I like to use our Rio Karma MP3 player in the car, but it's not nearly as good as it could be. So here are some jottings on what an ideal car dock would do for the player.
- Power and charge the player, of course
- Offer various options for sending audio to the car, including a built-in quality FM transmitter, a port for a special Cassette sized interface (more below) and various cables for car stereos that have an accessory jack (as mine has for a trunk CD-changer) or plain audio inputs.
- A wireless remote control to stick on the wheel (not needed if other remote control methods can work.)
- A microphone.
- To get really fancy, an 802.11 interface to allow it to sync up with computers inside the house while in the driveway. Though strictly, this would be even better inside the player, not in the dock.
The microphone would perform several roles. One, it would detect the ambient sound level in the car, and boost the music volume as the car gets noisier. No more super-loud when you start the car either.
Secondly, it would listen for the sound of the music the player is playing. It would try to tell if it was playing, so it could detect when the stereo is turned off or switched to something else, or when the car is turned off (if the loss of power from the accessory jack doesn't already reveal this.) When the sound stops (even if this takes 5 seconds to confirm) just pause the music back in time when the sound was first detected to stop. One could then from time to time send out pulses of the forthcoming audio, and if it hears them, treat that as a resumption of play.