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ion boosting for improved transients and dc rejection below 3 hz two new vbr modes were added unconstrained for more consistent quality and temporal vbr that boosts louder frames and generally improves quality libopus 1 1 1 was released on november 26 2015 and 1 1 2 on january 12 2016 both adding speed optimizations and bug fixes july 15 2016 saw the release of version 1 1 3 and includes bug fixes optimizations documentation updates and experimental ambisonics work 1 2 edit libopus 1 2 beta was released on may 24 2017 libopus 1 2 was released on june 20 2017 37 improvements brought in 1 2 allow it to create fullband music at bitrates as low as 32 kbit s and wideband speech at just 12 kbit s 38 libopus 1 2 includes optional support for the decoder specification changes made in drafts of rfc 8251 improving the quality of output from such low rate streams 39 1 3 edit libopus 1 3 was released on october 18 2018 40 the opus 1 3 major release again brings quality improvements new features and bug fixes 41 changes since 1 2 x include improvements to voice activity detection vad and speech music classification using a recurrent neural network rnn support for ambisonics coding using channel mapping families 2 and 3 improvements to stereo speech coding at low bitrate using wideband speech encoding down to 9 kbit s mediumband is no longer used making it possible to use silk down to bitrates around 5 kbit s minor quality improvement on tones enabling the spec fixes in rfc 8251 by default security hardening improvements notable bug fixes include fixes to the celt plc bandwidth detection fixes 1 3 1 edit libopus 1 3 1 was released on april 12 2019 42 this opus 1 3 1 minor release fixes an issue with the analysis on files with digital silence all zeros especially on x87 builds mostly affects 32 bit builds it also includes two new features a new opus_get_in_dtx query to know if the encoder is in dtx mode last frame was either a comfort noise frame or not encoded at all a new and still experimental cmake based build system that is eventually meant to replace the vs2015 build system the autotools build system will stay 1 4 edit libopus 1 4 was released on april 20 2023 43 opus 1 4 brings the following improvements and fixes improved tuning of the opus in band fec called lbrr low bitrate redundancy 44 which previously was causing a significant drop in audio quality under certain circumstances 45 added a opus_set_inband_fec 2 option that turns on fec but does not force silk mode fec will be disabled in celt mode improved tuning and various fixes to dtx added meson support improved cmake support 1 5 edit libopus 1 5 was released on march 4 2024 46 it added the following backward compatible improvements improved packet loss concealment using a deep neural network improved redundancy to prevent packet loss using a rate distortion optimized variational autoencoder improved concealment of coding artifacts by adjusting post filter coefficients using a deep neural network support for additional simd cpu instructions avx2 on x86 64 and neon on aarch64 1 6 edit libopus 1 6 was released on december 15 2025 25 it added the following backward compatible improvements a new wideband to fullband bandwidth extension bwe module experimental and optional support for 96 khz audio with opus hd significant improvement to deep redundancy dred a new 24 bit encoder decoder api current development edit the codec is under active development 47 the current focus is on adding a deep learning based redundancy encoder that enhances packet loss concealment by embedding one second of recovery data in each encoded packet the deep redundancy dred algorithm was developed by among others jean marc valin ahmed mustafa jan büthe timothy terriberry chris montgomery michael klingbeil and paris smaragdis from amazon web services 48 with sponsorship to open source the algorithm and subsequently extend the ietf standard from sid rao 49 this encoder is a backwards compatible change to the codec enabling customers to easily upgrade applications to take advantage of this machine learning capability a draft rfc is underway to standardize the new capability 50 this rfc is one of the first attempts to standardize a deep learning algorithm in the ietf quality comparison and low latency performance edit comparison of coding efficiency between opus and other popular audio formats opus performs relatively well at both low and high bitrates 7 comparison between mp3 and opus the first is an uncompressed wav file the second is an mp3 file encoded at 16 kbit s using lame and the third is an opus file encoded at 16 kbit s problems playing this file see media help in listening tests around 64 kbit s opus shows superior quality compared to he aac codecs which were previously dominant due to their use of the patented spectral band replication sbr technology 51 15 in listening tests around 96 kbit s opus shows slightly superior quality compared to aac and significantly better quality compared to vorbis and mp3 16 52 opus has very low algorithmic delay 4 a necessity for use as part of a low audio latency communication link which can permit natural conversation networked music performances or lip sync at live events total algorithmic delay for an audio format is the sum of delays that must be incurred in the encoder and the decoder of a live audio stream regardless of processing speed and transmission speed such as buffering audio samples into blocks or frames allowing for window overlap and possibly allowing for noise shaping look ahead in a decoder and any other forms of look ahead or for an mp3 encoder the use of bit reservoir 53 total one way latency below 150 ms is the preferred target of most voip systems 54 to enable natural conversation with turn taking little affected by delay musicians typically feel in time with up to around 30 ms audio latency 55 roughly in accord with the fusion time of the haas effect though matching playback delay of each user s own instrument to the round trip latency can also help 56 it is suggested for lip sync that around 45 100 ms audio latency may be acceptable 57 opus permits trading off reduced quality or increased bitrate to achieve an even smaller algorithmic delay 5 0 ms minimum 58 while the reference implementation s default opus frame is 20 0 ms long the silk layer requires a further 5 0 ms lookahead plus 1 5 ms for resampling giving a default delay of 26 5 ms when the celt layer is active it requires 2 5 ms lookahead for window overlap to which a matching delay of 4 0 ms is added by default to synchronize with the silk layer if the encoder is instantiated in the special restricted low delay mode the 4 0 ms matching delay is removed and the silk layer is disabled permitting the minimal algorithmic delay of 5 0 ms 6 2 support edit the format and algorithms are openly documented and the reference implementation is published as free software xiph s reference implementation is called libopus and a package called opus tools provides command line encoder and decoder utilities it is published under the terms of a bsd like license it is written in c and can be compiled for hardware architectures with or without a floating point unit the accompanying diagnostic tool opusinfo reports detailed technical information about opus files including information on the standard compliance of the bitstream format it is based on ogginfo from the vorbis tools and therefore unlike the encoder and decoder is available under the terms of version 2 of the gpl implementations edit rfc 6716 contains a complete source code for an older version of the reference implementation written in c rfc 8251 contains errata libopus is the more up to date but non normative branch of the reference implementation the ffmpeg project 59 has encoder and decoder implementations not derived from the reference library the documentation describes it as celt only and poorer quality than the reference 60 the libopus reference library has been ported to c java and go as part of a project called concentus these ports sacrifice performance for the sake of being easily integrated into cross platform applications 61 software and content providers edit see also comparison of voip software digital radio mondiale a digital radio format for am frequencies can broadcast and receive opus audio albeit not recognised in official standard using dream software defined radio the wikimedia foundation sponsored a free and open source online javascript opus encoder for browsers supporting the required html5 features 62 a list of radio stations that stream using opus audio codec can be found on the xiph org foundation icecast directory 63 in late 2014 and 2015 google s video platform youtube started offering opus audio along with vp9 video in the webm file format through dash streaming 64 in july 2024 youtube rolled out an additional high quality audio format option 256 kbit s opus to youtube music premium subscribers 65 since 2016 whatsapp has been using opus as its audio file format 66 signal switched from speex to opus audio codec for better audio quality in the beginning of 2017 in 2018 soundcloud switched from mp3 to opus reducing half of its required bandwidth for music streaming 67 in january 2021 vimeo introduced opus to its video platform 68 in 2021 the danish journalism website zetland switched from mp3 to opus for its articles audio recordings which attained a 35 percent reduction in bandwidth and reduced climate footprint 69 70 operating system support edit most end user software relies on multimedia frameworks provided by the operating system native opus codec support is implemented in most major multimedia frameworks for unix like operating systems including gstreamer ffmpeg and libav libraries 71 72 73 the webm container webm is mostly used on online video platforms e g youtube and is usually treated as a video file by operating systems media players even if a webm file contains only opus audio and no video some music players do not recognize webm files as audio files and do not support reading of file metadata 74 the ogg container opus is preferred for audio only files and most media players have support for audio file metadata tagged in the vorbis comment format google added native support for opus audio playback in android 5 0 lollipop 75 however it was limited to opus audio encapsulated in matroska and webm containers such as mkv mka and webm files 76 77 android 7 0 nougat introduced support for opus audio encapsulated in ogg containers 78 android 10 finally added native support for opus extensions 79 due to the addition of webrtc support in apple s webkit rendering engine macos high sierra and ios 11 were released with native playback support for opus audio encapsulated in core audio format containers 80 macos sonoma added support for mono and stereo opus audio encapsulated in mpeg 4 and webm containers in safari 81 82 safari 18 4 added support for opus and vorbis codecs with ogg containers when using macos sequoia 15 4 or ios 18 4 and later 83 84 on windows 10 version 1607 microsoft provided native support for opus audio encapsulated in matroska and webm containers 85 on version 1709 support for opus audio encapsulated in ogg containers was made available through a pre installed add on called web media extensions 86 on windows 10 version 1903 native support for the opus extension was added 79 on windows 8 1 and older third party decoders such as lav filters are available to provide support for the format 87 a january 2024 update for windows 10 11 caused file explorer to freeze up when renaming or deleting ogg files including oga ogg ogm ogv ogx opus due to bugs involving the mf media source pack property handler shell extension by microsoft and the web media extensions package in windows which were not patched before the windows updates were rolled out 88 ios 17 includes support for natively encoding and decoding the opus codec through the operating system s audiotoolbox framework playback of ogg files in the opus container is supported through the files application opus is additionally supported within the core audio format caf container the quicktime mov container and the isobmff or mp4 file format mp4 container note 3 as the audiotoolbox framework is shared with macos similar support should be present in both operating systems as they further develop 90 in 2024 apple podcasts does not support opus 91 opus support by different operating systems windows macos linux android ios codec support yes partial win 10 v1607 1709 1809 full win 10 v1903 yes partial macos high sierra 10 13 full macos sonoma 14 0 yes yes partial android 5 6 7 full android 10 yes partial ios 11 full ios 17 container support on windows 10 anniversary update 1607 webm webm is not recognised requires pseudo extension matroska mka mkv on windows 10 fall creators update 1709 with web media extensions add on ogg opus is not recognised requires pseudo extension note 4 on windows 10 october 2018 update 1809 webm webm is recognised officially on windows 10 may 2019 update 1903 ogg opus oga ogg opus is recognised officially on macos high sierra core audio format caf on macos monterey webm webm experimental support 93 94 on macos sonoma mono and stereo mpeg 4 and webm webm 81 82 on macos sequoia ogg container support in safari 18 4 and later 83 84 ogg opus webm webm matroska mka mkv mpeg ts ts on android 5 webm webm matroska mka mkv on android 7 ogg oga ogg opus is not recognised requires pseudo extension note 4 on android 10 ogg opus oga ogg opus is recognised officially mp4 mp4 together with av1 video on ios 17 and later supports playback through files supports ogg as opus supported in mp4 standalone note 3 or in combination with any officially supported video codec standalone and expanded but unofficially supported combinations in mov standalone support in caf on ios 18 4 and later ogg container support in safari 18 4 and later 83 84 notes on windows 10 windows 11 as of june 2023 windows media player 2022 does not support opus audio tracks that accompany videos in mp4 containers 95 on windows 10 on anniversary update 1607 limited support is available in microsoft edge via mse only and universal windows platform apps windows media player does not support ogg only webm and matroska on april 2018 update 1803 with web media extensions preinstalled microsoft edge edgehtml 17 supports opus audio embedded in audio tags up till october 2018 update 1809 the filename extension opus was not recognised substitute with a pseudo file extension such as m4a 92 on windows 8 1 and older requires installation of a third party multimedia framework lav filters in safari 15 apple added support for opus audio in webm containers experimental support is only present in macos 96 n a up till android 10 the filename extension opus was not recognised substitute with a pseudo file extension such as ogg or m4a 78 when originally introduced in ios 11 only constant bitra...