Speex is based on CELP and is designed to compress voice at bitrates ranging from 2 to 44 kbps. Some of Speex features include:
- Narrowband (8 kHz), wideband (16 kHz), and ultra-wideband (32 kHz) compression in the same bitstream
- Intensity stereo encoding
- Packet loss concealment
- Variable bitrate operation (VBR)
- Voice Activity Detection (VAD)
- Discontinuous Transmission (DTX)
- In-progress fixed-point port.
Changes in Speex 1.2 beta 3
- The most obvious change in this release is that all the non-codec components (preprocessor, echo cancellation, jitter buffer) have been moved to a new libspeexdsp library. Other changes include a new jitter buffer algorithm and resampler improvements/fixes. This is also the first release where libspeex can be built without any floating point support. To do this, the float compatibility API must be disabled (--disable-float-api or DISABLE_FLOAT_API) and the VBR feature must be disabled (--disable-vbr or DISABLE_VBR).
Changes in Speex 1.0.5
- The main change with this release is that it includes API additions from the 1.1.x branch (while being backward compatible), so that transition from 1.0.x to 1.1.x can be made easier.
Moreover, Speex is well-adapted to Internet applications and provides useful features that are not present in most other codecs.