Audio Over USB-C Specification Published (Analog and Digital Possible)

[LAwLz]

USB-IF has now publiched the USB Audio Device Class 3.0 specifications. It is meant to standardize audio over USB Type-C and act as a replacement for the 3.5mm headphone jack.

The most interesting part of the specification, in my opinion, is that it allows for analog audio over the USB connector. What this means is that apart from needing an adapter for backwards compatibility, there won't really be any drawbacks with the move to USB for audio.

 

The specification allows for the regular USB type-C connectivity to take place at the same time as analog audio. So you can (with the help of an adapter, hub, dock, or whatever), send analog audio at the same time as you send files over the same connector (it uses the SBU wires for analog audio). Analog over type-C will also be easy to implement.

 

 

 

It's not all fine and good though. Analog over USB type-C is optional, and since the standard was not out until now it will not work for current type-C devices. This makes one of the biggest issues with USB type-C even bigger. The issue being that there are so many optional modes that you will have to research quite a lot if your two USB type-C devices will support each other, and the average user will be very confused about why their new (analog) type-C audio devices will not work with their Galaxy S7 for example (does not support analog over type-C).

In order to help with this issue a bit, all Audio Device Class 3.0 devices has to support "headset adapter devices" (as in, analog over the USB connector). Not all USB type-C devices will be Audio Device Class 3.0 though.

 

 

All digital USB type-C headphones will require a "Multi-function Processing Unit" (MPU for short). The MPU is responsible for things such as negotiation, synchronization, digital-to-analog conversion, noise-cancellation, volume control and all the other tasks required for audio over a digital connector. This requirement is an effort to standardize features, quality and compatibility for future USB type-C headphones. This will hopefully avoid a situation where some headphones only work on Samsung phones, some only on Asus motherboard, and so on. These chips will also contain the amplifiers.

A few of these MPUs have already been announced but prices of them are still unknown, and it is not certain that they are Audio Device Class 3.0 compatible.

 

 

 

 

Source: Anandtech

 

 

I am fairly OK with this. The biggest drawback of moving to USB for audio was in my opinion the fact that it was digital (which has a ton of drawbacks for audio). With the analog now being an optional mode (and mandatory if you want the USB audio classification) then that issue might not be so big after all. Passive adapters should be very, very cheap to make and a lot of manufacturers will probably throw an adapter in for free with new headphones.

 

Using the same port for charging and audio will be a pain though, and I doubt phone manufacturers will want to add the (big) complexity increase of having two ports.

[tlink]

USB type c is such a mess, they should just make different types already and standerdize those. just make 5 tiers of usb c connectors and let manufacturers choose from that instead of this mess. its like intel calling their M cpu's as i5's etc. it just creates an unsafe buying envioment for consumers because they dont know what the hell they are getting when it says "usb c connector"

[Misanthrope]

If the standard allows for no extra cost on the headphones (With direct analog wiring it shouldn't) and it sounds ok (no reason to think it shouldn't) I think that this is finally reasonable. Too bad smartphone makers jumped ahead of this to catch all the unnecessary grief.

[DrMikeNZ]

2 important questions IMO that manufacturers need to ask before dropping 3.5mm.

1. Does USB-C fit firmly into the device like 3.5mm well enough so it won't fall out.

2. Will phones get 2 (or more) USB-C ports before they take away the 3.5mm jack.

[zMeul]

the drawback is exactly the same as for the iPhone 7 - the need for an adapter

• you can't listen to the headphones same time as charging or doing anything that requires the USB port at the same time
• existing USB type C interfaces out there aren't even remotely compatible with this new spec, making them obsolete

USB type C is becoming a nightmare

[Prysin]

this is neat, but i have to agree with @zMeul that they are causing too much confustion

[Hunter115]

25 minutes ago, tlink said:

USB type c is such a mess, they should just make different types already and standerdize those. just make 5 tiers of usb c connectors and let manufacturers choose from that instead of this mess. its like intel calling their M cpu's as i5's etc. it just creates an unsafe buying envioment for consumers because they dont know what the hell they are getting when it says "usb c connector"

are there different standerdize usb c standards (Gen1,Gen2)

[Misanthrope]

10 minutes ago, zMeul said:

the drawback is exactly the same as for the iPhone 7 - the need for an adapter

• you can't listed to the headphones same time as charging or doing anything that requires the USB port at the same time
• existing USB type C interfaces out there aren't even remotely compatible with this new spec, making them obsolete

USB type C is becoming a nightmare

1) That's just their stupid design though: Phones used to have 2 or even 3 different ports at one point (headphones, data and power) there's no reason why they can't make a dual USB type C phone, other than Apple and their stupid decisions and Samsung copying every fucking thing they do.

 

2) Existing USB type C interfaces are fucked yes, but I'd argue that they're really not that many so fuck em. Early adopter's tax I'd call it.

[Sauron]

Well, it beats having samsung and apple splitting the market with proprietary nonsense.

[tlink]

3 minutes ago, Hunter115 said:

are there different standerdize usb c standards (Gen1,Gen2)

that is usb 3.1 not usb type c.

[Hunter115]

hopefully smartphones have two type c ports (probably not)

[Hunter115]

1 minute ago, tlink said:

that is usb 3.1 not usb type c.

ok thats fucking weird

[tlink]

Just now, Hunter115 said:

ok thats fucking weird

worst of it is that usb 3.1 gen 1 is just usb 3.0

[Hunter115]

this musst be a nightmare for sales Persons with all the different specs and also thunderbolt 

[rattacko123]

They should have a requirement so that the manufacturer declares what the USB-C supports. There should be generations as well, so currently it should be gen 1. For example for a cable they should say whether it supports the gen 1 standard and whether it supports usb 3.0 or 3.1 and thunderbolt 3

[Doobeedoo]

Ugh, USB Type-C is in a bit mess indeed. Couldn't they just waited a bit, sorted it and just publish it as just one and the only connector, not so many different to confuse everyone. Also it departs from being next universal cable.

[zMeul]

2 hours ago, Sauron said:

Well, it beats having samsung and apple splitting the market with proprietary nonsense.

right now, Apple's Lightning connector sounds better - it's a single standard

USB type C is a mess ... multiple generations, spec that are still being added to it

[Sauron]

44 minutes ago, zMeul said:

right now, Apple's Lightning connector sounds better - it's a single standard

USB type C is a mess ... multiple generations, spec that are still being added to it

But it's an open standard, it has the potential to become the go to once they figured out all the versions. lightning will only ever be on iStuff. I don't want a situation where I have to buy headphones based on what brand of phone I'm using at that time and then have to adapt it even for my desktop, which in my mind should be the jack of all trades in this regard.

[zMeul]

9 minutes ago, Sauron said:

But it's an open standard, it has the potential to become the go to once they figured out all the versions. lightning will only ever be on iStuff. I don't want a situation where I have to buy headphones based on what brand of phone I'm using at that time and then have to adapt it even for my desktop, which in my mind should be the jack of all trades in this regard.

open standard like open source - there is a moment when proprietary is better

right now, type C is all over the place

 

the moment they fucked with the connector, just because they wanted it reversible, it's the moment that fucked type C

and, in their infinite wisdom, the released hardware wasn't even final spec

[Sauron]

8 minutes ago, zMeul said:

open standard like open source - there is a moment when proprietary is better

right now, type C is all over the place

 

the moment they fucked with the connector, just because they wanted it reversible, it's the moment that fucked type C

and, in their infinite wisdom, the released hardware wasn't even final spec

I don't think proprietary is better when it comes to something as widely used as an audio port. LVDS interfaces, fair enough - audio connectors, please no.

 

If completely open is not an option, at least make it available for use by others like HDMI. Wether type-c is ready or not is a legitimate concern but we need it or something that can fill that role if we don't want to go crazy over something as common as audio equipment.

[Misanthrope]

1 hour ago, zMeul said:

right now, Apple's Lightning connector sounds better - it's a single standard

USB type C is a mess ... multiple generations, spec that are still being added to it

Is Apple willing to license it out to others? Can I call Apple and say "Yo fam, your shit's cool but ima compete" and request their standard to be used elsewhere?

 

And I don't mean third party accessories that might just go "fuck this" and release lightning connector stuff regardless because they have the built-in market of iphone owners. I mean a standard other companies can push.

 

And yes this is a legit question since I know they've collaborated with Intel and others for firewire and thunderbolt even though it hasn't caught on too much, I'm not sure if they're willing to do the same with the lightning connector. Because if they are then you legit have an excellent point indeed.

[The Benjamins]

4 hours ago, LAwLz said:

USB-IF has now publiched the USB Audio Device Class 3.0 specifications. It is meant to standardize audio over USB Type-C and act as a replacement for the 3.5mm headphone jack.

The most interesting part of the specification, in my opinion, is that it allows for analog audio over the USB connector. What this means is that apart from needing an adapter for backwards compatibility, there won't really be any drawbacks with the move to USB for audio.

 

The specification allows for the regular USB type-C connectivity to take place at the same time as analog audio. So you can (with the help of an adapter, hub, dock, or whatever), send analog audio at the same time as you send files over the same connector (it uses the SBU wires for analog audio). Analog over type-C will also be easy to implement.

 

PIC.jpg

 

It's not all fine and good though. Analog over USB type-C is optional, and since the standard was not out until now it will not work for current type-C devices. This makes one of the biggest issues with USB type-C even bigger. The issue being that there are so many optional modes that you will have to research quite a lot if your two USB type-C devices will support each other, and the average user will be very confused about why their new (analog) type-C audio devices will not work with their Galaxy S7 for example (does not support analog over type-C).

In order to help with this issue a bit, all Audio Device Class 3.0 devices has to support "headset adapter devices" (as in, analog over the USB connector). Not all USB type-C devices will be Audio Device Class 3.0 though.

 

 

All digital USB type-C headphones will require a "Multi-function Processing Unit" (MPU for short). The MPU is responsible for things such as negotiation, synchronization, digital-to-analog conversion, noise-cancellation, volume control and all the other tasks required for audio over a digital connector. This requirement is an effort to standardize features, quality and compatibility for future USB type-C headphones. This will hopefully avoid a situation where some headphones only work on Samsung phones, some only on Asus motherboard, and so on. These chips will also contain the amplifiers.

A few of these MPUs have already been announced but prices of them are still unknown, and it is not certain that they are Audio Device Class 3.0 compatible.

 

 

 

 

Source: Anandtech

 

 

I am fairly OK with this. The biggest drawback of moving to USB for audio was in my opinion the fact that it was digital (which has a ton of drawbacks for audio). With the analog now being an optional mode (and mandatory if you want the USB audio classification) then that issue might not be so big after all. Passive adapters should be very, very cheap to make and a lot of manufacturers will probably throw an adapter in for free with new headphones.

 

Using the same port for charging and audio will be a pain though, and I doubt phone manufacturers will want to add the (big) complexity increase of having two ports.

Uh the spec does not once mention USB type C or Analog output though a USB interface. were did you get this information from. and any legacy devices with use ADC 1.0 (1998) or ADC (2006) so compatibility should be a issue.

 

EDIT it mentions analog output though a USB interface. but does not go into any detail about it.

 

You should remove USB type C from you post and title it causes confusion. USB type C is a physical interface.

[captain cactus]

This is dumb.

 

Let's take the MacBook as an example. It has one USB-C port. It handles, among other things, a USB 3.0 signal. The new MacBook Pros are rumoured to only have USB-C ports with Thunderbolt on them as well. There's your problem. One device can handle Thunderbolt connectivity, the other one can't, yet they still have the same port making the not-so-tech-savy people think one will work with the other while it just won't. Adding this audio spec (both analog and digital which is completely retarded since a "digital audio" signal has to be converted to an analog one anyway at some point so why even bother with having "digital audio" coming out of the bloody port anyway) into it makes it even worse because it adds yet another connectivity standard to a plug that already has more than one version on it.

 

This is why you have multiple connectors for multiple standards. A 3.5mm jack for audio. USB for file transfers. HDMI/DVI for display stuff. Trying to shoehorn everything into one plug but then not change the plug when new functionality is added will only result in confusing as fuck situations where people think their device will work on all other devices with a USB-C plug because it has that plug. The USB-C port wants to become an industry standard but it's fucked beyond recognition before it's even mainstream. 

[abazigal]

Is it safe to assume that cramming more functionality into the USB-C port will increase its price? If so, I foresee a situation where the USB-C port on higher-end, more expensive laptops might sport more functionality than the same port on a lower-end laptop. 

 

Sounds messy. 

[LAwLz]

1 hour ago, The Benjamins said:

Uh the spec does not once mention USB type C or Analog output though a USB interface. were did you get this information from. and any legacy devices with use ADC 1.0 (1998) or ADC (2006) so compatibility should be a issue.

 

EDIT it mentions analog output though a USB interface. but does not go into any detail about it.

 

You should remove USB type C from you post and title it causes confusion. USB type C is a physical interface.

The title is correct. This specification was specifically designed for USB Type-C, and will in fact only work over Type-C because it uses the SBU pins for the analog audio. Those pins only exist in the Type-C connector.

 

 

 

42 minutes ago, abazigal said:

Is it safe to assume that cramming more functionality into the USB-C port will increase its price? If so, I foresee a situation where the USB-C port on higher-end, more expensive laptops might sport more functionality than the same port on a lower-end laptop. 

 

Sounds messy. 

It would not necessarily increase the price of USB type-C ports, because these things are optional. That's why it is so messy though. There are a ton of different things which can run over USB type-C, such as HDMI, DP, analog audio and so on, but manufacturers are free to implement whichever parts they want. What this means is that not all USB type-C ports are created equally.

So on one phone the USB type-C connector might be able to plug into your TV and send HDMI over it, but another phone with USB type-C might not be able to do the same.