Subtitle formats: what are they and which ones to use?

Jean-Marc
July 23, 2024

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You want to subtitle your video and don't know in which format to transcribe it?

There are definitely many subtitle files out there.

We give you our list to guide you through all these possibilities.

1. SRT (SubRip Subtitle)

What is it?

SRT, or SubRip Subtitle, is a widely used subtitle format. It contains the basic elements you need: the sequence number, time codes, and the subtitle text. This format is simple, making it accessible even if you don't have technical expertise.

Compatibility and Support

SRT is known for its broad compatibility. Almost all media players and platforms support SRT files, including VLC, Windows Media Player, YouTube, Facebook, and Instagram​​.

How to Code

Creating an SRT file is straightforward. You can use any plain text editor, like Notepad or TextEdit. Follow these steps:

  1. Sequence Number: Start with the sequence number to indicate the order of the subtitles.
  2. Time Codes: Add the start and end times in the format hours:minutes:seconds,milliseconds (e.g., 00:00:10,500 --> 00:00:13,000). This tells the media player when to display the subtitle.
  3. Subtitle Text: Type the subtitle text on the next line.
  4. Blank Line: Leave a blank line before starting the next subtitle entry.

Here’s a basic example:

1
00:00:10,500 --> 00:00:13,000
Hello, welcome to our video!

2
00:00:15,000 --> 00:00:17,500
Let's dive into the topic.

Benefits and Limitations

SRT files are universally supported and easy to create and edit.

However, they do not support advanced features like text styling, positioning, or metadata. This means you can’t customize the appearance of your subtitles beyond basic text.

2. WebVTT (Web Video Text Tracks)

What is it?

WebVTT, or Web Video Text Tracks, is a subtitle format designed for web-based videos. It allows you to add text tracks to HTML5 videos, making it ideal for online content. WebVTT supports additional features like text styling and metadata, which can enhance the appearance and functionality of your subtitles​​.

Compatibility and Support

WebVTT is widely supported by online video platforms such as YouTube, Vimeo, Brightcove, and Kaltura. This makes it a preferred choice for web developers and video creators who need a more flexible and robust subtitle format. Unlike SRT, WebVTT is specifically designed to integrate seamlessly with HTML5 video players, offering better compatibility with modern web technologies​.

How to Code

Creating a WebVTT file involves a few more steps than creating an SRT file, but it’s still quite manageable.

Here’s how you can do it:

  1. File Header: Start with the line "WEBVTT" to indicate the file type.
  2. Time Codes and Text: Add the time codes in the format hours:minutes:seconds.milliseconds (e.g., 00:00:10.500 --> 00:00:13.000) followed by the subtitle text.
  3. Styling and Positioning: You can include styling options like bold, italics, and text color. Positioning cues allow you to place subtitles at different parts of the screen.

Here’s a basic example:

WEBVTT

1
00:00:10.500 --> 00:00:13.000
<b>Hello</b>, welcome to our video!

2
00:00:15.000 --> 00:00:17.500
<i>Let's dive into the topic.</i>

Benefits and Limitations

WebVTT offers several advantages over simpler formats like SRT. You can style the text with HTML-like tags to make it bold, italic, or colored. You can also position the text to avoid overlapping with important video elements. These features enhance the viewing experience, making your subtitles more readable and visually appealing.

However, the added complexity means that creating and editing WebVTT files can be more time-consuming compared to SRT. Also, while WebVTT is excellent for web-based videos, it is not as universally supported by offline media players as SRT.

3. TTML (Timed Text Markup Language)

What is it?

TTML, or Timed Text Markup Language, is a versatile subtitle format used in broadcasting and streaming. Developed by the W3C, TTML allows for detailed text formatting and precise timing, making it suitable for both live and pre-recorded content.

Compatibility and Support

TTML is widely supported in the broadcasting industry and by streaming services. It is the preferred format for television networks and VOD platforms due to its flexibility and detailed formatting options. TTML files can be easily integrated into video streams, providing broadcasters with a powerful tool for delivering high-quality subtitles​​. This format is also used in international standards such as SMPTE-TT and EBU-TT, ensuring broad compatibility across different systems​.

How to Code

Creating a TTML file is more complex than creating SRT or WebVTT files due to its extensive features. Here’s how to get started:

  1. File Header: Begin with the XML declaration and TTML namespace.
  2. Head Section: Define the metadata and styling, including font sizes, colors, and layout.
  3. Body Section: Add the timed text blocks with precise start and end times.

Here’s a simplified example:

<?xml version="1.0" encoding="UTF-8"?>
<tt xmlns="http://www.w3.org/ns/ttml">
 <head>
   <styling>
     <style xml:id="s1" tts:fontFamily="sansSerif" tts:fontSize="12px" tts:color="white"/>
   </styling>
 </head>
 <body>
   <div>
     <p begin="00:00:10.500" end="00:00:13.000" style="s1">Hello, welcome to our video!</p>
     <p begin="00:00:15.000" end="00:00:17.500" style="s1">Let's dive into the topic.</p>
   </div>
 </body>
</tt>

Benefits and Limitations

TTML offers extensive formatting options, including font styles, colors, text alignment, and precise timing controls. These features make it ideal for professional use, where high-quality, customizable subtitles are needed. You can also include metadata, such as language and region information, which is crucial for international broadcasting​​.

However, the complexity of TTML can be a drawback if you need a simple and quick solution. The detailed coding required for TTML files can be time-consuming and requires a good understanding of XML and subtitle formatting​​. Additionally, while TTML is powerful, it is not as widely supported by basic media players as SRT, which may limit its use in some applications​.

4. SSA (SubStation Alpha)

What is it?

SSA, or SubStation Alpha, is a subtitle format known for its advanced features and flexibility. It was originally developed for anime fansubs but has since gained popularity for various types of video content.

Compatibility and Support

SSA is supported by several advanced media players like VLC and subtitle editing software such as Aegisub. This format is favored in scenarios where detailed styling and positioning of subtitles are crucial, such as anime, karaoke videos, and other entertainment content that demands a high level of visual precision​.

However, SSA is not as universally supported as SRT or WebVTT, which might limit its use on some platforms and devices​.

How to Code

Creating an SSA file involves defining various styles and then applying these styles to the subtitles. Here’s a basic guide:

  1. File Header: Start with the [Script Info] section to define general information.
  2. Styles Section: Use [V4+ Styles] to define the visual appearance of the subtitles, such as font type, size, color, and position.
  3. Events Section: In [Events], define the actual subtitle text along with its timing and style.

Here’s a simplified example:

[Script Info]
Title: Example SSA File
ScriptType: v4.00+

[V4+ Styles]
Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, OutlineColour, BackColour, Bold, Italic, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, Encoding
Style: Default, Arial, 20, &H00FFFFFF, &H000000FF, &H00000000, &H00000000, -1, 0, 1, 1, 0, 2, 10, 10, 10, 1

[Events]
Format: Marked, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:10.50,0:00:13.00,Default,,0,0,0,,Hello, welcome to our video!
Dialogue: 0,0:00:15.00,0:00:17.50,Default,,0,0,0,,Let's dive into the topic.

Benefits and Limitations

SSA’s advanced features include customizable fonts, colors, and text positioning. You can even add effects like karaoke-style animations, making it ideal for projects where visual appeal is critical. This level of customization allows you to create subtitles that match the aesthetic and style of your video content precisely​.

However, SSA’s complexity can be a drawback if you need a quick and simple solution. The detailed coding required can be time-consuming and may require familiarity with the format and subtitle editing tools. Additionally, SSA is not as widely supported as simpler formats like SRT, limiting its use on some platforms and devices​.

5. STL (EBU Subtitle Data Exchange Format)

What is it?

STL, or EBU Subtitle Data Exchange format, is a subtitle format developed by the European Broadcasting Union (EBU). It is a standard format used widely in the broadcast industry, particularly in Europe. STL files contain not only the subtitle text but also extensive metadata, including information about the program, episode, and language​​.

Compatibility and Support

STL is primarily used in broadcast television and video on demand (VOD) services. It is a legacy format that has been adopted by many broadcasters due to its reliability and comprehensive metadata support. This format is particularly useful for maintaining subtitle quality and consistency in professional broadcast environments. However, it is not as commonly supported by basic media players and online video platforms, which might limit its use outside of broadcasting​.

How to Code

Creating an STL file involves more complexity compared to SRT or WebVTT. STL files are typically created using specialized software rather than plain text editors due to their binary format. Here’s a basic outline of the process:

  1. File Header: Contains metadata such as program title, language, and time code settings.
  2. Text Blocks: Each subtitle is defined with precise timing and text, along with formatting and positioning information.

An example of an STL file structure includes several metadata fields and binary-encoded text data. Here’s a conceptual overview:

Program Title: Example Program
Language: EN
Start Time: 00:00:10:00
End Time: 00:00:13:00
Subtitle Text: Hello, welcome to our video!
...

To create and edit STL files, you generally need professional subtitle editing software like EZTitles or Annotation Edit, which can handle the format's complexity​​.

Benefits and Limitations

STL’s main advantage is its robustness and detailed metadata support, making it ideal for professional broadcasting. The format allows for precise control over subtitle appearance and synchronization, which is crucial in a broadcast setting. It also supports multiple languages and character sets, catering to a global audience.

However, the complexity of STL files can be a significant drawback. Creating and editing these files requires specialized software and knowledge, making the process less accessible to casual users. Additionally, the binary nature of STL files means they are not easily readable or editable with simple text editors, unlike SRT or WebVTT​ ​.

6. EBU-TT (EBU Timed Text)

What is it?

EBU-TT, or EBU Timed Text, is a subtitle format developed by the European Broadcasting Union (EBU). It is an XML-based format that builds upon the legacy STL format, incorporating modern features and improved flexibility. EBU-TT was designed to meet the needs of both broadcast and online video environments, providing a comprehensive solution for high-quality subtitle delivery​.

Compatibility and Support

EBU-TT is widely used in the broadcast industry, particularly by major broadcasters such as the BBC. It is compatible with various broadcasting and streaming platforms, making it a versatile choice for delivering subtitles across multiple channels. The format is also suitable for archiving and repurposing subtitle content due to its rich metadata support. However, like STL, EBU-TT is not as commonly supported by basic media players, which might limit its use in some applications.

How to Code

Creating an EBU-TT file involves defining detailed metadata and styling within an XML structure. Here’s a basic outline of how to structure an EBU-TT file:

  1. File Header: Includes metadata such as program title, language, and authoring information.
  2. Body Section: Contains the timed text elements with precise start and end times, along with styling and positioning information.

Here’s a simplified example:

<?xml version="1.0" encoding="UTF-8"?>
<tt xmlns="http://www.w3.org/ns/ttml">
 <head>
   <metadata>
     <title>Example Program</title>
     <language>en</language>
     <author>Author Name</author>
   </metadata>
   <styling>
     <style xml:id="s1" tts:fontFamily="sansSerif" tts:fontSize="12px" tts:color="white"/>
   </styling>
 </head>
 <body>
   <div>
     <p begin="00:00:10.500" end="00:00:13.000" style="s1">Hello, welcome to our video!</p>
     <p begin="00:00:15.000" end="00:00:17.500" style="s1">Let's dive into the topic.</p>
   </div>
 </body>
</tt>

Benefits and Limitations

EBU-TT offers several advantages, including detailed metadata support, flexible styling, and precise timing control. It is designed to handle the complex needs of professional broadcasting, making it ideal for high-quality subtitle production. EBU-TT also supports multiple languages and character sets, ensuring that it can be used in diverse international contexts​.

However, the complexity of EBU-TT can be a significant drawback. Creating and editing these files requires familiarity with XML and specialized software, which may not be accessible to all users. Additionally, while EBU-TT is highly versatile, its adoption outside of professional broadcasting environments is limited, potentially restricting its use for more casual applications​.

7. VTT (VobSub)

What is it?

VobSub is a subtitle format used primarily for DVDs. Unlike text-based formats such as SRT or WebVTT, VobSub files are binary and contain graphical representations of the subtitles. This means that VobSub subtitles are images rather than text, allowing for complex visual styling and positioning that is fixed and independent of the playback device’s capabilities​​.

Compatibility and Support

VobSub is supported by most DVD players and some advanced media players like VLC. This format is ideal for situations where you need to maintain the exact visual appearance of the subtitles across all devices.

How to Code

Creating a VobSub file involves generating two files: an .idx file and a .sub file. The .idx file contains the index and timing information, while the .sub file contains the subtitle images. Here’s a simplified outline of the process:

  1. Rip Subtitles from DVD: Use a tool like SubRip or VSRip to extract subtitles from a DVD. This process will generate the .idx and .sub files.
  2. Edit the .idx File: The .idx file is a text file that can be opened with a text editor. It contains information about the timing and positioning of the subtitle images.

Here’s a conceptual overview of an .idx file:

# VobSub index file, v7 (do not modify this line!)
size: 720x480
palette: 000000, ff0000, 00ff00, 0000ff, ffff00, 00ffff, ff00ff, ffffff
timestamp: 00:00:10:500, filepos: 000000000
timestamp: 00:00:13:000, filepos: 000002000

Benefits and Limitations

VobSub's main advantage is its ability to maintain the exact visual appearance of subtitles, regardless of the playback device. This makes it ideal for DVDs and situations where precise styling and positioning are critical. However, the binary nature of VobSub files makes them less flexible than text-based formats. Editing VobSub subtitles requires specialized tools, and translating subtitles can be cumbersome because the images need to be regenerated for each language​.

8. SBV (SubViewer)

What is it?

SBV, or SubViewer, is a subtitle format commonly used for YouTube annotations. It is a simple text format that includes time codes and the subtitle text. SBV is easy to create and edit, making it a popular choice for online content creators who need a straightforward way to add subtitles to their videos​.

Compatibility and Support

SBV files are primarily used by YouTube, which makes them highly compatible with this platform. If you upload videos to YouTube and want to add subtitles, SBV is one of the best formats to use. However, SBV is not as widely supported by other platforms or media players. This limited compatibility means that while SBV is excellent for YouTube, it might not be the best choice if you need subtitles for multiple platforms​.

How to Code

Creating an SBV file is straightforward. You can use any plain text editor like Notepad or TextEdit. Follow these steps:

  1. Time Codes and Text: Begin with the start and end times in the format minutes:seconds.milliseconds (e.g., 0:00:10.500,0:00:13.000). This is followed by the subtitle text.
  2. New Line for Each Subtitle: Each subtitle entry should be on a new line.

Here’s a basic example:

0:00:10.500,0:00:13.000
Hello, welcome to our video!

0:00:15.000,0:00:17.500
Let's dive into the topic.

Benefits and Limitations

SBV’s main advantage is its simplicity. It’s easy to create and edit, which is perfect if you need to add subtitles quickly. The format’s compatibility with YouTube makes it an ideal choice for content creators focusing on this platform. However, SBV does not support advanced styling or positioning options. It’s a basic format that provides only the essential features needed for subtitling.

Another limitation is the format’s restricted use outside of YouTube. If you need subtitles that work across various platforms and media players, you might need to convert SBV files to more widely supported formats like SRT or WebVTT​​.

9. SCC (Scenarist Closed Caption)

What is it?

SCC, or Scenarist Closed Caption, is a subtitle format used primarily for closed captioning in broadcast television. Developed by Sonic Solutions for the Scenarist software, SCC files contain both text and positioning information. This format is widely used in North America for compliance with FCC regulations regarding closed captioning​.

Compatibility and Support

SCC is supported by many professional video editing and broadcasting software, including Adobe Premiere Pro and Avid Media Composer. It is the standard format for closed captions in North American television broadcasts and is required for compliance with legal standards. SCC files are also used for online video platforms that need to meet accessibility requirements. However, SCC is less commonly supported by basic media players and some international platforms, limiting its use outside of professional and regulatory contexts​​.

How to Code

Creating an SCC file is more complex than simpler text-based formats like SRT. SCC files encode captions in a hexadecimal format, which requires specialized software to generate accurately. Here’s a conceptual overview of the process:

  1. Hexadecimal Encoding: SCC files encode each character in hexadecimal, along with positioning and styling commands.
  2. Time Codes: Each caption includes time codes to indicate when it should appear and disappear.

Here’s a simplified example:

Scenarist_SCC V1.0

00:00:10:15 94ae 94ae 9420 9420 9470 9470 97a1 97a1 97a2 97a2 97a3 97a3 94f2 94f2 9452 9452
00:00:13:00 94ae 94ae 9420 9420 9470 9470 97a1 97a1 97a2 97a2 97a3 97a3 94f2 94f2 9452 9452

This snippet shows the hexadecimal encoding for caption text and positioning. To create SCC files, you typically need professional software that can handle this encoding, such as MacCaption or CaptionMaker​​.

Benefits and Limitations

The primary benefit of SCC files is their compliance with regulatory standards for closed captioning. They provide precise control over the appearance and timing of captions, which is crucial for broadcast television. SCC files also support multiple languages and character sets, making them versatile for diverse audiences.

However, the complexity of SCC files can be a significant drawback. Creating and editing these files requires specialized software and knowledge of hexadecimal encoding, which can be a barrier for casual users. Additionally, the limited support for SCC files outside of professional environments means they are not as versatile as simpler formats like SRT or WebVTT​​.

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