OPUS vs RMVB
A detailed comparison of Opus Audio and RealMedia VBR — file size, quality, compatibility, and which format to choose for your workflow.
Opus Audio
Audio FilesOpus is a versatile, open-source audio codec optimized for both speech and music at very low bitrates. It is the standard for WebRTC voice calls and excels at real-time communication.
About OPUS filesRealMedia VBR
Video FilesRMVB (RealMedia Variable Bitrate) is a variable bitrate extension of the RealMedia container. It was popular for distributing video content in Asian markets due to its efficient compression at low bitrates.
About RMVB filesStrengths Comparison
OPUS Strengths
- Best-in-class quality across the entire bitrate range.
- Royalty-free and patent-free.
- Ultra-low latency — suitable for live voice and music.
- Handles speech and music equally well — no need to switch codecs.
- Mandatory codec in WebRTC, so supported in every browser by design.
RMVB Strengths
- Better quality-at-bitrate than fixed RealMedia.
- Still playable in modern open-source players (VLC, mpv).
- Cultural archive value for 2000s Asian internet video.
Limitations
OPUS Limitations
- Very low hardware decoder adoption — software-only on most phones.
- Older platforms (legacy Windows apps, old cars) may not play .opus files.
- Container semantics confusing — Opus lives inside Ogg, WebM, or MP4.
- Encoder tooling is less polished than AAC's commercial ecosystem.
RMVB Limitations
- Tied to the dead RealNetworks ecosystem.
- H.264 is objectively better at equal bitrates.
- No modern encoder — content is archival only.
- Obscure format outside Asian regional archives.
Technical Specifications
| Specification | OPUS | RMVB |
|---|---|---|
| MIME type | audio/opus | application/vnd.rn-realmedia-vbr |
| Extensions | .opus, .ogg (container) | — |
| Standard | RFC 6716 (2012) | — |
| Sample rates | 8, 12, 16, 24, 48 kHz | — |
| Latency | 5-60 ms (configurable) | — |
| Extension | — | .rmvb |
| Codecs | — | RealVideo 9/10 (variable bitrate) |
| Audio | — | RealAudio Cook |
| Successor ecosystem | — | H.264 MP4 / MKV |
Typical File Sizes
OPUS
- Voice call (24 kbps) 180 KB/min
- Podcast (48 kbps) 21 MB/hour
- Music (128 kbps) ~1 MB/min
- High-fidelity music (160 kbps) ~1.2 MB/min
RMVB
- 45-min TV episode 150-350 MB
- 2-hour movie 300-800 MB
Ready to convert?
Convert between OPUS and RMVB online, free, and without installing anything. Encrypted upload, automatic deletion after 60 minutes.
Frequently Asked Questions
OPUS (Opus Audio) is an audio file format used to store sound recordings — music, voice, podcasts, sound effects. The format defines how the audio samples are compressed (or stored raw), what bitrates are supported, and how metadata such as title, artist, album, and cover art is embedded. It is part of the audio files family.
OPUS (Opus Audio) is an audio formatoo de arquivo used to store sound recordings — music, voice, podcasts, sound effects. The formato defines how the audio samples are comprimido (or stored raw), what bitrates are suportado, e how metadata como title, artist, album, e cover art is embedded. It is part of the audio arquivos family.
VLC, foobar2000, and the default media players on Windows and macOS handle OPUS natively. On mobile, iOS Music and Android media apps vary in their support — popular formats work everywhere; niche ones may need a dedicated app. If playback fails on a device, converting to MP3 or AAC usually solves it.
VLC, foobar2000, e the default media players no Windows e macOS handle OPUS natively. On mobile, iOS Music e Android media apps vary in their support — popular formatoos funcionar everywhere; niche ones may need a dedicated app. If playback fails em um device, convertendo to MP3 ou AAC Geralmente solves it.
Upload the OPUS to KaijuConverter and pick MP3, WAV, FLAC, AAC, OGG, or any other target. Our FFmpeg pipeline decodes the audio and re-encodes to the target format at sensible default bitrates (VBR ~190 kbps for music, 96 kbps for speech). Metadata and cover art travel with the audio where both formats support them.
OPUS can be lossy or lossless depending on the specific variant. Lossy variants (smaller files) discard some audio detail during compression in ways tuned to be inaudible; lossless variants preserve every sample exactly but produce larger files. For distribution, lossy at high bitrate is standard; for archival, lossless wins.