What Is WebVTT ? What Is Structure Of WebVTT File ? .VTT How To Create WebVTT File ?

what is webvtt


We have discussed about Captions and Subtitles already in our other articles in brief. Where we explained about SRT files. Where SRT is SubRip Subtitle. It is having .SRT extension.

Where we explained how to create .SRT File and how to implement in video for subtitling of video. It is done by using FFmpeg Tool.

So today in this article we are going to discuss about what is WebVTT , how it works and how it can be helpful for subtitle or captions in video. Also how we can create this file and its formats etc.

What Is WebVTT ?

WebVTT stands for Web Video Text Track. It is Captioning / Subtitling file format. It is used to text overlays on the video. It was introduced in the 2010 year by WHATWG. WHATWG stands for Web Hypertext Application Technology Working Group.

It is a text format having spaces and tabs in it. This format of file is having the extension .vtt. It uses the UTF-8 Encoding.

WebVTT also facilitate you for insertion of metadata and description inside the frame. This description and metadata can not be viewed by users.

It is advanced version for subtitling and captioning in compared with .SRT..

What Are Captions In Brief ?

What Is Structure Of WebVTT File ?

As shown above in the screenshot we have taken a Headend INFO.vtt file to understand it.


There is first word “WebVTT” it is used because it indicate that it is a WebVtt file or it is the starting of WebVTT file.

Caption Number

There are some numbers indicated as 1,2,3 and 4. These numbers represents the caption numbers.

Timecode Duration

This timecode duration explain the starting time and ending time of caption texts mentioned below it.

This is explained in the format mentioned below,



Caption Text

This is text which you want to display in the video. It remains visible as per time duration mentioned above it.

On the other hand,

if you want to change the size and placement of these captions then you can use following codes as per format shown below,

01:03:45.300 –> 01:55:40.600 line:0 position:30% size:70% align:middle

Keep in mind one thing that there is limits of caption texts in this section. Maximum 32 characters are allowed only. You should use maximum 2 lines only.

Because if there is large number of characters on the screen then it irritate the users because it cover large area in video.


You can also include the comments in the frame. These comments will not be visible to users. You can add comments in two formats like,

NOTE This Is Comment For Testing.



This Is Comment For Testing.

So you can mention in single line or in double line.

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How To Create Your Own WebVTT File ?

(1) First Create a text file and give it name as you want.

(2) Then open the file and write down the codes in it as per format shown above.

(3) After writing down the codes as per format shown above in the screen shot. Now its time to check your code that it is working of not.

There is a online WebVTT checker Tool to check your coding. So copy the code and paste in this online tool.

WebVTT Code Checker

This tool will let you know if there is any mistake in your format. You just needs to copy paste your code in it.

(4) After checking the codes now save your file in .vtt extension.

Now your file is ready to upload in the captions system software.

One thing we would like to mention here is that if you are making this .vtt file manually by you then there are high number of chances of mistake.

Also it will take lot of time to make this file suppose there is a 10 minutes video then it will take around 1 hour to make it complete by you.

So we recommend you to hire a captioning service online. Which will save your effort and time too. Where you also need not to care for captioning laws because these captioning service take care for that.

In case , you want to convert your SRT file into WebVTT file then you can convert it by using this online SRT files into WebVTT file conversion tool.

Convert SRT into WebVTT File Tool


WebVTT is used for captioning or subtitling in the video in advanced mode. It can be called as improved version of .SRT format files. Because its format is similar to .SRT format file with some additional features.

These additional features are addition of metadata, description. You can also select the font, size and position of captions in the video.

Suggested Articles

What Are Captions ?

How To Add Subtitle In Video Using FFmpeg Tool ?

What Is FFmpeg Streaming How To Do It ?

reference : w3c

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