V1” features optical image stabilization, an active histogram in the viewfinder (like Sony’s A1), an optional hard disk recording system, an adjustable shutter angle in degrees like a motion picture film camera, a 20x optical zoom with a well-designed bayonet wide-angle adapter, a repeatable focusing ring, and full 1920 x 1080, 4:2:2, 60P signal processing under the hood. If that isn’t enough, Sony’s ClearVid CMOS technology alone is a breakthrough, introducing diamond-shaped pixels instead of square ones. There’s no way this 24P camcorder is not going to be a runaway hit.

But I’m under the impression, which may be a wrong one, that the V1’s HDMI output is 1440 x 1080, which, since HDV is a 1440 x 1080 format, would make sense if the HDMI signal were being tapped after horizontal subsampling and prior to the HDV codec. Let’s not lose sight of the fact that HDMI is consumer technology meant to simplify viewing of HD on digital TVs, not provide 1920 x 1080 output from camcorders for optimum results in postproduction. That would be the costly HD-SDI output.

But what if I were to tell you that HDMI 1.3 supports not only 4:2:2 component 1920 x 1080 HD (why Blackmagic’s Intensity handles all HDMI as 4:2:2) but also full 4:4:4, as well as 4:4:4 RGB? Or that it supports the brand-new xvYCC color space standard with 1.8 times the color gamut of existing HD — basically any color the human eye can see?

And that’s what’s so exciting about this striking new development. In the coming months and years we’ll all be exploring the possibilities of HDMI together, manufacturers and filmmakers alike. It’s going to be a fun ride, bumpy or not.