Handling raw material

I just went through a nightmare, conforming a short project shot on GoPro. What should have been a one hour job took two full days to do, because the framerates were wrong and there were ten sets of files with the same names and no timecode. The grading had to be postponed, and the client wasn’t too happy with the additional conform costs neither …
The production clearly lacked an experienced D.I.T., but a few simple steps could have kept the production on track and on budget.

When doing high-end post-production, you never work on full quality files while editing. I’ll explain why, and how to spot problems that can cause several days of extra conform time.

Raw files

Raw files are big in bytes (take up disk space and bandwidth), high resolution (has to be rescaled for display) and are in log-space, which mean they have to be color corrected to even look descent. AVC raw files from smaller cameras are smaller in file size, but are even worse to work with, because the inter-frame compression makes editing very slow.

The EDL

This is why you always create offline editing files in a more suited format. The most popular options today are the low-bitrate variants of ProRes and DNxHD. When the edit is locked, the offline editor will export an EDL, which will give the online editor the same timeline, but with full quality raw clips, rather the low quality offline files. Another important reason why it’s done this way, is so the cut can be changed without having to transfer huge video files to the online systems for each new version.

The traditional EDL formats are getting replaced by Avid AAF and Final Cut’s XML Interchange Format, but the principle is still the same. They do not contain any media, but describe how the film is put together from raw files and effects.

What can go wrong?

EDL, AAF and XML files are all great when they work, and should let the online editor conform a film with little manual labor. But when they fail, you might have a serious problem on your hands. Conform problems are usually caused by erroneous handling and conversion of video files.

The worst things to get wrong:

  • Framerate
  • Timecode
  • Filenames

Minor issues will always mean additional conform time, and it gets exponentially worse if you have multiple problems. Most online editors will have no way to fix this. Trust me – I’ve salvaged more than a few such projects.

Framerate

Every offline, or proxy file should have the same timebase as the final delivery. In Europe, this usually means 25fps. If raw files are shot at other frame rates, they cannot have synchronized audio and should be meant for slow-motion or fast-motion. That means a 100fps raw clip should default to 4x slow motion when used in a 25fps timeline, and must be sped up to 400% to appear as real-time.

Timecode

Timecode might seem like a relic from the tape days, but is still used for syncing multiple sources, and can save your day if you have problems with the file names. Make sure they are persistent in all copies of the proxy files, especially when using new or sketchy software to create files.

Filenames

Modern file-based workflows rely on file names just as much as timecode, so the proxy files should have the same name as the raw files. If the proxies have the same extension as the raw files, you probably want to give the proxy file names a suffix.

The most common mistake I see with filenames, is the failure to keep them unique. DSLRs, GoPros etc. usually don’t record timecode, and if you have 10 clips called GOPRO001.MOV, there’s no way to tell them apart. Rename them as soon as possible to avoid mixups down the line.

Limit the name of files, folders and disk names to A-Z, 0-9, dash (-), underscore (_) and dot (.). The name “Day#1 (drone & studio)” might work well for a while, but can put the whole workflow to a grinding halt when moving from one system to another.

Spotting trouble

  • Is everything the same framerate as the final delivery specification? If not: Have the camera assistant or DIT confirm this is intentional, and make sure the editorial department is informed.
  • Do the files have unique file names or unique timecode? If not: Halt production right away, and assign unique file names before doing any more damage.

Rules are meant to be broken, but if you want to do these thing differently, make sure everyone involved is on board.

 

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