_BRB_SCO_OPEN_CHANNEL structure (bthddi.h)
The _BRB_SCO_OPEN_CHANNEL structure describes a SCO channel to open to a remote device, or a response from the profile driver accepting or rejecting an incoming SCO connection request that was initiated by a remote device.
Syntax
struct _BRB_SCO_OPEN_CHANNEL {
BRB_HEADER Hdr;
BTH_ADDR BtAddress;
ULONG TransmitBandwidth;
ULONG ReceiveBandwidth;
USHORT MaxLatency;
USHORT PacketType;
USHORT ContentFormat;
USHORT Reserved;
SCO_RETRANSMISSION_EFFORT RetransmissionEffort;
ULONG ChannelFlags;
ULONG CallbackFlags;
PFNSCO_INDICATION_CALLBACK Callback;
PVOID CallbackContext;
PVOID ReferenceObject;
SCO_CHANNEL_HANDLE ChannelHandle;
UCHAR Response;
};
Members
Hdr
A BRB_HEADER structure that contains information about the current BRB.
BtAddress
The Bluetooth address of the remote device to open a SCO channel to.
TransmitBandwidth
The transmission bandwidth, in bytes per second, to be assigned to the SCO channel.
ReceiveBandwidth
The reception bandwidth, in bytes per second, to be assigned to the SCO channel.
MaxLatency
A value that represents, in milliseconds, the upper limit of the sum of the synchronous interval and the size of the (e)SCO window. Possible values are listed in the following table.
| Values | Description |
| 0x0000 to 0x0003 | Reserved for future use. |
| 0x0004 to 0xFFFE | The range of possible MaxLatency values for the channel. |
| 0xFFFF | The channel doesn't have a preferred MaxLatency setting. |
PacketType
A flag or combination of flags that indicate the type of data packets that the SCO connection supports. These SCO packet types are defined by the Bluetooth SIG. See the Bluetooth specification for more information about these flags. Possible values include:
SCO_HV1
SCO_HV2
SCO_HV3
SCO_EV3
SCO_EV4
SCO_EV5
ContentFormat
The audio voice settings for the channel. Use the following definitions to encode this member:
- SCO_VS_AIR_CODING_DATA
- SCO_VS_AIR_CODING_FORMAT_ALAW
- SCO_VS_AIR_CODING_FORMAT_CVSD
- SCO_VS_AIR_CODING_FORMAT_MASK
- SCO_VS_AIR_CODING_FORMAT_MULAW
- SCO_VS_IN_CODING_ALAW
- SCO_VS_IN_CODING_LINEAR
- SCO_VS_IN_CODING_MASK
- SCO_VS_IN_CODING_MULAW
- SCO_VS_IN_DATA_FORMAT_1C
- SCO_VS_IN_DATA_FORMAT_2C
- SCO_VS_IN_DATA_FORMAT_MASK
- SCO_VS_IN_DATA_FORMAT_SM
- SCO_VS_IN_DATA_FORMAT_US
- SCO_VS_IN_SAMPLE_SIZE_8BIT
- SCO_VS_IN_SAMPLE_SIZE_16BIT
- SCO_VS_IN_SAMPLE_SIZE_MASK
- SCO_VS_PCM_BIT_POS_MASK
- SCO_VS_SETTING_DEFAULT
Reserved
Reserved for future use. Do not use.
RetransmissionEffort
A SCO_RETRANSMISSION_EFFORT enumeration value that determines the retransmission policies for the channel.
ChannelFlags
Flags that specify the requirements for the channel to be opened. Valid flag values are listed in the following table:
| Flag | Description |
| SCO_CF_LINK_AUTHENTICATED | The link must be authenticated. |
| SCO_CF_LINK_ENCRYPTED | The link must be encrypted. Setting this flag also sets the SCO_CF_LINK_AUTHENTICATED flag. |
| SCO_CF_LINK_SUPPRESS_PIN | The profile driver indicates its preference that users not be prompted for a PIN. |
CallbackFlags
A flag that specifies when the function assigned to the Callback member should be sent to the client. Currently, there is only one valid flag:
| Flag | Description |
| SCO_CALLBACK_DISCONNECT | The profile driver should be notified when the remote device is disconnected. |
Callback
The SCO Callback Function implemented by the profile driver, that the Bluetooth driver stack should call to notify the profile driver about any changes to the SCO connection.
CallbackContext
The context to pass to the callback function specified in the Callback member. The profile driver defines this value.
ReferenceObject
A pointer to an object to pass to ObReferenceObject and ObDereferenceObject for which to maintain a reference count of.
ChannelHandle
A handle to identify the SCO channel, if the open channel request completes successfully.
Response
A flag that indicates whether the local server will accept or reject an incoming SCO connection. This member is used only when building and sending a BRB_SCO_OPEN_CHANNEL_RESPONSE request. Valid flag values are listed in the following table.
| Flag | Description |
|---|---|
| SCO_CONNECT_RSP_RESPONSE_SUCCESS | The local server accepts the SCO connection request. |
| SCO_CONNECT_RSP_RESPONSE_NO_RESOURCES | The local server rejects the SCO connection request due to a lack of resources. |
| SCO_CONNECT_RSP_RESPONSE_SECURITY_BLOCK | The local server rejects the SCO connection request because the request does not meet security requirements. |
| SCO_CONNECT_RSP_RESPONSE_BAD_BD_ADDR | The local server rejects the SCO connection request because it does not accept connections from the specified Bluetooth device address. |
Remarks
To open a SCO channel, profile drivers should build and send a BRB_SCO_OPEN_CHANNEL request.
If the asynchronous connectionless link to the remote device does not exist prior to the request, the Bluetooth driver stack creates one before it creates the SCO channel.
To accept or reject an incoming SCO connection request initiated by a remote device, profile drivers should build and send a BRB_SCO_OPEN_CHANNEL_RESPONSE request.
A profile driver should build and send a BRB_SCO_OPEN_CHANNEL_RESPONSE request when the Bluetooth driver stack calls the profile driver's SCO Callback Function and passes ScoIndicationRemoteConnect in the callback function's Indication parameter.
The profile driver specifies whether the connection should be accepted by storing an appropriate value in the Response member of this structure. In this context, the local system is the server.
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Versions:_Supported in Windows Vista, and later. |
| Header | bthddi.h (include Bthddi.h) |