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Zilla707
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Data input from an A/V cable

Thu Sep 05, 2019 11:01 pm

I need a way to get data from an a/v cable into python. Is there some library or module that I can use to do this? I am using python 3, not 2.
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mikronauts
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Re: Data input from an A/V cable)

Fri Sep 06, 2019 1:14 am

The Pi does not have av inputs.

Depending on what you want to do you may find a compatible usb video capture stick.
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Re: Data input from an A/V cable

Fri Sep 06, 2019 7:20 am

Zilla707 wrote:
Thu Sep 05, 2019 11:01 pm
I need a way to get data from an a/v cable into python. Is there some library or module that I can use to do this? I am using python 3, not 2.

You will need a Composite Capture Device, the cheapest are marketed as USB2 EasyCap.

https://www.linuxtv.org/wiki/index.php/Easycap

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Zilla707
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Re: Data input from an A/V cable

Fri Sep 06, 2019 5:15 pm

If I got a Composite Capture Device, can I still get the data coming through it with python, using a module or something, or would I need a different program?
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Paeryn
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Re: Data input from an A/V cable

Fri Sep 06, 2019 7:17 pm

Zilla707 wrote:
Fri Sep 06, 2019 5:15 pm
If I got a Composite Capture Device, can I still get the data coming through it with python, using a module or something, or would I need a different program?
Most likely when using a capture device it will appear as a v4l2 device in /dev/video* (the * will be a number). There is a v4l2 module for python, a quick look didn't see one listed in the repo but there is one in PyPi that you can install with pip3

Code: Select all

pip3 install v4l2
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Zilla707
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Re: Data input from an A/V cable

Fri Sep 06, 2019 8:43 pm

Neat! Thanks. I will try it. Does the av adapter have a power out wire?
I am trying to read and interpret from an induction velocity sensor, and it needs to be powered from the cable and be able to read the data coming from the sensor.
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drgeoff
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Re: Data input from an A/V cable

Fri Sep 06, 2019 9:38 pm

Zilla707 wrote:
Fri Sep 06, 2019 8:43 pm
Neat! Thanks. I will try it. Does the av adapter have a power out wire?
I am trying to read and interpret from an induction velocity sensor, and it needs to be powered from the cable and be able to read the data coming from the sensor.
Because you started the thread by asking about an "AV cable" you have been pointed to USB adaptors that can get analogue video into a RPi. Such an adaptor is of 0% use for other than video (and perhaps audio).

You need to provide detailed information about the sensor which is providing the data from the motor.

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Re: Data input from an A/V cable

Sat Sep 07, 2019 3:01 pm

This should have been the first reply in this thread.

What type of A/V cable?

What type of A/V data is used with the cable?

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Zilla707
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Re: Data input from an A/V cable

Sat Sep 07, 2019 10:57 pm

The same type that's used for connecting external speakers to a phone or computer. 3-poles.
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drgeoff
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Re: Data input from an A/V cable

Sun Sep 08, 2019 12:18 pm

Zilla707 wrote:
Sat Sep 07, 2019 10:57 pm
The same type that's used for connecting external speakers to a phone or computer. 3-poles.
For starters that is an audio cable. No video.

More importantly you have not answered the question about the type of signal on the cable.

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B.Goode
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Re: Data input from an A/V cable

Sun Sep 08, 2019 12:50 pm

Zilla707 wrote:
Fri Sep 06, 2019 8:43 pm
Neat! Thanks. I will try it. Does the av adapter have a power out wire?
I am trying to read and interpret from an induction velocity sensor, and it needs to be powered from the cable and be able to read the data coming from the sensor.

"I am trying to read and interpret from an induction velocity sensor "


Perhaps it would be more productive in getting meaningful advice from this forum if you provided links to further information, perhaps a datasheet, for that sensor that you hope to use.

At present all attempts to help are being derailed by your insistence on a solution that uses an A/V interface. Is that a fundamental requirement of the project or assignment you have been given?

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Zilla707
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Re: Data input from an A/V cable

Mon Sep 09, 2019 9:44 pm

Nevermind. I am just going to use PyAudio to read the data. Thanks for the help though.
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