David Birdy /
01.01.2008
Originally featured on BroadcastEngineering.com
High-def video cameras come of age

From live sporting events to news and entertainment, high-definition cameras are the wave of the future. And they have become a fixture on many movie sets and TV compounds.

Low-cost HDTV sets, new camera technology, fiber optics, MPEG-4 and faster CPU processors are making HD affordable and dependable for both consumer and professional applications.

As consumers grow to expect higher quality images, broadcasters and content producers will increasingly move to HD production. All roads lead to heavy demand for native HD programming.

To better understand the players in this space, let's take a closer look at some of the HD camera options available. While not every type and model of HD camera will be discussed, these units are representative of what's being used today to create HD programming. These thoughts are based on my 20 years of experience as a broadcast engineer.

What is available?

Ikegami, Sony and Thomson Grass Valley all make triax- and fiber-based HD cameras that are used for live sports and entertainment productions. Panasonic and Sony are key makers in the standalone, onboard recorder camera market. A new player, RED Digital Cinema, just delivered its first round of RED ONE HD cameras in September 2007. Marketed as an HD digital cinema camera, the unit provides a 12 megapixel CMOS imaging system. The camera has generated a lot of interest. We'll have to see if it can deliver on the claims. Now, let's look at some of the cameras available.

Thomson Grass Valley LDK 6000 mk II

Three 9.2 million HD-DPM (Dynamic Pixel Management) and CCDs (9.2 megapixels) coupled with 12-bit A/D conversion and native format switching from 720p to 1080i are all standard features for the Thomson Grass Valley LDK 6000 mk II camera. It was the first widely used HD camera to incorporate triax-based operation. Triax connectivity is an attractive option to facility providers and broadcasters because it makes camera setup quicker, and the cabling is less expensive to install and maintain for venues.

When triax lengths exceed 3000ft, a triax repeater is available, doubling the triax reach to 6000ft. By replacing the triax base station and camera adaptor with a SMPTE fiber base station and camera adaptor, it's possible to achieve more than 13,000ft of distance by adding a 110V power source to the camera. There are several third-party solutions that provide two single-mode fibers in a cable along with breakout boxes at both ends.

In addition to the advantage of incorporating triax, the LDK 6000 mk II also offers the option of 720p or 1080i output without crossconverting, which is an attractive option for both broadcasters and truck owners.

Sony HDC-1550

One of the newest additions to Sony's live broadcast cameras is the HDC-1550. The 1550 is a speedy work horse, configurable as a handheld or as a studio camera. The cameras use three newly designed 2/3in 2.2 megapixel progressive-scan Hyper Hole Accumulation Diode (HAD) CCDs. The new imaging system boasts a sensitivity rating of F10 at 2000lux. The camera provides 14bit A/D conversion and the ability to output all HD formats and frame rates, including 1080p 60f.

The company's engineering team decided to keep a SMPTE system on the base station side and camera side, and then convert the SMPTE fiber to triax as needed. By adding the HDTX-100 and HDFX-100, these cameras can operate on triax up to 4500ft using a 110V power source located at the base station. The camera end uses triax into the HDFX-100 and a SMPTE four-pin hermaphrodite cable from the HDFX-100 to the camera.

Ikegami HDK-79EC

Ikegami recently integrated CMOS imaging technology into the HDK-79EC. The CMOS system is cost-effective to manufacture and requires 20 percent less power than a comparable CCD imaging device. This camera features three 2/3in 2.2 megapixel CMOS images sensors. The AltaSens ProCamHD 3T sensors offer an imaging system-on-chip (SoC) solution. The company's Tapered-Rest technology reduces fixed pattern noise.

The standalone handheld camera fits into the SE-79D system expander kit. This includes a 9in low-lag color LCD viewfinder for use in a studio configuration. Two camera adaptors convert the SMPTE four-pin hermaphroditic cable to triax. The TFC-790 CCU-side unit of the converter system is placed on the base station side, and the TFH-790 unit is on the camera side to achieve operation over 4500ft of triax cable.

In perspective

The above three HD broadcast cameras work on both SMPTE fiber and triax. By adding the appropriate third-party adapters, these cameras can also operate on single-mode fiber.

Each camera chain has a specific power-up sequence. Sometimes, multiple power-up sequences may be needed to get both ends of the camera chain working together properly.

Now let's look at some standalone HD camcorders.

Panasonic AJ-HDC27H VariCam

Panasonic's AJ-HDC27H VariCam uses three 1.1 megapixel CCDs with a sensitivity rating of F12 at 2000lux to achieve a dynamic range of nine f-stops. The onboard recorder uses the DVCPRO HD tape format at multiple data rates up to 100Mb/s. Panasonic developed CineGamma to help the video look more like film by increasing the dynamic range through gamma setups.

This camera has a loyal following. The ability to shoot video at 24p — or any variable frame rate from 4p to 60p — generated interest, especially within the film industry. Each time a variable frame rate is selected, the camera re-records frames. Shooting at 30p (29.98) frames and recording at 60p (59.94) frames, the image will be recorded twice. For acquisition at a frame rate of 24p (23.97), the math is more complex and uses a mixture of fields combined into frames, commonly referred to as a 3:2 pull down. The DVCPRO HD recorder is always recording at a rate of 59.94. For selectable frame rates, the recorder uses pull-down technology, recording more frames as needed.

The 24p camera does not record in the same fashion as a film camera, but the end result is similar. The camera yields a 24p look by showing half of the progressive frames that were shot at 59.94. The onboard DVCPRO recorder allows a camera assistant to reload tapes and keep track of time code and frame rates in a similar fashion as with film reels. This was one of the first HD cameras offered at an affordable price and has garnered wide appeal.

Sony HDW-F900

The HDW-F900 HD HAD imaging system is equipped with three 2/3in CCDs ASA rated at 320 with a dynamic range of nine f-stops. The system is made up of three 2.2 million pixel CCDs, resulting in 1920 × 1080p resolution.

Imaging control features help to soften the crisp edges, making the picture appear more film-like. This system can record segmented frames (PsF) for a 24p look. Segmented frames are recorded in progressive frames, and then divided into two fields: one with odd line information and one with even line information. The user can select 23.97PsF, 25PsF or 30PsF, or interlace versions at the same frame rates.

Camera setup values and gamma curves can be plotted on a computer and then transferred to each individual camera using a memory stick. The F900, with an onboard HDCAM record deck, has gained wide acceptance from many DPs and HD producers.

RED Digital Cinema RED ONE

The RED ONE from RED Digital Cinema has finally hit the streets. This camera is often touted as a revolutionary device providing impressive stats at a reasonable price. It is being marketed specifically to digital cinema artists and independent filmmakers.

The camera's ability to add hardware to the main body allows this unit to be rigged on a variety of mounts. At the center of this system is the Mysterium sensor, a 12.2 megapixel Super 35mm CMOS imaging block capable of delivering 4520 × 2540 at 30fps and 4:4:4 sampling rates.

The data management system offers multiple format outputs and multiple frame options ranging from 1fps to 30fps at 4K and 1fps to 100fps in 2K. The sensor captures the image using the REDCODE RAW codec. This is a wavelet-based compression scheme that records the image RAW without color bias. While recording RAW can create some image monitoring issues, all of the image's data has been recorded without color modification.

Once recorded, the media is opened with a desktop application. The files are then colorized and converted to whatever file formats are desired. This might be uncompressed RGB or compressed 4:2:2 video formats, including ProRes, DN×HD, DV100 or M-JPEG QuickTime movies at 720p or 1080p.

The media is copied from the CompactFlash storage card to the computer's hard drive, or it can be mounted directly as a drive when the RED digital media drive is used. The spinning disk storage drives are two 180GB drives configured as RAID 0, which provides wide bandwidth and transfer rates, but not data redundancy.

HD capture

Manufacturers continue to push the envelope in finding innovative ways to capture and broadcast events in HD. One high-definition camera even made a trip to the moon onboard the Japanese explorer Kaguya in October of 2007. It sent back spectacular footage, including a scene of the earth setting behind the moon.

The next frontier for HD is 3-D imaging, and a few pioneers have already started down the trail. The movie “Speed Racer” is now in production, and a 3-D Hannah Montana concert will be shown as an encore companion to her sold-out live concerts.

David Birdy is the director of engineering with Digital DNA productions.

Frames and fields

The confusion is endless when we mix film and video terminology and then use naming conventions derived from each medium to explain frame rates and how they are converted. Variable frame rate broadcast cameras use old theories derived from telecine machines to accomplish variable frame rates. Here's a quick look at the basics of fields and frames and why we convert them.

Films broadcast on television are converted with a film-to-tape transfer machine called a telecine. The first telecine was a camera shooting a projected film recorded on tape then played back at 59.94 for use on broadcast television. Why 59.94? The electric system in the United States is 60Hz; picture flicker is avoided by maintaining video playback and acquisition at 59.94Hz to match the 60Hz power cycle.

To comply with broadcast standards, film is shot at 23.97fps. That is half of the NTSC rate of 59.94 fields, making up 30 frames. To even the math, the telecine machine scans in one progressive frame of film and then breaks that frame into two fields — field one with odd lines and field two with even lines. The film frames are split into two fields by odd and even lines, yielding eight frames. The two new frames are added by combining four fields into two frames derived from the original frames for a total of 10 frames.

The original film frames are split into odd and even fields and now yield A1 A2 B1 B2 C1 C2 D1 D2. Two frames are then added by combining fields to create new frames made up of A1 and B2 and B1 and C2. These are two separate fields derived from different frames that are combined to form a new frame of video. These new frames are referred to as the dirty frames, as they are a mixture of two different frames now in field form combined to make one new frame of video.

The result is now [A1 A2] [A1 B2] [B1 C2] [C1 C2] [D1 D2]. This is where cadence comes into play. The combined dirty frames always need to be in sequence and should never be an edit point. Some NLE software assumes a 3:2 pulldown and will not edit on a dirty frame. Early nonlinear editors would need to carefully calculate an edit point based on finding the lead frame and counting odd or even frames to avoid mixed frame edits.

Many multiple camera shoots have had long, agonizing edit sessions to match frames and audio. Preplanning frame rates for each shot and keeping an accurate log is the best approach to multiple camera, multiple frame rate projects.



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