[Freeswitch-dev] mod_portaudio multiple endpoints support

Moises Silva moises.silva at gmail.com
Thu May 26 09:20:45 MSD 2011


I've been doing some changes to mod_portaudio sponsored by Comrex
Corporation. The changes involve adding support for using multiple audio
devices simultaneously, including devices with multiple channels (note that
is not exactly the same as stereo).

The changes are available at git://

Complete documentation on the new functionality in portaudio can be found in
the sample configuration in the form of comments

The portaudio changes are totally backwards compatible, existing
configurations should keep working as expected.

In addition to the new portaudio functionality there are a few other changes
that were necessary to use the new functionality. All the changes described

1. mod_portaudio.c and pablio.c modifications to allow usage of multiple
streams, channels and devices.

2. uuid_outgoing_answer API added to mod_commands.c, this API allows to
answer outgoing channels. This may only be useful for portaudio endpoints
since most, if not all, endpoints receive the answer notification using some
sort of signaling message (200 OK for example).

3. Changes to switch_generate_sln_silence() in switch_resample.c to allow
specifying -1 as a special divisor value meaning to zero-out the buffer
completely. This option was required by Comrex too since the equipment they
have seems to be amplifying the random low-level noise that
switch_generate_sln_silence() currently generates by default and they don't
like the "hissing noise" on the background while the call is answered and
there is no ringback tone.

I'd appreciate anyone who can review and comment. I just merged a few
moments ago with latest git therefore reviewing should be easy with git diff
adding the github repo as a remote.

I'd like to get approval from the core FreeSWITCH team to merge this into
mainstream. Needless to say I'll be available in the case any bugs are
introduced in the portaudio code, virtually impossible, but just in case


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