GeneralSDH vs. CC | What are SDH Subtitles and Closed Captions?

March 1, 2024by admin

This comprehensive guide will focus on discussing the difference between CC and SDH.

Lately, you may have heard about subtitles for the deaf and hard of hearing (SDH) and closed captioning (CC) a lot. People often use these terms interchangeably, but they are different approaches to subtitling.

With the ongoing development of digital media, the significance of inclusive content becomes increasingly clear. 

Subtitles are an integral element when it comes to making multimedia files accessible. These text alternatives give those who are hard of hearing, deaf, non-native speakers, or just in noisy environments the necessary access to multimedia content. 

So, without further ado, let’s understand the SDH subtitles and CC.

What Are SDH Subtitles?

SDH is sometimes referred to as closed captions for the deaf or hard of hearing (CCDH). It is a type of subtitling specifically intended to meet the needs of those who are deaf or have different degrees of hearing loss. 

Besides, it is NOT just a reproduction of the spoken conversation. These subtitles offer extra information that aids viewers who are hard of hearing or deaf. These additional details may include: 

  • nonverbal cues, like [applause], [thunder]
  • speaker identification, like [Interviewer], [Narrator]
  • descriptions of music or sound effects, like [music playing], [door creaking]

SDH ensures that those with hearing impairments have a more engaging experience by including these cues. 

What are Closed Captions (CC)?

Closed captions are textual descriptions of audio content in videos that help viewers follow along with the conversation and other pertinent audio aspects. 

In contrast to SDH, CC focuses on verbatim transcription of the spoken dialogue, excluding any extraneous details regarding sound effects or speaker identification. 

CC appeals to various users. These audiences include those who do not have hearing problems but who would find subtitles helpful in specific scenarios, such as watching films in noisy places or picking up a new language. 

Key Difference – Closed Captions vs. SDH Subtitles

In this section, we will discuss the differences between CC and SDH in terms of their appearance, placement, accuracy, and encoding. But before diving into the details, here is a table giving a glimpse into the differences between the two subtitle techniques:




Suited For

Deaf and hard-of-hearing viewers General audience who want captions close to audio
Information Provided Dialogue, sound effects, music, speaker ID Dialogue

Character Limit

Up to 42 characters per line

Up to 32 characters per line


A multitude of font, size, and color choices



Centered and locked

Center bottom, right or left of the screen, and even the top of the screen


It varies. But it is generally white text on a black or semi-transparent background to resemble captions. 

White text on a black background.


Supported through HDMI

Not supported through HDMI

Timed text synched to video



Viewer can turn it on/off



Speaker identification Yes


Appearance – CC vs. SDH

Typically, closed captions appear as white text on a black background by default. White lettering on a black backdrop was first used in the CEA-608 standard for earlier analog television transmissions. They are still in use today since they work well with digital television.

Some user customization is possible with the more recent CTA-708 closed captioning standard for digital television broadcasts in the US and Canada. These choices, however, might change based on the specific TV model and additional hardware.

Conversely, SDH subtitles seem different and are more adaptable than closed captions. They provide a multitude of font, size, and color choices. They can be customized to resemble closed captions, to fit a platform’s requirements, or to satisfy audience preferences. 

However, these customization choices do not apply to every viewer in every circumstance, as they depend on a specific TV model, media player, streaming service, or other platform.

Placement – CC vs. SDH

Closed captions (apart from those prepared by CTA-708 standard) can appear anywhere on the screen. To match the speaker’s location in the frame, they can be in the center of the bottom of the screen or to the left or right. 

Besides, to avoid hiding important lower-third narrative titles or on-screen information, they can be positioned near the top of the screen. 

However, SDH subtitles are typically centered and locked at the bottom of the screen (just like subtitles) to facilitate easy reading and translation.

Accuracy – SDH vs. CC

The character-per-row restriction is another distinction between SDH subtitles and CC. Closed captions have a character limit of up to 32 characters per row. Whereas, SDH subtitles have a 42-character limit. 

As a result of this significant difference, SDH subtitle transcription is more accurate than closed caption transcription. It can contain information that closed caption transcription cannot cover due to character limits. 

Encoding – SDH vs. CC

Encoding SDH subtitles involves representing them as bitmap images or a collection of tiny dots or pixels. Contrarily, closed captions are stored as a stream of commands, control codes, and text. 

Simply put, ‘Teletext’ is usually the preferred method of supporting closed captions instead of digital connections like High-Definition Multimedia Interface (HDMI). 

Nonetheless, SDH subtitles have more practical applications due to their support for HDMI and streaming videos.

Why Do Some Streaming Platforms Offer Both SDH and CC?

There are several reasons why some streaming platforms offer both SDH and CC. Some of these are discussed below:

  • SDH and CC, with slightly different information, serve viewers with various needs. Platforms provide viewers the option to choose the format that best fits their needs by providing both.
  • Some platforms provide the customization of caption appearances, including font size, color, and positioning. Whether they select SDH or CC, viewers with visual impairments or reading challenges can benefit from this extra control.
  • Whereas CC might be more appropriate for live broadcasts or content with in-the-moment audio explanations, pre-recorded content often utilizes SDH. Having both guarantees that the platform can show captions that are accessible for different kinds of material.
  • While CC may be more widely compatible, older devices may not be able to accept more recent SDH formats. Providing both types of subtitles guarantees that viewers can access captions on various devices. 

Overall, streaming platforms offer both SDH and CC to provide viewers with wider choices, accessibility, and flexibility when viewing content.


Although both SDH subtitles and CC provide content accessibility to a larger audience, they are different types of subtitling services with different benefits. The choice will rely on the content, the target audience’s tastes, and the accessibility laws and standards in each nation.

This guide discussed the main differences between CC and SDH to help you understand and wisely choose the best approach for your media files.
Lime Green Media

Our multi-cultural teams do not simply “understand” customer needs; they are experts at fulfilling them. With our multi-channel solutions in place, we increase brand recognition and deliver key intelligence to our clients for core decision making.

Lime Green Media

Our multi-cultural teams do not simply “understand” customer needs; they are experts at fulfilling them. With our multi-channel solutions in place, we increase brand recognition and deliver key intelligence to our clients for core decision making.

© 2024 – All Rights Reserved Lime Green Media