Mediastreamer2 is a powerful and lightweight streaming engine specialized
in voice/video telephony applications.

It is the library that is responsible for all the receiving and sending of
multimedia streams in linphone, including voice/video capture, encoding and
decoding, and rendering.

Features:

* Capture and playback from various platform dependent sound architectures
* Send and receive RTP streams
* Encode and decode the following audio formats: speex, G711, GSM, iLBC,
  AMR, AMR-WB, G722, SILK, G729, and video formats H263, theora, MPEG4,
  H264 and VP8
* Read and write .wav files
* Read YUV pictures from a camera based on platform dependents APIs
* Optimized rendering of YUV pictures
* Dual tones generation
* Custom tone detector
* Echo cancelation, based on speex library or webrtc AEC on android
* Audio conferencing
* Audio parametric equalizer
* Volume control, automatic gain control
* ICE for optimized NAT traversal
* Adaptive bitrate control algorithm: for automatic adaption of encoder
  bitrate based on received RTCP feedback

WWW: http://www.linphone.org/eng/documentation/dev/mediastreamer2.html