Media Transfer Protocol and Symbian Implementation

Media Transport Protocol

The Media Transfer Protocol (MTP) is based upon, and is compatible with, the Picture Transfer Protocol (PTP) which is commonly used by digital imaging devices and printers for the exchange of pictures. PTP supports only the transfer of pictures. MTP allows the transfer of most types of media and is aimed at intelligent multifunction storage devices, such as digital cameras, portable media players and mobile phones.

Key aspects of MTP

• It is intended for transient connectivity between devices which normally function unconnected.

• It is optimised for very large data stores.

• A device may act as either a data producer or a data consumer. This refers to the direction in which data is transferred. For example image files may be uploaded from a Symbian device acting as a producer and music files downloaded to the same Symbian device acting as a consumer.

• A device may act as either an Initiator or a Responder. Typically the Initiator is the 'more responsible' of the two devices.

• Besides enabling data transfer MTP enables some command and control of the connected device (the responder)

• Data is transferred as an atomic binary object so the data types that can be transferred are not restricted.

For a more complete description of MTP, and to download the MTP Porting Kit, please visit the Microsoft website

Symbian Implementation

Support for MTP means that Symbian devices are able to interact with Microsoft Windows without the need to install any additional software on either device. The degree of interaction (the range and sophistication of features available) depends upon the software built into both the PC and the Symbian device.

The basic Symbian MTP implementation provides access to the public file system on the device over a USB connection. The PC user is able to view the file system using applications such as Windows Explorer and the Windows Media Player.

Figure 1. Basic MTP over USB

Within the Symbian platform MTP is implemented as a framework which allows the use of a variety of transports (e.g. USB, TCP/IP...), a variety of modes (MTP, PTP & PictBridge) and a variety of Data Providers (e.g. specific media and data type providers).

Figure 2. MTP Framework Interfaces

The Symbian MTP implementation is compatible with Microsoft's MTP Enhanced specification v0.95. Symbian devices conform to the Windows Portable Device (WPD) architecture. Compatible versions of Microsoft Windows are:

• Windows XP with Windows Media Player version 11 or higher

• Windows Vista

A Symbian device can take only the Responder role.