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Audio format

OPUS converter

An .opus file contains audio compressed with the Opus codec, stored in an Ogg container. Opus represents the current state of the art in lossy audio, beating MP3, AAC, and Vorbis in listening tests at nearly every bitrate from whisper-thin speech settings up to transparent music encoding.

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Convert supported files

Runs on your device

Drop OPUS files here

Batch files can each use a different output. Nothing uploads for local conversions.

Working inputs include camera RAW, browser-local audio/video, PDF, CBZ/CBR comics, office documents, ebooks, markup, 3D models, structured text, images, and archives.

Where OPUS comes from

The IETF standardized Opus as RFC 6716 in 2012, merging Skype's SILK speech codec with Xiph.Org's CELT music codec into one seamless hybrid. WebRTC made it mandatory, and services from WhatsApp voice notes to YouTube streaming adopted it within a few years.

How OPUS works

  • The hybrid SILK/CELT design switches coding modes automatically based on content
  • Bitrates span 6 to 510 kbps, with music approaching transparency around 128 to 160 kbps
  • Frame sizes reach down to 2.5 milliseconds, giving latency low enough for live conversation
  • Packet-loss concealment was a first-class design goal for the VoIP use case
  • Everything decodes to 48 kHz internally, and the licensing is royalty-free with published patent grants

When to use OPUS

  • Compressing podcast and voice-chat audio to tiny files
  • Encoding music at 128-160 kbps that rivals much higher-rate MP3
  • Serving as the audio track in WebM video for the web
  • Archiving long speech recordings at minimal cost

Strengths and limitations

Strengths

  • Best-in-class efficiency at essentially every bitrate
  • Royalty-free with an open reference implementation
  • Handles speech and music in a single codec without tuning
  • Latency low enough for real-time communication

Limitations

  • Older car stereos, AV receivers, and MP3 players have never heard of it
  • Apple's Music app will not import .opus files, though playback through other iOS apps works

Compatibility

Chrome, Firefox, and Edge have played Opus for a decade and Android supports it natively, while Safari initially accepted the codec only inside CAF or WebM wrappers before extending support to .opus files. Legacy hardware such as older car head units remains the real gap, and conversion to MP3 or AAC bridges it.

Vorbis comments in the OpusTags header, including cover art via METADATA_BLOCK_PICTURE, plus an output-gain field used for loudness normalization.

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