JavaScript Headphones Button

An attempt in using WebAudio API on a phone with a TRRS jack headset to detect button presses on the headset. If the headset shows up as a possible input stream in the WebAudio API, it should be possible to detect input pattern of the button press. Analyzer node with getByteFrequencyData and getByteTimeDomainData buffers in a requestAnimationFrame should be enough to tell.

This should bridge the gap between native APIs and web APIs. Both Google's Android and Apple's iPhone provide programmatic ways for listening for the headphones button press in an application:

• The Google API
• The Apple API

Conductor	Channel (Nokia)	Channel (Apple)
Tip	Left Out	Left Out
Ring	Right Out	Right Out
Ring	Microphone In	Ground
Sleeve	Ground	Microphone In

Findings

House of Marley Liberate XLBT - midnight with Google Chrome Android 64 do not show any specific pattern when pressing the headphone button. It appears as though the pulse is either too short to notice or the phones goes by the press-sound recording from the microphone matching. The phone is able to interpret the button press.

This is most likely because the headset button is handled at the OS/soundcard level and the browser only gets the audio stream.

https://electronics.stackexchange.com/a/242885/116328

Running

Prerequisite	Version	Purpose
Python	2.7	HTTP Server

python -m SimpleHTTPServer

On Bloggo

Testing

Use an Android phone on the same network with a TRRS jack.

Prerequisite	Version	Purpose
Chrome	63	async/await, WebAudio API
Jack	TRRS	Microphone input

On the phone go to http://(computer-local-ip):8000. Use chrome://inspect to use Chrome DevTools on the phone. You may need to enable Developer Mode on the phone as well as USB debugging. Ensure you have up-to-date version of Chrome on the phone.

To-Do

Log into the Google account on the Android phone and update Chrome

Try this out and document results