Opus
A royalty-free, highly versatile codec that handles both speech and music elegantly.
Pro Audio Converter can convert audio files to and from Opus (.opus).
Opus is a codec, not a container: .opus files store Opus-compressed audio inside an Ogg transport layer.
Opus is a totally open, royalty-free, highly versatile audio codec. Opus is unmatched for interactive speech and music transmission over the Internet, but is also intended for storage and streaming applications. It is standardized by the Internet Engineering Task Force (IETF) as RFC 6716, which incorporated technology from Skype's SILK codec and Xiph.Org's CELT codec.
Encoding Options
Bitrate Mode — Sets the bitrate mode. In VBR mode the bitrate may go up and down freely depending on the content to achieve more consistent quality. VBR Constrained is analogous to CBR in AAC/MP3 encoders and managed mode in Vorbis coders. It delivers less consistent quality than VBR mode but a consistent bitrate. With CBR, every frame is exactly the same size — similar to how speech codecs work. CBR delivers lower overall quality but is useful where bitrate changes might leak data in encrypted channels or on synchronous transports.
Bitrate — Sets the target bitrate in kbit/sec (6–256 per channel). In VBR mode this specifies the average rate for a large and diverse collection of audio. In VBR Constrained and CBR modes it specifies the specific output bitrate.
Complexity — Encoding computational complexity (0–10, default 10). Zero gives the fastest encodes but lower quality, while 10 gives the highest quality but slower encoding.
Frame Size — Maximum frame size in milliseconds (2.5, 5, 10, 20, 40, 60 — default 20). Smaller frame sizes achieve lower latency but less quality at a given bitrate. Sizes greater than 20 ms are only interesting at fairly low bitrates.
Channels — The number of audio channels in the output file. Auto attempts to match the input file's channel count. You can also force Stereo (2 channels) or Mono (1 channel).