On my Gentoo Linux host, running VirtualBox 1.6.28, I'm unable to negotiate a VRDP (RDP-4 version) connection because the rdesktop-vrdp client fails to initialize sound so it doesn't connect at all as a consequence, even if the VM has no sound enabled and a parameter is passed to the rdesktop client to disable it!
hatsumemio@mintpc:~$ rdesktop-vrdp -4 -a 16 -N localhost:3394 -r sound:off
Autoselected keyboard map en-gb
ERROR: channel_register
WARNING: Initializing sound-support failed!
ERROR: Connection closed
My VRDE settings
VRDE:
enabled (Address 127.0.0.1, Ports 3394, MultiConn: off, ReuseSingleConn: off, Authentication type: null)
VRDE port: 3394
Video redirection: enabled (Quality 80)
VRDE property : TCP/Ports = "3394"
VRDE property : TCP/Address = "127.0.0.1"
VRDE property : VideoChannel/Enabled = "1"
VRDE property : VideoChannel/Quality = "80"
VRDE property : VideoChannel/DownscaleProtection = <not set>
VRDE property : Client/DisableDisplay = "0"
VRDE property : Client/DisableInput = <not set>
VRDE property : Client/DisableAudio = "1"
VRDE property : Client/DisableUSB = "0"
VRDE property : Client/DisableClipboard = "0"
VRDE property : Client/DisableUpstreamAudio = <not set>
VRDE property : Client/DisableRDPDR = <not set>
VRDE property : H3DRedirect/Enabled = <not set>
VRDE property : Security/Method = <not set>
VRDE property : Security/ServerCertificate = <not set>
VRDE property : Security/ServerPrivateKey = <not set>
VRDE property : Security/CACertificate = <not set>
VRDE property : Audio/RateCorrectionMode = "VRDP_AUDIO_MODE_LPF"
VRDE property : Audio/LogPath = <not set>
Sound settings
Audio: disabled
Audio playback: disabled
Audio capture: disabled
The "Remote Desktops" chapter of VirtualBox's official manual has no mention of how to get sound to work. Therefore, my question is this: How can I initialize sound in order to the client to connect without falling back to plain RDP?