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Question

Is there a way to "pipe" video output to either audio left or audio right in the auxiliary port? Such that the audio cable from the RCA needs to be plugged into the video port on the TV.

Background

I bought the wrong 3.5mm to RCA adapter. I have the "standard" one which outputs only audio. If my understanding is correct (from searching and fiddling) then the 4 poles on the correct jack is as follows.

╭ ╮
│ │ ← Audio left
├─┤
│ │ ← Audio right
├─┤
│ │ ← Ground
├─┤
│ │ ← Video (On ones without video this is also ground)
┘ └

My jack is like this though.

╭ ╮
│ │ ← Audio left
├─┤
│ │ ← Audio right
├─┤
│ │ ← Ground
│ │ ← (Notice this is all one section.)
│ │ ← Also ground
┘ └

I am able to put it "two notches" in so that the audio right cable has the video output, all I need to do is take a wire from a GPIO ground pin and touch it so the ground portion of the jack, but this is really annoying.

 ╭─────╮
L│     │
 ├     ┤
R│     │
 ├ ╭ ╮ ┤
G│ │L│ │
 ├ ├─┤ ┤
V│ │R│ │
 ┘ ├─┤ └
   │G│
   │ │
   │G│
   ┘ └
3

No, there is no way to do this. While carried on the same connector the audio and video signals come from totally different places and there is no way the audio output circuitry on the Pi could possiblly generate a composite video signal.

  • There's gotta be some way, it may be impractical or there may be a delay when it's done in real time though. They are all the same types of connections. You can plug them into the wrong holes and see/hear static, so couldn't you do some encoding to some audio/video so when it's put through the opposite it appears/sounds correct? E.g., Take a video, "encode" as sound (would sound garbled if played through speakers), output the audio cable to video port, the video plays correctly. – Captain Man Apr 20 '17 at 14:36
  • 1
    Not going to happen. Firstly video signals need to be DC coupled to correctly encode the sync signals while audio outputs are nearly always AC coupled. Secondly the sample rate and analogue bandwidth of audio output circuits is way too low. – Peter Green Apr 20 '17 at 14:44
  • I see, thanks for the input. I'll just go buy the right cable instead! – Captain Man Apr 20 '17 at 14:57
  • When you're considering questions like this you can often find useful hints in the Pi schematics. For the Pi 3, for example, the 3.5mm jack diagram is the rightmost on the bottom row (labelled 'A/V'). You can see from that that the composite video line (COMPAV) is distinct from the audio lines, and heads off to a completely different region of the board somewhere. – goobering Apr 20 '17 at 19:02

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