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The HDV Bullet Train

Sep 1, 2004 12:00 PM, By D. W. Leitner

Sony HDR-FX1 Signals New Era in Digital Filmmaking

Sony's September announcement of the HDR-FX1, the world's first prosumer three-chip HDV camcorder, sent waves of excitement through the professional production community. Here's why:

Available in November for $3,700, the HDR-FX1 has the size and form factor of a Sony DSR-PD170 yet captures both 1080i HD and 480i on MiniDV cassettes. The optical subsection is particularly impressive: a Carl Zeiss Vario Sonnar 12X zoom (f/1.6, 4.5mm to 54mm) with T* antireflection coatings and true 16:9 Super HAD 1/3in. CCDs, each 1.12 megapixels. Plus built-in optical stabilization, a first in a three-chip HD camcorder.

The HDR-FX1's debut is being compared to Sony's groundbreaking introduction of the three-chip DSR-VX1000 in 1996, which, with its audacious embrace of digital FireWire I/O, single-handedly launched the MiniDV revolution.

HDV, for those unfamiliar with this new format, is a MiniDV tape-based HD format announced in July 2003, by JVC, Canon, Sharp, and Sony. (That's right, three months after JVC broke ground with its own single-chip 720p HDV camcorders at NAB 2003.)

Uniquely, HDV is neither a new tape format nor an approach to compression. HDV simply marries standard MiniDV tape recording with standard MPEG-2 inter-frame compression. The efficiency of long-GOP (group-of-pictures) inter-frame MPEG-2 — as many as 12 frames condensed into one complete frame along with a balance of minimized “predictive” frames that don't exist by themselves — has long been the basis of digital satellite and cable transmission, DVD, and ATSC broadcasting. HDV's “short GOP” is six frames.

Equal measures visionary and opportunistic, this marriage succeeds because MPEG-2 inter-frame compression as implemented in HDV is more than 2.5X as efficient as intra-frame compression, in which each frame is individually compressed. Examples of intra-frame include Sony's own MPEG IMX and its first cousin, the DV compression common to MiniDV camcorders. (The 2.5X factor comes courtesy of Pinnacle, which emerged as an early leader in HDV editing at NAB 2004.)

As a result, the data rate of HDV's 720p (30fps) is only 19Mbps, while HDV's 1080i is less than 25Mbps. Ordinary MiniDV, by comparison, is 25Mbps. Put another way, a MiniDV tape that records 60 minutes of SD also records 60 minutes of HDV's 1080i.

Unlike JVC's GR-HD1 and JY-HD10U, which capture 720p but not 1080i, the HDR-FX1 offers no progressive-scan mode, which will come as a surprise and disappointment to fans of Panasonic's AG-DVX100A and Canon's superb new XL2. The NTSC-market version of the HDR-FX1 records only 480i and 1080i. Scenes of HDV and DV can, however, be mixed on the same MiniDV tape. Upon playback, the HDR-FX1 senses the necessary codec and switches on the fly. To avoid confusion in recording and playback, a format lamp on the HDR-FX1's side illuminates either an HDV or DV logo depending upon the format in use.

Because the HDR-FX1's CCDs are native 16:9, the decision to shoot 480i in 16:9 is — at long last — painless. No more agony over the discouraging Hobson's choice of cropping the picture's top and bottom versus adding expensive anamorphic optics to achieve full-frame 16:9. If 480i at 4:3 is desired instead, the high pixel densities of the HD CCDs offset any loss of horizontal resolution while cropping the sides of the 16:9 frame. (Note that when capturing images in 4:3, horizontal angle-of-view is several degrees narrower than 16:9 for any given focal length.)

Complementing the HDR-FX1's native aspect ratio are a large 16:9 color (!) view-finder and 3.5in. LCD screen, both featuring 250,000-pixel resolutions. The 3.5in. LCD swivel screen is uniquely mounted atop the handle at the front, eye-level with the viewfinder. Like that introduced in the PD170, the LCD screen is a hybrid: backlit in dark circumstances and reflective in bright sunlight.

Under the hood there's 14-bit HD signal processing, a realtime HD codec, and menu control of such image parameters as edge sharpening, skin-tone enhancement, color phase, plus the expected settings for gain, lens, and shutter. Novel are “Cinematone Gamma,” which Sony says better preserves highlight detail à la film, and two curious “Cineframe” modes, which Sony says “reproduce the mood” of film at either 24fps or 30fps. Cineframe 24 is described as a 2:3:3:2 field cadence, akin to Panasonic's 24p Advance Mode, and Cineframe 30 a slower shutter speed (1/30th sec?) with consequent motion blur. Up to six custom Picture Profiles combining user's settings can be stored, as well.

Thankfully there are SMPTE color bars with PLUGE for both HD and SD, easily accessed by external button. Unknown as of this writing: Rec. 601 or 709 colorimetry? 7.5 IRE setup added to SD analog output for proper display of NTSC black levels?

Audio recording is MPEG-1 Audio Layer II (48kHz, 16 bits) as specified in the HDV standard. HDV audio, in other words, is not linear PCM encoded (pulse code modulated) — a distinct departure from DAT, CDs, DigiBeta, MiniDV, even Digital8. PCM coding samples, quantizes, and digitizes analog signals; its compression is lossless and results (ideally) in a perfect reconstruction of the original signal.

MPEG-1 Audio Layer II, on the other hand, is lossy, meaning that it utilizes perceptual masking techniques to eliminate frequencies not deemed critical to the human ear. The goal, instead of perfect signal reconstruction, is perfect subjective experience, i.e., transparency to the listener. Audio professionals may balk at recording in MPEG-1 Audio Layer II, fearing an accumulation of distortions in the audio signal after repeated reproduction in editing and postproduction. (Which is why last year the MPEG-4 audio subgroup added lossless PCM coding to its audio standard.)

As befits a consumer camcorder, audio I/O is 1/4in. stereo minijack. The two channels cannot be individually controlled. (Dust off that old BeachTek XLR adapter.) The well-designed external auto/manual switch has a day-glo orange status indicator and a protective cover to prevent bumping the level control. The HDR-FX1 also includes, as a matter of course, a built-in stereo mic.

HDV output is via iLink (FireWire) or component analog via a special breakout cable. The HDR-FX1 additionally downconverts 1080i HDV in realtime to 480i in 16:9 or 4:3 for output via S-Video or composite RCA connector. DV output is conventional.

A light, rugged magnesium chassis contributes to a bantam 4lbs., 7oz., or slightly more if you attach Sony's custom .8X wide-angle zoom-through adapter ($550). An optional flip-down shoulder brace, VCT-FXA ($400), relieves some of this load from the operator's arm during handholding. It attaches to the threaded hole at the bottom of the HDR-FX1, but it has its own threaded hole for tripod mounting so that it can remain attached to the HDR-FX1 when on a tripod. If the HDR-FX1 must suddenly go handheld, the hinged brace swings down from the camcorder's rear and rapidly locks in place.

Bayonet-mount 16:9 lens shade introduces a built-in, dual-shutter lens capping device others would do well to copy. (Goodbye, lost cap!) There are three prominent assignable buttons on the side and two built-in ND filters. H/M/L gain settings and Preset/A/B white balance settings are switched with professional mini-toggles, just like on the big boys. A manually operated zoom ring invites cine-style zooming. The Zeiss lens accepts 72mm screw-on filters. A customized soft case ($200) and hard shipping case ($400) are available from Sony.

Batteries are InfoLithium L series NP-F570 and NP-970. Sony says the first delivers about 2 hours of operation when using the viewfinder and 1.5 hours using the LCD screen. The latter battery delivers 6.5 hours and 6 hours, respectively. In the context of a three-chip 1080i HD camcorder, that's astonishing.

While the HDV standard specifies conventional MiniDV tapes — HDV azimuth, track width and pitch, and head-to-tape speed are identical to MiniDV — Sony has nevertheless introduced in tandem with the HDR-FX1 a new advanced metal-evaporated tape, DVM-63HD, for 63 minutes of HDV recording. Improved dropout rate and lower carrier-to-noise ratio are promised. Cost is $17. (Beyond price, there's no reason not to use premium tapes like DVM-63HD for all professional MiniDV recording.)

Not ready to junk those VX2100s and PD170s just yet? Consider the following: Because the HDR-FX1 is equally an HDV and MiniDV camcorder, and because it uses the same Zeiss T* zoom, HD CCDs, and 14-bit A/D converter to capture both formats, it must now rate, hands down, as the finest Handycam-style 480i MiniDV camcorder available. With a price ironically below original list for the PD170, which shipped nine months earlier.

The HDR-FX1 is distributed by Sony's consumer division, and a pro version will appear first quarter of 2005, with splashdown likely at next April's NAB. The pro version's prototype, showcased last April at NAB, looked identical to the new HDR-FX1 with the exception of dual XLR audio connectors, which I'm delighted to report are at the base of the lens barrel. (Grafting them to the handle above, as in the PD170, unbalanced the camcorder.)

Sony has said that the pro version will be less than $7,000 (in fact it lists at $5,946). That's a big bump for incorporating adjustable timecode and female XLRs. Perhaps lossless audio compression will be added, too? Or do Cineframe 30 and Cineframe 24 prefigure progressive scanning in the pro version?

As it happens, last year's HDV consortium endorsed 720/60p, 720/30p, 720/50p, 720/25p, 1080/60i, and 1080/50i. That's right, no provision for 720/24p or 1080/24p despite the evident popularity of 24p in the MiniDV community (ask Panasonic).

Fear, perhaps, of undercutting some other HD camcorder? After all, HDV's 1080i recording spec is 8 bits, 4:2:0, 1440×1080 samples. Come to think of it, isn't 1080i HDCAM 8 bits, 3:1:1, 1440×1080 samples? Yes, and that's why Sony last year upgraded HDCAM to HDCAM SR (Superior Resolution), with both reduced MPEG-4 compression and 10-bit sampling at 4:2:2 or 4:4:4 of all 1,920 horizontal pixels.

But wait, aren't there always 1,920 horizontal pixels in 1080i? Yes and no. In HDCAM the initial 1,920 horizontal samples captured by the CCD are subsampled prior to compression to create 1,440 samples of luminance and 480 samples each of the two chrominance signals. Later, upon uncompression, a full count of 1,920 pixels is restored. The HDR-FX1's CCDs capture a mere 960 horizontal pixels, which after a pixel-shifting technique yield 1,440 samples. Devices that display these images must subsequently up- or down-res HDV's horizontal resolution to match their own.

Compared to HDV's total data rate of 25Mbps, HDCAM's subsampled video requires a whopping 140Mbps — this after further 4.4:1 compression. When audio and metadata are combined, HDCAM's total data rate rises to 185Mbps. (HDCAM SR's is 600Mbps!)

Pinnacle has said that video quality matching HDCAM's 140Mbps can be achieved with MPEG-2 compression of less than 50Mpbs.

The implications of this are flooring.

Will there be a professional HDVCAM format that breaks rank with basic HDV, as DVCAM and DVCPRO did with the original DV standard? What about rumors of a 50Mbps Pro HDV standard that features 24p, under the code name HDV2? Or a new High Profile @ High Level extension, the basis of a future HDV codec capable of 100Mbps?

What justifies the leap from $3,700 to $5,000 for an outwardly identical camcorder?

You can track official developments in the burgeoning HDV world at www.hdv-info.org. As of this writing the site lists 28 companies that support HDV including heavies Avid, Apple, Adobe, and Matrox.

With 100 percent certainty, what can be said at this point is that with the debut of Sony's impressive HDR-FX1, the HDV bullet train has accelerated smoothly out of the station.

© 2008 Penton Media, Inc.