I would like to try out the Rode Videomic Pro to see if if improves the audio capture on an iPhone 4.

I have a 3.5 mm TRRS plug ready to make up an adaptor cable. Can anyone confirm that connections at the iPhone end should be like this:

Tip - not connected (left audio output)
Ring 1 - not connected (right audio output)
Ring 2 - ground
Sleeve - bridged left and right mic input

These connections would be necessary for the iPhone to be compatible with an ordinary stereo headphone jack, but what about the switch function that comes with the iPhone headphones that have a built in mic? Does that work as a push-to-short on the mic connection, and if so is there a voltage present between Ring 2 and the sleeve?

Don't want to fry anything on the phone or the VMP.

The VMP end of the cable is fine being standard unbalanced l & r connections for a mono mic via a 3.5mm line jack socket.

Anyone already tried this?

I do know that there are adaptor cables on the market but I'm an old skinflint.

Here is a link to what your after.........
Apple iPhone headphone jack adapter pinout and wiring @ pinouts.ru (http://pinouts.ru/PortableDevices/iphone_headphone_pinout.shtml)

Thanks, Brian - that's exactly what I needed!
I had worked out what it was likely to be but it's reassuring to see it confirmed.

Well, that turned out to be a waste of time. Made up a cable easily enough but the iPhone 4 doesn't seem to take an audio in through the mic connection while recording video. The built in mics aren't disabled when plugging in an external mic.

... from the folks who brought you incompatible / non-standard everything. (Is my bias showing?)

Well, that turned out to be a waste of time. Made up a cable easily enough but the iPhone 4 doesn't seem to take an audio in through the mic connection while recording video. The built in mics aren't disabled when plugging in an external mic.

Well it is a phone isn't it, maybe if you hire a sound recordist that will solve the problem? ;0)

You're looking at the wrong connector. For mic in, you want the docking connector on the bottom of the iPhone. The Fostex AR-4i (http://www.fostexinternational.com/docs/latest_news/EFpkpyAuukEeGfbdUf.shtml) adds external microphones to the iPhone by this route.

And yes, it comes complete with an app for controlling levels, EQ, etc. and a headphone jack for monitoring. It actually looks like a fairly complete solution to adding external mics to an iPhone.

Thanks for the heads up, Bruce. It also looks a good solution for mounting on to monopods and other camera support - certainly better than my first Heath Robinson solution. Will be interested to see what it costs when it's released in the summer.

Nice try Gary - but I could always just use a Zoom H or H4n and sync it up later. Just that even the H2 is several sizes bigger than the phone.

You gave me an amusing metal picture of a set all rigged with lights and a sound guy with all the gear and instead of a camera there's just a phone. Might just do it to annoy the DSLR fraternity :-)

Personally I have an i-fone 4 inside a full rycote blimp to cut down the wind noise, I have then cut a small hole in the blimp so that the pictures can be recorded! ;0)