AJA GEN10 and VIVE Mars CamTrack Keep Virtual Production in Sync at S4 Studios

Visual effects company S4 Studios operates a studio in Los Angeles and a virtual production stage nearby in Canoga Park. Founded in 1999 as a design and VFX studio, the company moved into virtual production and in-camera visual effects (ICVFX) two years ago. Today, S4’s stage is kept busy servicing commercial, music video, in-car, film and TV projects.

The 2,300sqft stage comprises a three-wall setup, and works well for in-vehicle processes and smaller budget-conscious productions. S4 Studios Owner and Creative Director Geoffrey Kater said, “We want people to understand that virtual production doesn’t have to cost $50K a day. Our stage is designed to let clients come in and shoot two or three locations in the same day without having to go anywhere else. We swap out the locations for you, and you have complete control over the set. Then you leave with your final pixels.”

Setting the Stage

As virtual production involves many elements and devices, sychronisation is a key factor throughout. Computers at the studio are equipped with NVIDIA Quadro cards with Quadro Sync boards connected, synchronizing them with the displays or projectors attached to them. Further along the pipeline, this allows all device outputs to be synced together on the wall.

Moving media into the LED processors is the next step, and then projecting that media onto the wall. Tracking is handled by the HTC VIVE Mars CamTrack system. VIVE Mars CamTrack integrates the VIVE Tracker, SteamVR Base Stations and several other VIVE devices and tools, and helps producers use VR tracking in virtual productions.“Considering the size of our stage, Mars is ideal,” said Geoffrey. “We’ve hung the Base Stations up in a grid at about 10 by 10 meters, so it works perfectly for the amount of shooting that you can do in there.”

Image Tearing

The next challenges are making sure the system will track the client’s camera, and accessing the media from the shoot. When S4 initially set up their pipeline, they quickly discovered that images were tearing – displaying information from multiple frames in a single screen – due to sync issues. Geoffrey said, “Since I come from the VFX side of production, the idea of genlock still feels fairly new to me. As various issues arose, I took my experiences to the Mars Facebook Group where I found it was a fairly common problem.”

A member of the group suggested using the AJA GEN10 sync generator as the timing reference. All other audio and video devices can connect to this device and synchronise to its internal clock, and users can precisely frequency-lock their video signals so that every device knows when a frame starts and ends.

“We brought the AJA GEN10 into the studio, configured the little dip switches on the back, plugged everything in, and all of a sudden there was no more tearing, no more lines and everything was synced. The walls, the camera, the computers and the Mars tracking system were all synchronised at 24,” said Geoffrey.

Genlocked from the Start

Genlock is now part of S4’s client prep consultation whenever they shoot on the stage, especially when the clients haven't been working with genlock already. Geoffrey and the team specifically explain to the client why it’s important, and then test their cameras, because every camera is different. Some work quite well without genlock, but S4 recommends it as a safety precaution.

He said, “With the AJA GEN10 sync generator and HTC VIVE Mars CamTrack, I know that we are covered and all of our computer equipment, walls and everything are in sync. That's the most important aspect of it for me.”

Source: Digital Media World