USB Audio 2.0 Drivers

  • Commodity
  • 11 minutes to read

Starting with Windows 10, release 1703, a USB Sound 2.0 driver is shipped with Windows. It is designed to back up the USB Audio 2.0 device class. The driver is a WaveRT audio port class miniport. For more information about the USB Audio 2.0 device course, see https://world wide web.usb.org/documents?search=&type%5B0%5D=55&items_per_page=50.

The driver is named: usbaudio2.sys and the associated inf file is usbaudio2.inf.

The commuter will identify in device manager as "USB Audio Class two Device". This proper noun will be overwritten with a USB Product string, if information technology is available.

The driver is automatically enabled when a compatible device is attached to the system. Nevertheless, if a third-party commuter exists on the system or Windows Update, that driver will be installed and override the grade driver.

Compages

usbaudio2.sys fits within the wider compages of Windows USB Audio as shown.

stack diagram showing Kmixer.sys at the top and a USB audio device at the bottom.

The post-obit USB specifications define USB Audio and are referenced in this topic.

  • USB-two refers to the Universal Serial Bus Specification, Revision 2.0
  • ADC-2 refers to the USB Device Class Definition for Audio Devices, Release 2.0.
  • FMT-ii refers to the Sound Information Formats specification, Release ii.0.

The USB-IF is a special interest group that maintains the Official USB Specification, test specifications and tools.

Audio formats

The driver supports the formats listed below. An alternate setting which specifies another format divers in FMT-2, or an unknown format, will be ignored.

Blazon I formats (FMT-2 2.3.1):

  • PCM Format with viii..32 bits per sample (FMT-2 2.three.1.7.1)
  • PCM8 Format (FMT-ii ii.3.i.vii.two)
  • IEEE_FLOAT Format (FMT-2 two.three.ane.vii.3)

Blazon Iii formats (FMT-2 2.3.three and A.ii.3):

  • IEC61937_AC-3
  • IEC61937_MPEG-2_AAC_ADTS
  • IEC61937_DTS-I
  • IEC61937_DTS-2
  • IEC61937_DTS-Iii
  • TYPE_III_WMA

Feature descriptions

This section describes the features of the USB Audio 2.0 driver.

Audio function topology

The driver supports all entity types defined in ADC-2 3.13.

Each Terminal Entity must have a valid clock connection in compatible USB Audio two.0 hardware. The clock path may optionally include Clock Multiplier and Clock Selector units and must terminate in a Clock Source Entity.

The driver supports one single clock source only. If a device implements multiple clock source entities and a clock selector, then the driver will use the clock source that is selected by default and will not modify the clock selector'due south position.

A Processing Unit (ADC-2 3.13.9) with more than one input pivot is not supported.

An Extension Unit (ADC-2 iii.13.x) with more 1 input pin is not supported.

Cyclic paths in the topology are not allowed.

Sound streaming

The driver supports the following endpoint synchronization types (USB-2 5.12.4.1):

  • Asynchronous IN and OUT
  • Synchronous IN and OUT
  • Adaptive IN and OUT

For the asynchronous OUT example the driver supports explicit feedback only. A feedback endpoint must be implemented in the respective alternate setting of the As interface. The driver does not back up implicit feedback.

At that place is currently limited support for devices using a shared clock for multiple endpoints.

For the Adaptive IN case the driver does not support a feedforward endpoint. If such an endpoint is present in the alternate setting, it will be ignored. The commuter handles the Adaptive IN stream in the same way as an Asynchronous IN stream.

The size of isochronous packets created by the device must be within the limits specified in FMT-2.0 section 2.3.one.1. This means that the deviation of actual parcel size from nominal size must not exceed +/- one audio slot (audio slot = channel count samples).

Descriptors

An audio function must implement exactly 1 AudioControl Interface Descriptor (ADC-2 4.7) and 1 or more than AudioStreaming Interface Descriptors (ADC-2 4.nine). A role with an audio control interface but no streaming interface is not supported.

The driver supports all descriptor types defined in ADC-ii, section 4. The post-obit subsections provide comments on some specific descriptor types.

Class-Specific AS interface descriptor

For details on this specification, refer to ADC-2 4.9.2.

An AS interface descriptor must start with alternate setting zero with no endpoint (no bandwidth consumption) and farther alternate settings must be specified in ascending lodge in compatible USB Audio ii.0 hardware.

An alternate setting with a format that is non supported by the driver will be ignored.

Each non-zero alternating setting must specify an isochronous data endpoint, and optionally a feedback endpoint. A non-aught alternate setting without whatever endpoint is non supported.

The bTerminalLink field must refer to a Terminal Entity in the topology and its value must exist identical in all alternate settings of an As interface.

The bFormatType field in the Equally interface descriptor must be identical to bFormatType specified in the Format Type Descriptor (FMT-2 2.3.one.6).

For Type I formats, exactly one bit must be ready to 1 in the bmFormats field of the AS interface descriptor. Otherwise, the format will be ignored past the driver.

To salvage bus bandwidth, one AS interface can implement multiple alternate settings with the same format (in terms of bNrChannels and AS Format Type Descriptor) but different wMaxPacketSize values in the isochronous data endpoint descriptor. For a given sample rate, the commuter selects the alternate setting with the smallest wMaxPacketSize that tin fulfill the data charge per unit requirements.

Type I format type descriptor

For details on this specification, refer to FMT-2 2.3.1.half dozen.

The following restrictions apply:

Format Subslot size Chip resolution
Type I PCM format: i <= bSubslotSize <= 4 viii <= bBitResolution <= 32
Type I PCM8 format: bSubslotSize == 1 bBitResolution == 8
Type I IEEE_FLOAT format: bSubslotSize == 4 bBitResolution == 32
Blazon III IEC61937 formats: bSubslotSize == 2 bBitResolution == xvi

Class-Specific AS isochronous audio data endpoint descriptor

For details on this specification, refer to ADC-2 4.ten.1.2.

The MaxPacketsOnly flag in the bmAttributes field is not supported and will be ignored.

The fields bmControls, bLockDelayUnits and wLockDelay volition exist ignored.

Class requests and interrupt data letters

The driver supports a subset of the command requests defined in ADC-2, section five.2, and supports interrupt information letters (ADC-two 6.1) for some controls. The post-obit table shows the subset that is implemented in the driver.

Entity Command GET CUR Gear up CUR GET RANGE INTERRUPT
Clock Source Sampling Frequency Control x x x
Clock Selector Clock Selector Control x
Clock Multiplier Numerator Control ten
Denominator Control x
Terminal Connector Command x ten
Mixer Unit Mixer Control x x ten
Selector Unit of measurement Selector Control ten x
Feature Unit Mute Command ten 10 10
Volume Control x ten ten x
Automatic Gain Control ten ten
Event Unit of measurement –
Processing Unit –
Extension Unit –

Boosted information on the controls and requests is bachelor in the following subsections.

Clock source entity

For details on this specification, refer to ADC-ii 5.2.5.ane.

At a minimum, a Clock Source Entity must implement Sampling Frequency Command GET RANGE and Become CUR requests (ADC-two v.two.five.1.1) in compatible USB Audio two.0 hardware.

The Sampling Frequency Control Become RANGE request returns a list of subranges (ADC-ii 5.2.one). Each subrange describes a discrete frequency, or a frequency range. A discrete sampling frequency must exist expressed by setting MIN and MAX fields to the respective frequency and RES to zilch. Individual subranges must not overlap. If a subrange overlaps a previous ane, it volition be ignored by the driver.

A Clock Source Entity which implements one single fixed frequency only does not need to implement Sampling Frequency Control SET CUR. It implements GET CUR which returns the fixed frequency, and information technology implements GET RANGE which reports one single discrete frequency.

Clock selector entity

For details on this specification, refer to ADC-ii v.ii.v.2

The USB Audio two.0 commuter does non back up clock selection. The driver uses the Clock Source Entity which is selected by default and never bug a Clock Selector Control Set up CUR request. The Clock Selector Control GET CUR request (ADC-ii five.2.v.ii.1) must be implemented in compatible USB Audio ii.0 hardware.

Feature unit

For details on this specification, refer to ADC-2 v.2.5.7.

The driver supports one single volume range just. If the Volume Control GET RANGE request returns more than than one range, then subsequent ranges volition exist ignored.

The book interval expressed by the MIN and MAX fields should exist an integer multiple of the step size specified in the RES field.

If a feature unit implements single channel controls too equally a primary control for Mute or Book, then the driver uses the unmarried channel controls and ignores the master control.

Additional Information for OEM and IHVs

OEMs and IHVs should test their existing and new devices against the supplied in-box driver.

There is non any specific partner customization that is associated with the in-box USB Sound 2.0 commuter.

This INF file entry (provided in a update to Windows Release 1703), is used to identify that the in-box driver is a generic device driver.

              GenericDriverInstalled,,,,1

The in-box driver registers for the following compatible IDs with usbaudio2.inf.

              USB\Class_01&SubClass_00&Prot_20 USB\Class_01&SubClass_01&Prot_20 USB\Class_01&SubClass_02&Prot_20 USB\Class_01&SubClass_03&Prot_20

See the USB sound 2.0 specification for bracket types.

USB Audio 2.0 Devices with MIDI (subclass 0x03 to a higher place) will enumerate the MIDI function as a divide multi-function device with usbaudio.sys (USB Audio i.0 driver) loaded.

The USB Audio 1.0 class driver registers this compatible ID with wdma_usb.inf.

              USB\Class_01

And has these exclusions:

              USB\Class_01&SubClass_00&Prot_20 USB\Class_01&SubClass_01&Prot_20 USB\Class_01&SubClass_02&Prot_20 USB\Class_01&SubClass_03&Prot_20

An capricious number of channels (greater than eight) are non supported in shared mode due to a limitation of the Windows sound stack.

IHV USB Audio 2.0 drivers and updates

For IHV provided third party driver USB Audio 2.0 drivers, those drivers will continue to exist preferred for their devices over our in-box driver unless they update their commuter to explicitly override this beliefs and use the in-box driver.

Audio Jack Registry Descriptions

Starting in Windows 10 release 1703, IHVs that create USB Audio Class 2.0 devices having one or more jacks have the adequacy to describe these jacks to the in-box Audio Class 2.0 driver. The in-box driver uses the supplied jack information when handling the KSPROPERTY_JACK_DESCRIPTION for this device.

Jack information is stored in the registry in the device case key (HW fundamental).

The following describes the audio jack information settings in the registry:

              REG_DWORD  T<tid>_NrJacks                 # of the jack on this device REG_DWORD  T<tid>_J<n>_ChannelMapping     Channel mask. The value is defined in ksmedia.h. e.grand. SPEAKER_FRONT_RIGHT or KSAUDIO_SPEAKER_5POINT1_SURROUND REG_DWORD  T<tid>_J<n>_ConnectorType      The enum value is define in EPcxConnectionType.  REG_DWORD  T<tid>_J<n>_GeoLocation        The enum value is define in EPcxGeoLocation. REG_DWORD  T<tid>_J<n>_GenLocation        The enum value is ascertain in EPcxGenLocation. REG_DWORD  T<tid>_J<north>_PortConnection     The enum value is ascertain in EPxcPortConnection. REG_DWORD  T<tid>_J<due north>_Color              The color needs to exist represent past RGB like this: 0x00RRGGBB (NOT a COLORREF).

<tid> = terminal ID (As divers in the descriptor)

<n> = Jack number (1 ~ n).

Convention for <tid> and <due north> is:

  • Base x (8, 9, 10 rather than 8, nine, a)
  • No leading zeros
  • n is 1-based (offset jack is jack 1 rather than jack 0)

For example:

T1_NrJacks, T1_J2_ChannelMapping, T1_J2_ConnectorType

For additional audio jack information, meet KSJACK_DESCRIPTION structure.

These registry values can be set in various ways:

  • By using custom INFs which wrap the in-box INF for the purpose to set these values.

  • Directly by the h/w device via a Microsoft OS Descriptors for USB devices (see case below). For more data nigh creating these descriptors, see Microsoft OS Descriptors for USB Devices.

Microsoft OS Descriptors for USB Example

The following Microsoft OS Descriptors for USB example contains the channel mapping and color for one jack. The example is for a non-composite device with single feature descriptor.

The IHV vendor should extend it to contain any other information for the jack description.

              UCHAR Example2_MSOS20DescriptorSetForUAC2 [0x76] = {     //     // Microsoft Os two.0 Descriptor Set Header     //     0x0A, 0x00,             // wLength - 10 bytes     0x00, 0x00,             // MSOS20_SET_HEADER_DESCRIPTOR     0x00, 0x00, 0x0?, 0x06, // dwWindowsVersion – 0x060?0000 for futurity Windows version     0x76, 0x00,             // wTotalLength – 118 bytes // update later      //     // Microsoft Bone 2.0 Registry Value Feature Descriptor     //     0x42, 0x00,             // bLength - 66 bytes     0x04, 0x00,             // wDescriptorType – 5 for Registry Property     0x04, 0x00,             // wPropertyDataType - 4 for REG_DWORD     0x34, 0x00,             // wPropertyNameLength – 52 bytes     0x54, 0x00, 0x30, 0x00, // Property Name - "T01_J01_ChannelMapping"     0x31, 0x00, 0x5f, 0x00,     0x4a, 0x00, 0x30, 0x00,     0x31, 0x00, 0x5f, 0x00,     0x43, 0x00, 0x68, 0x00,     0x61, 0x00, 0x6e, 0x00,     0x6e, 0x00, 0x65, 0x00,     0x6c, 0x00, 0x4d, 0x00,     0x61, 0x00, 0x70, 0x00,     0x70, 0x00, 0x69, 0x00,     0x6e, 0x00, 0x67, 0x00,     0x00, 0x00     0x04, 0x00,                       // wPropertyDataLength – 4 bytes     0x02, 0x00, 0x00, 0x00  // PropertyData - SPEAKER_FRONT_RIGHT      //     // Microsoft Os 2.0 Registry Value Feature Descriptor     //     0x2A, 0x00,             // bLength - 42 bytes     0x04, 0x00,             // wDescriptorType – 5 for Registry Property     0x04, 0x00,             // wPropertyDataType - four for REG_DWORD     0x1C, 0x00,             // wPropertyNameLength – 28 bytes     0x54, 0x00, 0x30, 0x00, // Holding Name - "T01_J01_Color"     0x31, 0x00, 0x5f, 0x00,     0x4a, 0x00, 0x30, 0x00,     0x31, 0x00, 0x5f, 0x00,     0x43, 0x00, 0x6f, 0x00,     0x6c, 0x00, 0x6f, 0x00,     0x72, 0x00, 0x00, 0x00,     0x04, 0x00,             // wPropertyDataLength – four bytes     0x00, 0x00, 0xff, 0x00  // PropertyData - 0xff0000 - Cerise }

Troubleshooting

If the driver does not beginning, the system event log should be checked. The driver logs events which betoken the reason for the failure. Similarly, audio logs can be manually nerveless following the steps described in this blog entry. If the failure may indicate a driver problem, please report information technology using the Feedback Hub described below, and include the logs.

For information on how to read logs for the USB Audio 2.0 class driver using supplemental TMF files, see this web log entry. For general information on working with TMF files, see Displaying a Trace Log with a TMF File.

For information on "Audio services not responding" error and USB audio device does not work in Windows x version 1703 see, USB Audio Not Playing

Feedback Hub

If you lot see a problem with this commuter, collect audio logs and then follow steps outlined in this weblog entry to bring it to our attention via the Feedback Hub.

Driver development

This USB Audio 2.0 class commuter was developed by Thesycon and is supported by Microsoft.

See likewise

Windows Driver Model (WDM)

Audio Drivers Overview

WaveRT Port Commuter

Low Latency Audio