Phil docPhil99

To get the list of webcams v4l2-ctl --list-devices

Example outout for 2 cameras

vi-output, imx219 7-0010 (platform:54080000.vi:0):
        /dev/video0

B525 HD Webcam (usb-70090000.xusb-2.2):
 /dev/video1

My USB speakers seem to have some buggy firmware in that the device name has been corrupted with some binary. At first I thought it was unicode, but uni2ascii said overwise. Since I need to be able to type the name into config files I had to rename the device using udev.

First we need to fine the name of the device. Run udevadm monitor --kernel --subsystem-match=sound

Unplug and re-plug in the DAC, this results in:


KERNEL[1585.716702] remove   /devices/pci0000:00/0000:00:12.0/usb4/4-5/4-5:1.0/sound/card1/controlC1 (sound)

My system consists of a host PC that has two ethernet cards. What I want to do is use one for connecting to the inernet and the other to run a private network of Raspberry Pi computers.

My first ethenet card is easy, it's basically grabbing its setting via DHCP from my router. What I need to do is create a different subnet for the second card. So first of all I need to look up current IP address. On linux I can run ip a I need to find the address and mask from there. In my case it's the line starting inet 192.168.86.36/24 The 24 is mask, in this case the last digit of the IP address are all on the same subnet. See https://www.calculator.net/ip-subnet-calculator.html here if you want to calculate your own range.

For the second card I need to pick a static IP address that's on a different subnet. There are a number of IP address that are reserved for private networks so it's best to use one of these.

Class A- 10.0.0.0 to 10.255.255.255
Class B- 172.16.0.0 to 172.31.255.255
Class C- 192.168.0.0 to 19

Batch convert HEIC using a fish shell

for p in *.HEIC;
  heif-convert $p (path change-extension jpg $p)
end

Note the path command required fish 3.5

Apply a cube LUT to mpv playback mpv -vf=lut3d=XT4_FLog_FGamut_to_ETERNA_BT.709_33grid_V.1.01.cube FILE.MOV or celluloid --mpv--vf=lut3d=XT4_FLog_FGamut_to_ETERNA_BT.709_33grid_V.1.01.cube FILE.MOV

Loguru is my favorite way to perform logging in python. It's generally so simple to use but a few things are missing from the documentation.

Logging over the network

This is based on the loguru example, but also includes the hostname of the sender. To add extra fields the pefered method is to add to record["extra"] dictionary (which is normally empty). The client code sends the log messages over the network and to stderr.

class LoggingSocketHandler:
    def __init__(self, host, port, timeout=600):

I have simple bash script that starts lots of processes. If one fails I want to stop everything. There maybe a better way to do this but I came up with this.

First create two scripts to test our main script. good_sleep that sleeps for 10 seconds and exits with no error.

#!/bin/bash
echo " good sleeping"
sleep 10
echo "done"

Dual Monitor Linux Mint Login Screen Fix

Linux mint has a few annoyances when using dual monitors. First fixing the log in screen. By default, it uses the same resolution as the primary monitor in the secondary screen. My secondary monitor is much larger so it doesn't display correctly. It's only cosmentic but it annoys me.

Create or append the file /etc/lightdm/lightdm.conf.d/70-linuxmint.conf so that it has the lines

[SeatDefaults]
user-session=cinnamon
display-setup-script=/usr/bin/lightdmxrandr.sh

Batch convert heic files to jpg in fish shell

First install sudo apt install libheif-examples
Then run in correct directory for p in *.heic; heif-convert $p (basename $p .heic)".jpg"; end

	# my conversion of Goodman's code
	import numpy as np
	import matplotlib.pyplot as plt

	# Program for simulating Speckle Formation by Free Space Propagation
	# Translate from Mathematica
	# Ref: Goodman, Joseph W. 2020. Speckle Phenomena in Optics: Theory and Applications, Second Edition. SPIE.


	n = 1024 # nxn array size