Thread: The protocols

Digital Still Photography Devices (DSP?) like digital still cameras are available in plenty from a variety of vendors. Standardisation is required for these devices so that they can interact with the PC or other digital devices like printers of different vendors. Picture Transfer Protocol (PTP) provides a standard way to interact with a DSPD. This protocol provides mechanisms to exchange images to and from the DSPD and PC. It also provides mechanisms to control DSPD and the ability to transfer auxiliary information such as non-image data files. PTP works on top of transport protocols like USB, IrDA, IEEE1394, but is not limited to these.



The Media Transfer Protocol (MTP) is an extension of PTP, promoted by Microsoft to enable media players to effectively and securely manage media files like songs or videos. Normally, these media devices are exposed as mass storage devices to the PC, and the PC gets exclusive access of the media data. This exclusive access can lead to data corruption. These protocols provide more controlled access. The media files are exposed as files or objects, which are locally maintained by the MTP devices. It also provides secure access to the media files and provides information on the file format and other capabilities.

To enable these protocols in Linux, we need a transport medium. The USB port is one of the most popular transport media for PCs and also in mobile devices. In the following sections we will explore how to bring in a generic USB driver into your kernel and successfully set up these protocol extensions.