No Results Found!
244 Related Articles

CELT

Opus combines the speech-oriented linear predictive coding SILK algorithm and the lower-latency, MDCT-based CELT algorithm, switching between or combining them as needed for maximal efficiency.
Development of the format was maintained by the Xiph.Org Foundation (as part of the Ogg codec family) and later coordinated by the Opus working group of the Internet Engineering Task Force (IETF).

Audio coding format

audio coding standardaudio compression formatAudio coding
Opus is a lossy audio coding format developed by the Xiph.Org Foundation and standardized by the Internet Engineering Task Force, designed to efficiently code speech and general audio in a single format, while remaining low-latency enough for real-time interactive communication and low-complexity enough for low-end embedded processors.
Examples of audio coding formats include MP3, AAC, Vorbis, FLAC, and Opus.

Speex

SPX.spxlibspeex
Opus replaces both Vorbis and Speex for new applications, and several blind listening tests have ranked it higher-quality than any other standard audio format at any given bitrate until transparency is reached, including MP3, AAC, and HE-AAC.
Xiph.Org now considers Speex obsolete; its successor is the more modern Opus codec, which surpasses its performance in all areas.

SILK

Skype SILKSteel Industrials Kerala Limited
Opus combines the speech-oriented linear predictive coding SILK algorithm and the lower-latency, MDCT-based CELT algorithm, switching between or combining them as needed for maximal efficiency.
It has been extended to the Internet standard Opus codec.

Vorbis

Ogg VorbisOGGaoTuV
Opus replaces both Vorbis and Speex for new applications, and several blind listening tests have ranked it higher-quality than any other standard audio format at any given bitrate until transparency is reached, including MP3, AAC, and HE-AAC. Opus has been shown to have excellent quality, and at higher bit rates, it turns out to be competitive with audio formats with much higher delay, such as HE-AAC and Vorbis.
2011, April comparison by Hydrogenaudio - Vorbis vs HE-AAC vs Opus at 64 kbit/s. Vorbis was on average between the LC-AAC low anchor and Nero HE-AAC, while the upcoming Opus (by Xiph) was best.

Variable bitrate

VBRvariable bit ratevariable
Opus supports constant and variable bitrate encoding from 6 kbit/s to 510 kbit/s, frame sizes from 2.5 ms to 60 ms, and five sampling rates from 8 kHz (with 4 kHz bandwidth) to 48 kHz (with 20 kHz bandwidth, the human hearing range).
MP3, WMA and AAC audio files can optionally be encoded in VBR, while Opus, Vorbis are always in VBR.

Ogg

.oggOGMogg123
Opus was originally specified for encapsulation in Ogg containers, specified as, and for Ogg Opus files the filename extension is recommended.
The audio layer is most commonly provided by the music-oriented Vorbis format or its successor Opus.

Xiph.Org Foundation

Xiph.orgXiphThe Xiph.Org Foundation
Opus is a lossy audio coding format developed by the Xiph.Org Foundation and standardized by the Internet Engineering Task Force, designed to efficiently code speech and general audio in a single format, while remaining low-latency enough for real-time interactive communication and low-complexity enough for low-end embedded processors.
Opus – a low delay lossy audio compression format originally intended for VoIP

WebM

.webm155-165 kbps Opus WebM
Opus streams are also supported in Matroska, WebM, MPEG-TS, and MP4. Although Internet Explorer will not provide Opus playback natively, support for the format is built into the Edge browser, along with VP9, for full WebM support.
In 2013, it was updated to accommodate VP9 video and Opus audio.

High-Efficiency Advanced Audio Coding

eAAC+eAACHE-AAC
Opus replaces both Vorbis and Speex for new applications, and several blind listening tests have ranked it higher-quality than any other standard audio format at any given bitrate until transparency is reached, including MP3, AAC, and HE-AAC. Opus has been shown to have excellent quality, and at higher bit rates, it turns out to be competitive with audio formats with much higher delay, such as HE-AAC and Vorbis.
A 2011 Public Listening Test compared the two best-rated HE AAC encoders at that time to Opus and Ogg Vorbis, indicated statistically significant superiority at 64 kbit/s for Opus over all other contenders, and second ranked Apple HE AAC statistically superior to both Ogg Vorbis and Nero HE AAC which were tied for third place.

MP3

.mp3MP3 downloadmp3s
Opus replaces both Vorbis and Speex for new applications, and several blind listening tests have ranked it higher-quality than any other standard audio format at any given bitrate until transparency is reached, including MP3, AAC, and HE-AAC.
There are also open compression formats like Opus and Vorbis that are available free of charge and without any known patent restrictions.

Networked music performance

network musicnetwork performance practicesSoundWire, CCRMA
Opus has the low algorithmic delay (26.5 ms by default) necessary for use as part of a real-time communication link, permitting natural conversation, networked music performances, and live lip sync; by trading-off quality or bitrate, the delay can be reduced down to 5 ms. Its delay is exceptionally low compared to competing codecs, which require well over 100 ms, yet Opus performs very competitively with these formats in terms of quality per bitrate.
CELT and Opus codecs designed for these applications

Advanced Audio Coding

AACAAC/AAC+/eAAC+.aac
Opus replaces both Vorbis and Speex for new applications, and several blind listening tests have ranked it higher-quality than any other standard audio format at any given bitrate until transparency is reached, including MP3, AAC, and HE-AAC.
Opus – an open, royalty-free codec for both pre-encoded and interactive use, standardized in 2012

Digital container format

container formatcontainercontainer formats
Opus packets are not self-delimiting, but are designed to be used inside a container of some sort which supplies the decoder with each packet's length.
Ogg (standard container for Xiph.org audio formats Vorbis and Opus and video format Theora)

Internet Speech Audio Codec

iSAC
The SILK part has been under development at Skype since January 2007 as the successor of their SVOPC, an internal project to make the company independent from third-party codecs like iSAC and iLBC and respective license payments.
Opus (audio codec)

AIMP

AIMP3
Such support was added to AIMP, Amarok, cmus, Music Player Daemon, foobar2000, Mpxplay, MusicBee, SMplayer, VLC media player, Winamp and Xmplay audio players; Icecast, Airtime (software) audio streaming software; and Asunder audio CD ripper, CDBurnerXP CD burner, FFmpeg, Libav and MediaCoder media encoding tools.
AIMP can play many file types, including MP3, Advanced Audio Coding (AAC), Dolby AC-3, Ogg Vorbis, Opus, Speex, Windows Media Audio, Apple Lossless, FLAC, WAV and Audio CDs.

VP9

Although Internet Explorer will not provide Opus playback natively, support for the format is built into the Edge browser, along with VP9, for full WebM support.
The combination of VP9 video and Opus audio in the WebM container, as served by YouTube, is supported by roughly 4⁄5 of the browser market (mobile included) as of June 2018.

Amarok (software)

AmarokAmarok 2Amarok Media Player
Such support was added to AIMP, Amarok, cmus, Music Player Daemon, foobar2000, Mpxplay, MusicBee, SMplayer, VLC media player, Winamp and Xmplay audio players; Icecast, Airtime (software) audio streaming software; and Asunder audio CD ripper, CDBurnerXP CD burner, FFmpeg, Libav and MediaCoder media encoding tools.
Playing media files in various formats including but not limited to (depending on the setup) FLAC, Ogg, Opus, MP3, AAC, WAV, Windows Media Audio, Apple Lossless, WavPack, TTA and Musepack. Amarok does not play digital music files embedded with DRM.

Music Player Daemon

MPDCantataMPC
Such support was added to AIMP, Amarok, cmus, Music Player Daemon, foobar2000, Mpxplay, MusicBee, SMplayer, VLC media player, Winamp and Xmplay audio players; Icecast, Airtime (software) audio streaming software; and Asunder audio CD ripper, CDBurnerXP CD burner, FFmpeg, Libav and MediaCoder media encoding tools.
Plays Ogg Vorbis, FLAC, Opus, WavPack, MP2, MP3, MP4/AAC, MOD, Musepack, wave files and any other files supported by FFmpeg.

MusicBee

Such support was added to AIMP, Amarok, cmus, Music Player Daemon, foobar2000, Mpxplay, MusicBee, SMplayer, VLC media player, Winamp and Xmplay audio players; Icecast, Airtime (software) audio streaming software; and Asunder audio CD ripper, CDBurnerXP CD burner, FFmpeg, Libav and MediaCoder media encoding tools.
Audio playback: MP3, AAC, M4A, MPC, OGG, FLAC, APE, Opus, TAK (audio format), WavPack, WMA, WAV, MIDI, MOD, UMX, XM.

FFmpeg

SnowlibavformatNUT
The FFmpeg project and GStreamer project have encoder and decoder implementation not derived from the reference library.

MediaCoder

Such support was added to AIMP, Amarok, cmus, Music Player Daemon, foobar2000, Mpxplay, MusicBee, SMplayer, VLC media player, Winamp and Xmplay audio players; Icecast, Airtime (software) audio streaming software; and Asunder audio CD ripper, CDBurnerXP CD burner, FFmpeg, Libav and MediaCoder media encoding tools.
Many formats are supported, including MP3, Vorbis, Opus, Advanced Audio Coding (AAC), Windows Media Audio (WMA), RealAudio, WAV, H.264/MPEG-4 AVC, MPEG-4 Part 2, MPEG-2, Audio Video Interleave (AVI), Video CD and DVD-Video.

Bit rate

bitratedata ratedata transfer rate
Opus has been shown to have excellent quality, and at higher bit rates, it turns out to be competitive with audio formats with much higher delay, such as HE-AAC and Vorbis.
6 kbit/s minimum bitrate available through the open-source Opus codec

Icecast

IceStechnical component of Icecast software
Such support was added to AIMP, Amarok, cmus, Music Player Daemon, foobar2000, Mpxplay, MusicBee, SMplayer, VLC media player, Winamp and Xmplay audio players; Icecast, Airtime (software) audio streaming software; and Asunder audio CD ripper, CDBurnerXP CD burner, FFmpeg, Libav and MediaCoder media encoding tools.
The Icecast server is capable of streaming audio content as Opus or Vorbis over standard HTTP, video as WebM or Theora over HTTP, MP3 over the communications protocol used by SHOUTcast, AAC, and NSV over the SHOUTcast protocol (Theora, AAC, and NSV are only supported in version 2.2.0 and newer).

WebRTC

peer-to-peer routingsecurity flawWeb RTC
Due to the addition of WebRTC support in Apple's WebKit rendering engine, macOS High Sierra and iOS 11 come with native playback support for Opus audio encapsulated in Core Audio Format containers.
RFC 7874 requires implementations to provide PCMA/PCMU, Telephone Event as DTMF, and Opus audio codecs as minimum capabilities.