Broadcast camera developments
Feb 1, 2008 12:00 PM, BY BERRY EBBEN
What does the future hold?
You might get the impression that there is a revolution going on in the world of cameras. However, SD is still with us, HD is in its growing phase, and the Internet is not ready for broadcast. In 2007, around half of the cameras sold worldwide were still SD.
Institutes like parliaments, high-end security and other audiovisual services are buying broadcast cameras as well, which is keeping the market for SD alive.
The majority of broadcast cameras now are 1920 × 1080/50i/60i, have a 16:9 aspect ratio with HD-SDI and HD analog outputs, and can be switched between popular formats and ratios. As a kind of insurance, SDI and analog composite video outputs are also provided. That means users can swap their SD cameras with an HD one without replacing their complete broadcast chain. This allows broadcasters to gradually upgrade their studios to HD operation.
Where are we going?
If you are attending NAB2008 to scope out new cameras, what should you be looking for in performance specification, and the features and facilities? We are moving from SD 720 × 576 to HD 1920 × 1080 resolution, and in a few years, the industry could move beyond HDTV. Japanese broadcaster NHK offers Ultra High Definition Television (UHDTV) with 7680 × 4320 resolution. In sports, there is a strong demand for high-speed, slow motion in HD, and this will be expected from UHDTV.
Figure 1. 3-CCD camera with separate video processing.
Click image to enlarge.
Another issue is 2-D or 3-D. At IBC2007, 3-D displays were demonstrated, but for professional use only. There is the potential for growth here.
The film industry is exploring digital acquisition. Digital cinematography cameras are used more as replacements for 16mm and 35mm film cameras. The latest HDTV cameras are not only producing 1080i but also progressive scan pictures.
Computers offer processing speed combined with high-capacity memories, which make them ideal to use in post production. The idea that future cameras will consist of a computer with a lens and a memory stick is not valid. The reliability of operating software seems to be acceptable for computing, but it is far away from what is acceptable in a live broadcast camera.
Figure 2. 3-CMOS camera with partly integrated video processing.
Click image to enlarge.
The developments of UHDTV and 3-D indicate that camera growth looks to higher pixel counts, more frames per second and higher bit rates. The existing architecture with CCD was introduced in the late 1980s and served broadcast's needs well. Over the years, problems such as lag, smear, fixed pattern noise and leaking pixels have been solved.
The CCD technology is mature now, and it will be around for another few years. However, it is clear that another architecture should be in place in that same time frame. The time to market for a new type of sensor technology is around five to eight years.
Camera applications
Whatever the application for a camera, is there revolution in the offing in camera technology? The best way to find out is to check the unit's components. Start with the lens, then check the optical input, and end with base station or recorder as an electronic output. Here's a closer look at each component:
- Lenses
Since the turret of fixed focal length lenses was replaced by the zoom, the evolution has been longer zoom ranges, digital interfacing and focus assist. The revolution will start when more camera electronics are integrated in the lens. This has already happened with black-and-white security and traffic control cameras. Cameras for these specific applications are really lenses with a video output, much like a webcam.
- Camera housing
Cameras have evolved from a large body to a portable (with hip-pack and portable processing unit) to the shoulder-mounted camera we know today. The weight has reduced from 25kg to less then 7kg. However, cameras are still front-heavy and roll off your shoulder. There are two possible solutions. One is a well-fitting and adjustable shoulder pad with balancing weights in the back of the camera. A second option is to create a small handheld camera. In the prosumer market, the HD handheld weighs around 3kg. In the consumer market, HD palmtops weigh about 0.5kg.
- Filters
In the past, a camera carried neutral density filters plus a cap. Today, it is common to include four-, five- and six-point stars in addition to mist filters. Apart from the matte-box in front of the lens, cameras generally carry two filter wheels between the lens and prism. Some cameras have memories on the video processing board where you can store electronic effect filter parameters. A revolution could be to move all effect filtering in the camera on RGB level, including the effect filters which are normally carried out in the production switcher. There are no contours on that level, so it will benefit the quality. A remote input controlled by the vision mixer is needed.
- Beam-splitter
Since the mirror cross was replaced by a three-way RGB prism block, only minor changes have been made to the beam-splitter design, mainly driven by quality issues. There is a move to use a single sensor with Bayer filter. The disadvantage is the loss in sensitivity of two stops, which is not acceptable for many applications.
- Imagers
Tubes have been replaced by CCDs, which in turn will be replaced by CMOS with system on chip (SoC). Camera video processing is integrated. Light is captured, and bits are coming out. The CMOS sensor chip with SoC can be seen as a digital device. The way to a single integrated circuit (IC) broadcast camera is open.
- Video processing
Nuvistors and tubes were replaced by discrete transistors, and then by ICs including ASICs, EPLDs and FPLAs. Processing has changed from dedicated analog to digital with embedded software. Integration with the sensor is on its way. The future could see the introduction of wide gamut color space like the new xvYCC color standard.
- Power
Power consumption on the CCD camera side grows to the extent that batteries need to increase in size or live shorter. The maximum cable length in an OB operation is decreasing. Digital processing consumes more power, and the higher the clock rates, the more the current. The more power, the more heat, the more fans, the more noise. Adding fill-in light, displays, tallies and floor monitoring does not help either. CMOS consumes far less compared with a CCD, and by integrating more video processing, the power consumption should decrease further.
- Audio
Audio quality for camera audio channels has improved with the move to digital. The improvement is such that it can be used for more than just ambient. The problem is the synchronization between video and audio. Digital video processing adds delay.
- Intercom and tally
The digital intercom benefits from improved quality with digital processing, which is much better than the old analog systems. As an example, a message box for the camera person can be added. The tally is triggered by the video mixer preset or program bus, but digital circuits can cause noticeable delay.
- Viewfinder
What was once a monochrome CRT has evolved to a full-color LCD. This revolution, however, is not for the best. Focussing an HD picture is already a problem with a black and white CRT; with an LCD, it is even worse. This area is ripe for development.
- Camera output
The camera output has evolved from multicore copper cable to triax with hybrid fiber that provides the bandwidth for HD signals plus a power supply to the head. Developments in this area must deliver a long cable length with wide bandwidth, but cost, reliability and field repair are major issues.
- CCU/base station
The CCU/base station has shrunk from a full-height rack to 2RU for the latest cameras. The ability to fit more cameras in a given space has created a revolution in the OB world, enabling association football coverage to expand from five cameras to the 24 cameras now expected for premier matches.
- Outputs formats
Apart from the standards used within the broadcast industry like SDI, the smaller camcorder can include FireWire and HDMI, with Ethernet starting to become a feature.
| Want to use this article? Click here for options! |  |
