An audio driver can send an IOCTL_BTHHFP_DEVICE_GET_CODEC_ID control code to query the Bluetooth driver stack about the codec ID used by the HFP service. This helps the audio driver determine the sampling rate for the data.

Major code


Input buffer

An HFP_BYPASS_CODEC_ID_VERSION enumeration value. Currently, only REQ_HFP_BYPASS_CODEC_ID_V1 is supported.

Input buffer length

The size of an HFP_BYPASS_CODEC_ID_VERSION enumeration value.

Output buffer

A codec ID structure containing the codec ID information. Currently, only HFP_BYPASS_CODEC_ID_V1 is supported.

Output buffer length

The size of a codec ID structure.

Status block

If the routine succeeds, then Status is set to STATUS_SUCCESS and the Information member is the codec ID.


Minimum supported client Windows 10
Minimum supported server Windows Server 2016
Header bthhfpddi.h

See also

Bluetooth HFP DDI IOCTLs