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USB-IF Publishes Audio Over USB Type-C Specifications (anandtech.com)

Posted by BeauHD on from the technical-specifications dept.

An anonymous reader quotes a report from AnandTech: The USB Implementers Forum this week published the USB Audio Device Class 3.0 (direct download) specification, which standardizes audio over USB Type-C interface. The new spec enables hardware makers to eliminate traditional 3.5mm mini-jacks from their devices and use USB-C ports to connect headsets and other audio equipment. Makers of peripherals can also build their audio solutions, which use USB-C instead of traditional analog connectors. Developers of the standard hope that elimination of mini-jacks will help to make devices slimmer, smarter and less power hungry. As reported, the USB Audio Device Class 3.0 specification supports both analog and digital audio. Analog audio is easy to implement and it does not impact data transfers and other functionality of USB-C cables since it uses the two secondary bus (SBU) pins. The USB ADC 3.0 defines minimum interoperability across analog and digital devices in order to avoid confusion of end-users because of incompatibility. In fact, all ADC 3.0-compliant hosts should support the so-called headset adapter devices, which allow to connect analog headsets to USB-C. However, digital audio is one of the primary reasons why companies like Intel wanted to develop the USB-C audio tech on the first place, hence, expect them to promote it. According to the USB ADC 3.0 standard, digital USB-C headphones will feature special multi-function processing units (MPUs), which will, to a large degree, define the feature set and quality of headsets. The MPUs will handle host and sink synchronization (this is a key challenge for digital USB audio), digital-to-analog conversion, low-latency active noise cancellation, acoustic echo canceling, equalization, microphone automatic gain control, volume control and others. Such chips will also contain programmable amplifiers and pre-amplifiers, which are currently located inside devices. Besides, USB ADC 3.0-compatible MPUs will also support USB Audio Type-III and Type-IV formats (the latest compressed formats), but will retain compatibility with formats supported by ADC 1.0 and 2.0. Finally, among the mandated things set to be supported by USB-C Audio devices are new Power Domains (allows devices to put certain domains in sleep mode when not in use) as well as BADD (basic audio device definition) 3.0 features for saving power and simplified discovery and management of various audio equipment (each type of devices has its own BADD profile).

6 of 135 comments (clear)

  1. First thing which comes to mind by Anonymous Coward · · Score: 3, Insightful

    DRM...

  2. Apple slides in for the win... by Trax3001BBS · · Score: 1, Insightful

    Now seen as innovative.

  3. Thin sucks by PopeRatzo · · Score: 4, Insightful

    I'm sitting here looking at my nice Nexus 5x phone, that has a perfectly good 3.5mm jack on it. If I lose my earbuds, I can walk into most any store and buy absolutely adequate replacements for $10 or less. The Nexus 5 is already so thin that it felt funny in my hand and I had to buy a case for it that makes it thicker.

    You think USB-C headphones that "will feature special multi-function processing units (MPUs)" are ever going to be $10?

    --
    You are welcome on my lawn.
    1. Re:Thin sucks by swb · · Score: 3, Insightful

      I'm 50 years old and have owned 3.5mm jack devices for about 40 of those years, starting with a Radio Shack pocket AM/FM radio, a good half dozen or more Walkman-style cassette players, most iPhone models, 3 iPods, and various PCs and laptops. Possibly 2 dozen devices added up.

      I think I've had problems with 1-2 of the cassette Walkman devices and the headphone jacks getting static problems, but the others have been fine and never developed problems. The Walkmans mostly likely became problems because they just got used hard, jammed into pockets with stress on the jacks.

      But I also wouldn't write off general improvements in construction of the jacks since then. We call it the 3.5mm jack like it hasn't changed, but over time everything about it has probably improved. Superior metallurgy means superior contacts with more durable spring force, more resistance to corrosion, engineering improvements in mounting such as tighter, closer tolerance mounting resulting in strain transferred to the housing and not the PCB.

      IMHO, Bluetooth hasn't improved at all other than perhaps slightly on the audio quality side. Pairing is still a PITA, source devices are prone to wandering and shifting to other devices -- I've lost connections on my phone when the headphones in my car were still on, causing my phone to shift to my car headset despite me actively using a headset in the house.

      Then there's Bluetooth's general limitations -- I've yet to see simultaneous pairing with a BT headset where you can get simultaneous mixed audio from two devices -- ie, why can't I pair my PC and phone at the same time and get audio from both in my headphones at the same time? Why do I have to fuck around disabling BT on one to shift the device to the other?

  4. Re:Slimmer my ass by Anonymous Coward · · Score: 3, Insightful

    It's about DRM

  5. SBU is not what you think it is. by JustNiz · · Score: 4, Insightful

    from here:
    http://ww1.microchip.com/downl...

    "The SBU wires are lower speed signal wires that is allocated for Alternate Mode use only. USB Power Delivery is required for Alternate Mode negotiation before these pins may be used for any purpose".

    Doesn't sound like headphone power-level or analog to me.