The Raspberry Pi Model B+ has a common 4-pin jack plug for audio and video signals. The datasheet or the circuit diagram of the model B+ shows the following picture detail for the assignment of the jack socket:
|1 (plug)||2||3||4 (top)|
|video||Ground (GND)||Right (right audio channel)||Left (left audio channel)|
The assignment is identical to the Apple iPod. However, not with the iPhone or iPad. There is no video output, but a microphone input, but the Raspberry Pi does not. Audio Enhancements The analog audio output of the Raspberry Pi is extremely bad. Noise, humming and a miserable sound are simply no fun. If it goes beyond experimentation, then audio extensions for GPIO or USB are recommended.