NEWS
24 and There's So Much More
Making Every Frame-per-Second Count
by Debra Kaufman
With new cameras have come new formats, including a digital version of film’s
24 fps. The DR Group, a solution provider for Final Cut Pro, including editing
services, support, training and facility planning, has often encountered the
confusion that 24-frame editing can cause among editors, and decided to do
something about it.
In early September, the DR Group held an open meeting for members of the Editors
Guild. On the agenda were several topics: an overview of 24-frame editing,
understanding the Media and Data requirements, defining the project and 24/23.98-frame
workflows at the DR Group.
“Over the last year we have received more consultation queries from editors working with 24 frame, than in any other format,” said Lowell Kay, the DR Group’s president. “It seems to be an area that many editors are finding work in, but have only a small amount of actual experience in. Holding this seminar was our way of giving back to the community that keeps us going.” The company has over 10 years experience in post-production services, after-market manufacturing, digital video solutions and motion picture film stock.
An Overview of 24-Frame Editing
The evening was hosted by Larry Jordan, author and trainer for Final Cut Pro,
DVD Studio Pro and Motion), and taught by Kay and other members of the DR
Group staff. Kay began the evening by asking what 24-frame editing actually
is. He noted that both Avid Film Composer and Final Cut Pro with Cinema Tools
were originally designed to work with film, and that they both remove the
extra frames based on the A-frame cadence. Most editors are now working with
material that is actually 23.98, not 24 fps, because the material is for high
definition (HD) or has been telecined at 23.98.
The formats that currently work with Final Cut Pro 5.1.1 include 2K; HD 4:4:4; HD 4:2:2 10-bit and 8-bit 1920x1080 (at 23.98, 29.97 and 59.94 frame rates); 720p 1200x720 (at variable frame rates) and high-definition video (HDV). HD-Cam, HD-Cam SR, D-5 and P2 are the formats that currently work with 23.98 psf (progressively segmented frames), and the only decks that can record 23.98 or 29.97 are the Sony HD-Cam HDW-F500, the Sony HD-Cam SR 5000 and 5500, and the Panasonic D5 AJDH-3700.
HDV has become popular as a low-cost, high-definition format, but Kay pointed out that all HDV formats record to decks only at 29.97 HD. (See figure 1.) The same goes for Sony HD-Cam’s HDW500 deck and the Panasonic Varicam decks AJHD-1200, 1400 and 1700. Furthermore, Varicam, JVC and Canon formats use metadata to create 24 frames out of the 60 frames they natively work with. (See figure 1.) Media that is not 24-frame native includes Digital Betacam, Betacam, DV-Cam, DVD-Pro 25/50 (except for the SDX900 camera), 3/4-inch, VHS and D9.
Breaking Down Your Next Project
At the beginning, you have to consider where you are going to exhibit—Theatrical
release? Television? DVD? The web?––and decide what format you’ll
use based on that information. At the same time, it’s important to consider
what types of media the project will include—graphics, stills, animations
and so on—to determine how many different frame rates your project will
involve. Finally, it’s crucial to determine what the distribution requirements
of your project will be: HD or Standard Definition (SD); 23.98, 29.97 or 59.94;
720p, 1080p or 1080i; NTSC or PAL? “Not considering these things in
advance is the single biggest mistake that people make,” warned Kay.
Storage is another crucial issue to consider. Frame sizes and data rates of the various formats will also determine storage requirements; the higher the frame size/data rate, the more storage required and the more expensive the editing solution. For cutting DV, HDV and DVC-Pro, a FireWire drive suffices; cutting in 2K, on the other hand, requires about $50,000 worth of hard drives. “Most offline editing is done at 5.74 Mb/sec or DVC-Pro,” he says. “Here, the storage requirements aren’t onerous. It’s easy to make real-time changes and project at high quality on a large screen. Above 5.74, we’re talking about RAID systems for storage requirements. Moving upward from DVC-Pro 100, which works out to about 21 Gb per hour of storage, you take a big leap upward with HD 1920x1080, which requires 477.97 Gb per hour. That requires RAID 5 over Fiber, is much more expensive and doesn’t move as fast as real-time. In other words: don’t cut there!” (See figures 2, 3 and 4.)
24-Frame Workflows
In the traditional workflow from film using 24 frames per second, the filmmaker
would shoot film and telecine to 23.98 fps HD, and then down-convert the tapes
to SD, adding a 3:2 cadence. The media would then be imported into an NLE,
while removing the cadence introduced in the down conversion, followed by
the edit, lock and conform. A workflow utilizing a 29.97 editing base changes
when the media is imported into an NLE at 29.97 without removing the cadence.
After editing and locking picture, the editor then creates a 29.97 EDL that
will be converted to 23.98. That requires the editor to check for changes,
make adjustments to the EDL and then conform. “You have to go back and
find the illegal frames, make another revision and make your final decisions,”
says Kay. “There are lots of extra steps.”
Instead, Kay suggests a new way to work in high definition: Shoot on film at 24 fps and telecine to 23.98, or shoot digitally at 23.98 fps. Next, capture the material to HD using a compressed HD Codec, edit and conform at full resolution. “It eliminates the steps in the middle,” says Kay. “Everything you had to do in a post house, you can now do yourself––but that means that the editors have to know the process.” Kay points out other advantages to this workflow: You no longer have to down-convert tapes to SD, which saves time and money; and you maintain a 1:1 relationship to the original material—there are no illegal frames and the final timeline does not need to be adjusted before the conform.
“You can use capture cards to input media and use a codec that will compress the HD material,” he adds. “You can project your edits directly from your computer to a large screen. Adjustments can be made during the screening process, reducing the need for change lists.” And finally, says Kay, there is simply less margin for error with this workflow. Assistant editors no longer have to worry about media starting on an A-frame. “We have been doing this for three years with success,” Kay notes. “All the big post houses do it. At this point, it makes no sense to do anything else.” (See figure 5.)
Mixing multiple frame rates and sizes on the same timeline is where it gets tricky. Once again, says Kay, consider the output. A 29.97 HD program for television use is a common type of project. The way to proceed is first to bring all formats to offline at 29.97 and create effects and graphics at 29.97. All the timecodes match––except HDV, which can go through a DVC-Pro HD codec, or convert to RAID and an offline version. “There is more than one way to deal with HDV at 29.97,” Kay says.
A 23.98 HD project is more complex. “If you’re working in film, it’s easy,” says Kay. “Just transfer all the film elements to D5 for one time-code base.” But when you have to bring in material from DV, DV-Cam, Betacam and other formats, it’s best to stay at 23.98 fps to preserve the HD all the way through the process. “First you have to remove extra frames to put the 29.97 frame formats into 23.98 HD timeline,” he says. “But it’s easier to add the 3:2 pull-down than remove it.” Do this at the beginning of the process, he advises. “Or you’ll have a big problem on the back end when it won’t line up,” he says. “Set a common time base at the beginning and get the material back on tape with time-code.”
Kay also briefly described the process of a film-out from high-definition material, urging filmmakers to do the digital intermediate (DI) process in HD SR at 4:4:4 color space, for the best end result.
A Q&A followed the presentation, and Kay, Jordan and other DR Group staffers answered more specific questions about workflow, formats and frame rates. One rule of thumb is that nothing in the timeline should have to render. “If it does, ask yourself why!” says Kay. “In other words, size the graphics and photos properly before you drop them in the timeline and make them the size they’ll have to be in the final project. This will make the pipeline work a lot smoother!”
The complexities of editing with so many different formats and frame rates on the timeline are still a byzantine puzzle for many editors in the industry. But, Kay, noted, one day in the not-so-distant future, “All these timecode problems will disappear, with the advent of data-based capture and post-production workflows. “The future is data-centric,” says Kay. “There will be no more cadences. It will be true 24 fps.”
In the meantime, the DR Group’s many tips and explanations are a welcomed addition to the body of knowledge. (All charts are from the DR Group’s Powerpoint presentation.
Debra Kaufman is a freelance writer who is also West Coast Editor of Film & Video Magazine, and editor of DI Studio, an online newsletter on digital intermediates. She can be reached at dkla@comcast.net.
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