= Enabling External Sound Device Configurations =

External sound device configuration enables application to provide its own sound device implementation rather than the implementation provided by PJMEDIA. This option was added in PJSIP version 0.9.5.

== GNU Build System ==

Follow these steps to enable external sound device with GNU build system.
 1. Enable external sound device in {{{./configure}}} command:
  {{{
./configure --enable-ext-sound
  }}}
 1. Edit {{{user.mak}}} in root PJSIP directory to add your sound device implementation in the link process. For example, if your sound device implementation is in {{{ext_snd.c}}} in your home directory, the content of {{{user.mak}}} file will look something like this:
  {{{
# This is the rule to compile your sound implementation
~/ext_snd.o: ~/ext_snd.c
        $(APP_CC) $(APP_CFLAGS) -c $< -o $@

# Specify this so that your file will be compiled when 'make all' is invoked
all:    ~/ext_snd.o

# Add your implementation to LDFLAGS
export LDFLAGS += ~/ext_snd.o

  }}}
  Note that all directory reference must use full path rather than relative path, since the {{{make}}} command will be invoked in {{{build}}} directory of the libraries rather than in root PJSIP directory.
 1. Build everything:
  {{{
make
  }}}


== Visual Studio and Others ==

Follow these steps to enable external sound device with Visual Studio build system.

 1. Declare this in your {{{config_site.h}}}:
  {{{
#define PJMEDIA_SOUND_IMPLEMENTATION    PJMEDIA_SOUND_EXTERNAL
  }}}
 1. Add your sound device implementation source file in the '''application''' project (e.g. in application's Visual Studio project, or in application's MMP file for Symbian).