Convert WEBM to captions

Create accessible closed captions from your WebM videos. Meet web accessibility requirements with professional captions for HTML5 video content.

ADA compliant
5-min turnaround
Accessible
Audio
Video
DOCX
SRT/VTT
PDF
53+ Languages
About This Format

Understanding WEBM files

What is a WEBM file?

Open web video format for HTML5 and streaming

WEBM is an open, high-quality video standard that is usually used for delivering online videos using the HTML tag. WEBM is a container file format: the video stream is usually compressed with the VP8 codec and the audio stream is compressed with the Ogg Vorbis codec. The WEBM container format itself is based off of the popular Matroska container (MKV files). Since WEBM is an alternative to the patented H.264 and MPEG4 formats and widely supported by most major web browsers, it is used in both commercial and non-commercial applications.
The WEBM file format was created by Google to store video content and implement compression standards optimized for video streaming over broadband and mobile internet connections. Thus, royalty-free video compression technologies were used (VP8/VP9 and Ogg Vorbis). In addition, WebVTT subtitle tracks can we included within a WEBM file. WEBM files are also widely supported by Chrome, Safari, Firefox, and Internet Explorer.

Common Uses

  • YouTube videos
  • HTML5 web video
  • Web streaming
  • Browser-based video

Audio Quality

High-quality open format backed by Google

Transcription Tips for WEBM

  • Very common web format - excellent support
  • VP8/VP9 video with Vorbis/Opus audio
  • Optimized for streaming clarity

Where WEBM Files Come From

  • YouTube downloads
  • Web video platforms
  • Screen recording software
  • OBS Studio exports
10x
Faster than real-time
Get your WEBM captions in minutes
99%
Accuracy rate
Industry-leading AI for WEBM files
53+
Languages
Captions in any language
30+
Export formats
SRT, VTT, SCC, and more
How It Works

Create captions from WEBM in 6 steps

Step 1

Create account

Sign up for Sonix's free trial. Includes 30 minutes free.

Step 2

Upload file

Upload your WEBM file from your computer or cloud storage.

Step 3

Select language

Choose from 53+ languages spoken in your file.

Step 4

Auto-transcribe

Sonix AI transcribes your WEBM with word-level timestamps.

Step 5

Edit captions

Fine-tune timing and formatting for accessibility.

Step 6

Export

Download closed captions in SRT, VTT, or SCC format.

Common Questions

Everything about WEBM captions

What's the difference between captions and subtitles for WebM?

Captions include speaker identification and sound descriptions (music, applause, typing sounds) for deaf and hard-of-hearing viewers. Subtitles assume the viewer can hear and focus on translating dialogue.

Are WebM-to-caption conversions ADA compliant?

Sonix generates captions meeting ADA, Section 508, and WCAG requirements when you include speaker labels and review for accuracy. Essential for accessible web content.

Can I add sound descriptions to WebM captions?

Yes! After transcription, add non-speech descriptions like [music playing], [keyboard typing], or [door closes] in Sonix's editor for fully accessible captions.

How do I create accessible captions for HTML5 WebM video?

Export captions from Sonix as VTT, add to your HTML5 video with kind='captions', and include sound descriptions. This meets accessibility standards for web video.

What caption format works for WebM on video platforms?

SRT is universally accepted by YouTube, Vimeo, and other platforms. Upload the SRT file through the platform's caption or accessibility settings.

How accurate are AI-generated captions from WebM?

Sonix achieves 99%+ accuracy on clear WebM audio. Opus audio, optimized for voice, produces excellent results. Quick human review ensures professional caption quality.

Why Sonix

Accessible captions from WEBM files

Accessibility First

Create captions that make your content accessible to deaf and hard-of-hearing viewers.

ADA Compliant

Meet accessibility requirements with properly formatted closed captions.

Sound Descriptions

Add non-speech elements like [music] and [applause] for full context.

SEO Benefits

Captions make video content searchable and improve discoverability.

Related

More ways to convert WEBM files

Other WEBM conversions

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Add Subtitles to WEBM

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Other file formats

OGX to text
MPEG to text
OGV to text
MK3D to text
3GP to text
MPE to text
MP4 to text
WMV to text
VOB to text
QT to text
See all supported file formats
Reviews

Trusted by accessibility teams

4.98 rating from 211 reviews

Very cool and fascinating too. Ahh the power of algorithms. I can tell you that I love the overall UI experience because it's pretty, dumbed down, and very easy for me to use. I've done a lot of radio and this service would be invaluable for that kind of work.
AF
Angela F.
San Francisco, CA USA
Sonix can quickly generate a transcript and it has cut my workload by half.
MB
Marina B.
San Francisco, CA USA
Sonix is just so smooth and simple. Love it. No bugs, very intuitive. Oh and your software is surprisingly accurate!
DS
Dominick S.
Mannheim, Germany
Super easy interface, easy to upload and great results.
DK
Dan K.
Seattle, OR, USA
I tried Sonix, and it’s amazing! Seriously, I think that you will revolutionize journalism.
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Caroline B.
Denver, CO USA
I was simply awed by speed and accuracy of your transcription service.
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Myung K.
Queens, NY, USA
One of the best sites/services on the Internet I've ever tried.
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Matteo L.
Brescia, Italy
Sonix is the best transcription program I have worked with.
VQ
Vitalyia Q.
Tomsk, Russia
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