Libav-tools installation

#1

I'm new with node-red.
I'm following the instructions on https://youtu.be/ihZWrJmbGFY
I installed the libav-tools as instructed, I can open the program on the Raspberry Pi with avconv.
I created the folder and edited the settings.js file.
When I open node-red, I don't see the nodes in the nodes panel. For instance the Grab a frame node.
Can you please give me some advice.

Thank you in advance.

Yvonne de Vries

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#2

Sorry i don’t have time to watch a 40minute video to find out what you did. But assuming you did it in a terminal window you should be able to use the history command to get a list of the commands you used.

How are you starting Node-RED?
What version of Node-RED and nodejs are you using?

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#3

Hi UKMoose

Node-Red version: v0.20.1
Version of nodejs: v10.15.3

Install of libav-tools: sudo apt-get install libav-tools
Avconv --> works

Opening node-red via ipaddres:1880/#flow

Is that the information you need?

Thank you for your reply.

Yvonne

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#4

so where have you actually installed any Node-RED nodes?

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#5

On the Raspberry Pi in the home directory there is a directory node_modules

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#6

and how did you install these nodes?

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#7

sudo apt-get install libav-tools

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#8

That isn’t a Node-RED node which is why none will be showing up.

To install node-RED nodes you would normally be in you .node-red directory and install nodes with a command like npm install node-red-contrib-something

You can see a near complete list of installable nodes at flows.nodered.org

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#9

Which nodes don't you see?

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#10

Grab a frame
Set filename
Static image

The above nodes that I supposed belong to the libav-tools.
My idea is to attach my IP camera. I need a rtsp stream. I have the address of the stream.
The instruction says: Grab a frame node and in the node properties write the command:
avconv -i rtsp:stream@ipaddress

Thanks

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#11

Hi @lodv

I have quickly scanned through the video, and it looks like he is using the built-in Exec node to run the avconv command-line tool. So there are no extra nodes to look for in your palette - use the exec node to run the command

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#12

Those are all standard node types, the Grab a frame one is an exec node. The problem is that the guy assumes you know a little bit about using node-red. I suggest you read through the Getting Started guide in the node-red docs, and then play about a bit till you get the hang of it.

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#13

Colin, ukmoose and knolleary thank you very much for your support.
I will do as you say. I will read the Getting Started guide and study a bit more.

Thank you so much.

Yvonne

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#14

Hi Yvonne,
Like the others already mentioned, it is indeed better if you study a bit about Node-RED first. Afterwards if you look again at those node in the video, you will see that the author uses a series of function nodes and exec nodes.

Basically he gets a RTSP stream from his camera, and then grabs individual images from that stream. Here you can find a rather similar test flow, based on ffmpeg (instead of avconv). In that discussion you can see that the author (of your YouTube video) has also put some feedback, but on my Raspberry the performance of ffmpeg was a bit better compared to avconf. But perhaps some optimisation is somehow possible.

But good luck first with the basics of Node-RED, and then we will probably meet again here...
Bart

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#15

Thank you Bart! I will study and watch the test flow.

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