Convert OPUS to captions

Sonix transcribes your OPUS file and creates closed captions that make your content accessible to everyone.

Free to start — no credit card required.See pricing

ADA compliant
5-min turnaround
Accessible
OPUS conversion guide

Create captions from OPUS in 6 steps

  1. 1
    Create account~30 sec

    Sign up for a free Sonix trial with 30 free minutes.

  2. 2
    Upload file~1 min

    Upload your OPUS file from your computer or cloud storage.

    44+ formats supported
  3. 3
    Select language~10 sec

    Select the language spoken in your file.

    54+ languages
  4. 4
    Auto-transcribe~5 min

    Sonix AI transcribes your OPUS with word-level timestamps.

  5. 5
    Edit captions~2 min

    Fine-tune timing and formatting for accessibility.

  6. 6
    Export~10 sec

    Download your closed captions as SRT or VTT files.

    30+ export formats
The OPUS file format

Understanding OPUS files

What is a OPUS file?

Modern audio codec optimized for voice and streaming

The OPUS file is an audio file format that was created for use in Voice over IP (VoIP), video conferencing, or in-game chat. Since the OPUS codec is primarily used in Internet streaming applications, it isn't common. However, is it a lossy audio format that uses both SILK (used by Skype) and CELT (from Xiph.Org) codecs and supports variable bit rates from 6 kb/s to 510 kb/s.

Common uses for OPUS files

  • VoIP calls (Discord, Teams)
  • Video conferencing audio
  • In-game voice chat
  • Low-latency streaming
  • Discord recordings
  • WebRTC applications
  • Voice chat exports

Who works with OPUS files?

Messaging apps such as WhatsApp and Telegram save voice notes as Opus files, so journalists, researchers, and customer-support teams frequently receive them from sources and clients. The codec is also the standard for Discord recordings, WebRTC video-conferencing audio, and in-game voice chat, so exported voice-chat sessions and VoIP recordings often arrive as Opus files too.

OPUS vs MP3: which should you use?

Opus is a newer codec that delivers better audio quality than MP3 at low bitrates, particularly for speech, and its low-latency design is why it dominates real-time voice applications. MP3 remains playable on virtually every device and media player, while Opus support is strongest in modern browsers, messaging apps, and recent media software. Choose Opus for voice recordings and bandwidth-efficient streaming; choose MP3 when maximum device compatibility matters.

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53+
Languages
Captions in any language
30+
Export formats
SRT, VTT, and TTML
OPUS conversion FAQ

OPUS captions: frequently asked questions

Can you create closed captions from OPUS files?

Yes! Sonix transcribes your OPUS file with precise timestamps and creates closed captions in standard formats.

What's the difference between subtitles and closed captions?

Closed captions include non-speech elements like [music], [applause], and speaker identification. They're designed for deaf and hard-of-hearing viewers.

Are Sonix captions ADA compliant?

Yes! Sonix captions meet accessibility requirements when properly reviewed and edited. Our editor helps ensure timing and accuracy standards.

What caption formats are supported?

Export captions as SRT, VTT, or TTML. Each format has specific use cases.

Can I add sound descriptions?

Yes! Use our editor to add [music], [laughter], and other non-speech descriptions for full accessibility.

Do captions help with SEO?

Absolutely! Captions make your video content searchable and improve accessibility, both of which can boost SEO rankings.

Why won't my OPUS file play on my computer?

Older media players and some built-in OS players lack Opus support. Opening the file in VLC or a modern web browser, or converting it to MP3 or WAV, usually resolves the issue.

Are WhatsApp voice messages OPUS files?

Yes, WhatsApp exports voice notes as .opus files. You can upload them for transcription directly without converting them first.

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