Shannon Scott ShannonScott

Backup SD card to Mac

List devices

diskutil list

Copy SD card to Mac

General AWS Notes

Get EC2 instance type

Get the EC2 instance type from within an EC2 instance.

Modified from Getting the AWS instance ID from within the EC2 instance.

curl https://169.254.169.254/latest/meta-data/instance-type

Check RAID health

diskutil appleRAID list

Get disk status

diskutil info disk0

Notes on setting up a headless Raspberry Pi for astrophotography

VNC rpi > mac

No route to internet - colliding DHCP and static addresses

Setup

Notes on using FFMPEG and FFPROBE

Count frames in a video

Get reported number of frames

Get the reported and actual number of frames in a video.

Note: I recently found a video that reported having 2985 frames, but actually only had 29 frames, which were all keyframes.

Boost the choral bass part on all MP3s in a folder

Boost the frequencies within +/- one octave of 200 Hz

BOOST=6
for filename in *.mp3; do
	ffmpeg -i $filename -af "equalizer=f=200:width_type=o:width=1:g=${BOOST}" "${filename%.*}.bassboost+${BOOST}db.mp3"
done

Bash Notes

General notes on using and scripting Bash.

Argument parsing

Here's a nice article on the topic of argument parsing in Bash: Bash: Argument Parsing

From the article:

Crop video

ffmpeg -i input.mp4 -vf "crop=500:300:0:0" -c:v libx264 -crf 0 -c:a copy output.mp4

Where the crop option is of the form: w:h:x:y.

Links

Capture a video of a given X Window with gstreamer.

X Window ID

Get the target window ID with the following:

xwininfo

	#!/bin/bash
	# Get a list of GPUs in a system
	#
	# Useful nvidia-smi Queries
	# https://nvidia.custhelp.com/app/answers/detail/a_id/3751/~/useful-nvidia-smi-queries

	# Get GPU names as a bach array, replace spaces with underscores
	gpu_names=($(nvidia-smi --query-gpu=gpu_name --format=csv,noheader \| tr -s ' ' '_'))

	for name in "${gpu_names[@]}"