USB Audio 2.0 Drivers

Starting with Windows ten, release 1703, a USB Audio 2.0 driver is shipped with Windows. It is designed to support the USB Audio 2.0 device course. The driver is a WaveRT audio port class miniport. For more data nigh the USB Audio 2.0 device grade, see
https://world wide

The driver is named:
and the associated inf file is

The driver will identify in device managing director equally “USB Sound Form 2 Device”. This proper noun volition exist overwritten with a USB Product string, if it is bachelor.

The driver is automatically enabled when a compatible device is attached to the system. However, if a third-political party driver exists on the system or Windows Update, that driver will exist installed and override the course driver.


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

Usb2 0 Serial Driver Download Windows 7

The following USB specifications ascertain 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 two.0.
  • FMT-2 refers to the Audio Data Formats specification, Release 2.0.

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

Audio formats

The commuter supports the formats listed below. An alternate setting which specifies another format defined in FMT-two, or an unknown format, will exist ignored.

Type I formats (FMT-2 two.3.i):

  • PCM Format with 8..32 bits per sample (FMT-2
  • PCM8 Format (FMT-2 2.3.i.7.2)
  • IEEE_FLOAT Format (FMT-2

Type III formats (FMT-ii 2.3.3 and A.2.3):

  • IEC61937_AC-iii
  • IEC61937_MPEG-2_AAC_ADTS
  • IEC61937_DTS-I
  • IEC61937_DTS-II
  • IEC61937_DTS-III

Feature descriptions

This section describes the features of the USB Audio two.0 driver.

Sound function topology

The driver supports all entity types divers in ADC-two 3.13.

Each Terminal Entity must have a valid clock connectedness in compatible USB Audio 2.0 hardware. The clock path may optionally include Clock Multiplier and Clock Selector units and must end in a Clock Source Entity.

The commuter supports one unmarried clock source simply. If a device implements multiple clock source entities and a clock selector, then the driver will apply the clock source that is selected by default and will not alter the clock selector’due south position.

A Processing Unit (ADC-two 3.13.nine) with more than ane input pivot is non supported.

An Extension Unit (ADC-2 3.13.ten) with more than one input pin is non supported.

Cyclic paths in the topology are not allowed.

Audio streaming

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

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

For the asynchronous OUT case the driver supports explicit feedback just. A feedback endpoint must exist implemented in the corresponding alternating setting of the Equally interface. The driver does non support implicit feedback.

There is currently express support for devices using a shared clock for multiple endpoints.

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

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The size of isochronous packets created by the device must be within the limits specified in FMT-2.0 department 2.3.1.i. This ways that the deviation of actual parcel size from nominal size must not exceed +/- one audio slot (audio slot = channel count samples).


An audio function must implement exactly one AudioControl Interface Descriptor (ADC-2 iv.7) and one or more AudioStreaming Interface Descriptors (ADC-two 4.9). A function with an audio control interface but no streaming interface is not supported.

The commuter supports all descriptor types defined in ADC-2, section four. The post-obit subsections provide comments on some specific descriptor types.

Grade-Specific As interface descriptor

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

An AS interface descriptor must get-go with alternate setting nada with no endpoint (no bandwidth consumption) and farther alternating settings must be specified in ascending order in compatible USB Sound ii.0 hardware.

An alternate setting with a format that is not supported by the commuter volition exist ignored.

Each non-zip alternate setting must specify an isochronous data endpoint, and optionally a feedback endpoint. A non-zero alternating setting without whatsoever endpoint is not supported.

The bTerminalLink field must refer to a Final Entity in the topology and its value must exist identical in all alternating settings of an AS interface.

The bFormatType field in the AS interface descriptor must be identical to bFormatType specified in the Format Type Descriptor (FMT-2 dozen).

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

To salve charabanc bandwidth, one Equally interface can implement multiple alternating settings with the aforementioned 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 driver selects the alternate setting with the smallest wMaxPacketSize that tin can fulfill the data charge per unit requirements.

Blazon I format type descriptor

For details on this specification, refer to FMT-2

The following restrictions apply:

Format Subslot size Scrap resolution
Type I PCM format: one <= bSubslotSize <= 4 8 <= bBitResolution <= 32
Type I PCM8 format: bSubslotSize == 1 bBitResolution == 8
Type I IEEE_FLOAT format: bSubslotSize == iv bBitResolution == 32
Blazon 3 IEC61937 formats: bSubslotSize == 2 bBitResolution == xvi

Class-Specific AS isochronous sound information endpoint descriptor

For details on this specification, refer to ADC-ii 4.x.1.2.

The MaxPacketsOnly flag in the bmAttributes field is not supported and volition exist ignored.

The fields bmControls, bLockDelayUnits and wLockDelay will be ignored.

Class requests and interrupt data messages

The driver supports a subset of the control requests divers in ADC-2, department five.2, and supports interrupt data letters (ADC-2 6.i) for some controls. The post-obit table shows the subset that is implemented in the commuter.

Clock Source Sampling Frequency Control x x x
Clock Selector Clock Selector Control ten
Clock Multiplier Numerator Control ten
Denominator Control x
Final Connector Control x x
Mixer Unit Mixer Control x ten x
Selector Unit Selector Control x x
Feature Unit Mute Control 10 x x
Book Command x x x x
Automatic Gain Command x 10
Effect Unit of measurement
Processing Unit
Extension Unit

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

Clock source entity

For details on this specification, refer to ADC-2 5.two.5.1.

At a minimum, a Clock Source Entity must implement Sampling Frequency Control Get RANGE and Get CUR requests (ADC-2 in uniform USB Audio 2.0 hardware.

The Sampling Frequency Control GET RANGE request returns a list of subranges (ADC-2 Each subrange describes a discrete frequency, or a frequency range. A detached sampling frequency must be expressed past setting MIN and MAX fields to the respective frequency and RES to nothing. Individual subranges must not overlap. If a subrange overlaps a previous 1, it will be ignored by the commuter.

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A Clock Source Entity which implements i single fixed frequency only does non demand to implement Sampling Frequency Control SET CUR. It implements Get CUR which returns the fixed frequency, and it implements GET RANGE which reports one single discrete frequency.

Clock selector entity

For details on this specification, refer to ADC-2

The USB Audio 2.0 driver does not support clock choice. The driver uses the Clock Source Entity which is selected by default and never bug a Clock Selector Control Ready CUR asking. The Clock Selector Control Become CUR request (ADC-ii v.ii.5.2.i) must be implemented in compatible USB Audio 2.0 hardware.

Feature unit

For details on this specification, refer to ADC-two 5.ii.5.7.

The driver supports one single volume range only. If the Book Control GET RANGE request returns more than than one range, and then subsequent ranges volition be ignored.

The volume interval expressed past 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 as well as a master control for Mute or Volume, then the driver uses the single channel controls and ignores the chief control.

Boosted Information for OEM and IHVs

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

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


The in-box commuter 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 audio ii.0 specification for subclass types.

USB Audio ii.0 Devices with MIDI (subclass 0x03 above) will enumerate the MIDI office as a separate multi-office device with usbaudio.sys (USB Sound one.0 driver) loaded.

The USB Audio i.0 class driver registers this uniform ID with wdma_usb.inf.


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 arbitrary number of channels (greater than eight) are not supported in shared mode due to a limitation of the Windows audio stack.

IHV USB Audio 2.0 drivers and updates

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

Sound Jack Registry Descriptions

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

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

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

            REG_DWORD  T<tid>_NrJacks                 # of the jack on this device REG_DWORD  T<tid>_J<north>_ChannelMapping     Channel mask. The value is defined in ksmedia.h. eastward.g. SPEAKER_FRONT_RIGHT or KSAUDIO_SPEAKER_5POINT1_SURROUND REG_DWORD  T<tid>_J<n>_ConnectorType      The enum value is ascertain 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 define in EPcxGenLocation. REG_DWORD  T<tid>_J<n>_PortConnection     The enum value is define in EPxcPortConnection. REG_DWORD  T<tid>_J<north>_Color              The colour needs to be represent by RGB similar this: 0x00RRGGBB (NOT a COLORREF).

<tid> = concluding ID (Equally divers in the descriptor)

<n> = Jack number (one ~ northward).

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Convention for <tid> and <northward> is:

  • Base of operations 10 (viii, 9, 10 rather than eight, 9, a)
  • No leading zeros
  • northward is 1-based (get-go jack is jack ane rather than jack 0)

For example:

T1_NrJacks, T1_J2_ChannelMapping, T1_J2_ConnectorType

For additional audio jack data, run into

These registry values can exist set in various ways:

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

  • Straight by the h/w device via a Microsoft Os Descriptors for USB devices (see example below). For more information about creating these descriptors, see
    Microsoft OS Descriptors for USB Devices.

Microsoft Bone Descriptors for USB Case

The post-obit Microsoft Bone Descriptors for USB example contains the channel mapping and color for ane jack. The case is for a non-composite device with single feature descriptor.

The IHV vendor should extend it to contain whatsoever other information for the jack clarification.

            UCHAR Example2_MSOS20DescriptorSetForUAC2 [0x76] = {     //     // Microsoft OS 2.0 Descriptor Fix Header     //     0x0A, 0x00,             // wLength - x bytes     0x00, 0x00,             // MSOS20_SET_HEADER_DESCRIPTOR     0x00, 0x00, 0x0?, 0x06, // dwWindowsVersion – 0x060?0000 for future Windows version     0x76, 0x00,             // wTotalLength – 118 bytes // update subsequently      //     // Microsoft OS 2.0 Registry Value Feature Descriptor     //     0x42, 0x00,             // bLength - 66 bytes     0x04, 0x00,             // wDescriptorType – v for Registry Property     0x04, 0x00,             // wPropertyDataType - four 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 Characteristic Descriptor     //     0x2A, 0x00,             // bLength - 42 bytes     0x04, 0x00,             // wDescriptorType – 5 for Registry Property     0x04, 0x00,             // wPropertyDataType - 4 for REG_DWORD     0x1C, 0x00,             // wPropertyNameLength – 28 bytes     0x54, 0x00, 0x30, 0x00, // Property 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 – 4 bytes     0x00, 0x00, 0xff, 0x00  // PropertyData - 0xff0000 - RED }


If the driver does not start, the system effect log should be checked. The driver logs events which indicate the reason for the failure. Similarly, audio logs tin be manually collected post-obit the steps described in
this blog entry. If the failure may signal a driver trouble, please report it using the Feedback Hub described below, and include the logs.

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

For information on “Sound services not responding” error and USB audio device does not work in Windows 10 version 1703 see,
USB Audio Non Playing

Feedback Hub

If you run into a problem with this driver, collect sound logs and then follow steps outlined in
this blog entry
to bring it to our attending via the Feedback Hub.

Driver development

This USB Audio 2.0 class driver was adult by Thesycon and is supported by Microsoft.

Come across also

Windows Commuter Model (WDM)

Audio Drivers Overview

WaveRT Port Driver

Low Latency Audio