USB-IF Publishes Audio Over USB Type-C Specifications | Hacker News Reader

USB-IF Publishes Audio Over USB Type-C Specifications

anandtech.com

88 pointsbased287 comments

The USB-C spec is just terrifying. All that functionality. All those pins in a tiny space. High-voltage high-current power, in either direction. HDMI. Analog audio. Even supports USB. Either end can be the master. There's even a protocol to support a tiny display on the cable to tell you what's going on or what's wrong. And some more features I missed. Yes, the mobile handset industry wants to get down to one connector, but they may have overloaded this one.

Nobody is going to get 100% of this right for some time. Coming soon: lots of questions on Stack Overflow that begin "When I plug a USB-C cable between my X and my Y, ..."

Let's also not forget that pure digital USB audio has been around for a long time, and works with any USB connector:

http://www.usb.org/developers/docs/devclass_docs/

The "Audio Class" was standardised in 1998. Many "USB soundcards" have appeared since then, and if the manufacturers really wanted to, they could've just used that standard instead of overcomplicating things by making yet another one.

That's the case already with USB Power Delivery Standard: The dream of "One Wall adapter and one car adapter" to charge all your devices (phones, laptops, battery driven accessories).

Actual situation: not really.

Examples: Apple's MacBook 12 charger delivers non-standard 14.5V and the Dell XPS 13 only accepts 19V. USB PD however allows 5-12-1USB and on top of that the old USB Battery Charging standard with 5V@2A.

Additionaly USB-C allows methods to authenticate peer devices. We will for sure get DRM'ed chargers and whitelisting for some accessories...

IIRC the Apple adapters are variable voltage and will increase up to "18.5V" depending on the load current, but the laptop itself is perfectly happy to receive full voltage --- and slightly more --- all the time.

In fact, laptops that have a 19V adapter will be fine with 20V too, and may actually run slightly cooler because of the lower current draw. I suspect all the funny voltages is just to create differentiation and a sense of lock-in, but the underlying engineering and tolerances on components mean that a 19V adapter may actually be in the range of 18-21V depending on load. It's amusing to find laptop adapters claiming 18.25, 18.75, 19.6, and a bunch of other "why!?" voltages which are technically all in the same tolerance range.

I've written about this before too: https://news.ycombinator.com/item?id=7594383

Some further discussion on MacBook-PSU-related details here: http://www.eevblog.com/forum/repair/replacing-apple-magsafe-...

http://www.eevblog.com/forum/projects/apple-magsafe-power-br... (last post is enlightening)

The real obstacle with the "one adapter for all laptops" is the proprietary DRM-ish ID schemes that a lot of them have, where they may complain/warnin and/or won't charge the battery with just pure voltage input.

Couldn't this DRM-esque stuff be a more innocent reflection of different manufacturers having different protection circuitry on their batteries?

Batteries are behind the charge controller which does have its own way of communicating with and authenticating the battery pack.

The term "laptop charger" is a misnomer; it's just a power supply without any battery charging circuitry.

> Examples: Apple's MacBook 12 charger delivers non-standard 14.5V and the Dell XPS 13 only accepts 19V.

Actually Profile 5 allows anything from 5 to 20 volts so they are both compliant.

I actually wouldn't mind a little white listing.

Folks like Underwriters Laboratory could serve as CAs, issuing certificates for compatibility with different profiles / standards. Then chargers could refuse to throw current at unproven devices.

Of course then you need the ability to boot your charger into some kind of "promiscuous" mode for development or backwards compatibility purposes.

To get REALLY ambitious, your charger could have an Internet connection and monitor a blockchain for certificate information. Some careful protocol design could let users override the DRM at will without letting cheap chinese crap factories ship exploding devices.

> your charger could have an Internet connection

Quoted out of context

> To get REALLY ambitious

Honestly we already have standards for tethering over USB... Still crazy, but it could actually work.

the day when chargers monitor a block chain for certificate information is the day I retire

Yes, but why worry, because adding another new subclass to USB isn't making the situation significantly worse than it already is. Stack Overflow is already full of USB questions.

Because there is already so much confusion about USB 1, 2, 3, 3.1, low speed, full speed, high speed, super speed, super speed+, USB A, micro-B, micro-AB, mini-A, mini-AB, mini-B, USB PD (rev 1 & 2), OTG, MHL, Samsung's 11-pin micro, and even non-USB lightning....

Can it get worse?

> Samsung's 11-pin micro

That’s actually USB 3.0 micro super speed+

All of those however top out at 5V 2.5A.

With this new power spec, that is actually independent of the C plug spec, but unveiled at the same time, can go anywhere from 5V to 20V depending on negotiations between devices.

On top of that the C plug and the data speeds are also interchangeable. So you can get a C plug and 2 speed, or you can get an A plug and 3.1 speed.

It probably could work of one assumes two equally smart devices on both ends, but USB always included shortcuts to allow the cheapest and flimsiest implementation (add a resistor between two pins) by garage shops building Phone chargers for 30¢/piece. And for them, its easy to mess around randomly, until their nonstandard non compliant junk means who-knows-what to a USB-C device.

So, your $300 headphones will pretty certainly work with your $800 iPhone, but plugging them into that $3 (including shipping) charger?

Actually that's a good point. Will we end up needing drivers for headsets if they add any non standard features?

I can't help thinking planned obsolecense when I see these moves.

> There's even a protocol to support a tiny display on the cable to tell you what's going on or what's wrong.

You mean, like the light on the plug on the "computer" end of the Apple magsafe charger cable? Or something more complicated?

Indeed. Rather than have the power spec etc demand a C plug, you can mix the power spec with old A and B plugs. You can even end up with C plugs that only deliver USB2 speeds.

Never mind that C devices actually have to negotiate what side is up, rather than sort it out mechanically.

You mean, nobody will manage to do it exactly as in Lightning?

It is already being done.

Lightning is none of those things.

I don't understand the point about saving space by eliminating the DAC. At the end of the day, to produce sound, we need a DAC. So there will have to be a DAC somewhere. How is creating bigger dongles "saving space". The users have to carry bigger accessories.

It's like Intel's Skull Canyon mini-PC. They miniaturised the PC but the power supply is now nearly as big as the PC. What's the point of shipping a mini-PC with a humongous power supply?

At least in term of Apple, it makes a bit more sense when you consider that apple owns Beats, the best selling Bluetooth headphones in the world, and also that they'll get paid a flat fee for each lightning compatible set of headphones made.

It's about the courage to make lots of money!

Yeah, isn't that what all those personal development gurus were telling us for years? You need courage to be rich!

The courage to lock users in. Apple has that in spades.

Not to mention that you still need DACs to drive the two/three onboard speakers.

Good point!

Although that's technically true, the DAC and the transducer do not necessarily need to be discrete components. There's some super interesting research on digital sound reproduction: https://www.ece.cmu.edu/~mems/pubs/pdfs/ieee/mems/0071_diamo... and I'm aware of at least one company that is (apparently) in fairly late stages of commercialisation (http://www.audiopixels.com.au).

In the mini-PC case I can see it as a positive thing, where you can hide the power supply somewhere and just have the smallish PC box visible. So, to me, the mini PC box makes sense even if it comes with a large power supply.

In the case of the DAC I'm not sure if the end-user will really have any benefit.

I think all the supposed benefits are just a distraction away from the main reason behind this change: it's the corporations trying to slowly close off the analogue hole by moving the more difficult-to-work-with digital signal closer to the user-device boundary, giving them more control over content distribution --- if they could, some of these people would add DRM to your ears and brain or even eliminate the DAC and replace it with a direct neural interface --- all under their control.

If you were using Bluetooth audio, or some other source that accepts a digital feed, previously you'd be carrying around two sets of DACs, one of which would be doing nothing but taking up space. Attaching an analog audio cable to a device already dramatically increase it's size; stashing a DAC and ADC in there doesn't make it much bigger. Moving the DAC outside of the device also means you get less analog interference from other noisy stuff inside your device, like radios.

The mini PC example isn't quite the same; you always need a power source to actually use the thing. That being said, I could imagine the PS being much smaller if you had access to 12V direct current, like in a car. So it's potentially nice to not require NUC people to carry an internal AC->DC when they don't need it.

but you need a DAC for the internal speakers anyway.

Most phones use extremely mediocre DACs. This might actually be better than being stuck with the DAC in your phone.

Yea, let's replace a 3.5mm diameter jack with an 8.4mm x 2.6mm jack. All that space saving!!!!

Note the supported formats are all DRM-encumbered? No Vorbis? no FLAC?

Gotta love that money grab.

After moving audio to USB-C, you only need one jack for charging and audio. Space saved right there. You'll also notice that 3.5 > 2.6, so it allows for thinner phones (for whatever that's worth...).

USB-C also grips the jack on the inside, likely making the connector inside the phone smaller. Please correct me if I'm wrong.

After moving audio to USB-C, you only need one jack for charging and audio. Space saved right there.

You're kidding, right? It's not "space saved" if phones are still hand-sized (or larger); there is plenty of empty space around the edge for two, three, or more ports even after allowing for blank areas to hold onto. A dumbphone from 10 years ago was smaller, yet still managed to include audio and charging/data.

The situation is even more puzzling with laptops and tablets, where the device is obviously large enough to accommodate several full-size USB ports around its edge, and yet manufacturers seem reluctant to add even one; there's also this amusing site: http://www.tabletswithusbports.net/

"You'll also notice that 3.5 > 2.6"

And originally phones came with a 2.5mm plug for audio.

Not a convincing argument you're making, here.

"After moving audio to USB-C, you only need one jack for charging and audio."

Okay, so I'm back to a splitter for audio and power at the same time (which is very often when you're on the road using the GPS on your phone and avoiding local FM stations.)

"USB-C also grips the jack on the inside, likely making the connector inside the phone smaller."

Guess how a TRS jack works?

Which is great, right up until you want to charge the device and use the audio jack. Now we're back to a splitter.

This argument, which was everywhere when apple launched the 7, seems like such a straw man. How often do people actually do this? Me: never. If you are charging your device, odds are good that you are within a foot of your desktop of laptop.

3am saturday morning. Big critical system goes down, multiple teams involved to fix the mess so conference call needed, I get paged into it too.

My phone wouldn't have lasted the 4-5 hours that call lasted without being connected to the USB port at the same time, I fear. :)

I think the trend of designing devices by shedding use-cases until they become good at one very specific thing but almost completely useless at everything else is somewhat unsettling and a bit disappointing. Of course it could go too far in the other direction, but I think sacrificing so much flexibility is not a good solution in the long term.

Then again, the companies probably don't want to put out such flexible devices; they want you to pay for it in the form of extra adapters and such.

Gaming on the go is one example, but also - if you happen to have a workplace that frowns on streaming music, or for some reason decide to use phone as your music source, then you actually want to listen while charging, so that when you leave work you don't have an almost-dead battery.

Four words: power bank + Pokemon Go.

Or substitute ANY popular mobile game, because gaming essentially guzzles your battery, and you don't want your fellow subway riders have to listen to your game. (People actually have gotten violent towards offenders)

On road trips, my phone provides music via a 3.5mm connection and I power it using a charger that plus into my lighter socket, the phone is plugged in via a lightning connector. It also does navigation with the on screen map and directions spoken over the music.

If it were just music it would be ok, but once you want the screen showing a map all the time you're going to run out of juice really fast.

I agree it's not often that I do it, but it does happen. For instance if you're on a plane? Normally I'll have my phone charging via powerbank or USB port, and I'll have my headphones plugged in obviously so I don't annoy everyone.

It's not everyday, but it's still going to be annoying the times where it does come into play.

My wife does this pretty much every night with her iPhone SE. Listens to music on her EarPods while keeping it charged up.

Twice daily. Charge the phone while running a line into the car's aux in.

do they even make car stereos anymore that do not have Bluetooth?

Problem: phones drop standard audio connector.

Solution: buy a new car.

Bluetooth audio quality is lossy and poor, compared to an analog line. Plus, my car's Bluetooth driver crapped out, putting it in a constant "starting up" state that even pulling the battery hasn't resolved.

> Bluetooth audio quality is lossy and poor

Bluetooth audio can be lossy and poor.

The default minimum standard SBC codec is pretty terrible, no doubt, but every device worth using supports many other codecs which are sufficiently high quality for car use. AAC and MP3 are commonly supported, which also happen to be the formats your audio probably is already in. A player focused on quality could, in theory, pass the raw input data over the Bluetooth link for it to be decoded on the car/headphone side. In that case there would be no quality loss, though you'd lose the ability to mix in other audio such as notifications, so I doubt this mode is used by default on smartphones. Dedicated music players may support it.

Since there's arbitrary codec support technically with support from both sides you could also send a lossless stream up to the bandwidth limits. I don't believe there's widespread support for any lossless codecs, but the technology definitely allows it.

Even if you're just using one of the high-quality lossy codecs like aptX you still have to keep in mind the environment. Unless you have an uber-luxury car the noises of normal driving will have more of an effect on the audio quality than the Bluetooth stream. Sure, you might be able to tell the difference when parked, but unless you spend a lot of time sitting around waiting in your car that's not very relevant.

On average, probably four out of five work days a week for me.

My phone already indexes all of my podcasts and audiobooks, why wouldn't I want it to play them everywhere?

Or you can have two general purpose ports.

Or,you know, add another port..

If smartphone manufacturer replace the 3.5mm jack with a USB-C port to save space, doesn't adding a second USB-C port (which will remained unused most of the time) defeat the point and also increase their costs?

For the last year I've been doing exactly that with an iPhone dock. Yes it's an additional accessory, but if you have a $600+ phone plus $600/yr for service then you can probably afford a dock. So, let's move on from this talking point.

So, then you use a splitter. Most people don't do this. Optimize for the many, not the few.

Wouldn't the better solution be to have wireless headphones so you are tethered to the chair while your phone is charging?

The majority of devices that implement type C will likely also have induction charging.

Nope, with faster charge via usb power delivery built in, inductive charging is on its way out. The premise is that a short plug in gives enough charge to keep going. See the nexus line, which used to include inductive charging and dropped it with the usb-c compatible phones.

Sadly, the number of phones with wireless charging have plummeted over the years. There's practically only Samsung left now. It's dead, Jim. Such a shame.

Or, just switch charging to a 3.5mm jack.

The later iPod shuffles did that, if I remember correctly. Not bad except for the fact that some people are going to be plugging chargers into audio-only ports, inevitably causing some damage.

It seems like the spec supports digital and analog audio data. That seems like a potential nightmare for consumers - your headphones may plug in to you phone, but they don't have a DAC, and neither does your phone. Or what if they both have DACs?

I'm sure this will be standardized in the future, and I can see the advantages of dropping the connector. I just really like cool things that can be done with the DACs and ADCs built into people's phones

"The USB ADC 3.0 defines minimum interoperability across analog and digital devices in order to avoid confusion of end-users because of incompatibility."

The article says the headphones would have a DAC. You gotta get those headphone cones pumpin' somehow!

USB type C specification is looking like the F35 specifications: able to do everything.

Jack of all trades often are masters of none, and audio is a little sensitive topic in electronic ; it does not need a big bandwidth but it hates lag, and non guaranteed time slices and it hates noisy background.

If Audio in this case do works without surprises I will be surprised and will admit that I was a miscreant unbeliever.

Still putting smartness in a device that is so far from the CPU violates some clear common sense in async handling in the realm of hardware for time critical devices...

An interesting confluence; Headroom just published an article about attempting to use a dongle, and the cost to the sound quality.

https://www.headphone.com/blogs/news/this-is-the-dawning-of-...

Not the best comparison, but a good quick overview of the "state of the art" right now.

Allowing support for analog over the SBU pins and pure-digital sounds like it will cause confusion and support headaches when people buy cheap analog-only headphones and try to use them with a digital-only device...

The analog audio is the supposedly less common and it still requires some digital hardware in the connector to negotiate the move. Might add well put a small cheap DAC and amp in.

I'm pretty sure analog only headphones will become quite rare. Still much better than forced digital only.

Analog-only headphones (mid-range to high-end ones at least) will never go away. People who care about having good headphones also care about having an equally good DAC and amplifier to go with them, and they're not going to be willing to pay the premium for decent ones every time they buy a new pair of headphones (good DACs and amplifiers are NOT cheap), nor will they be willing to pay for a mediocre DAC that they never use.

It would be suicide for headphone companies to stop producing analog-only headphones, unless they can force everyone to scrap their analog-only sources (it might be possible with consumer toys like smartphones, and they might be able to convince gullible audiophiles if they can find the right marketing gimmick, but it will never happen in the professional world).

And what about all of the analog-only headphones already in use? Quality headphones are not disposable products (they can last for decades when properly maintained), and nobody in their right mind is going to throw them out until every last analog output in the world has been magicked out of existence.

> good DACs and amplifiers are NOT cheap:

You consider "a few dollars" as not cheap? https://para.maximintegrated.com/search.mvp?fam=precision-da...

Anyway it doesn't matter. If you want the best quality, the source (i.e. the phone) has to feed a digital signal.

Then it's turned into sound by either a $10 earphone or a $1000 Hi-Fi system. How well that external device amplifies and generates the sound is up to that external device, they both get the same (good) quality source.

And if your sound system doesn't support digital, you can get a USB-to-Jack35 converter.

Here we are talking about saving space, so that's mostly on mobile devices. And irrespective of its quality, I don't think one can expect headphones that one carries around every day in one's pocket to last decades. I purchase reasonably good quality ones, but have to replace them every year. Which is also why I am not excited with those becoming even more expensive.

The main grief I have is rather interoperativity. Right now I have a single set of headphones that I can forget on my pocket and that will work on any of the devices I use: ipad when traveling, home laptop, iphone, work desktop. Apple is introducing its own format. Intel is introducing its own. IT in my company will not replace my desktop for another 5 years. I will end up having to use 3 different headphones or have a pocket full of dongles.

Yeah, they won't go away, but they probably won't change to use a USB C connector. Instead they will stay at 3.5 or 6.3mm. That means you need an adapter anyway to connect those headphones to the device.

Now there's the valid question why you want to produce a passive adapter that is only working with devices that support analog audio on USB C instead of producing an adapter with a DAC that works on all USB C devices. I guess the answer is as usual: Price. The manufacturers might be flooding ebay and co with supercheap adapters. And the end users will as usual have trouble to find out which ones will work with their phones and which not.

> The analog audio is the supposedly less common

Maybe in the future, but there is like billions of analog headphones already in the wild.

I can easily imagine appearance of semi-passive (only the negotiation logic) USB-C to jack adapters which would have exactly the kind of problem parent described.

And face it, even if the standard prohibits such devices, they will still be made because there is a need for them. See USB A-A extensions cables.

Adding a DAC to that semi-passive adapter wouldn't make it prohibitively expensive.

Even if manufacturing costs doubled, I doubt sales prices and, with it, sales numbers, would go up much, if at all because margins on this kind of cable typically are enormous.

So if analog audio support is optional and all headphones are required to support digital, why would a vendor actually bother to implement analog output?

The niche audiophile market will pay large sums for questionably effective hardware.

For anyone doing serious audio work, being able to change your DAC might be nice.

I agree though, the justifications seem shaky

I agree that there are benefits to consumers to have an analog interface - I just don't see any incentives for vendors to implement then. (Aside from vendors serving niche markets as you described)

Does this imply that "audio over lightning" is on the way? I'm looking at you, Apple.

I'm not sure what you mean. I use this every day in my car.

In your car's situation you are sending digital to your car stereo and its decoding and sending to your speakers. I believe OP was referencing analog audio.

Thanks for clarifying. Yes, I mean a little adapter box that I stick on the end of my iPhone that converts from digital to audio, so I can use my regular 1/8" aux cable for headphones.

Isn't this exactly what the adapter that comes with the iPhone 7 does? Either that or there's analog over lightning.

Will this support existing devices with USB type-c?

The comments associated with that article are abysmal.

Standard Internet tech blog comments really. On a higher plane than Engadget/Gizmodo/Verge comments, but still dominated by enraged teens who really really want to prove to everyone that the phone their parents bought for them is better than the phone someone else's parents bought for them.

In the Usenet days, there were comp.*.advocacy groups created specifically to absorb those kinds of discussions, but nowadays every comment section everywhere is an advocacy group. Lousy comments beget more lousy comments and drive away good comments.

> Lousy comments beget more lousy comments and drive away good comments.

Solving this problem would make for quite a company.

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