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How Subtitles for the Deaf and Hard-of-Hearing (SDH) Differ from Closed Captions

  • How Subtitles for the Deaf and Hard-of-Hearing (SDH) Differ from Closed Captions

    In order to fully understand the difference between subtitles for the deaf and hard-of-hearing (SDH) and closed captions, let’s first explore the how subtitles and closed captions are not the same thing.

    Subtitles vs. Closed Captions

    How are they alike?

    Both subtitles and closed captions are synchronized with the media so the text can be viewed at the same time the words are spoken. Closed captions and usually subtitles can be turned on or off by the user.

    How are they different?

    Subtitles are intended for viewers who can hear the audio, but cannot understand the language. They communicate the spoken content but not the sound effects. They are usually used to refer to translations, such as subtitles on a foreign film.

    Closed captions, on the other hand, communicate all audio information, including sound effects, speaker IDs, and non-speech elements. They are written in the source language of the video. They originated in the 1980s and are required by law for most video programming in the United States.

    What Are Subtitles for the Deaf and Hard-of-Hearing?

    SDH are subtitles in the source language of the video that also include important non-dialogue audio sound effects and speaker identification. While normal subtitles assume the viewer can hear the audio but doesn’t know the spoken language, SDH assume that the viewer cannot hear the audio (like with captions). They are intended to emulate closed captions on media that does not support closed captions, such as Blu-ray.

    The Difference Between SDH and Closed Captions

    Subtitles SDH Closed Captions
    Synched with video Yes Yes Yes
    Can be turned on/off Yes Yes Yes
    In source language Yes Yes
    Speaker Identification Yes Yes
    Sound effects Yes Yes
    Text appearance Varies Varies Usually white text on black background
    Onscreen placement Centered lower bottom third Centered lower bottom third Varies
    Encoding Supported through HDMI (Blu-ray or HD DVD) Supported through HDMI (Blu-ray or HD DVD) Not supported through HDMI (Blu-ray or HD DVD)


    SDH differ from closed captionsin a couple of ways. The first difference is in appearance. Closed captions are traditionally displayed as white text on a black band, while SDH subtitles are usually displayed with the same proportional font of translation subtitles. More and more often, however, both subtitles and closed captions have user control options that allow the viewer to change the color, font, and size of the text.


    SDH and closed captions also differ in terms of placement. Closed captions can usually be aligned to different parts of the screen, which is helpful for speaker identification, overlapping conversation, and avoiding interference with important on-screen activity. SDH text is usually centered and locked in the lower bottom third of the screen.


    The biggest difference between SDH and closed captions is that they are encoded differently. Certain high-definition media, including Blu-ray and HD DVDs, do not support closed captioning. In fact, any disc playing through an HDMI connection will not play closed captioning, but will support SDH subtitles.

    While closed captions are encoded as a stream of commands, control codes, and text, subtitles are often encoded as bitmap images. This makes it much harder to decode the subtitles back into text form or to convert them into other formats, whereas it is generally easy to do so with closed captions.

    Just as closed captions are used by people who aren’t deaf or hard of hearing, SDH subtitles provide accessibility to a wide range of people:

    • They improve comprehension for ESL speakers
    • They help viewers with attention deficits or cognitive differences focus on the video
    • They help viewers understand people with thick accents or speech impediments
    • They improve the viewing experience in sound-sensitive environments

    It should be noted that while SDH do provide accessibility for HD disc media, they do not currently satisfy the FCC’s requirements for closed captioning of broadcast video.

    The FCC put out an order in June, 2013 requesting comment on the possibility of reconsidering this ruling, but a decision has not yet been made as to whether SDH will satisfy the FCC’s requirements moving forward.

    Subtitle File Formats

    Some subtitle file formats are text-based, while others are image-based. Text-based subtitle formats include SubRip SRT, WebVTT, iTunes iTT, PAC, DLP Cinema XML, and EBU-STL. Image-based (or “bitmap subtitles”) include Blu-ray BDN, UYC/USF, and any other format that includes image files like PNG, TIFF, or BMP.

    A common way to add SDH to Blu-ray is to create a BDN.xml file, along with PNG (image) files.

    Need closed captions, subtitles, or both? Check out 3Play Media’s professional closed captioning and video transcription services.

9 Responses to How Subtitles for the Deaf and Hard-of-Hearing (SDH) Differ from Closed Captions

  1. Terry says:

    Thank you for the comparison. A few followup questions – looking at:

    SDH … do not currently satisfy the FCC’s requirements for closed captioning of broadcast video.

    I followed the link to try to learn why:

    In the Report and Order, the Commission recognized that SDH does not offer the same user control
    features as closed captioning. See Report and Order, 27 FCC Rcd at 846, 100.

    What user control features would be missing from text-based SDH that has been converted to closed captioning? Also, is the black background preferred (or even required) for broadcast?

    To add to the comparison above – there is the tendency for CC to appear as live stenography, with backspacing, spelling errors, & sponsorship messages, whereas SDH is apparently more carefully prepared offline with the intention of DVD/BluRay providing a premium product. I would love to know if this is how SDH is actually perceived compared to CC.

  2. I am interested in passing along your articles on captioning. I started the open captioned movie program and recently sold Captionfish, the only website that lists captioned, subtitled and described movies\content.

    My followers are interested and look to me for as much captioning information as there is out there and you have fantastic articles.

  3. Mario Batusic says:


    I am Accessibility co-ordinator at Fabasoft Company (Austria) and also full blind.

    I was very interrested in the subject and jumped immediately to this article about the comparison between SDH and closed captions, wenn I got the LinkedIn remark.

    But it is really sad that also accessibility specialists do not follow WCAG. In this article there is an interresting data table comparing various Features of SDH and closed captions. This table is fully inaccessible for blind Readers, because of using Background Images for all yes/no Statements. To be a specialist for the concerns of deaf and hard of Hearing persons may not mean to have no knowledge or interrest for the Needs of other disabled Groups.

    Unrelated to this criticism: thanks a lot for this very nice and clear distinguishing text.
    Ciao Mario

    • Emily Griffin says:

      Mario, thanks for voicing your concerns. The checkmark images in the table have Alt text that reads “Yes,” making it accessible to a screen reader.

  4. Dennis Cowdery says:

    Thank you for the explanation.
    I suffer from severe high frequency hearing loss which has a major effect upon my ability to discriminate the spoken word. The best audio solution I have found is to boost my hearing aid frequencies substantially (which ruins listening to music). CC subtitles etc. are essential for my enjoyment of audio/video. Theatre attendance at new movie releases are essentially a waste of time, the audio is frequently incomprehensible. Further, trying to determine what visual audio is available on the ultimate DVD release is often an exercise in futility. Thanks for letting me display my frustrations.

  5. Doug says:

    I recently purchased a Sony Spanish language BluRay which listed: English, English, SDH, French as subtitles. However to my surprise the SDH was just another English subtitle… so there are no Spanish subtitles and the language is Argentinean Spanish which has a strong accent and I needed the Spanish subtitles occasionally. I am very disappointed in Sony… this is misleading and I believe incorrect. SDH is supposed to be in the films native lanugage!!!

  6. Chris Hunter says:

    Unfortunately many new DVDs currently on the market do not have English subtitles but only closed captions. They have to be played on old DVD players. Do you know any make and model of Blu-ray players that can play DVDs with closed captions showing?

    • Rc says:

      You may use the composite cables (yellow/white/red) on the Blu ray and the TV. Choose this input on your TV NOT the HDMI to view DVDs with cc.

      Additionally complain to HDMI.org (#hdmi) for neglecting adding support for cc over HDMI. They kept releasing new revisions on HDMI completely ignoring cc. This caused widespread frustration for users of CC/Subtitles. On Blu-ray players you have to turn on subtitles every time you play a movie. In the past, the TV handles the CC so it’s always on.

      Sadly it makes me prefer pirated content because media players have enabled subtitles on by default.

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