[Opalvoip-devel] Help about audio plugin system OPAL

[Ignacio P. <ig....@gm...>]

Hi all!

 I write this email because I need help about audio plugin system for OPAL.
I want to add my own codec like a plugin for later use it in Ekiga building
my_own_codec_audio_pwplugin.so file.

 I've been researching the source code of opal-3.6.8 and reading the
document: http://www.voxgratia.org/docs/codec_plugins.html. I searched info
in forums and mailing list too.

 I undestood how the audio codec “my_own_codec.c” are built (create codec,
destroyCodec, Code-Decode functions... PluginCodec_information and
PluginCodec_Definition structs) but I don't undestand how to create
instances of an H323Capability.

 *I refere to this lines:*

 “*A H.323 endpoint advertises the codecs it supports by providing a table
of capabilities. Each capability specifies a media format, plus other
codec-specific parameters such as frames per packet. In OpenH323, a
capability is represented by the H323Capability class, and instances of the
H323Capability class can are collected into a list represented by a class
named H323Capabilities. *

*An endpoint uses a H323Capabilities to perform the capability negotiation
during call setup, and an application can manipulate endpoint's
H323CapabilityList using various member functions on the H323Endpoint.*

*There are three ways to create instances of an H323Capability. Firstly,
the capability class can be instantiated directly, as follows:*

*H323Capability * cap = new H323_GSM0610Capability;*

*Secondly, the static function H323Capability::Create can be used to create
a H.323 capability that explicitly matches the string:*

*H323Capability * newCap = H323Capability::Create("G.711-uLaw-64k")*

*Note that the string must explicitly match the string specified. The
return value is NULL if there is no match.*

*Thirdly, all capabilities that match a wildcard string can be added to a
H323CapabilityList using the following function:*

*H323Capabilities caps;
caps.AddAllCapabilities(0, 0, "711");*

*For historical reasons, the names used by capabilities are the same as the
corresponding codec (or media format) name, but may have a suffix of "{sw}"
or "{hw}" added to indicate whether it is purely a software or hardware
codec. By default, AddAllCapabilities will include any "{sw}" codecs that
match the string provided, but will not match any "{hw}" codecs unless that
is included in the original codec specification.*

*A user program must populate an endpoint's capability table with the list
of capabilities that match the abilities of the program and endpoint
software. This is normally done as follows:*

*ep.AddAllCapabilities(0, 0, "*");
ep.AddAllUserInputCapabilities(0, P_MAX_INDEX);”*

 *Some questions...*


   -

   Where and how i have to do it? In my_own_codec.c or in other file?
   -

   I supose my codec would be a PluginCodec_H323NonStandardCodecData? Am I
   right? What defines if a plugin codec is or not a non standar codec data?
   -

   And the last question, why Ekiga doesn't recognized
   ima_adpcm_audio_pwplugin.so? This file is included in opal plugins
   directory. I fixed it in /usr/local/lib/opal with the other binary files,
   but it does't appear on Ekiga. It's important because my own codec is a
   modification of this codec.


 My C++ knowledge is poor so please keep it in mind for your reply, thank
you very much.

 Best regards,

 Ignacio Palacios