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Starting with Windows 10, release 1703, a USB Audio 2.0 driver is shipped with Windows. It is designed to support 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 class, see https://www.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 driver will identify in device manager as 'USB Audio Class 2 Device'. This name will be overwritten with a USB Product string, if it is available.

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

Architecture

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

Related USB specifications

The following USB specifications define USB Audio and are referenced in this topic.

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

Type I formats (FMT-2 2.3.1):

• PCM Format with 8..32 bits per sample (FMT-2 2.3.1.7.1)
• PCM8 Format (FMT-2 2.3.1.7.2)
• IEEE_FLOAT Format (FMT-2 2.3.1.7.3)

Type III formats (FMT-2 2.3.3 and A.2.3):

• IEC61937_AC-3
• IEC61937_MPEG-2_AAC_ADTS
• IEC61937_DTS-I
• IEC61937_DTS-II
• 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 2.0 hardware. The clock path may optionally include Clock Multiplier and Clock Selector units and must end 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’s position.

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

An Extension Unit (ADC-2 3.13.10) with more than one input pin is not supported.

Cyclic paths in the topology are not allowed.

Audio 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 case 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 support implicit feedback.

There 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 driver 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 2.3.1.1. This means that the deviation of actual packet size from nominal size must not exceed +/- one audio slot (audio slot = channel count samples).

Descriptors

An audio function must implement exactly one AudioControl Interface Descriptor (ADC-2 4.7) and one or more AudioStreaming Interface Descriptors (ADC-2 4.9). A function with an audio control interface but no streaming interface is not supported.

The driver supports all descriptor types defined in ADC-2, section 4. The following 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 further alternate settings must be specified in ascending order in compatible USB Audio 2.0 hardware.

An alternate setting with a format that is not supported by the driver will be ignored.

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

The bTerminalLink field must refer to a Terminal Entity in the topology and its value must be identical in all alternate 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 2.3.1.6).

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

To save 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 driver selects the alternate setting with the smallest wMaxPacketSize that can fulfill the data rate requirements.

Type I format type descriptor

For details on this specification, refer to FMT-2 2.3.1.6.

The following restrictions apply:

Format	Subslot size	Bit resolution
Type I PCM format:	1 <= bSubslotSize <= 4	8 <= bBitResolution <= 32
Type I PCM8 format:	bSubslotSize 1	bBitResolution 8
Type I IEEE_FLOAT format:	bSubslotSize 4	bBitResolution 32
Type III IEC61937 formats:	bSubslotSize 2	bBitResolution 16

Class-Specific AS isochronous audio data endpoint descriptor

For details on this specification, refer to ADC-2 4.10.1.2.

The MaxPacketsOnly flag in the bmAttributes field is not supported and will be 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 defined in ADC-2, section 5.2, and supports interrupt data messages (ADC-2 6.1) for some controls. The following table shows the subset that is implemented in the driver.

Entity	Control	GET CUR	SET CUR	GET RANGE	INTERRUPT
Clock Source	Sampling Frequency Control	x	x	x
Clock Selector	Clock Selector Control	x
Clock Multiplier	Numerator Control	x
Denominator Control	x
Terminal	Connector Control	x	x
Mixer Unit	Mixer Control	x	x	x
Selector Unit	Selector Control	x	x
Feature Unit	Mute Control	x	x	x
Volume Control	x	x	x	x
Automatic Gain Control	x	x
Effect Unit	–
Processing Unit	–
Extension Unit	–

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

Clock source entity

For details on this specification, refer to ADC-2 5.2.5.1.

At a minimum, a Clock Source Entity must implement Sampling Frequency Control GET RANGE and GET CUR requests (ADC-2 5.2.5.1.1) in compatible USB Audio 2.0 hardware.

The Sampling Frequency Control GET RANGE request returns a list of subranges (ADC-2 5.2.1). Each subrange describes a discrete frequency, or a frequency range. A discrete sampling frequency must be expressed by setting MIN and MAX fields to the respective frequency and RES to zero. Individual subranges must not overlap. If a subrange overlaps a previous one, it will 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 it implements GET RANGE which reports one single discrete frequency.

Clock selector entity

For details on this specification, refer to ADC-2 5.2.5.2

The USB Audio 2.0 driver does not support clock selection. The driver uses the Clock Source Entity which is selected by default and never issues a Clock Selector Control SET CUR request. The Clock Selector Control GET CUR request (ADC-2 5.2.5.2.1) must be implemented in compatible USB Audio 2.0 hardware.

Feature unit

For details on this specification, refer to ADC-2 5.2.5.7.

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

The volume interval expressed by the MIN and MAX fields should be 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 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 not any specific partner customization that is associated with the in-box USB Audio 2.0 driver.

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 driver registers for the following compatible IDs with usbaudio2.inf.

See the USB audio 2.0 specification for subclass types.

USB Audio 2.0 Devices with MIDI (subclass 0x03 above) will enumerate the MIDI function as a separate multi-function device with usbaudio.sys (USB Audio 1.0 driver) loaded.

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

And has these exclusions:

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

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IHV USB Audio 2.0 drivers and updates

For IHV provided third party driver USB Audio 2.0 drivers, those drivers will continue to be preferred for their devices over our in-box driver unless they update their driver to explicitly override this behavior 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 capability 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 instance key (HW key).

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

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

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

Convention for <tid> and <n> is:

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

For example:

T1_NrJacks, T1_J2_ChannelMapping, T1_J2_ConnectorType

For additional audio jack information, see 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 example below). For more information about 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.

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

Troubleshooting

If the driver does not start, the system event log should be checked. The driver logs events which indicate the reason for the failure. Similarly, audio logs can be manually collected following the steps described in this blog entry. If the failure may indicate a driver problem, please report it 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 blog 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 10 version 1703 see, USB Audio Not Playing

Feedback Hub

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

Driver development

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

See also

Download MTP driver for Windows 10, 8, or 7 to transfer media files from external storage devices to your PC or vice versa. The guide also describes how to update the MTP USB driver if it is outdated. Read on to know more.

Media Transfer Protocol (MTP) helps you transfer multimedia files from an external storage to Windows PC or vice versa. To ensure its smooth functioning, you require the correct MTP driver. Or else, you may face issues such as ‘MTP USB device or driver failed.’ It makes you unable to transfer files between your PC and an external storage device like your smartphone. Hence, it is necessary to download the MTP driver for Windows 10, 8, or 7 and install it.

However, you have to regularly update the MTP USB driver if you already have it. But not everyone knows how to get the latest version of the MTP device driver for Windows 10, 8.1, 8, or 7. Do not worry. Here we are again to help you get rid of another technical system driver issue. Let’s check out how to download, install, & update the driver for an MTP USB device on Windows 10 and other Windows versions (64/32 Bit).

Ways To Download & Update MTP USB Driver On Windows 10, 8, & 7

Here is how you can download the latest MTP USB device driver on your Windows 10, 8, or 7 PC and update it.

Download Latest MTP Driver Using Windows Device Manager

It is one of the most prominent manual way of downloading drivers on Windows PCs. The OS provides a default utility, Device Manager, to manage all the hardware and installed drivers. You can also use it to get the latest MTP USB device driver for Windows.

However, it is not that easy to download, install, and update the MTP USB driver using Windows Device Manager. You have to follow a lot of steps. And they are also pretty time-consuming. Here is how you can download the driver for your MTP device via Device Manager.

• Launch the Run dialog box by using your keyboard. You simply have to press the Windows and R keys on your keyboard simultaneously.
• Enter the ‘devmgmt.msc’ command in the text box. You can also copy it from here and then paste it into the Run dialog box.
  
• Click OK.
• After that, scroll to Other devices.
• Expand the hardware category.
• Right-click the MTP option listed in it.
• Select Update driver to download the required version of the MTP USB device driver.
  
• Now, choose among Search automatically for updated driver and Browse my computer for driver software options. Preferably it is better to go with the first one.
  

Once you choose the automatic way of searching for an updated MTP driver software, your OS starts finding the suitable driver version. Monitor the whole process. Approve the permissions asked by the system to download and install the driver for the MTP USB device on your PC.

Also Read: Guide to Install and Download USB-Serial Controller D Driver

Update MTP Driver Using Windows Update

Another way of updating the MTP USB device driver via a Windows default utility or feature is using the Windows Update. The method helps in upgrading the entire OS along with the necessary software and driver updates. Hence, if your MTP driver has become outdated, then you can try using Windows Update to get its latest version on your PC.

The feature dedicatedly focuses on upgrading the Windows. It is not that effective when it comes to updating PC drivers. But, if you still want to give it a try, then below are the instructions that you should follow.

• Click the Start icon. You can find it on your taskbar.
• Do a click on Settings.
• Now choose Updates & Security in the Settings window.
  
• After that, go to the Windows Update settings.
• In the update settings, choose Check for updates.
  

Following the above steps initiates Windows search for the available updates. The OS asks you for permission to download and install the detected software or driver upgrades. You have to approve the request.

Use Bit Driver Updater To Download & Update MTP Driver For Windows 10

Let’s discuss the fastest & easiest way, in short, the best way to download the MTP driver for Windows 10, 8, & 7. Among all the above methods, some cons may bother you while downloading and installing a driver for your MTP device. You can avoid them by using the Bit Driver Updater for the task.

The software comes with almost no con. It offers a variety of helpful features that eventually helps users to update their PC drivers with ease. So, first of all, let’s have a glance at the benefits of using Bit Driver Updater to update the MTP USB driver.

• The software ensures a safe driver upgrade by creating a restorable backup of the current drivers.
• Users who are running short of time can use Bit Driver Updater to repair all their driver problems with a single click.
• The interface is also beginner-friendly. You do not have to be a tech expert to update your drivers and tweak the system performance.
• It comes with an option to plan your PC driver schedule.

If you have came this long, then it seems that you are interested in using Bit Driver Updater. For you, below, we have shared a brief guide to use the program.

• Click the button provided below and download the feature-rich driver update program.
  
• Go to the Downloads and run the software installer to install Bit Driver Updater.
• Follow the mere instructions provided on the screen.
• Launch to tool once it gets successfully installed.
• Do a click on Scan Drivers.
• Review the provided list of driver issues and click Update Now to fix them.

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As discussed in the features, you can also fix all the driver issues simultaneously. Just go with the Update All option.

Best Solution To Download & Update MTP USB Driver On Windows

We hope you have fixed the ‘MTP USB device or driver failed’ issue by updating the MTP driver with the above solutions. It is essential to get rid of such problems to ensure a smooth transfer of media files among an external storage device like your smartphone and your PC. We like to conclude this guide by sharing our opinion on the best way to download and update the MTP USB device driver on Windows 10, 8, or 7. And we suggest using Bit Driver Updater as the best way to resolve any such PC driver issue.