Mark Collings is a Toronto-based technical consultant who works in marketing and sales in the production and post-production sectors.

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Advanced television describes the new digital broadcast standards for production, transmission and reception of digital television, which includes high-definition television.

The specifications for atv were devised in the u.s. by the Advanced Television Service Committee. Canada officially adopted the atsc standard (ATSC A/53) in November 1997.

There are 18 variations within the proposed atsc A/53 standard for atv. The reason for this is the need for backward compatibility to the existing television system and incorporation of new forms of data transmission.

To appreciate the issue of technical standards consider television’s utility. For example, if you took a modern tv set back in time to 1948 and plugged it in, you would receive the over-the-air transmission of that day. Conversely, a 50-year-old tv set will receive today’s broadcast signals. This is the legacy addressed by the atsc.

To sustain this utility, complex engineering has been developed to establish a workable framework for the new digital system. Keep in mind, atv standards relate only to terrestrial (over-the-air) broadcasting and not cable, direct satellite transmission or home video formats (vhs and dvd).

ATV standards

It is helpful to know a little about the current television standard to understand atv standards. The current standard for North American television is called ntsc. An ntsc picture contains 525 horizontal lines of information. The picture is delivered in two stages. The first 262.5 lines are scanned at 1/60th of a second followed by the second 262.5 lines scanned at 1/60th of a second. This produces one 525-line ‘interlaced’ picture (one frame), at 1/30th of a second (or 30 frames per second). Audio can be mono, stereo or surround sound.

The atv standard includes two types of scanning: interlaced scanning, as in ntsc, and progressive scanning, as is used in computer monitors. In progressive scanning the television picture is scanned in one pass, unlike the two-pass process in interlace scanning.

Interlace scanning produces artifacts that are absent in progressive scanning. Progressive scanned pictures appear at higher resolution. Most home viewing will be done on interlaced television sets (with the progressive scan image converted to interlace) because of the high cost of progressive scan monitors.

Three levels of horizontal line resolution are included in the atv standard: 480 lines, 720 lines and 1080 lines. A 480-line picture is almost identical to the current 525-line picture.

Keeping this in mind, here are the four basic descriptions for atv: 480i, 480p, 720p and 1080i.

A designation ‘i’ is used for interlace picture and ‘p’ for progressive scanning. It is the variations within each of these, such as frame rates and aspect ratios, that produces a total of 18 different specifications.

Broadcasters in the u.s. are required to transmit analog service until 2007, when the analog system will be retired. This means u.s. broadcasters have to provide a dual service, digital and analog. Digital service will be phased in and must be fully operational by 2005.

In Canada, outside of the adoption of the ATSC A/53 specifications and the frequency assignments, there has been no decision made with regard to time lines for retirement of the analog service and implementation of a digital service. Historically, Canada has followed the u.s., trailing two years behind, as was the case with color television.

The cost of converting to a digital broadcast system will be considerable. Broadcasters stand to bear the lion’s share of cost, at a time of declining revenue. The prospect of increased revenue from more channels and services could be a incentive for investing in the digital system.

How will ATV affect producers?

Today the market for digital television services is, to quote a u.s. broadcaster, ‘a zero billion-dollar business.’ There are few receivers for dtv or hdtv broadcasts. The time line for full implementation is a minimum of six years away. We are talking about the future. But that future is unfolding today.

In the u.s., broadcasters were mandated to begin digital broadcasting Nov. 1, 1998. To be prepared it may be prudent to factor this future into today’s production plan.

A digital broadcast system will allow changes to the type of delivery and forms of media distributed in the future. tv services, as we know them today, will remain essentially the same.

However, there will be more channels and higher quality pictures and sound available. There is also the added feature of parallel data delivery (text, software, computer networking) with television programming.

Program delivery

The convergence of digital media will bring new variations in communication. Inclusion of progressive scan image display in the dtv standard will allow video display on computer monitors (and higher resolutions than hdtv). Video on demand, integration of the Internet with broadcasting, accessing text and other data during broadcasts, purchasing products and participating in game shows are a few examples.

dtv will offer producers new types of program outlets and profit centers.

The convergence of media companies addresses the fact that programs, films, books, characters, brands and ideas have to be leveraged through numerous media outlets in order to be profitable.

Television or film properties that translate to other media outlets such as the Web, interactive entertainment and product promotion/sales stand to do well.

Picture

One important issue for producers to consider is the higher quality picture and aspect ratio offered by dtv. Standard definition television (sdtv) and high-definition television have a different aspect ratio than ntsc – 16:9 rather than 4:3. The 16:9 aspect ratio is similar to 35mm and Super 16mm film (note: there are specifications for digital 4:3 broadcasting in sdtv).

Capturing and editing programs on 16:9 equipment (either film or digital tape) will be required.

Sound

Another important issue is the higher quality sound reproduction in dtv. The Dolby AC-3 standard means that viewers can reproduce six separate audio channels. The creation of a six-channel mix requires a studio equipped for 5.1 sound monitoring and encoding. It will also mean additional time in production and post-production.

DTV: SDTV and HDTV

dtv broadcasting is distinguished by several characteristics:

1) Digital transmission (MPEG-2 for picture, Dolby AC-3 for sound)

2) Image resolution and size: standard television, high-definition television

3) Display: interlaced (tv set) or progressive scan (computer monitor)

MPEG-2 (Motion Picture Experts Group) is a standard for compressing video information for transmission. Compression allows more channels to be broadcast in the 6 mhz bandwidth each broadcaster licenses. MPEG-2 is also used to compress video in consumer dvd discs. It works by sampling a series of video frames and saving only the information that changes from frame to frame. In this process information is lost, so they call mpeg ‘lossy’ compression.

Dolby AC-3 is a compression standard for the audio portion of a dtv broadcast. It will allow for the decoding of all types of audio currently used in home reproduction, up to 5.1 channels. These include mono, stereo, surround sound and Dolby 5.1.

Audio for the new digital broadcast system is Dolby 5.1. The designation ‘5.1’ relates to the number of separate audio channels. There are five full channels: left front, right front, center front, left rear, right rear and a low frequency effects channel (with the designation point ‘one’) that is played through a subwoofer.

The home has to have a Dolby AC-3 decoder and six speakers for playback. If not, the dtv receiver will decode the signal for playback in whatever sound reproduction is available – surround sound, stereo or mono.

There are two television standards for dtv: standard digital television (sdtv) and high-definition television. Both sdtv and hdtv have a wide-screen aspect ratio, 16:9 as opposed to 4:3 for ntsc. sdtv has the same image quality to the current analog service.

sdtv can be 480i, with either a 4:3 or 16:9 aspect ratio and 480p. Initially broadcasters will transmit 480i with a 4:3 aspect ratio, moving toward higher quality when older equipment is replaced by new digital television systems.

hdtv can be either 1080i or 720p. There is no consumer demand for hdtv, yet.

Expect the cost of hdtv television sets to come down in the future. Advances in display technology will make large, high-resolution flat panel screens (which do not require floor space) affordable soon. Broadcasters and manufacturers will create the demand for hdtv.

Both the u.s. and Canada have assigned digital frequencies to broadcasters. Each broadcaster has a licence to 6 mHz of aerial bandwidth. One tv channel of current analog transmission takes up 6 mHz. One channel of standard digital television (sdtv) transmission uses approximately 1 mhz. So, broadcasters could potentially increase the number of channels they broadcast from one to six.

For example, a broadcaster could use 1 mhz for sdtv broadcasting, 1 mhz for video conference services, 1 mhz for repeat broadcast of earlier programming.

Another use for the additional channel capacity is sending other digital information other than television over the air. This could be text information to accompany on-air programs, stock quotes, news, interactive features for game shows, advertising services and paging. This is referred to as digital multicasting.

hdtv will require the full 6 mHz of bandwidth to transmit one signal. Since broadcasters look at the added channel capacity as new revenue, possibly offering pay tv services, they may restrict hdtv transmission to primetime program schedules to avoid losing revenue in multicasting.

Aerial transmission of digital signals is error prone. If the signal is blocked by physical or atmospheric obstruction (rf interference) it is rendered unusable. A special receiving antenna is needed to receive digital broadcasts and a set-top box is needed for televisions not equipped to decode these signals.

dtv will initially be an over-the-air service. Cable companies are waiting until a standard transmission format is established. The current cable system is capable of distributing dtv with relatively minor upgrades (encoding and head-end costs).

There has been some speculation that what fueled the launch of dtv is the fcc’s desire to increase licensing revenue. However, broadcasters see the potential of dtv to bring new revenues through a higher quality television service. Integral to this is hdtv, which could possibly replace sdtv completely in time.

cbs and nbc have chosen the 1080i-line picture at 30 frames per second for hdtv and 480p at 60 frames per second for sdtv broadcasting. abc and Fox have chosen the 720p-line picture at 60 fps for hdtv and 480p at 30 fps for sdtv broadcasting. Unity Broadcasting launched the first all-hdtv satellite service last year.

There are many productions being done in hdtv. In Canada, The Secret Adventures of Jules Verne is being shot on a Sony HDW-700 hdcam in Montreal. Post-production is being done by Voodoo Arts on a hybrid system using Avid ds systems with Sony HDW-500 hdcam vtrs.

Post-production

Your local post house is not going to upgrade to dtv/hdtv until there is sufficient demand. The cost of converting a serial digital edit bay to hdtv is very high. For the next few years there will be minimal demand for hdtv, with most work being done in sdtv.

Post companies will have to prepare to work with material in a 16:9 aspect ratio, in higher resolutions and in Dolby 5.1 audio. However, there are other ways to service television productions facing the dtv future.

Many of today’s post-production tools are ready for dtv or easily upgraded. The television business is one of the most computer intensive. Post-production is already largely performed digitally, either on digital tape or on computer systems. Desktop systems used by post operations can be upgraded to handle dtv specifications with the addition of a vtr, monitor or graphics card.

Resolution-independent compression technology is expensive and will add significant cost to a system. Higher resolution pictures are more complex and this will mean increasing the power of computer processing and data storage in desktop systems.

High-cost hdtv online systems will bring back the importance of offline editing before conforming a program. Transferring hdtv and 35mm to ntsc for offline, conform, sound editing and mixing is a logical short-term solution for a current ntsc release.

There is no question digital television will transform the post business. The distribution of material through networks and storage of material on servers will allow new creative synergies to develop in post-production. For producers this will mean an increased number of services, customization of services and lower cost of services.

Serial digital tape editing

Suites designed for serial digital tape editing are ideal for upgrading to dtv post-production because video information is processed in component form (high-quality television signals can only be maintained in the component digital domain, where the picture’s color and exposure information are managed separately).

Component dtv hardware (switchers, monitors, color correctors and vtrs) is very expensive (20% to 25% higher than ntsc equipment). Only high-end post houses with deep pockets will be upgrading their tape edit bays to dtv and hdtv.

Because they service the higher budget clients with film-to-tape transfers, there may be a rationale for making these upgrades. Not many of these post houses have transfer bays capable of dtv output yet. As long as 35mm origination continues to dominate the primetime television production market, the future of the large post house is secure.

Nonlinear picture editing

Manufacturers of broadcast nonlinear editing systems all plan to release dtv versions of their products. In fact, many nonlinear editing systems are able to work in sdtv, and a few are able to handle hdtv.

Avid, which dominates the nonlinear editing system market with its Media Composer products (and now has the ds product from Softimage), recently announced plans to produce a dtv/hdtv system.

Avid plans to continue developing offline systems. They propose two-stage editorial (offline and online) for hdtv. By using the current Media Composer to drive hdtv equipment, it is possible to conform an hdtv program.

Avid is also developing resolution-independent systems for dtv online editing in the future.

Fire, an editing system from Discreet Logic, is capable of resolution-independent editing, which means it can meet the atv format specifications, including hdtv. Owners of these systems may have to upgrade them with more processing power and more storage.

Quantel, the maker of Henry and Editbox, will continue to make its proprietary hardware systems for the editing and processing of dtv and hdtv material, aiming at lowering cost. Quantel will be introducing a digital networking technology called Clipnet for its current systems.

At a lower end of the nonlinear broadcast desktop system market, current Media 100 systems are able to edit 16:9 images with the addition of a monitor. Like most purveyors of editing equipment, they are waiting until there is a settling down in technical specifications before launching dtv/hdtv products.

Computer graphic images

The 16:9 aspect ratio of dtv and hdtv gives graphics artists a new canvas to work with.

For the broadcast designers this means richer colors, higher resolution and a wider format. It also means anticipating the legacy of 4:3 in the transition to a digital broadcast system in the years ahead.

There are many resolution-independent systems for graphics, animation and compositing in the marketplace already. Current systems that are resolution independent include Inferno, Maya, Jaleo and Illusion. They can work with images in a 16:9 aspect ratio and in film quality (although these are not hdtv systems, they do exceed hdtv specs).

There is the potential for new graphical formats for programming integrating the delivery of text data, parallel programming or interactive features such as product purchasing.

5.1 sound recording & mixing

In Dolby 5.1 encoded audio there are five discrete, full channels of audio (front: left, right, center; and rear: left and right) and one subwoofer channel providing low-frequency information that is described as ‘point one.’

5.1 sound must be designed to be heard in three dimensions. Sound editing and mixing has to be done in rooms equipped with 5.1 monitoring.

The higher intensity of 5.1 audio reproduction may tempt producers to embellish the track. As the cost of soundtracks is related to the time required to create them, producers should be careful not to have more detail in the track than is necessary.

Converting in post

In the case of ntsc- or pal-originated programs there is conversion technology that will allow cropping and image enhancement for reformatting shows from a 4:3 aspect ratio to a 16:9 aspect ratio. It is easy to imagine that a ‘conversionist’ will become as valuable as a ‘colorist’ is in post-production.

Video compression

Compression of video is necessary for cost-efficient production and distribution. By its nature, compression eliminates information in the recording. Compression is more critical in origination. Using the least amount of compression in capturing an image is best because through post-production and distribution compression is increasingly added.

For example, Digital Betacam has a compression of 2:1. Editing on a nonlinear system at highest resolution adds 3:1 compression. Broadcasting in dtv adds 65:1 compression.

Throughout this process information in the picture is continually lost.

High-end post houses like to process uncompressed component video in order to monitor the quality of the material. This adds considerable cost to the facility, especially for hdtv post-production, as hdtv has six times the amount of information as standard television.

Low-cost hdtv post-production will come in several years when more desktop editing systems are capable of managing the larger amounts of hdtv data.

Transferring film to data

Transferring film to digital data (instead of video) allows material to be converted to any video standard later on. One issue this process addresses is interlaced scanning in broadcasting.

Converting progressive scan images to interlace picture for broadcasting is more likely than the other way around. Film transferred to interlaced video can have motion artifacts that cannot be removed. Progressive scanning, as is the process in a film-to-data transfer, does not carry these artifacts. Therefore it is better to begin with progressive scanned images in a film transfer and convert to interlaced pictures. Systems available for data transfers are the Spirit DataCine, Kodak Cineon and Quantel Domino.

HDTV and film

For dhtv productions that want the aesthetic look of film, all post should be done in 601 component. Time is needed for scene balancing, color correcting or color treatment (timing), but no more time than required for correcting a film-originated project. It is possible to pan an image originated in a 16:9 aspect ratio to get 4:3 aspect ratio, as is done in film transfers.

hdtv recorders have a ‘pan and scan’ feature built in. It is also necessary to add grain to the picture. The addition of 3:2 pull down, a characteristic of film transferred to video, can be done by eliminating fields or by frame interpolation. It follows that on the video side most dtv and hdtv post-production will be done on desktop systems.

Future proofing

The major issue facing producers today is future proofing their programs for the new digital broadcast environment, whether dtv or hdtv. It is only worth considering future proofing if the product has shelf life that will mean future sales in the hdtv or sdtv market.

The majority of programming, for the foreseeable future, will be viewed in sdtv (digital 4:3).

No one can predict how quickly dtv will be embraced by consumers. Regardless, broadcasters will be delivering dtv in Canada. With declining network revenues and increased competition from cablecasting, having the competitive edge offered by dtv and hdtv programs (especially drama, sports and variety) will be valuable.

With 75% of primetime drama currently shot on 35mm film, negative is archived for future re-edit and transfer to dtv’s wide-screen format. Filmed programming will see new release potential with 16:9 viewing, and older programs in syndication will be seen for the first time in their original wide-screen format.

If delivery is intended for hdtv broadcast, high-quality origination is important. hdtv cameras produce 1000 tv/ph, higher than 35mm film. Video formats have a history of change, so one shortcoming of tape may be future technical limitations of the originals.

On the other hand, 35mm film originals can be converted to any video format without degrading image quality.

Super 16mm film performance might be too low for hdtv, with its imperfections accentuated when transferred to hdtv. Testing is recommended before committing to Super 16mm origination.

Conversion issues

The primary issue facing all businesses involved in television production is ensuring the future value of current product. For producers, this means either originating a production on the highest quality format (hdtv or 35mm film) and ‘down-converting’ to other release formats (sdtv and ntsc) or taking ntsc and sdtv and ‘up-converting’ to hdtv. There will be a need for scan conversion in post-production to deal with both interlace and progressive scan pictures.

Down-converting

The wisdom for starting with the highest quality image and down-converting to lower resolutions can be appreciated when considering the dual nature of broadcasting in the future.

Broadcasters will have to simulcast programming in analog and digital for at least the next eight years and will want to down-convert from hdtv to ntsc when possible.

Up-converting

It is possible to convert standard television to hdtv using line-doubling technology.

High-quality results can be achieved by capturing on a 525-line camera using an anamorphic lens (Sony DVW 700) and up-converting using a line-doubling device to dtv or hdtv. Images captured this way must be ‘unsqueezed’ and panned to deliver a 4:3 aspect ratio (letterbox picture can also be delivered). Image enhancement, or color correction, can then be carried out in post-production.

Cropping will be necessary to deal with the change in aspect ratio from 4:3 to 16:9.

Cropping is not an issue if programming is shot in 16:9. Here are some aspect ratio solutions and shortcomings:

1) Shoot 16:9 and letterbox for 4:3 – letterboxed images are not as acceptable to viewers as full-screen images.

2) Shoot 16:9, crop the sides for 4:3 and enlarge image: results in loss of 25% of picture; enlargement will soften image.

3) Shoot 16:9 with action framed for 4:3 and transfer for 4:3: there is difficulty keeping action in the 4:3 safe area; scenes with a lot of side entrances and exits will suffer in the transfer; loss of 25% picture area.

4) Shoot 4:3 and crop top and bottom and enlarge image for 16:9: cannot archive a 16:9 picture.

It is less expensive to produce programs in sdtv than hdtv. Technology used in up-converting images can produce very good images. However, up-converting sdtv does not produce the same resolution picture as native hdtv. The difference in image quality is more apparent when compared side by side with hdtv. Up-converted programs will be common in the early days of dtv, but their value will decrease as more native hdtv shows are produced.

Although viewing old ntsc programs in 4:3 on wide-screen sets could add to the nostalgia, especially if they are black and white, dtv will more likely render old ntsc shows less valuable if not unsalable.

Mark Collings can be reached at collings@interlog.com. For a glossary of terms and links to more information on advanced television, go to www.interlog.com/~collings.