The 3G-324M stack includes a set of APIs to develop multimedia communication solutions for 3G servers and handsets. It can also be used to develop multimedia-based solutions for UMTS and TD-SCDMA networks. RADVISION’s 3G-324M Toolkit delivers very high performance with a small memory footprint.
The 3G-324M stack is designed for video telephony applications over live circuit switch (UMTS, TD-SCDM) networks.
The 3G-324M architecture is divided into several modules and Add-ons.
User Application - The user application uses the Call Manager of the Stack to open calls and deal with video and audio channels. The user application is also responsible for dealing with the actual codecs that will be used in the call. A sample user application is provided with the Toolkit.
Call Manager - The Call Manager is responsible for the creation and destruction of calls. The Call Manager is actually the “glue” between the H.245 Control object of the call and the H.223 Multiplexer/Demultiplexer object of the call. This module is also
responsible for sending and receiving data operations over the logical channels after the H.245 module has completed establishing them.
Codec’s Interface – Codec’s Interface – once the call is connected, the media need to be set for sending and receiving Audio and Video and opening Media channels.
This module includes the relevant interfaces that need to be used to integrate the media into the 3G-324M and allow the correct flow of the media in the call.
H.245 Layer - The H.245 Module is responsible for performing the H.245 procedures and for opening and closing the logical channels. The Capabilities Exchange and
Master/Slave Determination procedures are the first to be performed during the
H.245 control process.
H.223 Layer - The H.223 Multiplexer/Demultiplexer module is responsible for communication with the modem. This module replaces the TCP/IP interface used in VoIP protocols.
The H.223 module has two sets of interfaces:
- APIs for the various channels (H.245 and codecs).
- APIs for the modem interface.
PVT Layer – The PVT (Program Value Tree) is a data structure of the Stack that contains instances of the messages. The Stack generates some of the messages, others are received from remote hosts on the network, and some you can create using the PVT functions also provided with the API of the Toolkit.
PST (Program Syntax Tree) is a data structure used by some of the
RADVISION Toolkits that contains data about the ASN.1 message syntax. The
PST is a read-only database that is created by the ASN.1 compiler. The PST
functions provided with the API of this Toolkit enable you to navigate through the PST and retrieve its data.
Baseband - Baseband - The baseband application layer is responsible for integration with the modem of the device and allows 3G-324M communication over circuit switch networks.
Auto Caps Add-on
This add-on module handles capability negotiation and channel opening. The
application needs only to state its capabilities and the H.245 AutoCaps add-on will negotiate the best channels to be opened for the call, while managing any conflicts that might occur during the process. For mobile phone applications, this reduces the hassle of having to deal with all channel conflict scenarios. The H.245 AutoCaps add-on module requires the GEF add-on.
The new Generic Extensibility Framework (GEF) add-on module contains
simple APIs for codecs defined by H.245 GEF, such as MPEG-4, AMR, H.264,