Media Transport Adapter

Table of Contents

1. Introduction

This article describes the media transport adapter and how to implement and integrate your custom adapter to your application.

Introduction

Media transport is an object to connect the media application to the network. The most obvious tasks of the media transport are of course to send and receive RTP and RTCP packets. But media transports task can be more than that; the ICE media transport, for example, also takes care of NAT traversal, while the SRTP transport secures your media communication. See ​Media Transport reference documentation for more info.

The media transport also has access to SDP during SDP negotiation; it has access to both local and remote offer and answer, and may add or modify local SDP offer or answer. But note that this feature is only available if PJSUA-LIB is used at the higher level.

Media transport adapter is a variant of media transport, where instead of transmitting and receiving packets directly to/from the network, it uses another media transport to do that. The adapter is installed between the media stream object and another transport adapter, and have full access to the RTP/RTCP packets that are exchanged between the two. The adapter may even inject it's own packets to either direction if it wants to, or drop them. Because of this arrangement, the obvious use of the adapter is to add processing to the media packets without having to be burdened with the actual management of the network. Once the adapter is implemented, it will immediately be able to take advantage of existing and future media transports in PJMEDIA, such as UDP and ICE media transports, including other transport adapters!

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