Preparing Digital Camera Files

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The modern direction in file-based post production workflows is to keep your camera files native throughout the enter pipeline. While this might work within a closed loop, like a self-contained Avid, Adobe or Apple workflow, it breaks down when you have to move your project across multiple applications. It’s common for an editor to send files to a Pro Tools studio for the final mix and to a colorist running Resolve, Baselight, etc. for the final grade. In doing so, you have to ensure that editorial decisions aren’t incorrectly translated in the process, because the NLE might handle a native camera format differently than the mixer’s or colorist’s tool. To keep the process solid, I’ve developed some disciplines in how I like to handle media. The applications I mention are for Mac OS, but most of these companies offer Windows versions, too. If not, you can easily find equivalents.

Copying media

df0815_media_6_smThe first step is to get the media from the camera cards to a reliable hard drive. It’s preferable to have at least two copies (from the location) and to make the copies using software that verifies the back-up. This is a process often done on location by the lowly “data wrangler” under less than ideal conditions. A number of applications, such as Imagine Products’ ShotPut Pro and Adobe Prelude let you do this task, but my current favorite is Red Giant’s Offload. It uses a dirt simple interface permitting one source and two target locations. It has the sole purpose of safely transferring media with no other frills.

Processing media on location

df0815_media_5_smWith the practice of shooting footage with a flat-looking log gamma profile, many productions like to also see the final, adjusted look on location. This often involves some on-site color grading to create either a temporary look or even the final look. Usually this task falls to a DIT (digital imaging technician). Several applications are available, including DaVinci Resolve, Pomfort Silverstack and Redcine-X Pro. Some new applications, specifically designed for field use, include Red Giant’s BulletProof and Catalyst Browse/Prepare from Sony Creative Software. Catalyst Browse in free and designed for all Sony cameras, whereas Catalyst Prepare is a paid application that covers Sony cameras, but also other brands, including Canon and GoPro. Depending on the application, these tools may be used to add color correction, organize the media, transcode file formats, and even prepare simple rough assemblies of selected footage.

All of these tools add a lot of power, but frankly, I’d prefer that the production company leave these tasks up to the editorial team and allow more time in post. In my testing, most of the aforementioned apps work as advertised; however, BulletProof continues to have issues with the proper handling of timecode.

Transcoding media

df0815_media_2_smI’m not a big believer in always using native media for the edit, unless you are in a fast turnaround situation. To get the maximum advantage for interchanging files between applications, it is ideal to end up in one of several common media formats, if that isn’t how the original footage was recorded. You also want every file to have unique and consistent metadata, including file names, reel IDs and timecode. The easiest common media format is QuickTime using the .mov wrapper and encoded using either Apple ProRes, Panasonic AVC-Intra, Sony XDCAM, or Avid DNxHD codecs. These are generally readable in most applications running on Mac or PC. My preference is to first convert all files into QuickTime using one of these codecs, if they originated as something else. That’s because the file is relatively malleable at that point and doesn’t require a rigid external folder structure.

Applications like BulletProof and Catalyst can transcode camera files into another format. Of course, there are dedicated batch encoders like Sorenson Squeeze, Apple Compressor, Adobe Media Encoder and Telestream Episode. My personal choice for a tool to transcode camera media is either MPEG Streamclip (free) or Divergent Media’s EditReady. Both feature easy-to-use batch processing interfaces, but EditReady adds the ability to apply LUTs, change file names and export to multiple targets. It also reads formats that MPEG Streamclip doesn’t, such as C300 files (Canon XF codec wrapped as .mxf). If you want to generate a clean master copy preserving the log gamma profile, as well as a second lower resolution editorial file with a LUT applied, then EditReady is the right application.

Altering your media

df0815_media_3_smI will go to extra lengths to make sure that files have proper names, timecode and source/tape/reel ID metadata. Most professional video cameras will correctly embed that information. Others, like the Canon 5D Mark III, might encode a non-standard timecode format, allow duplicated file names, and not add reel IDs.

Once the media has been transcoded, I will use two applications to adjust the file metadata. For timecode, I rely on VideoToolShed’s QtChange. This application lets you alter QuickTime files in a number of ways, but I primarily use it to strip off unnecessary audio tracks and bad timecode. Then I use it to embed proper reel IDs and timecode. Because it does this by altering header information, processing a lot of files happens quickly. The second tool in this mix is Better Rename, which is batch renaming utility. I use it frequently for adding, deleting or changing all or part of the file name for a batch of files. For instance, I might append a production job number to the front of a set of Canon 5D files. The point in doing all of this is so that you can easily locate the exact same point within any file using any application, even several years apart.

df0815_media_1_smSpeed is a special condition. Most NLEs handle files with mixed frame rates within the same project and sequences, but often such timelines do not correctly translate from one piece of software to the next. Edit lists are interchanged using EDL, XML, FCPXML and AAF formats and each company has its own variation of the format that they use. Some formats, like FCPXML, require third party utilities to translate the list, adding another variable. Round-tripping, such as going from NLE “A” (for offline) to Color Correction System “B” (for grading) and then to NLE “C” (for finishing), often involves several translations. Apart from effects, speed differences in native camera files can be a huge problem.

A common mixed frame rate situation in the edit is combining 23.98fps and 29.97fps footage. If both of these were intended to run in real-time, then it’s usually OK. However, if the footage was recorded with the intent to overcrank for slomo (59.94 or 29.97 native for a timebase of 23.98) then you start to run into issues. As long as the camera properly flags the file, so that every application plays it at the proper timebase (slowed), then things are fine. This isn’t true of DSLRs, where you might shoot 720p/59.94 for use as slomo in a 1080p/29.97 or 23.98 sequence. With these files, my recommendation is to alter the speed of the file first, before using it inside the NLE. One way to do this is to use Apple Cinema Tools (part of the defunct Final Cut Studio package, but can still be found). You can batch-conform a set of 59.94fps files to play natively at 23.98fps in very short order. This should be done BEFORE adding any timecode with QtChange. Remember that any audio will have its sample rate shifted, which I’ve found to be a problem with FCP X. Therefore, when you do this, also strip off the audio tracks using QtChange. They play slow anyway and so are useless in most cases where you want overcranked, slow motion files.

Audio in your NLE

The last point to understand is that not all NLEs deal with audio tracks in the same fashion. Often camera files are recorded with multiple mono audio sources, such as a boom and a lav mic on channels 1 and 2. These may be interpreted either as stereo or as dual mono, depending on the NLE. Premiere Pro CC in particular sees these as stereo when imported. If you edit them to the timeline as a single stereo track, you will not be able to correct this in the sequence afterwards by panning. Therefore, it’s important to remember to first set-up your camera files with a dual mono channel assignment before making the first edit. This same issue crops up when round-tripping files through Resolve. It may not properly handle audio, depending on how it interprets these files, so be careful.

These steps add a bit more time at the front end of any given edit, but are guaranteed to give you a better editing experience on complex projects. The results will be easier interchange between applications and more reliable relinking. Finally, when you revisit a project a year or more down the road, everything should pop back up, right where you left it.

Originally written for Digital Video magazine / CreativePlanetNetwork.

©2015 Oliver Peters