Prior to file-based camera capture, film and then videotape were the dominant visual acquisition technologies. To accommodate, post-production adopted a two-stage solution: work print editing + negative conform for film, offline/online editing for video. During the linear editing era high-res media on tape was transferred to a low-res tape format, like 3/4″, for creative editing (offline). The locked cut was assembled and enhanced with effects and graphics in a high-end online suite using an edit decision list and the high-res media. The inherent constraints of tape formats forced consistency in media standards and frame rates.
In the early nonlinear days, storage capacities were low and hard drives expensive, so this offline/online methodology persisted. Eventually storage could cost-effectively handle high-res media, but this didn’t eliminate these workflows. File-based camera acquisition has brought down operating cost, but the proliferation of formats and ever-increasing resolutions have meant that there is still a need for such a two-stage approach. This is now generally referred to as proxy versus full-resolution editing. The reasons vary, but typically it’s a matter of storage size, system performance, or the capabilities of the systems and operator/artist running the finishing/full-res (aka “online”) system.
All of this requires moving media around among drives, systems, locations, and facilities, thus making correct list management essential. Whether or not it works well depends on the ability to accurately relink media with each of these moves. Despite the ability of most modern NLEs to freely mix and match formats, sizes, frame rates, etc., ignoring certain criteria will break media relinking. You must be able to relink the same media between systems or between low and high-res media on the same or different systems.
Criterial for successful relinking
– Unique file names that match between low and high-res media (extensions are usually not important).
– Proper timecode that does not repeat within a single clip.
– A single, standard frame rate that matches the project’s base frame-rate. Using conform or interpret functions within an NLE to alter a clip’s frame rate will mess up relinking on another system. Constant speed changes (such as slomo at 50%) is generally OK, but speed ramp effects tend to be proprietary with every NLE and typically do not translate correctly between different edit or grading applications.
– Match audio configurations between low and high-res media. If your camera source has eight channels of audio, then so must the low-res proxy media.
– Match clip duration. High-res media and proxies must be of the exact same length.
– Note that what is not important is matching frame size or codec or movie wrapper type (extension).
Proxy workflows
Several NLE applications – particularly Final Cut Pro X and Premiere Pro – offer built-in proxy workflows, which automatically generate proxy media and let the editor seamlessly toggle between full-res and proxy files. These are nice as long as you don’t move files around between hard drives.
In the case of Premiere Pro, you can delete proxy files once you no longer need them. From that point on you are only working with full-res media. However, the Premiere project continues to expect to have the proxy file available and wants to locate them when you launch the project. You can, of course, ignore this prompt, but it’s still hard to get rid of completely.
With FCPX, any time you move media and the Library file to another drive with a different volume name, FCPX prompts a relink dialogue. It seems to relink master clips just fine, but not the proxy media that it generated IF stored outside of the Library package. The solution is to set your proxy location to be inside the Library. However, this will cause the Library file to bloat in size, making transfers of Library files between drives and editors that much more cumbersome. So for these and other reasons (like not adhering strictly to the criteria listed above) relinking can often be problematic to impossible (Avid, I’m looking at you).
Instead of using the built-in proxy workflows for projects with extended timetables or huge amounts of media, I prefer an old-school method. Simply transcode everything, work with low-res media, and then relink to the master clips for finishing. Final Cut Pro X, Premiere Pro, and Resolve all allow the relinking of master clips to different media if the criteria match.
Here are five simple steps to make that foolproof.
1. Transcode all non-professional camera originals to a high-quality mastering codec for optimized performance on your systems. I’m talking about footage from DSLRs, GoPros, drones, smart phones, etc. On Macs this will tend to be the ProRes codec family. On PCs, I would recommend DNxHD/HR. Make sure file names are unique (rename if needed) and that there is proper timecode. Adjust frame rates in the transcode if needed. For example, 29.97fps recordings for a playback base rate of 23.98fps should be transcoded to play natively at 23.98fps. This new media will become your master files, so park the camera originals on the shelf with the intent of never needing them (but for safety, DO NOT erase).
2. Transcode all master clips (both pro formats like RED or ARRI, as well as those transcoded in step 1) to your proxy format. Typically this might be ProRes Proxy at a lower frame size, like 1280 x 720. (This is obviously an optional step. If your system has sufficient performance and you have enough available drive space, then you may be able to simply edit with your master source files.)
3. Edit with your proxy media.
4. When you are ready to finish, relink the locked cut to your master files – pro formats like RED and ARRI – and/or the high-res transcodes from step 1.
5. Color correct/grade and add any final effects for finish and delivery.
©2019 Oliver Peters
digitalfilms 