3-D
Jan 1, 2011 12:00 PM, By Chris Lennon with Stan Moote
A new dimension in broadcast facility planning.
It's hard to think of an industry development that has generated as much excitement as 3-D television. The rise of 3-D in terms of industry buzz has been quick and all-inclusive, touching every corner of the broadcast world. We have been bombarded by this on a global level: helping broadcasters get on the air, speaking about the topic (individually and on panels) and participating in 3-D standards efforts.
When planning a new channel launch, the wealth of detail can overwhelm even the most knowledgeable engineering staff without even putting 3-D into the equation.
As the ESPNs and Discovery Networks of the world bring their 3-D channel visions to life, engineers across the industry need to start planning their own 3-D strategies. The reality is that management could come calling any day with a 3-D agenda and a launch plan.
When learning about 3-D, don't get caught in the loop of how 3-D production and distribution is accomplished today. This will come back and bite you. 3-D is now far different than it's likely to be in the near future. The cool thing is that planning for the near future now will allow for future 3-D developments. The 3-D craze took everyone by surprise, and everyone scrambled to get on-air. Some of the shortcuts taken will definitely hurt later.
Figure 1. 3-D end-to-end workflow
Select figure to enlarge.
The first step is to understand 3-D visually, whether doing a simple pass-through or adding some production. 3-D is an illusion, and it clearly has drawbacks. A logo insertion could look great on one size screen and completely fall apart on a smaller screen. How do you account for this? Keep it simple. Don't try to be fancy, and don't exaggerate the 3-D illusion.
In terms of setting up your facility to handle 3-D, distill the pertinent details from a very deep well. It all starts with one question: How do I get on the air with 3-D? It is entirely possible that there is gear in place, notably in the infrastructure, that can accommodate 3-D signals as-is or with a simple upgrade. In other cases, some existing equipment may require replacement.
The good news is that this can be done without breaking the bank or creating a technology dead end. 3-D-capable gear doubles as HD gear, so the risk factor is generally low if the decision is made to upgrade certain components to handle 3-D. They will serve HD needs well, even if 3-D plans don't develop as expected.
3-D workflow
As engineers, we want to maintain the highest quality. Certainly this isn't being done now for 3-D, not because we can't, but because of the need to get on-air quickly. Reality often hits hard when dealing with one-off events and the need to maintain compatibility with existing infrastructure.
A survey of products and vendors is likely to result in some confusion and intimidation. There will certainly be mixed messages when disparate voices speak to 3-D requirements.
Figure 2. Router control system selecting 3-D modes for simultaneous L/R switching.
Select figure to enlarge.
This is not to say that talking to different sources is a bad idea. However, it is a better idea to first understand the 3-D workflow from production through to broadcast. A broad view of the workflow and equipment interoperability will provide a clearer frame of reference moving forward.
The cleanest and highest-quality approach to 3-D television starts with true image preservation. Most broadcasters will opt to maintain full-resolution HD images for each eye through the production and air chain.
A frame-compatible approach will degrade the resolution by half in the case of side-by-side. Storing the images in this format for later conversion to another format, such as over-under, will potentially lower the resolution by half. The result is quarter-resolution images, which are not a pretty sight.
The following overview will consider deployments for full-resolution 3-D broadcasts, focused on content and production, facility infrastructure and workflows, post production, and external networking and distribution. Figure 1 outlines the various stages and specific components in the end-to-end chain.
Production
The large orange box represents the first stage: mobile content acquisition. This is particularly crucial in remote and outside broadcast applications such as sports and live event production.
The camera remains the starting point. There are a number of 3-D camera options from multiple vendors, including side-by-side dual camera rigs, beam-splitter rigs, and single camera units with single or dual lens options. Developments in fiber-optic systems have made this the ideal method to transport left and right images to the router as two distinct, full-resolution pictures.
Table 1. Infrastructure effects
Select figure to enlarge.
The router presents the first technical challenge in the chain. In a 1.5Gb/s infrastructure, a full-resolution 3-D environment requires two feeds for every source at the input and output. The router must treat L/R dual-link signals as a 3-D pair and frame-accurately route them to dual-link destinations in single control transactions. (See Figure 2.) A typical HD-capable router may not be large enough to accommodate 3-D production due to this doubling of inputs and outputs.
A 3Gb/s-capable router and infrastructure ensures that full-resolution signals are transported on a single wire. This supports routing two full-resolution 3-D signals to multiple points, including storage platforms, multiviewers, production graphics and networking systems. In this environment, only half the inputs and outputs that would have been required for full-resolution 3-D in a 1.5Gb/s infrastructure are needed.
In the area of production storage platforms, 3-D-capable servers must be able to handle synchronized dual ingest and playout. Editing systems present a larger challenge, as some are not capable of supporting 3-D. A talented editor working on a capable system must be able to edit the two eyes as if working with a single video source.
Continue on next page
| Want to use this article? Click here for options! |  |
