Making A DCP: Accessibility

Aaron Owen

Jun 4
4 minutes

The Digital Cinema Package (DCP) format used in cinemas contains a bunch of features that can help make your film accessible. These features are useful for audiences who don’t speak the language used in your film, who can’t see the screen, or who can’t hear the soundtrack. Here we’ll discuss what these features are, and how to take advantage of them.

Subtitles & Captions

DCPs support two different types of timed-text tracks: subtitles and captions. What’s the difference? In a DCP, the difference is partly content, partly labeling for the projectionist, and partly metadata flags that alert the playback server to the intent of the content owner.

Content: The main difference between these timed text tracks is the aim of the content itself. For Subtitles, the purpose is to allow audience members to understand the dialog of a different language spoken by the characters on screen. Consider the following use case: let’s say you are sending a film with primarily English dialogue to a non-English speaking market like Brazil. You’ll probably need to create subtitle tracks in Spanish and Portuguese. Subtitles are displayed on screen usually near the bottom so everyone in the theater can see them.

Captions on the other hand are meant to give information about what is happening audibly in the film for someone who is deaf or hard of hearing. In addition to dialogue, there may be text which describes sound effects or music.

Dolby CaptiView is a personal LCD screen meant to display Closed Captions for hearing impaired patrons.

Some playback systems will route caption text data to a separate system for broadcasting the text to special equipment such as Dolby’s CaptiView that is meant to display the text only to users who need it.

Labeling: The Digital Cinema Naming Convention (DCNC) is the complicated naming structure that projectionists use to parse out different versions of the same film. If the timed text track is meant to be a subtitle, the DCNC requires a two-chracter language code following the audio’s two-language code separated by a dash.

If the timed text track is meant to be a caption track, the DCNC requires that you specify whether the captions are open captions (OCAP) or closed captions (CCAP). Open captions are meant to be displayed on screen and visible to everyone in the theater, just like a subtitle track. Closed captions are broadcast to a special device which displays the text only to those who need it.

Metadata: Depending on the type of timed text track that’s being added to the DCP, the creator will need to specify the use so that the playback system can appropriately handle the display of the text in the correct manner.

Methods: There are a couple of methods for subtitling a film for a foreign language or providing captioning for the hard of hearing and the deaf. The first is to burn in the text data to the picture so that it is always displayed. The second is to let the projector render the text and place it on top of the clean picture.

Burning subtitles into the picture is the most foolproof way to ensure that your subtitles are seen as intended. Many film festivals have requirements that subtitles must be burned in. Most of the time this is because they’ve had a foreign language film play without subtitles to an audience who can’t understand the audio. This might sound like the simplest way to deliver your DCP, and many times it is. But there are some drawbacks as well. If you plan on releasing your title to multiple language markets, you’ll have to create a new DCP for each language. This can quickly become very costly in terms of either encoding time or money.

The alternative to burning in subtitles is to create a DCP without subtitle text and have the projector render the words over the picture. This allows for greater flexibility, and you can change the text content without needing to re-encode the picture or audio tracks. Additional supplemental DCPs can be created for each new language version. This greatly reduces the size of your delivery and is the way the major Hollywood studios release their films internationally.

Audio Accessibility

While it may seem counter-intuitive, blind and visually impaired (VI) audiences enjoy going to the theater to experience films. Likewise, hearing impaired (HI) audience members also enjoy the cinema. DCP provides a way to package these accessibility assets right alongside the regular movie content.

Audio Description for the Visually Impaired

An audio description track is a special audio track that is broadcast to a wireless headphone system so visually impaired audiences can listen to a narrator describe the action happening on screen. This is an additional mono audio track that is created by either the filmmaker or the distributor and is wrapped into the DCP. The server takes this audio track and sends it out to a separate system for wireless transmission. When done properly, this track is part of the DCP, but will never be heard inside the theater without the special headphones.

Hearing Impaired Soundtrack

Some audience members may have hearing aids or need special help hearing the dialogue over the music and sound effects. The hearing impaired track is a mono audio track which contains an enhanced mix to allow the audience member to better be able to hear the dialogue. This track is broadcast to the same wireless headphone system that the visually impaired track uses, but there’s a switch on the receiver that switches between the HI and VI tracks.

Digital cinema was built from the ground up for accessibility. There are lots of reasons to make your film as accessible as possible, and many festivals like Sundance are now requesting feature films include these accessibility assets. For more on how to create VI / audio description tracks, visit the WGBH descriptive video website. For more information about HI / hearing impaired mixes, visit this site.

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