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• Raspberry Pi Camera feedback freezes when moving NEMA 17 stepper motor with A4988 stepper motor driver [closed]

  31 août 2023, par Broteen Das

  I have a Raspberry Pi with a camera module and a NEMA 17 stepper motor connected to it. When I run the command ffplay /dev/video0, the video runs perfectly. However, whilst the video is running, and I run a script that moves the Stepper motor with the A4988 stepper motor driver, the video feed freezes and needs to be restarted.

  


  At first I thought it was ffmpeg's fault, so I tried viewing the feed with OpenCV, but the same probelem persisted.

  


  I also thought that the CPU prioritization was causing the problem, but this one time, the entire Raspberry Pi froze. The Keyboard, mouse, keys, numlock key, everything was dead (the Numlock light on my keyboard was on, I tried toggling the NumLock, but it did not go off) and so I had to turn off and turn on again the power supply to reboot the Pi.

  


  How do I get rid of this issue ?

  


• Animation with gnuplot : only one cruve plotted in an animation whereas 2 expected

  26 mai 2022, par stefan

  I have the following script which is expected to produce the animations of 2 curves :

  


  #!/bin/bash

for i in {1..397}; do
gnuplot -p <<-EOFMarker
set terminal png;
set output "pic$i.png";
set title "power spectrum";
set xlabel "scale (k)";
set ylabel "P(k)";
set key top left;
set grid;
set ytics out nomirror;
set xtics out nomirror;
set logscale x;
set logscale y;
set format x "10^{%L}";
set yrange [0:30000];
plot "CAMB-1.3.5/matter_camb$i" u 1:2 w l;
replot "EFTCAMB_v3_beta/matter_eftcamb$i" u 1:2 w l;
EOFMarker
done

# Build movie with ffmpeg
ffmpeg -start_number 1 -i pic%d.png  movie.mpeg


  


  Every works fine excepted the fact that only one curve is plotted in animation (CAMB-1.3.5) :

  


  Here is an example of frame :

  


  

  


  Why the "replot" command is not taken into account in the generated image ?

  


• Forwarding RTSP streams to client from private networked server via proxy

  21 juin 2016, par beNerd

  I have a setup where I have two physical machines (remote VPSes) :

  1. Server One - This has good processing power in terms of hardware and it’s IP can’t be accessed publicly. It’s private networked to a proxy (server 2) i.e it can only be accessed by the proxy server. Running nodejs/expressjs and ffmpeg/ffserver on ubuntu.

  2. Server Two : Reverse Proxy. Publicly accessible. Implements nginx which pipes the requests to Server One.

  Now, I have client apps that needs to play RTSP streams configured in the FFSERVER residing on Server One. Since I cannot access server one directly and only via proxy, I need a mechanism where I can accept RTSP requests on my nodejs api (which receives requests from nginx proxy via proxy pass config block), do some validations (session tokens here) and then when validated, contact the underlying ffserver asking for the stream. As soon as I receive the stream, I should be able to forward to the asking client.

  Possible ? How ?