# Sample Opus audio files for testing, free, CC0 and hotlinkable 2 Opus test files from 122.5 KB to 431.6 KB. Direct URLs, a SHA-256 for each and CC0, so curl and CI can fetch them with no signup and no keys. The page: . This is a sample Opus file: stereo Opus audio in an Ogg container, free to hotlink or download. | Path | Size | MIME | Properties | |---|---|---|---| | [`opus/30s.opus`](https://loremfile.dev/opus/30s.opus) | 431.6 KB (431,592 bytes) | `audio/opus` | 30.006 s, opus, 48 kHz, 2 channels | Opus is the royalty-free audio codec the IETF standardised in RFC 6716, and the one browsers, WebRTC and voice applications settled on. A `.opus` file is Opus inside an Ogg container, as RFC 7845 specifies. `opus/30s.opus` is a sine tone, and the same kind of tone appears across the other audio formats here, so one pipeline can be compared across codecs. One gotcha is built into the format: Opus decoders produce 48 kHz output, and tools report 48 kHz whatever rate the source had. The original rate survives only as an informational header field. Code that expects the source rate back, or that assumes 44.1 kHz, gets this file wrong in a way a quick listen will not reveal. `opus/cbr-32k-30s.opus` is encoded at a constant 32 kbps. Opus varies its rate by default, and on a pure tone it overshoots: `opus/30s.opus` averages 114 kbps. A fixed rate is the case for code that limits, budgets or transcodes by bitrate. Use them to test browser playback, transcoders, waveform renderers, audio upload forms and handling of the `audio/opus` media type. They also check that code reads the codec from the stream: an Ogg file can carry Opus, Vorbis or FLAC. Related formats: [Ogg Vorbis](https://loremfile.dev/ogg), [MP3](https://loremfile.dev/mp3) and [M4A](https://loremfile.dev/m4a). ## Files | Path | Size | MIME | Properties | |---|---|---|---| | [`opus/30s.opus`](https://loremfile.dev/opus/30s.opus) | 431.6 KB (431,592 bytes) | `audio/opus` | 30.006 s, opus, 48 kHz, 2 channels | | [`opus/cbr-32k-30s.opus`](https://loremfile.dev/opus/cbr-32k-30s.opus) | 122.5 KB (122,539 bytes) | `audio/opus` | 30.006 s, opus, 48 kHz, 2 channels | The same list as JSON: .