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MillimeterShooting for Sundance
Jan 1, 2003 12:00 PM, by D. W. Leitner
A Story of IMX, PAL, and Native MPEG-2
 As we go to press, cinematographer D.W. Leitner’s film, The Technical Writer, has been accepted into Sundance. It becomes the first-ever feature shot with Sony’s IMX camera, thus the first of its kind to screen at Sundance. In the following pages Leitner details his pioneering experiences in production (he also shot with the new Zeiss DigiPrimes), as well as postproduction adventures on the desktop, on Sony’s Xprí, and at indie lab DuArt.(Photo by Chris Freilich) |
Production
Timing can be everything. My partner Michael Yanko and I were in the
process of forming our production company, Damage Control, to produce a
slate of New York indie features when I encountered Sony's MSW-900P
“Digital Super 16” at NAB 2002. We decided this new
camcorder and its MPEG IMX format were an ideal match for our first
film, The Technical Writer.
It's a wry Gotham tale of an agoraphobic computer manual writer (Michael Harris) teased from the squalor of his basement apartment by the racy couple in the penthouse upstairs (Tatum O'Neal and William Forsythe). Indie auteur Scott Saunders directed and co-wrote it with Harris. One of our goals for The Technical Writer was a 35mm film finish. So why would we choose a Betacam-like 1/2in. tape format over S-16, 35mm, or either flavor of HD, all of which I've had favorable experiences with in the past?
The “P” in MSW-900P is for PAL — to me, a more remarkable development than the “Super 16” handle. For the first time, PAL-only equipment was promoted into the U.S. broadcast market, which Sony did to facilitate blow-up to 35mm. Digital PAL yields 576 active lines over NTSC's 483, a 20% increase in vertical definition, and PAL's frame rate, 25 frames per second, almost matches film's 24fps. For these reasons, PAL is popular in the U.S. with low-budget digital filmmakers, despite their having to slow down the picture to 24fps and pitch-correct production audio in post.
Whether PAL or not, digital origination until now has mostly confined itself to MiniDV at the impecunious end and 24p HDCAM at the gilded end. What if there were a middle ground, a poor man's 24p? (“24” stands for video recorded at 24fps like film, and the small “p” for progressive scanning, which yields noticeably sharper results than the interlaced scanning typical of broadcast TV.) Sony's answer, for the moment, is the 25p MSW-900P camcorder, recently introduced in Europe as a replacement for the Betacam line, and switchable between 50i and 25p.
So not only would the MSW-900P be expected to provide an extra hundred lines of PAL vertical definition, but its progressively scanned images ought to be sharper and less marred by artifacts than conventional interlaced images.
But even we at Damage Control weren't prepared for the leap in image quality demonstrated by the $40K MSW-900P. With its new megapixel 16:9 2/3 Power HAD EX CCDs and high-performance Digital Signal Processing LSI (large-scale integrated) circuitry, which Sony says, “builds on the sophisticated DSP technology developed for digital Betacam camcorders,” we came to think of the MSW-900P as quasi-HD. In fact, based on our experience, we suspect there's a little DNA from the HDCAM F900 in there too.
For instance, before we began principal photography, our DIT (digital imaging technician) and audio recordist Steven Robinson and I had a long phone conversation with Jeff Cree, Sony's ace HD acquisition system specialist, concerning camera setup for 35mm blow-up. Jeff guided us through a custom setup that included ITU 709 color matrix settings. Isn't ITU 709 the HD production standard? At first I thought Jeff had confused the MSW-900P with the F900, both tagged “the nine hundred.” Not to worry, he knew the difference all right.
As far as compression and bit-stream recording goes, Sony's IMX format is 50Mbps, 4:2:2, I-frame (intra-frame) MPEG-2 with near-lossless 3.3:1 compression — double the bit rate and color resolution of 25Mbps, 4:2:0 PAL MiniDV. (Intriguing math: 720 lines are only a 25% increase over 576.)
In other words, this ain't no MiniDV. Yet there are MiniDV-like aspects to MPEG IMX production that any low-budget producer rubbing two nickels together will appreciate: While the MSW-900P creates near-HD images, its output is PAL, which can be edited on common nonlinear editing systems such as Final Cut Pro; and an IMX tape lists for $18 and records 71 minutes, which compares favorably to a $60 HDCAM tape, identical in size, which records 50 minutes at 24p.
 Leitner prepares to shoot principals Tatum O’Neal and William Forsythe (photo by David Gross). |
Scott Saunders wanted a camcorder that wouldn't get in the way and would provide a MiniDV experience on the set, yet surpass MiniDV in quality. Without lens and battery, the MSW-900P weighs less than 8lbs., which factored into our choosing this camera. The MSW-900P's form factor is also stubby, almost snub-nosed, and somehow shorter than other recent Sony ENG-style camcorders with sideways cassette loading. That's one reason I decided to shoot with prime lenses, to keep the camera as compact as possible.
We were able to obtain an early set of Zeiss DigiPrimes from Band Pro Film/Video in Burbank — 7mm, 14mm, and 40mm — with which we shot the entire film (minus a few exceptions such as exterior time-lapse — more below). Once again, timing is everything. I would need to write another article altogether to express my praise for these peerless lenses, which were integral to the look of The Technical Writer. Suffice to say that they extended the capabilities of the MSW-900P, and in turn the MSW-900P showcased their extraordinary qualities. A brief example: I like to shoot directly into light sources. That's OK in film, not OK in video. Well, the rules have changed. No veiling glare, no flaring, and, for that matter, no vertical streaking from the MSW-900P's CCDs. Simply none.
On occasion we utilized a Porta-Jib or Long Valley Equipment dolly, but most of The Technical Writer was handheld. Since prime lenses don't have handgrips, I added a wooden Aaton handgrip adapted by Abel Cine Tech to a base plate that snapped directly into the Sony tripod quick-release. The baseplate also held short rods for following focus gears and a left-hand grip for added stability. Abel Cine Tech supplied our lightweight clip-on the Chrosziel matte box as well, which with a donut, fit the Zeiss primes perfectly and kept the weight of the rig to a minimum.
Others who came to our aid: Plus 8 Video Rentals supplied the large PAL CRT monitor we used on-set, as well as the handheld, battery operated, hi-res Panasonic 16:9 LCD display. The display was fed by the MSW-900P's auxiliary SDI output with results sharp enough to judge focus. Liman Video Rental helped with an Arri handgrip for our B-camera (another MSW-900P) when a second Aaton grip was unavailable. HD zooms for time-lapse and a nighttime Central Park scene that demanded a lens longer than 40mm came from Broadcast Video Rentals and Abel Cine Tech. Fujinon also jumped in, supplying us with its new HAe5×6 (6mm to 30mm) cine-style HD zoom for a pick-up long after principal photography. (For supporting indie production, New York rental houses rock — they're second-to-none in generosity and open spirit.)
I've mentioned time-lapse. The MSW-900P introduces a built-in intervalometer function, the first true single-frame time-lapse capability in a video camcorder. It's not a gimmick — our opening credits are built around time-lapse, including spectacular shots of Manhattan at night from the top of the Empire State Building. In the MSW-900P's auto interval recording mode, an internal RAM cache collects single frames at specified intervals, up to eight second's worth at playback speed, then lays them off to tape while continuing to collect the next eight seconds. Turning the tape transport on and off for recording eight seconds at a time, as needed, eliminates head wear over long shooting durations typical of time-lapse.
 Director Scott Saunders (left), shares writing credits with star Michael Harris (photo by Richard Sylvarnes). |
I was also able to review my time-lapse results instantly, which has never before been possible with film. This is a boon to the art of time-lapse, which necessarily involves guesswork and experimentation. Instant playback informed all my decisions, aesthetic and technical, including the juggle of auto and manual iris control (I had to rely on HD zooms with auto-iris, which prime lenses lack, when shooting exteriors with changing light conditions) and the use of NDs and Polas (polarizers).
Timing is everything? Here's proof: We are the first MPEG IMX-originated feature film to be invited to the Dramatic Competition at Sundance Film Festival, where The Technical Writer will premiere this month; the first feature film shot with the MSW-900P; the first shot with Zeiss DigiPrimes; the first edited in native MPEG-2 with Sony's Xprí nonlinear editing system (no offline!); and the first MPEG IMX blow-up to 35mm at New York's renowned DuArt Film and Video, which collaborated with us from the outset to optimize the 35mm outcome. My A.C., Amy Bostwick, is the first to pull focus with DigiPrimes for an entire feature, and to her credit, I don't think a single shot was unusable due to soft focus.
Post
These days, choosing your origination format, whether film or digital, is only half the fun. Choosing the best postproduction path is equally perplexing, given recent outpourings of new, do-it-yourself-on-a-PC solutions. But there's a natural law of digital post that says that complexity expands exponentially in relationship to the number of low-cost choices. Call it the costs of opportunity law. The more alternatives, the more potential for brain-lock.
In producing The Technical Writer, our goal was a 35mm print — this much was certain. And our decision last May, a month after the MSW-900P's debut at NAB, to shoot our feature on Sony's PAL version of the MPEG IMX format was simple too, especially upon viewing an MPEG IMX blow-up test produced by DuArt. In DuArt's test, an out-of-box MSW-900P using progressive scanning and an ENG-style HD zoom captured everyday scenes in Manhattan — bustling downtown sidewalks, a bright Times Square at night, New York's harbor sparkling at dusk — and closeups of faces under unflattering indoor fluorescent light. The results, blown-up to 35mm using DuArt's Arrilaser Recorder, were way better than they had any right to be. They rivaled a blow-up from HD.
We were also drawn by the notion we could edit our results as conventional PAL on a low-cost nonlinear editing system. No hidden HD dubbing costs for us!
But we soon woke up to a central drawback of shooting PAL for 35mm blow-up: audio. Perversely, while playing back 25fps digital video at 24fps is a breeze for nonlinear systems, playing back digital audio with a comparable 4% slow-down and digital pitch-correction proved a very slippery slope.
Unlike analog audio, which lowers in pitch when tape speed is retarded but remains clearly audible, a digital audio stream slowed during playback drops in bit rate, which disrupts the timing necessary to reconstruct an audio waveform from the original sampling rate and quantization levels. However you approach it, slowing down digital audio to match “slow PAL” at 24fps is a complex task of sample-rate interpolation, with sometimes unwelcome side effects (more below).
 A.C. Amy Bostwick helps set up a Zeiss prime on the smallest, handheld configuration of the Sony MSW-900P (photo by David Gross). |
During production of The Technical Writer, we recorded single-system, 16 bits, taking full advantage of the MSW-900P's four audio tracks. (Audio recordist Steven Robinson, to his credit, was not ideologically opposed to recording production audio with a camcorder. He wirelessly transmitted audio to the MSW-900P, typically three tracks, and always made DAT backups, which were seldom needed but reassuring nonetheless.) The resulting audio was first-rate in recording quality, and single-system saved significant time in post, with no synching necessary.
So, we had a basic editing choice to make: Do we cut PAL as PAL at 25fps, including production audio, then mix our audio at the PAL rate, then slow the final mix by 4% to match the 24fps of the 35mm blow-up? But what about music or effects? In order to retain original pitch and tempo while editing in PAL, music or effects tracks would have to be sped up 4% and pitched lower to correspond to the faster PAL frame rate. Only when the final mix was slowed 4% and the music or effects tracks were pitch-corrected up again would they assume their original register and tempo.
A downside to this approach is that during PAL playback, music tempos would always be fast. Another disadvantage is that when pitch-corrected back down, any sustained high-frequency tones (think violins) would have a tendency to reproduce unevenly, depending on the interpolation technology used. (Like mic design, digital pitch-correction remains part art, part science.)
An alternative choice: Edit at 25fps, then slow all final edited tracks 4%, then replace music edits only with fresh realtime tracks, then mix everything at 24fps. This would work because production audio tracks contain mostly human voices, which unlike music, aren't rich in sustained high frequencies. They readily survive the process of slowing down and pitching up.
Another choice: Use a nonlinear editing system to capture and edit PAL images at 24fps while simultaneously slowing down and pitching up production audio using a specialized A/V capture board, audio software plug-in, or outboard Lexicon-type hardware device. Using this approach, editing would commence at 24fps and remain at 24fps. Sounds simple. Doesn't exist.
At least we couldn't figure it out. We looked long and hard at a variety of Final Cut Pro configurations, mixing and matching capture boards, realtime technologies, and storage options. Final Cut Pro 3 and Cinema Tools had just debuted, and we had hoped to uncover advantages in FCP's newfound 24fps capabilities. Weeks of investigation by director Scott Saunders, a veteran video editor and digital pioneer in his own right, and I, aided by the technical staff at DuArt, produced no ideal solution. We were flummoxed.
Might such a solution someday exist? Did America once put a man on the moon? In the meantime, we had some hard choices to make. Instead of a lowest-cost solution, we chose to edit on Sony's own MPEG-2 Xprí, which held an intriguing advantage: It alone permitted direct editing in MPEG-2, the compression we recorded in. The edge? Think of it as super-MiniDV. Using an MSW-2000 IMX deck with SDTI (serial data transport interface), a sort of super-FireWire, we captured our data to disk directly from our MPEG IMX tapes, with no further uncompression or recompression. At two times realtime speed, I might add. Which adds up, when you have 50 tapes of up to 71 minutes each to capture.
By capturing, editing, and outputting in native MPEG-2 compression, we overcame the offline/online hurdle, exactly as MiniDV editing has. Our direct output was our “online master.” Our editor David Leonard (Nadja, Palookaville, Julie Johnson) probably wouldn't have chosen to become an MPEG-2 Xprí pioneer, since in the several months we edited, he cut a swath through several beta and release versions of the Windows-based Xprí software. But the pleasures of watching edit choices instantly on a hi-res 16:9 video monitor in full resolution, and better yet, on a big 42in. 16:9 plasma display perched on a nearby table cannot be denied.
And the audio conundrum? We cut audio in PAL at 25fps. Music was laid in as temp only. As we neared the mix, we made a standards-converted NTSC master of the locked final edit with which to mix at 24fps (this is a standard practice, since 30fps NTSC — 29.97 precisely — converts readily to 24fps — 23.98 precisely). Composer Stephen Cullo then created original music for The Technical Writer against the NTSC master. Sound designer Damian Volpe used the NTSC master to build aural urban landscapes to match the shifting emotional states of the central character of The Technical Writer. In the end, only the production audio was slowed and pitch-corrected by Volpe, using Pro Tools plug-ins. The production tracks were transferred to Pro Tools as OMFI files, output from the Xprí to a portable FireWire drive. (Strictly roll-your-own, however: Saunders, my nine-year-old daughter Simone, and I spent a Sunday afternoon installing a FireWire card in the Xprí.)
The true secret to our success: We cast as technology co-partners the willing tech staffs of DuArt, including Lloyd Forcellini, Maurice Schechter, Roman Rossell, Marcus Janner, Carmen Borgia, and Irwin Young himself, and the Sony Xprí team, including Andre Floyd, Chris Marchitelli, Lliver José, Leigh Herman, and Rob Willox. On the MSW-900P side, Jon Reiner, Larry Thorpe, and Jeff Cree. All of whom we at Damage Control approached from the very outset. As a result, we achieved a number of unusual synergies: The MPEG-2 Xprí was installed on premises at DuArt on West 55th Street in the same building where our looping, Pro Tools dialogue editing, and Digital Dolby audio mix took place, as well as DaVinci color correction, digital titles output, Arrilaser Recording of reels one through five, processing, negative cutting, printing, and telecine transfer. Talk about vertical integration!
