Barry Goch
June 2, 2010


One of the many hats I wear, in addition to being an Autodesk Smoke artist and trainer, is as an Avid DS operator. The Post Group’s lead DS artist, Derek Herr, worked on the season finale of House, which was shot using the Canon 5D Mark II. I asked Vorhies for an introduction and, like any good editor, Herr was on the job in the hot seat. He was kind enough to explain the workflow to me.

He said that the decision to use the Canon camera was due to the fact that the season finale of House was to be shot in close quarters and the director of photography wanted to exploit the extreme shallow focus that the camera allows. Herr explained that they had tested the 5D on a previous episode for several shots before committing to shooting an entire episode using the camera. Since the offline for House has always been cut on Avid Media Composers in SD using DVCAM dailies, The Post Group developed a solution that would not disrupt the workflow for the show’s offline editorial department.

The Canon 5D Mark II records highly compressed H.264 QuickTime files. After some testing involving DS, Final Cut and Clipster, they decided to use the Avid DS to convert the H.264 QuickTimes to 4:4:4 media on HDCAM SR tape that then received a color pass by The Post Group’s dailies colorist Scott Fox. Fox’s color was only applied to the DVCAM downconversions of the reels, which were used by offline editorial.

Once the cut was locked, the timeline was sent back to The Post Group for finishing. Here’s where the story gets even more interesting. Due to the compressed nature of the footage, there was banding in some gradient areas of the image. After some experimentation with off-the-shelf “de-banding” plug-ins, Herr instead built an effects tree in Avid DS which pulled a key to isolate the highlights and mid-tones of the image and add grain in those areas to match the Fuji film stock that the show usually uses. This tree was added to every shot in the episode and allowed the treatment to be adjusted on a per-shot basis. Adding the grain eliminated nearly all of the banding, and created a more filmic look.

The extremely shallow depth of field also presented challenges in post. Using the DS, Herr tracked animatable graphic shapes filled with a customized sharpening effect tree to create a “power window” of sharpening when necessary. Another post issue with the camera was dead pixels. When a dead pixel is discovered, it typically is present on all the shots from that particular camera. Using source side effects in the Avid DS, Herr was able to apply his dead pixel fix automatically to all the shots from that source in one go.

Another challenge was stabilizing shots. Due to the nature of how the image is scanned internally from the Canon sensor, each frame is not completely captured at the same instant as in a film camera. Rather the image is drawn top to bottom over several microseconds. This issue makes it difficult to stabilize shots in post because of the temporal difference between the top and bottom of the frame.  Treating shaky hand-held footage requires multi-point tracking.

When the initial online was finished, Herr output a DPX sequence shared by Keith Shaw, the colorist, who used a Nucoda system to create the final color. As work continued on the episode, all in-house VFX work was completed using the Avid DS and an Autodesk Inferno system using these DPX files. The master DPX sequence was constantly updated.

Editorial revisions and out-of-house VFX on tape from another vendor were integrated into the master DPX sequence using the DS system. When Shaw had completed the final color, he created a separate “colored” DPX sequence that Herr linked to using the DS for titling, and finally outputting to an SR tape, which became the master for final delivery.

Herr and Shaw have used this file-based finishing process successfully on the entire sixth season of the show.

So that’s how it goes. You go to a party at a post house and come out with an education. I hope you did as well.