Plenty to do, still, with this project. The main questions generally involve what OTS cables should be supported, if any. With a software-configurable AV switcher & the proper configuration, the shield could be compatible with any analog 3.5mm AV cable you might find. That said, it may be best to just support the following design & modes:

Two 3.5mm jacks:

  • one for modes:
    • Standard Analog Audio
      1. av-bus-audio-left
      2. av-bus-audio-right
      3. av-bus-common
    • Standard Analog Headset
      1. av-bus-audio-left
      2. av-bus-audio-right
      3. av-bus-common
      4. av-bus-audio-mic
  • a second jack, for modes:
    • Standard Definition:
      1. av-bus-audio-left
      2. av-bus-audio-right
      3. av-bus-common
      4. av-bus-composite
    • High Definition:
      1. av-bus-component-pb
      2. av-bus-component-pr
      3. av-bus-common
      4. av-bus-component-y

Notes:

  • The Standard Analog Headset mode should, ideally, support the analysis of basic on-headset remote commands (e.g. volume up/down & play/pause). These signals could be analyzed on the shield & sent to the C.H.I.P. digitally.
    • The control signals should be sent to C.H.I.P as standard keyboard "media" key presses.

Reference: