As 24p for you? (That's 24 frames per second, progressive or single-frame image.) It's got a historical pedigree: 24 frames per second has ruled the feature-film world ever since it was chosen in the late 1920s as the best speed for those first sync-sound films. Now it's being touted as a potential panacea, the one acceptable frame rate for film and video productions worldwide. In many minds, it's the first universal mastering format.

Consider the current format landscape. Since the introduction of HDTV and DTV broadcasting, networks and independent broadcasters everywhere have been requesting a dizzying array of formats. "In the pre-digital era, clients worried about NTSC and PAL, but now the deliverables are all different," says Dave Satin, vice president and engineer at New York-based SMA Video. "Now I have to ask, 'Where is it going to run?' Fox wants 480p, ABC 720p, CBS wants 1125i. There's no way to have lossless transfers from one to the other."

"Beyond that," Satin continues, "CBS wants an HDCAM cassette, ABC wants a D-5 tape, and we don't know what Fox or PBS want yet. We have to be able to make every combo of line rate, pixel size, and aspect ratio in every possible tape format, the same way we do it now, on Betacam SP, Digi Beta, D-1, D-2, High 8, C, and any other format."

Today's solution is to reintroduce the concept of a universal HD mastering format-24p. The benefits are many (see sidebar), and the basic idea is straightforward enough: Use film or one of the new-generation 24p camcorders and configure post operations around a progressive-frame video standard, one that matches frame-to-frame with film.

That idea has a problematic history, though. When experimental HDTV production began in 1986, it was 1080i that carried hopes of becoming the first universal video-production, post, and broadcasting format. However, that utopian vision fell victim to a disagreement that turned out to be fatal for the nascent format: working out the differences between contending line rates. Suddenly, that one-world vision turned into two contending camps: the NTSC countries and the PAL countries. Each wanted an HD TVL (television line) resolution that was a simple multiple of its native television format-whether 525 (NTSC) or 625 (PAL)-since this would ease up-conversion of the libraries of existing standard-definition material. Further, the differences between 50 Hz and 60 Hz electricity, the basis of each format, proved too difficult to leap between with the available technology.

Today, the demand for various HD formats reflects the real-world needs of the thousands of production and post communities worldwide. Even more so than before, a universal mastering system seems essential. So why 24p?

One reason for a 24fps post format comes from a desire to circumvent the complexities of 3:2 pulldown. During telecine transfer in 3:2 pulldown mode, one frame of film is transferred to three video fields. The second frame is transferred to two fields. This cycle repeats until the transfer is complete. But problems can arise with the 3:2 pulldown if, during editing and effects work, the correct sequence isn't kept. Working carelessly could result in an edit smack in the middle of one of the field sequences. This rhythm change both harms the image and decreases the efficiency of compression schemes. (MPEG relies on similar, continuous video sequences to deliver the best compression ratios.)

So, the potential benefits of 24fps video post are substantial. One early example helped prove the point. For Lucasfilm's The Young Indiana Jones Chronicles, a one-to-one film-to-video transfer technique cut both time and costs. To edit the TV series, which was shot in Super 16mm (another first), San Francisco's Western Images transferred the film on a one-to-one frame basis, according to C. Park Seward, an independent television engineer. While that still meant editing with interlaced video, the usual 3:2 pulldown sequence was not created for the video. Without those extra frames, the editors now worked with a tape that ran 20 percent faster than real-time.

But the real reason for that type of transfer was to improve effects and compositing operations. Spreading an effect over constantly changing sequences of 3 and 2 fields blurs the results. So not having to deal with 3:2's staggered field sequences yielded sharper images. Effects work went more quickly as graphics artists applied effects to 24-frame sequences, not 60 fields. Finally, at the end of the process, Quantel's Cine Expand software inserted the 3:2 pulldown sequence for television playback.

Over the past year, Los Angeles-based Laser Pacific, working in partnership with Sony, has brought 24p to day-to-day post operations. Claimed as the first facility to offer 24p from telecine to final master, Laser Pacific now employs the format for 8 prime-time series, says president and COO Emory Cohen. "We think the quality and flexibility of 24p offers great utility to the production community. Currently, in-house, we've got about 80 percent standard-definition post, with 20 percent in HD. I think that it will be the other way around in the near future."

Alluding to the poor motion handling of 24p origination, Cohen says, "Nobody would shoot a basketball game at 24p, but for what we do-telling stories-24p is the one format that lets the producer deliver a quality product to any network, no matter their standard. This includes European delivery [at 1080P/50 frame]."

Cohen estimates that 84 percent of prime-time shows are currently shot in film. This keeps Laser Pacific's three Philips DataCines busy. (A fourth will soon be installed.) Sony provided much of LP's initial 24p gear, including its first delivered HDW F500 VTRs, HDS-7000 switchers, HME-7000 digital-effects generators, and monitors. Other 24p products on board include da Vinci (2K color correctors), Digital Vision (HD 24p color corrector), Evertz (time code, interfacing), and N-Vision (router).

But even as 24p gains adherents in post, it's clear that the two coasts-Los Angeles and New York, really-are the most obvious beneficiaries. 24p postproduction of film-originated material for features, TV sitcoms, and commercials seems ideal for these two film-oriented markets.

However, some see no benefit to everyone jumping into 24p post. "Look at the market," says Jim Fancher, "chief science officer" at Santa Monica-based Pacific Ocean Post, a part of the 4MC Group. "There's only so many companies in the world that do prime-time post, and that's a tiny group. If I'm in New Orleans, maybe I'll think that I should be buying 24p gear and get ready for the big 24p rush. But guess what? It ain't going to happen. [After all], how many prime-time shows are [posted] in New Orleans?"

C. Park Seward once owned one of those post houses in New Orleans. Now, however, he's an independent engineer and production specialist working out of Los Angeles-and he agrees with Fancher's point. "To come up with that kind of money, the move to 24p is obviously a major undertaking for facilities and independents." There's more to the economic argument, Seward says, than just post facilities' decisions. Production folk face big decisions too. "I see a reluctance, especially by the many independent camera operators, on changing to anything [like 24p HD]. Everyone's shooting Betacam SP. To buy something new, I think everyone would want to standardize on the same format. They don't want to spend another $150,000 if they don't have to."

However, with more and more sitcoms and television movies opting in, Los Angeles-based houses now must confront the move to HD. There's no question that facilities must provide HD post, though there is concern about getting too far ahead of client demand. "For entertainment TV and feature films, 24p makes sense," says Larry Chernoff, president of 4MC's Encore Group. Last year, Encore Hollywood added a number of 24p linear-edit bays. "But it would be foolish for any company or individual to take a religious view of any format. There's just no panacea."

Chernoff, noting the limited temporal resolution of 24fps film (it causes cars or wagon wheels to appear to move backwards), says the problem with 24p lies in the set frame rate. Sports production, for example, whether with film or video, requires higher frame rates. Otherwise, action on the field would appear blurred, and slow-motion replay wouldn't deliver any detail.

"This is an extraordinarily important issue that is not highly understood, nor highly regarded, by most of the community," says Chernoff. "People use temporal resolution without knowing about it. They shoot at 24fps, but then transfer at 525 (line), 60i, or integrate 60i graphics into 24-frame film. We're finding people are jumping on the 24p bandwagon, then jumping off as soon as they hit a creative roadblock. Our advice to customers? Use 24p if they're willing to work within the confines of the temporal resolution of the format."

POP's Jim Fancher agrees on the limits of 24p production-and the inevitability of its replacement. "Music videos and commercials shoot at all kinds of speeds. Maybe you're shooting for a certain effect, say slow motion. You're going in and replacing the sound anyway, so you want the most flexibility in production. I don't see 24p as a long-term format. Cameras with variable frame rates-say from 7 to 72 frames per second-that's what's coming next."

The advent of feature film-style 24p cameras from Sony and Panavision made news last year. Lucasfilm announced that the next two Star Wars installments would employ Sony's HDCAM technology, saving money in film-stock costs as well as speeding the post process.

However, video origination for feature films generates its share of disagreement. "24 frame progressive (for post) should be shot on film," says David Wiswell, group manager of advanced television product development and engineering at Panasonic Broadcast. "Our position is that 24p masteri ng only makes sense if it is based on film-originated video at 24 frames. The primary focus of our 24p program is mastering image quality, and our position is that we can only achieve that with 35mm film and [10-bit depth] D-5 HD [recorders]."

Larry Thorpe, vice president of acquisition systems at Sony Broadcast, doesn't agree that 8-bit recording such as HDCAM's can't offer adequate color resolution. Thorpe points out that while bit depth affects tonal and color reproduction, state-of-the-art A/D converters, as well as nonlinear RGB processing in the camera, well represent the original 10-bit image as it is recorded in 8-bit.

Aside from differences over bit depth, there's also some disagreement about implementing compression. Panasonic's Wiswell says that "D-5 is a full-resolution recorder; it's not heavily prefiltered." (He's referring to Sony's HDCAM, which filters the image before compression.) Thorpe, on the other hand, points out that Panasonic's D-5 employs 4:1 compression when operating at 8-bits, "the most common operation at present."

There's also a trade-off between bit depth and the amount of compression. "Recently," Thorpe says, "they have attacked our 24p HDCAM as being 'only' 8-bits, and that they, Panasonic, will operate their future 24p HD D-5 at 10-bits. That's fine, as long as they also publicly point out that their compression ratio now must increase to 5.1:1, which has its own perils when handling taxing picture content, especially as they have no prefiltering."

The issue gets more complex. Sony may announce, possibly at NAB, a higher-bit-rate, higher-performance MPEG HD recording format. Also on tap: an HD camera that switches among 24/25/30p, as well as 50i and 60i, and less expensive 60i-only HDCAMs. Stay tuned for continued debate.

Last fall, Avid Technologies announced that 96 percent of the prime-time fall shows were edited on either a Media Composer or Film Composer system. Last year, the company launched its first 24p product, the Symphony Universal. (Visit Avid's site at http://www.avid.com/products/tv/index.html for a white paper on "Managing the Content Explosion: 24p Universal Editing and Mastering.") Avid lists several reasons why the move to 24p post makes good sense:

*PAL and NTSC masters can be created from a single 24p video source, much like the telecine. Without 24p, this requires expensive standards converters, where motion artifacts are introduced in converting from NTSC to PAL for international distribution. High-end boxes that will remove motion artifacts resulting from NTSC pulldown are available, but they are very expensive, costing upwards of $300 per finished minute of programming. This can add $15,600 to the cost of delivering the PAL version of a one-hour program.

*24p provides a one-to-one correlation with the master source, allowing far more precise editing, painting, and effects. It also provides frame accuracy for both film cut lists and EDLs.

*Storage is more efficient in digital nonlinear systems, requiring 20 percent less disk space than when working in NTSC.

*Greater performance is realized in the rendering of effects and composites, with results up to 20 percent faster than in NTSC.

*Workflow can be faster. Working in 24p delivers smooth motion-picture playback in NTSC because of the continuous 2:3 insertion upon playout. PAL is smooth due to a 1:1 frame correlation at 25fps.

*Frame accuracy is maintained. EDLs no longer need to be adjusted for the + or - frame discrepancy introduced when editing 24fps material at 30fps or 25fps. These discrepancies can make a program containing two or more layers unusable.

With the introduction of DTV, the variety of distribution formats has become mind-boggling. Some want 1080x1920 at 30i, some want 720x1280 at 60p fps, and others want 480x640 at 30i fps, according to Jim Mendrala in a DTV Tech Notes article. (See www.scri.com/index2.html, December 1998)

A variety of solutions now appear to have solved the puzzle of multiformat HD. (Consumer set-top boxes automatically handle the 18 ATSC HD formats.) Panasonic offers two solutions: the AJ-HD3000, a multiformat D-5 HD mastering recorder, and the AJ-UFC1800 Universal Video Format Converter. The AJ-HD3000, the latest D-5 iteration, picks up on the popularity accorded the AJ-2700, Panasonic's earlier D-5 VTR. Both offer 10-bit, full-bandwidth recording with minimal video compression. Supported frame rates are 60i, 50i, 60p, 25p, and 24p. Another useful feature: 8 discrete audio channels to support Dolby AC-3 Surround Sound.

"We're changing the D-5 slightly so that it's truly a multiple image-format recorder," says Panasonic's David Wiswell. "The AJ-HD3000 provides input, output, and transcoding of 601, 1080i, 720p, and 24p, and records each format as if it's a native recorder. It also slews between 24p and 25p so that you can do frame-rate conversions without introducing any temporal artifacts."

Panasonic's AJ-UFC1800, a stand-alone "universal format converter," can up-, down-, and cross-convert between any ATSC image format. It can even handle additional image formats. And it has the ability to add and remove 3:2 pulldown, manage audio delay to match video-processing delays, and accomplish pan and scan.

Sony's HDW-500 offers switchable, multiple frame rates, with recording of 1080x1920 images at picture rates of 24/25/30 frames progressive and 50/60 field interlaced. Besides a cassette, the F500 accepts and outputs these formats via a standard HD SDI interface. Material shot at 24p can be played back into 50 Hz or 60 Hz at the push of a button. One interesting capability is that the F500 analyzes recorded time-code data and can then output to the appropriate time code. Recording capacity of HDCAM cassettes increases when using 24fps frame rates. For example, over 2 1/2 hours of 24p recording fit on a standard 60-Hz cassette.

Rumor has it that Sony is at work on a wide-bandwidth product, which it may announce at NAB. This VTR should offer specifications comparable to those of the Panasonic D-5, as well as the higher quality needed for electronic-cinema projects such as Lucasfilm's upcoming Star Wars movies.

Employing a unique approach to multiformat conversion, Teranex's Xantus uses a programmable parallel-processing computer to up-convert, down-convert, and cross-convert between any video formats. That includes any existing and emerging SDTV and HDTV standards, as well as non-standard formats. Each new conversion ability comes solely from a software change sent over the Internet or through a CD-ROM.

Xantus' real-time processing, which started delivering this past December, has come courtesy of millions spent by the Defense Department to develop extremely high-speed processing for image recognition on the battlefield. Internal processing runs at 1 TeraOp per second, with a sustained I/O rate of 3.6 GB/s.

Orlando, Florida-based Teranex employs three techniques that the company says distinguish it from any currently available technology. PixelComp handles pixel-by-pixel motion compensation via an algorithm that retains the full vertical resolution of interlaced video throughout the de-interlacing process. The device actually realigns each video field on the fly before processing. Gamma Correct Colorspace Conversion maintains the correct color from one format to another, and FrameComp enables frame-rate conversion without double images or jitter.

"It's really about the way you want to portray motion," says Jim Fancher, chief science officer of Pacific Ocean Post. "It's an artistic choice."

Certain situations call for speedier image capture-sports and other fast-paced action or graphics, for example. In these situations, slowing down playback to 24fps can result in jerky, blurred movement. Here's where 60i shines, especially during slow-motion playback.

But will 1080/60p do away with 24p post? Probably not in the near future, as output to film for theatrical projection will stay at the 24fps international standard. However, when theatrical projection moves entirely to data streams, 24p will lose much of its appeal.

The holy grail of 1080/60p, a subset of the proposed MPEG-4 standard currently being finalized by the MPEG-4 committee, is already on Sony's schedule. At last fall's SMPTE conference, Sony's Larry Thorpe announced that NAB 2001 will see a line of 1080/50/60p gear. Jeff Merritt, product marketing manager, ADTV group of Panasonic, says that they could not comment on a technology that far in the future.

One problem: Even with the compression inherent in MPEG-4 at ultra-high level, 1080/60p devices need to record up to 600 Mb/second. That's a lot of data. In comparison, Sony's first offering of a full-bandwidth HD recorder, intended for high-end mastering, falls under the MPEG 4:2:2p@HL standard of 300 Mb/second. Expect to see this Sony recorder sometime in '00.

Another solution for HD recording, Philips' D-6 format recorder, should deliver by NAB. Since it's not compressed (and both D-5 and HDCAM are), it might be a solution to check out. Estimated pricing pegs the D-6 at about $180,000, with 1 hour of tape at $1,000.

In the post industry, the term black box refers to all-in-one, integrated turnkey systems. As the major editing and graphics black-box maker, Quantel makes post gear that has total control over its environment.

This control results in fast-to-market delivery of new technologies. At NAB '99, Quantel presented a deliverable, 24-fps progressive option for Editbox FX. The company wants to keep costs down for its users by supporting the existing population of standard DVTRs. In other words, as Quantel would say, don't rush out and buy HDCAM or D-5 gear just yet.

Quantel prides itself on the development and use of sophisticated algorithms in its graphics product line, and its "real-time, multipoint, bicubic, spatial interpolation" technology is no exception. The company says its Hibridge technology can up-res SD material to HD without the image degradation caused by standards converters.

That's where Quantel's new Publisher HD comes in handy. Publisher HD codes the output directly into the desired PAL and NTSC formats. This retains the image quality of the original material.

Meanwhile, Chaser technology delivers native HD editing at any standard, including 24fps 1080p. To get around editing with full-res material, Chaser allows working in lower-res proxies. After proxy editing is complete, the full-bandwidth editing then goes on in the background.