Speex

SPX.spxlibspeexSpeex audio codec
Speex is an audio compression format specifically tuned for the reproduction of human speech and also a free software speech codec that may be used on VoIP applications and podcasts.wikipedia
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Opus (audio format)

OpusOpus audio format.opus
Xiph.Org now considers Speex obsolete; its successor is the more modern Opus codec, which surpasses its performance in all areas.
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.

Ogg

.oggOGMogg123
It may be used with the Ogg container format or directly transmitted over UDP/RTP.
It has since been adopted in the specifications of Ogg encapsulations for other Xiph.Org codecs including Theora, Speex and FLAC.

Speech coding

speech codecspeech encodingspeech
Speex is an audio compression format specifically tuned for the reproduction of human speech and also a free software speech codec that may be used on VoIP applications and podcasts.
G.722, G.722.1, Speex, IP-MR and others for VoIP and videoconferencing

Code-excited linear prediction

CELPcode excited linear predictionCode-excited linear prediction (CELP)
It is based on the CELP speech coding algorithm.
This codebook can be algebraic (ACELP) or be stored explicitly (e.g. Speex).

Podcast

podcastspodcastingpodcaster
Speex is an audio compression format specifically tuned for the reproduction of human speech and also a free software speech codec that may be used on VoIP applications and podcasts.
In contrast, a podcast distributed in both the Vorbis and Speex codecs would meet the strict definition of an oggcast.

Bit rate

bitratedata ratedata transfer rate
One of the main reasons is that CELP has long proven that it could do the job and scale well to both low bit rates (as evidenced by DoD CELP @ 4.8 kbit/s) and high bit rates (as with G.728 @ 16 kbit/s).
2.15 kbit/s minimum bitrate available through the open-source Speex codec

Lossy compression

lossylossy data compressioncompressed
Speex is a lossy format, i.e. quality is permanently degraded to reduce file size.
Speex (noted for its lack of patent restrictions)

Rockbox

Rockbox Project.rockRockbox kernel
The Rockbox project uses Speex for its voice interface.
Speex

Ekiga

Most of these are based on the DirectShow filter or OpenACM codec (e.g. Microsoft NetMeeting) on Microsoft Windows, or Xiph.org's reference implementation, libvorbis, on Linux (e.g. Ekiga).
Audio codec algorithms: iLBC, GSM 06.10, MS-GSM, G.711 A-law, G.711 µ-law, G.726, G.721, Speex, G.722, CELT (also G.723.1, G.728, G.729, GSM 06.10, GSM-AMR, G.722.2 [GSM‑AMR-WB] using Intel IPP)

Flash Video

FLVFlash.flv
It may also be used with the FLV container format.
(Flash Player 10 released in 2008 also supports the open source Speex codec.

Mumble (software)

MumbleMumble room
Streaming applications like teleconference (e.g. TeamSpeak, Mumble)
Mumble uses the low-latency audio codec Opus as of version 1.2.4, the codec that succeeds the previous defaults Speex and CELT.

Voice activity detection

VADdetecting a voice signalvoice-detection
Voice activity detection (VAD, integrated with VBR) (not working from version 1.2).
The Speex audio compression library uses a procedure named Improved Minima Controlled Recursive Averaging, which uses a smoothed representation of spectral power and then looks at the minima of a smoothed periodogram. From version 1.2 it was replaced by a kludge in words of the author.

Xiph.Org Foundation

Xiph.orgXiphThe Xiph.Org Foundation
These include Speex, an audio codec designed for speech, and FLAC, a lossless audio codec.

Asao (codec)

Nellymoser AsaoNellymoserAsao
Speex can be decoded or converted to any format unlike Nellymoser audio, which was the only speech format in previous versions of Flash Player.
(Flash Player 10 released in 2008 also supports the open source Speex codec.

Adobe Flash Player

FlashFlash PlayerAdobe Flash
Adobe Flash Player supports Speex starting with Flash Player 10.0.12.36, released in October 2008.
Speex audio codec

Audio coding format

audio coding standardaudio compression formatAudio coding
Speex is an audio compression format specifically tuned for the reproduction of human speech and also a free software speech codec that may be used on VoIP applications and podcasts.

Free software

freefree-softwarefreely
Speex is an audio compression format specifically tuned for the reproduction of human speech and also a free software speech codec that may be used on VoIP applications and podcasts.

Voice over IP

VoIPvoice over Internet Protocolvoice-over-IP
Speex is an audio compression format specifically tuned for the reproduction of human speech and also a free software speech codec that may be used on VoIP applications and podcasts.

Software patent

software patentspatentpatents
Speex claims to be free of any patent restrictions and is licensed under the revised (3-clause) BSD license.

Digital container format

container formatcontainercontainer formats
It may be used with the Ogg container format or directly transmitted over UDP/RTP.

User Datagram Protocol

UDPUDP/IPUDP protocol
It may be used with the Ogg container format or directly transmitted over UDP/RTP.

Real-time Transport Protocol

RTPReal-Time ProtocolRTP / RTCP
It may be used with the Ogg container format or directly transmitted over UDP/RTP.

Vorbis

Ogg VorbisOGGaoTuV
The Speex designers see their project as complementary to the Vorbis general-purpose audio compression project.

GNU Lesser General Public License

LGPLGNU LGPLLGPLv3
The first development versions of Speex were released under LGPL license, but as of version 1.0 beta 1, Speex is released under Xiph's version of the (revised) BSD license.