Another important aspect of the new generation of flexible 24p cameras is that they offer nonlinear gamma settings as adjustable contrast profiles that can emulate the response of film to light. The upper HD 24p image was obtained with a normal gamma response typical of a properly adjusted video camera. The lower image is typical of the film response curve that 24p cameras emulate through their nonlinear gamma settings. This response to light, coupled with progressive scanning at 24 frames, contributes to the final visual effect — a video camera that can behave like film. Click here to see an enlarged diagram.
I once heard the look of film described most succinctly by an ad agency client. I was writing and directing a series of film commercials for him. In the small talk that fills those time gaps between moments of progress, he opined, “Film offers this wonderful diaphanous veil of fantasy that you don't get from video.”
My brain gnawed on that phrase. Diafph-a-what?
Well, it's been about 25 years and many rolls of both film and tape since I first absorbed some part of what that sweeping insight meant. In the last couple of years, digital 24p cameras and editing systems have substantially closed the visual gap between film and video. And, to fully cover this aspect of acquisition would require a sizable book. What I'd like to emphasize here is that new technologies are becoming available that will enable 24p video to be a new medium of visual expression for stations and other content producers.
The bottom line is that at the NAB2005 convention, attendees can see, try and even buy new 24p tools at price points previously not thought possible.
The benefits of 24p
Several new and low-cost 24p cameras and technology are being shown for the first time at this year's convention. Readers will want to be sure they examine these new 24p technologies at exhibitors' booths. While all the solutions aren't yet completed, vendors assure me that we will see products on the street this year.
Today, many prime-time programs have moved from film to 24p high-definition video. Network sitcoms are regularly shot in 24p with three to four cameras. Dramas are shot on location, film-style, but using video cameras. Even national and regional commercials are now routinely created in 24p. Is the image film or video? It's no longer obvious.
Now, as smaller and less expensive 24p cameras come online, shooting content in 24p is something that I recommend broadcasters and content producers consider seriously.
Why? Put simply, this technology represents an opportunity to significantly expand a station's visual palette. Shooting in 24p enables the station's creatives to develop a sophisticated station look that is more visually consistent and competitive with national network programs and commercials that surround the local inserts. Locally-produced promos, show openings, bumpers and other interstitial visual elements that define a local station's identity can become visually richer when properly shot film style in 24p.
The new lower-cost cameras and editors mean 24p capabilities are no longer limited to high-dollar content. Even the local station can bring that high-end film look to its audience. Armed with this new technology, staff directors, videographers and editors can be encouraged to reach creatively beyond the limits of SD production.
To see if I am on track with others' viewpoints, I contacted two seasoned experts for some practical pointers on shooting and editing in 24p.
Sean Fairburn is an HD cinematographer/DP in Los Angeles and a regular contributor to HD magazines. Michael E. Phillips is the principal product designer for Avid Technology, a practicing editor/post-supervisor and Webmaster of 24P.com. I asked both of them to comment on the advantages and challenges of using 24p technology.
Sean: While 24p can provide attractive moving images, there's more to achieving a rich film look than just having a camera that shoots 24-frame progressive images. Having the time and resources for proper lighting and camera support also are part of the visual equation. Video projects that are lit and framed beautifully will look all the better in 24p.
Michael: Because 24p is a video format, users have that valuable real-time visual feedback along with the usual benefits of efficiency and convenience of shooting with videotape. Videotapes can also run five times longer than film magazines.
An Avid UI shot of the frame shows the metadata tracking that can be done in a 24-frame project — 30-frame master drop and non-drop, as well as 24fps source and record.
Pete: True. The longer run time and lower cost of videotape do make it easier to maintain momentum with fewer reload breaks. As a director, I like to keep that shoot energy up on the set, and work with the talent to mix it up a bit with some extra takes when appropriate without worrying about running out of film.
Sean: I do see the lighting crew and others on set get into a shoot more when the images are available to everyone. As with any video shoot, seeing what the photo filters, lighting and so on can really do then and there can be a plus. You can't do that with film. Plus, the immediacy of video greatly reduces guesswork. However, like any good film project, the director and the DP should have a firmly established visual goal — an appropriate look that they've already discussed and defined in reproduction to complement the narrative objectives. Should the look of the project be hot, bright and colorful? Dark and mysterious? These questions of visual style should be answered in reproduction for all projects, film or 24p video.
Michael: Once you have the video, the editing process becomes the focus. Again, 24p has advantages. When properly shot 24p footage reaches the editor, it already looks and feels like film. This makes it easier for the editor to apply appropriate color correction and contrast management techniques to further enhance the look of the 24p material. The workflow is the same for both video and film.
Sean: Ideally, the final look comes from a plan that the videographers and editor can execute as creative partners. Many DPs here in Los Angeles are learning much more about what's possible in post-production to enhance their work following the shoot.
One point to note about 24p is that, like film, the camera's normal exposure time should be set to 1/48th of a second for most work. That's the time equivalent of a film camera exposing 24 frames each second with a typical 180-degree shutter. The progressive scan video camera at 24 frames then generates the same resulting motion blur and integration as normally exposed film. The 24p frame rate and exposure timing provide the technical basis for the film look.
Pete: Keep in mind also that the same camera movement practices, pan rates, etc. used when shooting film also work well with the 24p video camera's motion characteristics. It's not like the shooter has to learn a whole new way of doing his job.
Michael: It's also important to understand that 24p as a video acquisition format easily dovetails into all the other video delivery formats, for example, 30i. The 24p material moves through post-production workflow just like standard video. Again, the staff doesn't need to learn a new set of skills. You shoot 24p video, and you edit using the same basic techniques as if the project were originally shot on film and transferred to videotape. The normal film-to-video 2:3 pull-down for playing back 24p images in the 30i video signal path is all managed by the editing system.
An editing system will also handle and track all of the timecode math for 24p and 30i video rates simultaneously and automatically. You always know exactly how long the project run time is to the frame and exactly where you are on the timeline.
Many people who are unfamiliar with 24p acquisition don't realize that it is just an acquisition format. What is delivered by the editing systems in the end is a normal video stream that matches whatever digital standard they've adopted for transmission, be it 30i or 60p.
Sean: Though we talk about working in 24p, we are actually shooting at 23.98 frames. However, there are no drop frame/non-drop frame settings to worry about. All of that is managed later on in the editing system. One important point about audio, however, is that when working with double system sound, I recommend that the separate digital sound recorders be run at the 29.97 frame rate, non-drop mode.
HD versus SD
I prefer to operate my camera timecode in “Record Run” mode rather than time of day “Free Run.” It's also smart in either timecode mode to maintain the good habit of running several seconds of video “speed” before the director calls “Action.”
Michael: It's important to realize that the choice to work with the advantages of 24p can be made independently of the image resolution. What you shoot in and what you deliver in need not be the same.
Sean: Whether you are shooting an HD or SD project, if you think and work the project as though you were shooting film, and you apply the proper production values and principles in 24p videography, you will achieve a very pleasing film-like result. The technology will definitely support your creativity.
Michael: Editing in 24p doesn't have to be any more complicated than working at any other frame rate, and delivering the project in any of the other HD and SD frame rates is straightforward.
Sean: For me, working in 24p is a new art form. It's an opportunity to create something that can enjoy that desirable narrative fantasy of film while working with the convenience and immediacy of video. Production practices that create high-end images will always be important. What the new digital cameras do is help simplify and lower the cost of 24p acquisition.
Michael: In light of the new inexpensive 24p technologies, cameras and editors being shown at this NAB, readers should know that using 24p is no longer limited to high-end budgets.
Pete: So, as a TV station in a local market, if I wanted to embrace that diaphanously veiled film image for my station look, I could achieve it in-house using 24p equipment with a thinner, say, more diaphanous budget?
Michael: In a manner of speaking. You're the writer.
Sean: Diaphanous is good. 24p is good.
Peter Fasciano is a fellow and advanced development and co-founder of Avid Technology. The views expressed in this article do not necessarily represent the views of Avid Technology.
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