
USB-IF Publishes Audio Over USB Type-C Specifications - based2
http://www.anandtech.com/show/10719/usbif-publishes-audio-over-usb-typec-specifications
======
Animats
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, ..."

~~~
ce4
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...

~~~
edraferi
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.

~~~
madeofpalk
> your charger could have an Internet connection

~~~
witty_username
Quoted out of context

> To get REALLY ambitious

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

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cm2187
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?

~~~
andai
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!

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

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lightedman
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.

~~~
greenpresident
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.

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

~~~
hyperbovine
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.

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

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

~~~
falcolas
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.

~~~
wolrah
> 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.

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highd
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

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

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SFJulie
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...

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falcolas
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-...](https://www.headphone.com/blogs/news/this-is-the-dawning-of-a-new-era-
for-portable-devices)

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

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kalleboo
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...

~~~
AstralStorm
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.

~~~
blockoperation
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.

~~~
user5994461
> good DACs and amplifiers are NOT cheap:

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

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.

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xg15
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?

~~~
TOMDM
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

~~~
xg15
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)

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

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

~~~
notyourwork
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.

~~~
nerdponx
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.

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

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lyonlim
Will this support existing devices with USB type-c?

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notyourwork
The comments associated with that article are abysmal.

~~~
mwfunk
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.

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

Solving this problem would make for quite a company.

