Subtitles are a common aspect in videos when they are published for a wider range of audience. Often used in films, YouTube videos, anime, and other long-format videos, this is done to gather the attention of audiences from different regions or countries. Although the display of subtitles is standard and can look the same for all, there are several formats in which subtitles are created and updated. Some of the common formats and how to differentiate between them are discussed in this article.
What is a subtitle file format?
A subtitle file format is a plain text or binary file that stores text dialogue, start and end timecodes, and optional styling rules to display synchronized captions alongside a video. There are also subtitle files that are created separately from the video. These types of files allow users to upload, edit, or even replace the subtitles without making major changes to the videos.
SRT (SubRip) – most widely supported
One of the most commonly used and discussed types of subtitles is SRT or SubRip Subtitles. They are generally used to create, edit, or upload subtitles for online videos. This type of format works with numerical entries, where the editor has to add the start and end timestamps. After adding timestamps, the text within this duration automatically appears on the screen, making it easier to edit or replace.
These SRT files can be edited using a plain-text editor, which results in easy corrections. Although this format has limited styling and positioning options, it is still common because of its easy editing style.
WebVTT (VTT) – web and HTML5 native
If your requirement for subtitles includes web videos that can work with HTML5 video players, then try working with the WebVTT format. This feature can help your brand with captions, chapters, and timed text, along with various styling and positioning options. To identify a WebVTT file, you can look for a file that starts with WEBVTT. Although not every platform supports this format, players like Vimeo accept and even recommend it.
WebVTT can be the perfect choice for your next big project if the requirements are for websites or online video players. To decide between the two most common formats, see this SRT vs VTT guide.
TTML / DFXP – broadcast and OTT standard
If you are using subtitles for your videos for the first time and don’t know where to start, look for the TTML format. TTML stands for Timed Text Markup Language and is an XML-based format. This is generally used for video workflows, broadcast, and OTT streaming platforms. Since high-quality OTT dubbing and subtitling depends on files that match each platform’s specification, confirm the required TTML profile before production starts.
Another format that is associated with TTML is DFXP, which is an abbreviation for Distribution Format Exchange Profile. The different uses of these extensions generally depend on the workflows. A TTML file can record the timing, styling, and even position information in the desired structure. A TTML file is generally more complex to create or validate. This makes it not the first choice of any creators, but it is a reliable source once a subtitle editor can get the basics controlled.
SCC (Scenarist) – TV broadcast US standard
If your videos are specifically broadcast in the US and are associated with CEA-608 closed-caption data, then you can use the SCC format. SCC, abbreviated as Scenarist Closed Caption. This format safeguards information of the caption for workflows, depending on the conventions. You can also use SCC on YouTube under specific caption delivery needs. If caption workflows are new to you, start with what closed captioning is and how it differs from subtitles.
SCC is not the most common or first choice of many subtitle editors. This is because it requires a specialized format and can be used only when the broadcaster or the platform demands it.
ASS/SSA – advanced styling for anime/karaoke
Another type of subtitle format is ASS and SSA. ASS stands for Advanced SubStation Alpha, while SSA is an abbreviation for SubStation Alpha. This type of format is used when the workflow requires detailed subtitle design. This is also not as conventionally popular as SRT and other formats, and is used when the platforms or broadcasters explicitly demand its usage for subtitles.
This format can support fonts, colours, outlines, positioning, and even visual effects. This is generally used when working on anime, karaoke, and videos that are created for specific purposes or audiences.
STL – European broadcast standard
If your video is created for the European broadcast standard and subtitle exchange workflows, then look for STL. STL is known to store subtitle text and timing information, which is relevant when working with older broadcast systems and archived material.
If you are working with STL for the first time, it is crucial to know that this format is used for specialized formats, and not for general options for online videos. They are not easy to edit or can be used as a manual plain-text file. This format can be used only when the broadcaster or platforms specifically demands for it.
Platform compatibility chart (YouTube, Netflix, Vimeo, etc.)
Subtitle requirements vary between platforms and can change depending on the content and delivery workflow. The following guide provides a general starting point.
- Websites: WebVTT is suitable for websites using compatible HTML5 video players.
- YouTube: SRT is a straightforward choice for many uploads. YouTube also supports formats such as WebVTT, TTML/DFXP, SCC, and STL.
- Broadcast television: SCC, EBU-STL, or another specified format may be required, depending on the broadcaster and caption standards.
- Vimeo: SRT and WebVTT are supported. WebVTT is recommended for this platform.
- Netflix: Professional delivery workflows may require TTML or other specified formats. Follow the latest technical requirements provided for the project.
How to choose the right subtitle format
To understand which is the right format of subtitle for your videos, first identify the publishing platform. The platform requirements make the overall decision easier. If you have a common online video with no complexity and no requirements from the broadcasters, then you can easily opt for SRT. Easy to use, edit, and upload, SRT is one of the best options available when working with subtitles.
If you are working with websites that have HTML5 video players, then look for WebVTT, but if the requirement is for professional streaming workflows, then go for TTML. SCC and STL are generally used by subtitle editors when they are bound to specific broadcast needs. If you need advanced styling to be included in subtitles, then using ASS or SSA would be appropriate. When a project needs several of these formats at once, professional subtitling services can prepare and check each file against the platform’s specification.
How to convert between subtitle formats
In subtitling, changing the format of the file is a common practice. This is done so that an already edited file can work on different platforms or players. However, to convert a file, you must follow these steps one by one closely. If not, the risk of losing the edited content is high. Following subtitling best practices for timing and formatting checks reduces this risk after every conversion.
- Open the original file in a subtitle editor or a reliable conversion tool.
- Select the format required by the destination platform.
- Review the text, timestamps, punctuation, and line breaks.
- Check whether styling and positioning have been preserved.
- Save the converted file and verify its format and encoding.
- Play the subtitles with the video or test them on the target platform.
Conclusion
When you are trying to make your content accessible for a larger audience, choosing the correct format is very important. This is done not only to make the process easier, but also to ensure that the video can be played on the desired platform without any hassle. The advantages of including subtitles and closed captions in video only show up when the file actually plays correctly for every viewer.
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FAQs
The most common subtitle format is SRT, which can be edited and is supported by many video platforms and media players.
If you are looking for a format that can work with websites and is compatible with HTML5 video players, you can opt for WebVTT as your desired subtitle format.
When working with a video that is LMS and is supported by its video players, the two available options are SRT and WebVTT. However, checking the client’s requirements and platform guidelines before working on the project is still necessary.
ASS, an abbreviation for Advanced SubStation Alpha, is best suited for a video that requires styling, positioning, and visual effects. This is most commonly used for anime-style videos.
No, subtitles and captions are not the same file format.
If you are planning to upload your video on YouTube and want to keep the format simple and easy to use, you can try working with SRT. Although YouTube allows other formats as well, the complexity of the format or the stringent guidelines can be difficult to follow.
