News USB-IF announces Audio over USB Type-C standard

April 2015: http://www.letvmobilestore.com/news/leeco-le-2-super-phones-no-3-5mm-earphone-port/

LeEco / LeTV (whichever one they go by today) actually has since launched phones with a 3.5mm port again, which may well be an indication that the phones without one didn't really make potential buyers throw money at them...

 

You can make USB "soundcard" as simple or as complicated as you want.
USB Audio class (UAC1) has been specified since USB 1.0. In this class raw(PCM, max 96kHz@24b stereo) audio data is transferred isochronously (in real time , just dump that datastream to DAC), it also specifies controls for volume, mute, etc. You don't need special drivers for that, pretty much all OS'es support it out of the box (Android since v5).
UAC2 was standardised in 2006. It reduced the latency from 4ms to 500us, added DSD encoding, increased bandwidth (more channels at higher sampling rate). Windows and android don't support it out of the box, ios/osx/linux do and vast majority of users don't really need it.
And now we have UAC3, "a new standard specifically for digital audio"....

I'm guessing the real reason for this push, as always, is money - now headphone manufacturers will need to pay for vID, for use of USB logo and prob for UAC3-compatible stamp.

 

Analog passthrough for USB Type C was included in the standard released years ago. From P.175 Section A.1:

A standard for USB DACs is nice, as the current state of USB DACs over USB OTG is a bit of a mess. For those worried aobut analog output, that was in the standard all along.

 

So to clear things up.

We now have this digital standard, but we can also pass analog audio through USB Type C?

Because that's pretty cool if the case. I'd have no qualms with USB type C replacing standard audio jacks, you could just use a small adapter for existing equipment (like we already do on so many headphones, even high end ones). It's one more cable down the drain, can't complain about that. Plus it's an opportunity for snake oil merchants to rip off audiophiles with stupid things like solid silver cables, so they get their fill too.

 

LOL at the article tags. I thought us commoners weren't allowed to edit them in this forum.

 

I'm almost certain that clicking the edit tags button and trying to add new ones used to cause a permissions error in your article threads specifically. Maybe I'm just gone mental.

 

I haven't actually used a type C cable before so didn't know that. I'm an iPhoner so the closest I use is the lightning cable, I sort of assumed that Type C was similar enough. Is it actually a bit flimsy?

 

The spec has provisions for passing analog audio signals over the unused pins (you only need the USB 2.0 lines for digital audio). This was talked about at IDF 2016, and Anandtech covered it here

I've used both microUSB and USB-C with power packs, and both have held on fine in my pocket, including when I've piulled the phone out by the cable. I will, however, say that a proper USB3.x USB-C cables have a much longer connector than the USB2.0 USB-C cables, purely because of the active electronics in the cable, so if you're buying extra USB-C cables for your devices, do keep that in mind.

Far more annoying to me is that HTC and Sony put the headphone port at the top (ffs guys, it's so much nicer to store your phone in your pocket upside down so you can pull it out and have it the right way up already) than the USB cable dropping out.

Thanks to that annoyance and the fact that my current headphones have a broken cable, I have gone the bluetooth route now (since I don't care about sound quality outdoors or in a car...). Why not USB-C you ask? IMO the USB-C market is far too immature right now.

 

Hmm.. this may require digging into the spec itself to confirm then.. As I interpreted it, it was part of the digital audio spec, but optional.

 

I see where this could be going, but I want a phone that I can hold at the sides without slicing through my fingers. Yes, make it flexible, but no so thin it blows away in a breeze. And maybe give it a battery that lasts more than a day.

 

Just had a browse through the various specs.. Looks like they are indeed seperate specs.

That said, the analog mode USB-C output had made it into the spec before the digital audio part was even finalized, so I expect most devices that go USB-C-only to have a passive analog adapter.

The complete spec is still a bit out of date though, so I have no clue if the analog fallback is mandatory or not. Give it a week and the global spec should pull the digital audio extra in and we'll know for sure.

 

The problem this raises for me is to do with Jack durability. Any socket, port, or jack has a finite lifespan and the more it gets used the shorter that lifespan is. Add the abuse element in and you get a situation where the connector dies before the phone does.

When every function of the phone (ie charging, audio output and data transfer) has to go through the same connection then it will wear out that much faster and be more likely to be damaged.

We already have this problem at work where each vehicle has an assigned phone (Samsung S3s and S4s). The vehicles are on the road almost constantly and more and more of the phones have broken USB connectors and can't be charged in the vehicle. This means we have to carry spare batteries and disassemble the phone part way through the shift in order to keep using it. Currently we also use credit card readers that interface via the 3.5mm jack, and in addition to these already being unreliable, if they we're dependent on the USB port they too wouldn't work.

 

The best thing to do in your case would be to make a very small extension lead that you leave plugged into the phone, and then connect and disconnect from the other end, thus saving the phone connector and wearing out what should be a very cheap consumable cable. I'm assuming the phones are tied to the cars and are not used when outside the vehicle.

 

For all of my complaining about it, could do with this right about now, since my new phone doesn't seem to want to pass audio to my car over USB, so I'm stuck with Bluetooth for the foreseeable future :/

I think in the long term this is probably a good thing, but between now and 10 years from now, there's going to be a transition period which may prove to be a restrictive pain.

 

I refuse to be excited over a new way of connecting something that already works well. Give me an advance in battery tech any day.

In addition, using one port for everything, regardless of the "wearing out" argument, limits use of the device. They'll need to add more than one of any port to retain usefulness whilst charging, for example.

"Sorry, Mum - can't talk. Not because the phone is dead, but because I'm charging it. So in effect, yes, it's dead."