One of the most frequently asked questions by our clients is about the difference between SRT and WebVTT subtitle formats. This question is understandable – they look similar, and most online players can accept both formats. However, any multimedia localization professional should have a practical understanding of their differences, especially in terms of capabilities and workflow.
This post highlights the differences between SRT and WebVTT subtitle formats.
What is the SRT subtitle format?
The SubRip text format – commonly known as SRT – was initially developed as part of a program for extracting subtitles and captions from media files. This SRT text format was notable for its simplicity and ease of use, particularly compared to other formats available at the time, many of which used XML-based code. In the following screenshot of a Spanish subtitle SRT file, you can see how simple this format is.
As you can imagine, this format was very appealing for post-production and online media video localization, and in 2008, YouTube adopted it. Vimeo and Netflix followed suit, and today, it is the standard format for many video streaming platforms.
What is the WebVTT subtitle format?
The Web Video Text Tracks format (WebVTT, also known as VTT) was initially created in 2010. The idea was to base the format on SRT – in fact, it was initially called WebSRT – but also make it more robust, especially by enabling HTML5 code features. The resulting subtitle and caption text files have a “.vtt” extension and resemble SRT format, as you can see in the following screenshot. (We will discuss the highlighted differences in yellow below).
WebVTT is also widely used, particularly for e-learning localization and multimedia applications, as it works particularly well with HTML5-based platforms.
So, what are the key differences for subtitling and captioning?
While many platforms and post-production suites accept both formats, SRT and WebVTT are different enough to not be truly compatible. In other words, if a program or platform exclusively expects one of them, it won’t work with the other. For this reason, it is essential to know the key differences.
Time annotation format: SRT separates seconds and milliseconds with a comma. VTT uses a dot instead (see the yellow time annotation above). Additionally, VTT files should not include hour timecode, although it is almost always provided.
Metadata: WebVTT files can have metadata, and in fact, some are required, notably having WEBVTT in the first line of the file. In the above VTT screenshot, the complete header is highlighted (it includes file type and language), as well as a metadata note within the file body. SRT does not support metadata.
Formatting options: WebVTT has very robust features, including font formatting, colors, text styles, and placement. Initially, SRT could not support any formatting, but it has been upgraded to support basic text formats (bold, italic, underline) and placement. However, it falls far short of the capabilities of VTT.
How do multimedia localization professionals choose a format?
There are two main factors to consider when choosing between the formats.
Video player: If your video player or your client’s player only supports one of them, the decision is made for you.
Feature set: VTT comes out as the winner here – it has many more features than SRT files, some of which are very useful for complex multimedia localization.
Simplicity: Of course, SRT is not as comprehensive as VTT, but that can be a virtue. For example, translators often prefer to translate directly in SRT because there are fewer code elements in the text or because almost any subtitle processing program can handle it. And don’t forget: despite its limitations, SRT can still support the necessary text formatting and placement for professional subtitle and caption production.
In summary, both formats excel in meeting the requirements of accessibility and video localization. A professional subtitling studio will be able to provide both options, and even convert VTT to SRT and vice versa. However, it’s important to remember that the workflows and actual code of each format are slightly different. For this reason, it’s crucial to know the format of your deliverable before starting your subtitling or captioning project. This is the best way to avoid rework and ensure you deliver on time and within budget.
What is the difference between SRT and VTT subtitles?
Here is how to convert an SRT (SubRip Subtitle) file to VTT (WebVTT) format using Subtitle Edit, and vice versa:
To convert SRT to VTT with Subtitle Edit:
1. Download and install Subtitle Edit: Go to the official Subtitle Edit website (https://www.nikse.dk/SubtitleEdit) and download the appropriate version for your operating system. Install the software on your computer.
2. Open Subtitle Edit: Launch the Subtitle Edit application on your computer.
3. Load the SRT file: To load the SRT subtitle file you want to convert, click on “File” in the menu bar and choose “Open.” Locate the SRT file on your computer and select it.
4. Adjust subtitle settings (optional): If necessary, you can modify the subtitle settings such as the font, color, and position by clicking on “Subtitle” in the menu bar and selecting “Options.” Adjust the settings according to your preferences.
5. Save the subtitle as VTT: To save the loaded SRT subtitle file as a VTT file, click on “File” in the menu bar and select “Save As.” In the “Save as type” dropdown, choose “WebVTT (*.vtt)” as the file format. Specify the desired location and file name for the VTT file, then click “Save.”
6. Confirm VTT conversion: A dialog box will appear asking if you want to convert the subtitle format. Click “Yes” to proceed with the conversion from SRT to VTT.
7. Conversion complete: Subtitle Edit will generate the VTT file based on the provided SRT file. Once the conversion is complete, you can find the converted VTT file at the specified location.
That’s it! You have successfully converted an SRT subtitle file to VTT format using Subtitle Edit. The generated VTT file can now be used for online video players or other applications that support the WebVTT format.
And here is the approach to convert an SRT file to VTT using Python:
input_file = “path/to/input.srt”
output_file = “path/to/output.vtt”
subs = pysubs2.load(input_file)
Make sure to replace “path/to/input.srt” with the actual path to your SRT file, and “path/to/output.vtt” with the desired path for the output VTT file.
Remember to install the `pysubs2` library using pip before running the script. Once executed, the script will convert the SRT file to VTT, and the converted VTT file will be available at the specified location. Additionally, the original SRT file will be removed.