Essays on Technology and Culture

Dongles and DRM in the Wireless Audio Future

The furor over the iPhone 7’s headphone jack, or lack thereof, seems to be fading. It was doomed to be a non-issue anyway, so I’m not surprised. This is, in part, because Apple was so far out in front of the reveal, and because it’s a minor inconvenience at worst. Charging and listening via wired gear at the same time is still a concern, but solutions will come down the pike for that. Just wait a month or two, or join us happy Bluetooth headphone users in the wonderful world of wireless listening. You don’t even need $160 AirPods to do it.

But there’s still some cause for concern with the removal of the headphone jack. It’s just not the concerns I hear a lot of people screaming about. While I’d need to see a teardown to be certain, evidence suggests that the Lightning to 3.5mm Headphone Jack Adapter is about as passive as you can get with a Lightning dongle. It probably consists of a Lightning adapter chip, a Digital to Analog Converter, and an Analog to Digital Converter for the microphone on your headset. Square has already come out and said their old 3.5mm headphone jack-based card reader works with the dongle. Other devices that input audio via that jack should work fine, albeit in mono. [1]

I’ve heard some people float the idea that there could be a DRM lockout in future iPhones, or future versions of the dongle, to prevent unauthorized devices. That’s not likely giving how the headphone jack works. As long as there’s conversion of digital to analog along the path to the speakers, there’s a way to tap it. Even high-resolution, 192k/24-bit audio can be output over 3.5mm, as long as it’s stereo. The PonoPlayer doesn’t have any fancy outputs, just two standard 3.5mm jacks, one amplified and one not. Perhaps there might be a kill switch not to allow output via the Lightning to 3.5mm Adapter, but why? It could easily be bypassed with a third-party adapter, and all Lightning headphones would have a DAC in them anyway. You’d block legit users and potential pirates alike.

Any potential DRM risk is around other audio formats beyond stereo output. Let us imagine a future where Apple Music provides 5.1 surround sound audio. This is a bit preposterous on the face of it, but work with me. While there are “5.1” headphones, they connect over USB, since you can’t output 5.1 sound through the headphone jack. You can, however, output 5.1 through an optical audio port, and most modern Macs combine optical audio and 3.5mm phone jacks, via the Mini-TOSLINK optical audio connector. The hardware overhead of optical audio, however, makes me doubt there will ever be a Lightning-to-Mini-TOSLINK Adapter.

If you want to listen to 5.1 audio out of your iPhone, you’ll have to hook it to something via Lightning. It would be, at least theoretically, possible to capture each channel of the 5.1 signal after it passes through the DAC, but that’s a lot of work for minimal gain. Plus, I have my doubts Apple will ever bother with 5.1 audio on the iPhone or iPad. If streaming and wireless are the future of audio, bandwidth is too constrained to make high-fidelity and 5.1 worthwhile for the near-future. More importantly, most consumers don’t give two shits about high-fidelity audio or surround sound anyway.

So, I’m not worried about a DRM lockout in a headphone jack-free iPhone ecosystem. Unless Apple decides that you can’t connect any old DAC to a Lightning port, or forces everything to go over Bluetooth or a proprietary wireless method, we’ll be in good shape. When it comes to portable devices and audio, the future is wireless, at least for listening. As long as there’s a supported way to get audio out and audio in—which Lightning supports—over wires, things are going to be okay.

  1. This is a limit the headphone jacks have on all iPhones. The TRRS standard commonly used on smartphones has only four contacts: left audio, right audio, ground, and microphone.  ↩