This is a long shot ... but there may be someone who has done something like this before. I have an ancient CD player which my wife likes to use. I'd like to be able to detect when it starts playing to trigger a flow I can configure to ensure the playback amp is powered on and the right input selec…

It is not clear to me how the external CD player is “connected” with your raspberry pi.

I think he is suggesting using an audio feed to do it... but then if the amp isn't switched on how would the Pi hear the audio in the first place... catch-22.

[image] HonestJohn61: I was wondering if the RPi4 could detect an audio stream if I got an analogue to digital USB soundcard I would expect that if everything is setup well and you use pulseaudio (you might need to install it) that you would see at least an extra pulseaudio source (= audio in…

The cd player could be plugged in to a smart socket which can monitor power consumption. My node-red knows when my coffee machine is on because the smart socket sends "current consumption" 1200W. Not sure how well it would recognise a low power device.

@janvda @jbudd I suspect those solutions would just detect that the player was powered and connected to the pi, rather than actually playing.

Thanks for taking the time to make these suggestions. I was initially thinking that USB audio devices are cheap and easily available, but the software side is perhaps tricky, if not impossible. Also there's a lot of CPU overhead listening all the time when all I'm after is an infrequent change of st…

Can you hack the player? If so, you could inline a sensor that detects power to an LED that comes on when the device is playing, or similar. Or, if there is a physical play button that gets depressed, add contacts underneath it.

Or attach a light sensor over the front of the LED.

[image] HonestJohn61: I'd like to be able to detect when it starts playing to trigger a flow I can configure to ensure the playback amp is powered on and the right input selected. I admit that it is not clear to me which playback amp you want to power and which input you want to select. I am…

[image] brendonhatcher: Can you hack the player? If so, you could inline a sensor that detects power to an LED that comes on when the device is playing, or similar. Or, if there is a physical play button that gets depressed, add contacts underneath it. It looks like I might have to hack som…

Trigger a flow when a dumb external CD player starts playing

General

HonestJohn61 6 December 2021 10:15 19

Thanks @Colin and @Buckskin - all really helpful suggestions. I think I can assemble the solution from this information, although it may take a little time to get the hardware. Thanks again.

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Trigger a flow when a dumb external CD player starts playing

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