An Introduction to DVD and Web Captioning

1 Described and Captioned Media Program

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Funding for the Described and Captioned Media Program is provided by the U.S. Department of Education

Revised November 2008

An Introduction to DVD and Web Captioning

By Kevin Jones

DVD Captioning

By now, you are probably very familiar with the DVD format as sales of DVDs and DVD players overtook those for

the VHS format as far back as 2002. The DVD format is now considered to be the medium of choice for video

distribution. DVD players have become nearly ubiquitous in the marketplace and are now very affordable. Major

video retailers such as Blockbuster and Best Buy have vastly reduced—or eliminated—their VHS tape collection in

favor of DVDs. This is all very good news, as DVDs have a number of advantages over VHS tapes, particularly when

it comes to providing accessibility. Not only can DVDs carry the same “Line 21” closed captions used with analog

mediums such as VHS and analog television broadcasting, they can also carry up to 32 subtracks of digital captions

using MPEG2 technology to present the captions as images superimposed on the video. Captions presented in this

way are called “subtitles.” With 32 subtitle tracks available on a DVD, it is possible for the producer to offer

multiple languages as well as various captioning styles. Moving from an analog to a digital world, however, poses

some very serious challenges for captioning.

You may have noticed that some DVDs offer “subtitles for the deaf and hard of hearing,” commonly called “SDH.”

Alternately, you might see this option listed as “English for the hearing impaired.” SDH combines the features of

subtitles (proportional, attractive lettering superimposed over the video) with the benefits of captions (e.g.,

speaker identification, sound effects description, and precise timing). The result is that the subtitle sentences are

easy to read and can be turned on or off at the viewer’s discretion.

Unfortunately for deaf and hard of hearing consumers, the acronym SDH (or, for that matter, the word

“subtitled”) has not been used in a consistent fashion. For example, occasionally the DVD menu will indicate that





the movie has been subtitled in English, when in fact it is SDH or vice versa. The menu might also indicate the

movie contains “captions” when, in fact, they are actually subtitles or SDH. Sometimes the program has been

closed captioned, but the box the DVD comes packaged in is not properly marked with the closed-captioning “CC”

symbol. If closed captions are present, you will see them on your TV screen in the same way they appear on a

normal broadcast television signal—assuming you have the CC option for your TV turned on. You should be aware,

however, that the newer digital connections (e.g., component and HDMI) will not pass through the analog closed-

caption data in many cases. Therefore, it may be necessary to use the standard analog RCA (i.e., red, white, and

yellow) connections to view closed captions with newer digital formats, such as DVD and HDTV.

Additionally, the DVD format can present some technical challenges with

respect to captioning. For instance, DVD authoring systems frequently use

competing caption/subtitle file formats, which can be quite confusing to a

novice user. Some consumer-level DVD authoring systems are unable to

integrate existing Line-21 closed-caption formats, and even professional-

level authoring systems are oftentimes unable to convert all of the various

caption and subtitle file formats. Line-21 captions are necessary for

programs that will be broadcast on television; however, subtitles offer

much more flexibility in the way they are displayed on the screen and

should be used in place of the analog closed-caption formats when captioning for the newer digital mediums.

Unfortunately, there is no common format that can be used to display both captions and subtitles, so it is

necessary to pick the format(s) which best suit(s) your particular requirements and use software to convert the

files to a different format as needed. Programs such as MPEGRepairHD will allow you to convert Line-21 captions

to a MPEG2 file that can be used in various digital mediums, such as DVD and HDTV.

Given the vast number of options and formats, it is not surprising that video producers are frequently unfamiliar

with both the accessibility needs of their intended audience as well as the processes involved in creating

accessibility features, such as captions or SDH. As such, when producers are ready to release their productions on

DVD, they will need to decide whether to author the DVD master in-house or have an outside vendor do it for

them. The DVD authoring process can be expensive and time-consuming when it comes to captioning unless you

have the right tools and knowledge. You can search the DCMP gateway to learn more about DVD captioning

techniques, or view the Approved Captioning Service Vendors list to find a DCMP-approved vendor who can

provide that service for you.

Web Captioning

“Thanks very much, but how do I get captions for videos on the Web?” you ask. As you might imagine, there is no

simple answer, but we can try to steer you in the right direction. By now, you are probably well aware that the

proliferation of broadband Internet access has paved the way for a flood of video programming on the Web. From

home movies to TV shows to music videos, streaming “webcast” media is everywhere. Many different media

players are available for viewing streamed audio and video on the Internet. Unfortunately, most videos online are

not captioned or subtitled, and creating caption files is different for each player.

http://www.pixeltools.com/tech_tip_closed_captioning.html

http://www.dcmp.org/Search/Default.aspx?A=1

http://www.dcmp.org/caai/nadh11.pdf





There are two main categories to be aware of regarding streaming media

players: stand-alone players (which display the video in a separate

window outside of the Web browser) and embedded players (which

display the video inside of a Web page). The most popular stand-alone

options are Windows Media Player, Real Player, and QuickTime. In the

embedded category, the most popular options are Flash-based (e.g.,

YouTube and Google Video) and Java-based (e.g., Clipstream) players,

with several other competing players and formats on the horizon (e.g.,

Microsoft’s Silverlight technology, though it is currently limited to the

Microsoft Windows and Apple Mac operating systems only).

Stand-Alone Players

Each of the stand-alone players has integrated accessibility

features that give users the ability to turn on captioning if it is

available. Finding these features in each of the players can be

difficult. For starters, each player has its own individual menu

options. The location of the accessibility features on Windows

Media Player’s menu differs from that of RealPlayer, and so

on. Also, player menus may vary by operating system and will

frequently change when newer versions of the players are

released. In Real Player version 11.0, for example, captions are

turned on by going to the “Tools” menu, selecting

“Preferences,” and clicking on “Content.” Under the heading

“Accessibility,” choose “use supplemental text captioning

when available.” In Windows Media Player version 11.0, go to

the “Play” menu (right-click the top of the player to access the

“Play” menu option if it is not visible by default), point to “Lyrics,” “Captions and Subtitles,” and select “on if

available.” You may also need to enable the option to “show local captions when present” under “Tools” >

“Options” > “Security.” You can turn them on in QuickTime version 7.3 by going to the “Edit” menu, selecting

“Preferences” > “Player Preferences,” and choosing “show closed captioning when available” under the

“Movies” category.

Creating captions for streaming media players is similar to creating captions for both the VHS and DVD

formats, and each uses similar tools and software. Captioning for the Web, however, presents its own set of

challenges. Just as different DVD authoring systems use varying caption or subtitle file formats, each of the

various streaming media players requires specially formatted caption files as well. Windows Media Player,

Real Player, and QuickTime, for instance, all have their own special requirements for the makeup of these

files, how they are named, and where they go in conjunction with the video file. Video producers will need to

research the various players and formats before deciding which ones are right for their needs.

http://en.wikipedia.org/wiki/Comparison_of_media_players#Subtitle_support





Stand-alone players currently have more options for providing

accessibility and copyright protection features than embedded

players, but they have a few drawbacks as well. Most notably, you

have to download an installation file to your computer and then

install the player as a stand-alone software application. This poses

several potential issues related to operating system compatibility

and security. In many cases, it is not possible for a user on a large

network (e.g., on a school campus) to install stand-alone software

applications without permission from the network administrator.

Stand-alone player adoption has therefore lagged behind

embedded video players for this and other reasons. Please note

that all of the stand-alone players mentioned in this article are

capable of playing as embedded players as well; however, the

accessibility features are generally very limited as the player

menus may be partially or completely unavailable when embedded into a Web site.

Embedded Players

Embedded video has emerged as the most popular streaming video format on the Internet today. The Flash-

based video format, by Adobe Systems, Inc., is used on thousands of Web sites around the world and has

become the de-facto standard for video and multimedia content on the Web. Streaming video sites such as

YouTube and Google Video have popularized the format due to the ease of player installation, support for

multiple browsers and operating systems, and a video compression technology that offers VHS-or-higher

quality using a relatively small amount of bandwidth. The installation process for the Adobe Flash player is

accomplished via a small plug-in for your Web browser which takes only a few mouse clicks to install.

Adobe provides a number of accessibility options for Flash video using the Distribution Format Exchange

Profile (DFXP) of the timed text authoring format to embed subtitles into the video file. To learn more about

creating captions for the Flash format, visit the National Center for Accessible Media’s (NCAM) CC for Flash

Web site. You can download the free CC for Flash captioning tool, which will allow you to either create a new

caption file or import an existing caption file from any of several different formats for use in a Flash video.

Additionally, you can learn more about efforts underway to create an Internet Captioning Forum (ICF) at the

NCAM Web site. The ICF is being developed to help coordinate captioning technologies between the various

multimedia vendors on the Internet. This exciting new initiative has the potential to bring a wealth of new

captions and interest in accessibility to the streaming media format. To learn more about providing captions

for Flash media, and to keep up with the latest developments in Flash player accessibility, visit Adobe’s

accessibility blog.

Clipstream is one of the few streaming video providers utilizing a Java-based player that runs in its own

“virtual machine” independent of the PC. The Java platform runs on every major operating system, so it is

possible to set up a Java-based video player quickly without relying on the end user to install any extra

http://ncam.wgbh.org/webaccess/ccforflash/index.html

http://ncam.wgbh.org/news/icf.html

http://blogs.adobe.com/accessibility/

http://www.clipstream.com/





software. Java is already installed on well over 90% of the operating systems in use on the Internet today, so

it’s a safe bet that most users will be able to play your video without any installation issues. Clipstream also

offers a copyright protection mechanism that prevents unauthorized copying of a streamed video.

Unfortunately, as of this writing, they do not currently offer a simple way to incorporate caption files, which

makes them unsuitable for playing accessible media for the deaf and hard of hearing community.

For producers who are interested in streaming their videos on the Web, but are concerned about protecting

their content, there are many options available. All of the streaming media technologies mentioned in this

article provide some form of Digital Rights Management (DRM) technology to protect copyrighted content.

While there is generally no foolproof way to protect digital media from all forms of copyright infringement,

DRM technologies can prevent the majority of users from either accessing or copying your content without

your permission. In the case of Flash video, the engineers at Adobe have written an in-depth technical paper

that explains a few of the options available for securing Flash media.

Conclusion

As you can tell, there are many options available for creating and distributing accessible videos, either through the

Internet or through traditional physical media. Be sure to visit the DCMP accessibility search gateway to learn

more about the tools and practices involved in adding captions for whichever media format(s) you choose.

Captioning is an essential feature for giving both deaf and hard of hearing viewers access to the massive amount

of video information surrounding us every day. With technology advancing at exponential rates, it is becoming

easier and easier for producers to caption their media given the proper tools and knowledge. Whether your video

is professionally made or shot in your back yard with a camcorder, deaf and hard of hearing viewers want to

“hear” your message as well. With a little effort, you can make that happen with captioning!

About the Author

Kevin Jones is the former Information Technologist for the Described and Captioned Media Program. He holds a bachelor of science in computer science, is a Microsoft Certified Professional, and has worked in systems administration for over seven years. When he is not working on computers, he is spending time with his wife and their three young children.

http://www.adobe.com/devnet/flashmediaserver/articles/protecting_video_fms.pdf

http://www.dcmp.org/Search/Default.aspx?A=1

An Introduction to DVD and Web Captioning

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