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Making Sense of HDTV Formats

DTV refers to digital television, which can be broadly described as all broadcasts sent to the home digitally, whether over the air, by cable, by satellite or any other means.

There are a multitude of DTV formats, all of which fall into two families: Standard Definition Television (SDTV) and High Definition Television (HDTV). SDTV refers to the digital equivalents of our standard 601 NTSC and PAL interlaced formats, as well as similar spatial resolutions that are progressively scanned. HDTV refers to high-resolution widescreen DTV formats. The two prevailing HDTV formats include 1920x1080 at 30 fps interlaced scanning and 1280x720 at 60 fps progressive scanning.

 

The DTV standards and HDTV seen as a complex maze, composed of a myriad of formats. There are four components, or dimensions, to any DTV format: Resolution, scanning method, frame rate and aspect ratio.

Resolution Resolution simply refers to the number of pixels and lines that make up an image. The number of lines can be 480, 576, 720 or 1080 lines. The number of pixels per line may include 720, 1280 or 1920 pixels.
Scanning Method Scanning method refers to whether the image is interlaced ("i") or progressive ("p"). An interlaced frame sweeps the image as two fields that are interlaced to form a given frame. A progressive frame is scanned in a single vertical sweep rather than scanning as two interlaced fields.
Frame Rate Frame rate refers to the number of frames presented per second - 24 fps, 25 fps, 30 fps, 50 fps or 60 fps. It also includes NTSC derivatives such as 23.976, 29.97 and 59.94.
Aspect Ratio Aspect ratio refers to the horizontal and vertical dimensions of each individual frame, typically 4:3 or 16:9.

Every format is composed of some combination of these four components. For SDTV and HDTV the combinations are:

DTV Component SDTV HDTV
Resolution 720x486 (digital NTSC) 720x576 (digital PAL) 1280x720 (US standard) 720x576 (digital PAL) 1920x1080 (US standard)
Scanning Method "i" and "p" "i" and "p"
Frame Rate 30 or 25 fps 24, 25, 30, 50 and 60 fps
Aspect Ratio 4:3 or 16:9 16:9

 

The New Reality: A Multi-format, Multi-version World

HDTV is rapidly becoming part of all production and post-production landscapes as the demand for HDTV programming increases.

The growth of HDTV is inevitable. HD enhances the viewer's experience and represents exciting new opportunities for content producers. Furthermore, HDTV masters ensure the archival value of content. We are moving to a digital world - from acquisition to consumption. The debate is about the duration of that transition, not whether or not it will occur. The transition initiates the dawn of a multi-format world. Multi-format distribution ensures the maximum number of viewers, and reaching viewers drives advertising dollars, subscription revenues, and the very business of broadcasting. HDTV and SDTV adoption will continue, but 601 delivery will be critical to reaching the mass market and driving the largest portion of revenue streams for years to come. In this context, HDTV is not a solution unto itself, but an important element in multi-format distribution.

But multi-format distribution is only one part of the coming revolution. The challenge is not simply to create compelling content and distribute it to the widest possible audience. Content must also be made geographically and demographically relevant in as many ways as possible. Gone are the days of creating a single version of a program. Now we create the network version, the syndicated version, the cable version, the domestic and international versions, the airline version, and so on.

In this new multi-format, multi-version world, the television post-production process becomes considerably more complex. Multiple DTV, PAL and NTSC masters in 16:9, 4:3 and letterbox aspect ratios, along with multiple versions for different markets, result in a far more complex fulfillment task. The solution is not simply narrative offline editing systems and HD conforming stations. The solution must provide an economical and efficient means to produce all of the necessary formats and versions.

1080i

Generally considered the most popular of the HD formats, 108Oi is used by more producers than 720p. Sony’s HDCAM tape format is also the most widely used 1080i gear to date. HDCAM 1080i camera equipment and VTR decks are readily available in most rental houses around the country and are the gear most used by broadcasters and independent cameramen.

720p

Growing in popularity 720p, the format developed by Panasonic, is favored by many broadcasters and distributors, including ABC in the United States and Bell ExpressVu in Canada. 

Panasonic’s most popular 720p tape format for production use is DVC Pro HD. There are a number of cameras and decks available to shoot this format and, while not as easily rented as 1080i gear, is getting more accessible.

24P HD

With all of these new formats expanding the world of content distribution, there is a tremendous amount of new interest in the 24 fps progressive versions of HD recording. It is possible to shoot 24P in both 1080 and 720P formats.

One of the key advantages of 24P is that it offers a film-like image quality compared to traditional 30 fps interlace video.

PAL and NTSC masters can be created from a single 24P video source, much like the telecine. Without 24P this requires expensive standards converters, where motion artifacts are introduced when converting from NTSC to PAL for international distribution.  Storage is more efficient in digital nonlinear systems (requiring 20% less disk space than NTSC).

Greater performance is realized in the rendering of effects and composites (20% faster than NTSC).
Producing a master from a sequence edited natively in 24P delivers smooth motion picture playback in NTSC due to the continuous 2:3 insertion upon playout. PAL is smooth due to a 1:1 frame correlation at 25 fps.

Enter the concept of Universal Mastering. Universal Mastering provides the ability to work on a nonlinear system with 24 fps progressive media and produce all masters and versions from a single source. Imagine enjoying all the performance, workflow, storage and precision benefits of 24 fps progressive. Imagine the press of a button producing NTSC, PAL, 4:3, 16:9, film cutlists and more, all from a single source.

HDV

While the newest kid on the format block, HDV cameras and equipment are rapidly gaining attention.  HDV is a highly compressed format that is currently centred around  low cost entry-level HD production.

Broadcast producers should carefully review delivery specs to see if HDV footage is acceptable to your broadcaster.  Many broadcasters, such as Discovery Channel,  limit the quantity of HDV footage that may be used in a show.

For more detailed information on formats, please click here to download a comprehensive PPT presentation on HD formats.

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