PJMEDIA-AudioDev

Overview

PJMEDIA Audio Device API is a cross-platform audio API appropriate for use with VoIP applications and other types of audio streaming applications.

PJMEDIA-Audiodev supports the following platforms/devices:

Older devices that are no longer supported:

  • Blackberry BB10

  • Symbian audio streaming/multimedia framework (MMF) implementation

  • Nokia Audio Proxy Server (APS) implementation

  • null-audio implementation

Core features supported by PJMEDIA Audio Device API:

  • Forward compatibility:

    The new API has been designed to be extensible, it will support new API’s as well as new features that may be introduced in the future without breaking compatibility with applications that use this API as well as compatibility with existing device implementations.

  • Device capabilities:

    At the heart of the API is device capabilities management, where all possible audio capabilities of audio devices should be able to be handled in a generic manner. With this framework, new capabilities that may be discovered in the future can be handled in manner without breaking existing applications.

  • Built-in features:

    The device capabilities framework enables applications to use and control audio features built-in in the device, such as:

    • audio format,

    • echo cancellation,

    • built-in codecs,

    • audio routing (e.g. to earpiece or loudspeaker),

    • volume control,

    • latency control,

    • volume meter,

    • voice activity detector,

    • comfort noise

  • Codec support:

    Some audio devices such as Nokia/Symbian Audio Proxy Server (APS) and Nokia VoIP Audio Services (VAS) support built-in hardware audio codecs (e.g. G.729, iLBC, and AMR), and application can use the sound device in encoded mode to make use of these hardware codecs.

  • Multiple backends:

    The new API supports multiple audio backends (called factories or drivers in the code) to be active simultaneously, and audio backends may be added or removed during run-time.

Using the Audio Device API

See Using Audio Device API

API Reference

Supported devices:

Follow the instructions below to enable the device. TBD.

ALSA

ALSA support is detected and enabled automatically by the configure script. Check the configure output for ALSA detection:

checking for alsa/version.h... yes
Checking sound device backend... alsa

If ALSA is not detected, make sure ALSA development package is installed (e.g. on Debian it’s libasound2-dev).

Once ALSA is built, you should see ALSA device detection results on pjsua log level 5 like this:

$ pjsip-apps/bin/pjsua-x86_64-unknown-linux-gnu --log-level 5
..
07:46:25.081             alsa_dev.c  ..ALSA driver found 32 devices
07:46:25.081             alsa_dev.c  ..ALSA initialized
..

Android OpenSL

Android JNI

Android Oboe

From Oboe GitHub page: “Oboe is a C++ library which makes it easy to build high-performance audio apps on Android”. PJMEDIA support Oboe audio capture and playback device.

bdIMAD by BdSound

bdIMAD (BdSound IMproved Audio Device) is bdSound advanced audio device for PJSIP, supporting advanced speech processing features such as Full Duplex Acoustic Echo Cancellation, Noise Reduction, Automatic Level Control, Loudness Manager, Adaptive Comfort Noise)

This driver supports Windows, Mac OS X, Linux, Embedded Linux, Windows Embedded, iOS, and Android. Please see http://www.bdsound.com/support/category/bdimad/ for most up to to date information and instructions on how to use it.

CoreAudio (Mac OS X and iPhone)

TBD.

WMME (Windows and Windows Mobile devices)

WMME is Windows Multimedia API that is available in every Windows operating systems. PJMEDIA has native support for WMME audio device.

To enable WMME suport, add this to your config_site.h:

#define PJMEDIA_AUDIO_DEV_HAS_WMME  1

And rebuild the Visual Studio project.

WASAPI (Windows Audio Session API)

No longer supported devices:

PortAudio

PortAudio (PA) is a open source portable audio device abstraction by http://portaudio.com/. It supports Windows, Macintosh OS X, and Unix (OSS/ALSA). Since PJMEDIA already supports native many audio devices in platforms that PA supports, we no longer actively maintain PortAudio support.

Follow these guides below to enable PA support in PJMEDIA:

  1. Download and build PortAudio for your platform

  2. For Mac OS/Linux/Unix, run configure with --with-external-pa option. This should pick up PortAudio headers and libs in standard locations. If PA is not in standard locations, you need to set CFLAGS and LDFLAGS accordingly:

    $ ./configure --with-external-pa
$ make

  3. For Windows:

    1. Make sure PA headers and libs are in standard location. If not, modify pjmedia-audiodev Visual Studio project and set header and library directories as appropriate.

    2. Add this to your config_site.h:

      #define PJMEDIA_AUDIO_DEV_HAS_PORTAUDIO 1

    3. Rebuild the workspace

Blackberry BB10

Nokia APS/VAS

Symbian MMF