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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.

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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:

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.

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.

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.

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

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

See also

One of the key drivers of travel’s evolution from a primarily offline, manually processed business to one increasingly coordinated online has been the transformation of the payments industry.
The development of the internet, followed by the birth of e-commerce - notably Amazon in 1994, eBay in 1995 and shortly thereafter online travel brands such as Travelocity and Expedia - spurred a need for digital payment options.
One of the first was PayPal, launched in 1999, and today there are hundreds of ways for consumers around the world to pay for products and services online.
According to the World Payments Report 2018 from Capgemini and BNP Paribas, global non-cash transaction volumes grew at 10.1% in 2016 to reach 482.6 billion. That rate is expected to accelerate through 2021 to 12.7% compound annual growth rate globally, with emerging markets growing at 21.6%.
Throughout June, we are exploring the topic of travel payments from a variety of angles.
We begin with a look at some of options within the growing inventory of alternative payments.

Background

The term “alternative payments” is generally defined to include a variety of transaction models such as bank transfers (Trustly, Sofort, iDEAL), local card schemes (Cartes Bancaires, Girocard, RuPay), cryptocurrency (Bitcoin, Litecoin, Dash) and the most common and fastest-growing model – e-wallets (PayPal, Alipay, WeChat Pay, Google Pay, Apple Pay).
According to WorldPay’s 2018 Global Payments Report, “Online shopping demands equal measures of convenience and security. Digital wallets deliver on both counts. Mobile applications integrate the act of payment into daily lifestyles and routines, while preloaded credentials speeds online checkout. E-wallets do all of this safely with encryption, tokenization and device authentication providing extra layers of security.”
Worldpay predicts e-wallets will account for 47% of all e-commerce payments globally by 2022 - nearly three times the share it predicts for the second-most common payment method, credits cards (17%). Much of the growth in the next few years, it says, will come from continued adoption in China and “a surge of adoption in North America.”

And likely the bulk of the e-wallet transaction volume will flow through what Capgemini and BNP Paribas call “BigTechs” -Google, Amazon, Facebook, Apple, Alibaba and Tencent - which accounted for 71% of the global e-wallet market in 2016.

“These companies are leveraging their large-platform user base to make an impact in the payments space, focusing on providing seamless user experience, value-added features and making use of network effects,” the report says.

Beyond Driven Apparel

Application in travel

Beyond Driven

For travel merchants, one of the challenges to offering a variety of digital payment options is the technical work that must happen to integrate these offerings.
Payment processing companies such as UATP bridge these systems.
UATP provides a variety of payment solutions for thousands of airlines, travel agencies and rail carriers, and one of those is to connect those suppliers to nearly two dozen alternative payment brands around the globe.
In 2018, UATP’s alternative payment processing business posted a record-setting 11% growth compared to 2017, and president and CEO Ralph Kaiser says he expects 2019’s figures to be even higher.
“We basically set a new record every month - our transaction growth and our volume growth are both in double digits,” Kaiser says.
“We are very bullish on the marketplace. We are offering new and different programs and technology to our airline members to facilitate the acceptance of alternative brands. And we’re going to start putting out more products and services in that side of our business, because there seems to be demand for it in our airline membership base.”
Kaiser says initially merchants were attracted to options such as PayPal was because it was cheaper to take a booking through alternative platforms than through a traditional credit card. Now, he says, it’s primarily about offering whatever options will satisfy customers.
“So now it boils down to ‘can I sell more things by accepting an additional form of payment.’ That’s a big driver these days. And what we’re finding with airlines, to get more ticket sales and incremental revenue, you have to offer a method of payment that people have and want to use. In some markets there aren’t credit cards or a large part of the population can’t qualify for one.”
Consumers that do have a credit card may not have a credit limit that is high enough to use it for a travel purchase, or the card may not be enabled for cross-border transactions. And consumers in some regions simply prefer to pay with cash, so bank transfers are the preferred method.
Rehman Baig is vice president of payment partnerships at Yapstone, which provides payment services to marketplace-style businesses including travel brands such as Vrbo, Kigo and RentPath.
Baig says the value of alternative payment methods comes from providing simplicity and accessibility for consumers -particularly important in an industry such as travel where brands are trying to court customers from all over the world and where those customers are often paying in advance for accommodations and other aspects of their trip in foreign countries and currencies.
“These tend to be larger transactions that elicit more anxiety, more fear, more excitement for that matter - I want to do this and know for certain my bus is booked or my flight is confirmed,” Baig says.
“An alternative payment method can ease your way into that transaction. You can pay on your terms ... rather than how someone else chooses to pay. And you want the consumer to feel good about completing that transaction.”

Installment options

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For some consumers, point-of-sale financing is a type of alternative payment option that does more than make them “feel good” about booking a trip - it is enabling travel that would not otherwise be possible.
Founded in 2017, Uplift is one company that offers installment payments for travel.
Through partnerships with about 100 brands including Kayak, United Vacations, American Airlines and Universal Orlando Resort - and, since March, UATP - Uplift enables travelers to book instantly but pay for their trips over time through fixed payments each month.
Uplift CEO Brian Bath says the company is on track to exceed its goal of facilitating payments for one million customers in 2019.
He says those travelers are equally split into three segments: those with little disposable income and low credit scores who would not travel without the option of paying in installments, those with ample savings and high credit scores who use installments to take a more “luxury” trip and those in the middle for whom installments convince them to “stop shopping and pull the trigger,” says Barth.
Loans are priced according to risk, with interest rates as low as 4.35% and as high as 35.99%.
“What it does fundamentally is it changes the conversion rate of the purchase for leisure travelers,” Barth says.
“What we really are is a marketing company, using payments to drive marketing metrics.”
One of those metrics is ancillary sales: Barth says Uplift’s partners are making an average of $43 more per booking.
Today there are hundreds of alternative payment brands globally, but Kaiser says he expects to see consolidation in the future.
“You’ll see a convergence of the traditional and the alternative coming more toward the center and maybe taking different pieces until everyone has an offering for their specific customer base.'