24p for the Rest of Us

Thisarticle contains charts that are only viewable in PDFformat. To view it, you must have the Adobe Acrobat Reader,which can be downloaded for free.

With a price of less than $4,000, Panasonic's AG-DVX100 and thebenefits of shooting 24p are now available to more video pros.

Panasonic introduced the AG-DVX100 at NAB 2002; by the Oct. 1 shipdate, the company reported back orders of several thousand units.

For DV shooters with aspirations of working on feature films,network shows, and other high-end dramatic presentations, few camerashold the promise to so utterly transform the way we work and the way wesee the world as Panasonic's new 24p DV model, the AG-DVX100.

Until recently, 24p and DV would have surely seemed like anoxymoron. After all, George Lucas and his colleagues in the upperechelons of the motion picture industry are the ones taking advantageof 24p video production. Now, thanks to Panasonic's new $3,800 DVwonder, the benefits of shooting 24p are available to the rest ofus.

In mid-September, I had the opportunity to work with a prototype ofthe DVX100, and was blown away by the camera's performance.

At the Tiffen Technical Center overlooking the Warner lot inBurbank, I constructed several intimate daylight- and tungsten-balancedscenes with male and female subjects. In one challenging setup, Iplaced the subject against a large picture window with a pair ofdaylight-balanced Gyoury lights providing the required soft edge andfill. In another setup more typical of a studio environment, I used avariety of tungsten fresnel units to model the subject's facenicely.

Resolution and tonal reproduction in both progressive andnon-progressive modes were significantly better than what I'm used toseeing in this price range. This was largely due to thelatest-generation 1/3in., 410,000 pixel CCD and better-than-averagecamera optics. In 24p mode, the shadow detail is truly impressive, withlittle if any hue shift apparent in brightly saturated objects —a familiar nagging problem for DV cinematographers, especially in thereds.

From the moment of its announcement at NAB 2002, the DVX100 hasgenerated extraordinary interest. Will anyone forget the unrealspectacle at the Panasonic booth of the clambering hordes fawning overa gray plastic mock-up? Not surprisingly, by Oct. 1 — theexpected shipping date — the company had backorders of severalthousand units.

Still, for many DV shooters, the advantages of shooting 24p are notentirely clear. After all, NTSC monitors and displays are invariably60-field interlaced (60i). NLE 24p support is (for the moment, atleast) poor or nonexistent. And the DVX100 camera itself records totape at 30fps interlaced.

Hmm. So what's the point?

For one thing, 24p production (really 480p) offers substantiallybetter resolution than conventional NTSC. Image capture is performed ina continuous fashion at a rate of one complete scan per frame. This isin contrast to the conventional strategy of scanning every frame twicein order to achieve the appropriate odd and even fields required forinterlaced images.

Progressively scanning images eliminates the temporal artifacts thatmay occur between fields; the suppression of these artifacts is a majorfactor in improving apparent resolution. Of course, DV's relativelyhigh 5:1 compression is still a hurdle for many shooters, but the factremains that we're not pointlessly trying to encode hideous NTSCaliasing artifacts, as is the case now with 60i mode.

In the emerging 24p/DV world, the DVX100 is being acknowledged asthe first kid on the block, and as such, the camera must be consideredsomething of a pioneer. Panasonic seems to have acknowledged this inmaking some rather interesting choices.

First, shooters have the option of recording conventional interlacedfootage at 60i or one of three progressive modes. At 60i, the DVX100acts as a conventional DV camcorder, albeit with significantly betterresolution and improved gamma response.

Shooters may also select 30-frame progressive mode (30p). In thiscase, the camera captures high-quality still frames without the obviousNTSC interlacing artifacts.

At 24p, however, things get a bit more interesting. Panasonicengineers, perhaps cognizant of the limited support downstream, optedfor two 24p modes: standard and advanced.

In 24p standard mode, images are captured progressively at 24fps.The 24fps video stream is subsequently converted to a 60-fieldinterlaced signal using a conventional 3:2 pulldown scheme (see chart).The resulting video is then output to miniDV tape for editing incurrent 30fps-based systems.

The advantage is that images retain the relative look and feel ofmotion-picture footage shot at 24 fps, although with the inevitableimage shift, aliasing, and other degradation introduced in the standard3:2 60i conversion.

In the 24p advanced mode, images are also scanned progressively at24fps, but the conversion of frames to 60i is handled somewhatdifferently (see chart on page 24). Here, the higher-resolution framesrecorded originally at 24p are restored in the NLE (or compositingenvironment) by weeding out the extra frames added in the telecineprocess.

Apple has announced that Final Cut Pro 3 will soon have the abilityto restore original frame sequences in DVX100 footage captured in 24padvanced mode. Those posting on FCP should see little imagedeterioration from high-quality 24p capture.

At the moment, there is little support downstream for the advancedmode featured in the DVX100. However, in a joint statement withPanasonic, Apple has announced that Final Cut Pro 3 will soon have therequisite 24p capability to accurately restore the advanced mode'soriginal frame sequence. In effect, DV shooters posting on Final CutPro will see little image deterioration from original high-quality 24pcapture through output to film or DVD.

In my opinion, therein lies the real advantage of a 24p camera likethe DVX100. Even if you're not outputting your DV epic to 35mm film,you are almost certainly (or will be shortly) transferring your show toDVD. And many shooters may not even be aware that every DVD player isby default a 24p playback device!

Of course, authors have been encoding feature films at 24fps forsome time, then relying on the DVD player to perform the requisite 3:2pulldown for NTSC display. Encoding a movie at 24fps eliminates theartifacts generated by the encoder trying to compress the redundantfields introduced in the telecine suite. Encoding at 24fps also reducesfile size by 20% — not an insignificant amount in an era when DVDproducers are constantly pressed for space, and need to encode at thehighest video data rate possible.

Now it happens that today's MPEG-2 encoders and transcoders are notyet capable of correctly tagging 24p video streams. But this is only amatter of time as hardware and software developers (such as Apple) pickup the 24p gauntlet.

Clearly, the Panasonic AG-DVX100 is the first shot across the bow inwhat will surely become an exploding 24p/DV market. In addition to itsprogressive-scan capabilities, the camera boasts other significantprofessional features, such as Cinelook. This is an alternative gammasetting that mimics the pleasing look of motion picture film.

In terms of features, I particularly liked the 10X (f1.6,4.5mm-45mm) Leica-branded zoom, which offers shooters surprisingly goodperformance, especially when compared with the dubious“package” lenses typically provided in this pricerange.

Two XLR audio inputs with manual gain controls are provided on theside of the camera. I liked that, along with the user-settabletimecode, camera shake compensator, and a multitude of pro-level menusettings to control everything from dual zebra profiles to skin tonedetail and three color-response matrices.

The prototype camera I used had not been tightened sufficiently toadequately judge the mechanical functionality of the lens, a notoriousweak spot in most DV cameras. In the production model DVX100, I wouldexpect the manual focus and zoom rings to operate much more efficientlyand securely. However, the action of the lens, including the built-inzoom servo, is significantly better than anything I've seen in thisprice range.

My other criticisms of the camera include a persnickety menuselector — again a possible prototype issue — andunintuitive placement of some controls, including the manual iris. Itsposition adjacent to the white balance switch defies simple logic. Thelens shade with its open-back design is similarly tough to fathom.

In the December issue, I'll be updating my filter recommendationsfor several popular DV cameras, including the DVX100. Without lettingthe cat out of the bag, let's just say that if you're an old film guylike me, you should definitely not part with those little-used camerafilters. Who knows? Those old Pro-Mists and Softnets might be exactlywhat you're looking for in 24p.

For more on the Panasonic AG-DVX100, see the review on page 35 ofthis issue.

To comment on this article, email the Video Systems editorialstaff at vsfeedback@primediabusiness.com.