This extension to the RDP virtual channels protocol allows an RDP (remote desktop connection) client device's behavior, with respect to audio levels and drive letters, to mimic a Windows client PC session. The following sections provide an audio level and drive letter scenarios.
Audio level scenario
For example, a user logs onto a PC running a Windows client operating system, plugs in a headset, and finds the level is too loud. The user can lower the audio level by using the Windows user interface. If the audio level was initially set to 100%, the user might change it to 50% to get to a comfortable volume. If the user logs out, reboots the computer, and logs back on, the volume will still be set to 50%.
Contrast that to the experience of a user logging onto a remote session using a thin client. The user adjusts the audio level to 50%, but if the user logs out and back on, by default the audio level is always set back to 100%. This requires the user to re-adjust the audio level every time she logs off on. (This is also true for disconnecting and reconnecting to a session.) With the extension to the virtual channel protocol defined in this document, the audio level settings are saved on the client and each time the device connects to a remote session, the audio level will keep its preset value.
Drive letter scenario
For another example, a user logs onto a PC running a Windows client operating system, plugs a USB storage device into the PC, assigns it the drive letter N:, and then configures the system to automatically and periodically back up the user's folder onto the USB storage device which has the letter N: assigned to it. If the user then reboots the computer and logs back on, the USB storage device will still be assigned N: and the backups will continue to occur without problems.
Contrast that to the experience of a user logging on to a remote session using a thin client. The user sets the drive letter to N: and the backups can begin, but when the user logs off and back on, the drive letter has now been assigned the next available letter by the session (for example, the next available drive letter G: if the host server already has letters A through F assigned to drives). This will cause the backup to fail and require the user to reset the drive letter to N: every time he logs off and back on. With this extension to the virtual channel protocol, the drive letter settings for a specific storage device will be remembered on the client, and each time the device connects to a remote session, the drive letter will keep its preset value.