Mediastreamer

Project : mediastreamer2 - a modular sound and video processing and streaming
Email : simon.morlat@linphone.org
License : GPLv2(or later) or Commercial licensing
Home Page : http://www.mediastreamer2.com

Commercial support and licensing is provided by Belledonne Communications http://www.belledonne-communications.com

Mediastreamer2 is a library to make audio and video real-time streaming and processing. Written in pure C, it is based upon the ortp library.

Design

Using mediastreamer2 will allow you to chain filters in a graph. Each filter will be responsible for doing some kind of processing and will deliver data to the next filter. As an example, you could get some data from network and unpack it in an RTP filter. This RTP filter will deliver the data to a decoder (speex, G711...) which will deliver it to a filter that is able to play the PCM data or record it into a .wav file.

There is a doxygen documentation for more information.

Compilation and installation

Required dependencies:

bctoolbox[1]: portability layer
oRTP[2]: RTP stack
libspeexdsp: echo cancelation feature (disablable)
ffmpeg or libav: H263 codec, MPEG4 decodec and RAW picture rescaling (disablable)

Optional dependencies

libsrtp for SRTP encryption
bzrtp[3] for ZRTP encryption
libgsm: GSM codecs support
libbv16: BV16 codec support
libopus for Opus encoding and decoding
libspeex: SPEEX codec support
libalsa: ALSA support (GNU/Linux only)
libpulse: PulseAudio support (GNU/Linux only)
libv4l2: video capture (GNU/Linux only;disablable)
libx11 and libxv: video display with X11 (GNU/Linux only)
libglx: video dispaly with GLX (GNU/Linux only)
libvpx for VP8 encoding and decoding
libmastroska-c for recording/playing of audio/video streams
libturbojpeg: video screenshot feature

Build instructions:

The Autotools way is deprecated. Use CMake to configure the source code.

cmake . -DCMAKE_INSTALL_PREFIX=<prefix> -DCMAKE_PREFIX_PATH=<search_path>

make
make install

Supported opitions:

CMAKE_INSTALL_PREFIX=<string> : install prefix
CMAKE_PREFIX_PATH=<string> : column-separated list of prefixes where to search for dependencies
ENABLE_SHARED=NO : do not build the shared library
ENABLE_STATIC=NO : do not build the static library
ENABLE_STRICT=NO : build without strict compilation flags (-Wall -Werror)
ENABLE_UNIT_TESTS=YES : build tester binaries
ENABLE_DOC=NO : do not generate the documentation
ENABLE_DEBUG_LOGS=YES : turn on debug-level logs

Note for packagers:

Our CMake scripts may automatically add some paths into research paths of generated binaries. To ensure that the installed binaries are striped of any rpath, use -DCMAKE_SKIP_INSTALL_RPATH=ON while you invoke cmake.

Rpm packaging mediastremer2 rpm can be generated with cmake3 using the following command: mkdir WORK cd WORK cmake3 ../ make package_source rpmbuild -ta --clean --rmsource --rmspec mediastreamer--.tar.gz

Environment variables used by mediastreamer2

MS2_RTP_FIXED_DELAY : default value is 0. When set to 1, RTP packets belonging from one tick execution are actually sent at the beginning of the next tick. This allows a zero jitter in the RTP timing at sender side. This is to be used for measurements, this mode has no interest for doing a real conversation and does not improve quality.

MS_AUDIO_PRIO, MS_VIDEO_PRIO : define the scheduling policy of the audio and video threads (MSTicker objects). Possible values are 'NORMAL', 'HIGH', 'REALTIME'. The corresponding behavior is as follows:

+-------------------+------------------------+------------------------+-------------------------+
| Priority type     |     GNU/Linux          |        MacOS           |         Windows         |
+-------------------+------------------------+------------------------+-------------------------+
| NORMAL            | SCHED_OTHER, def. prio | SCHED_OTHER, def. prio | Default priority.       |
| HIGH              | SCHED_RR, max prio     | SCHED_RR, max prio     | THREAD_PRIORITY_HIGHEST |
| REALTIME          | SCHED_FIFO, max prio   | SCHED_FIFO, max prio   | THREAD_PRIORITY_HIGHEST |
+-------------------+------------------------+------------------------+-------------------------+

Note that SCHED_FIFO leaves entire control of the cpu to the mediastreamer2 thread. In case of CPU overload due to heavy encoder processing for example, a mono-core machine will stop responding.

MS_TICKER_SCHEDPRIO : UNIX only. It is an integer defining the thread priority to be used by MSTicker. Values are OS specific and depend on the scheduling policy SCHED_FIFO, SCHED_RR or SCHED_OTHER.
MS2_OPUS_COMPLEXITY : opus codec complexity parameter. A value of -1 stands for mediastreamer2's own default value. Otherwise it must be between 0 and 10.
MEDIASTREAMER_DEBUG : when set to 1, verbose logging is activated by default.
DISPLAY : used by video display filters relying on X11 (GNU/Linux only).

Contact information

Use the linphone mailing list for question about mediastreamer2. linphone-developers@nongnu.org. Subscribe here: https://savannah.nongnu.org/mail/?group=linphone

[1] git://git.linphone.org/bctoolbox.git or http://www.linphone.org/releases/sources/bctoolbox
[2] git://git.linphone.org/ortp.git or http://www.linphone.org/releases/sources/ortp
[3] git://git.linphone.org/bzrtp.git or http://www.linphone.org/releases/sources/bzrtp

bernhardschmidt / mediastreamer2