plkumar

ffmpeg

Converting Audio into Different Formats / Sample Rates

Minimal example: transcode from MP3 to WMA:
ffmpeg -i input.mp3 output.wma

You can get the list of supported formats with:
ffmpeg -formats

Convert WAV to MP3, mix down to mono (use 1 audio channel), set bit rate to 64 kbps and sample rate to 22050 Hz:

plkumar

#!/bin/sh
#
# Wrapper script for the letsencrypt client to generate a server certificate in
# manual mode. It uses openssl to generate the key and should not modify the
# server configuration. It can be called off-side, i.e. not on the destination
# server.
#
# usage: letsencrypt_create.sh DOMAIN [DOMAIN...]
set -e

plkumar

Extract stuff from .mkv with ffmpeg

Full documentation: https://ffmpeg.org/ffmpeg.html

List all tracks

ffmpeg -i input.mkv

track indexes are zero-based.

Track types

plkumar

Installation

0. Spin up an AWS/Azure/GCP machine (Ubuntu - 16.04)
   • ensure you know how to use the web-interface of these IaaS to open ports for an instance
   • open ports 80, 443, 8000, 8888
1. Follow this link
2. Create a dir (.jupyterhub) which shall contain jupyterhub specific files
   • mkdir .jupyterhub
   • cd .jupyterhub
   • jupyterhub --generate-config
   • openssl rand -hex 8 > jupyterhub_cookie_secret

plkumar

- Open Automator 
- File -> New -> Service 
- Change "Service Receives" to "files or folders" in "Finder" 
- Add a "Run Shell Script" action 
- Change "Pass input" to "as arguments" 
- Paste the following in the shell script box: open -n -b "com.microsoft.VSCode" --args "$*" 
- Save it as something like "Open in Visual Studio Code"

plkumar

function onFormSubmit(e) {
  var form = FormApp.openById('1Z65umQSZ2drz3MvTWCWlwP4-ySeoB5D7RvX1LtusnEU');
  var formResponses = form.getResponses();
  var latestResponse = formResponses.length - 1;
  var formResponse = formResponses[latestResponse];
  
  var email = formResponse.getRespondentEmail();
  
  var items = formResponse.getItemResponses();

plkumar

How to resize a qcow2 disk image on Linux

This example takes olddisk.qcow2 and resizes it into newdisk.qcow2, extending one of the guest's partitions to fill the extra space.

1. qcow2 format

1.1. Verify the filesystems of olddisk.qcow2

plkumar

#!/usr/bin/env sh
set -e
set -x

# Boilerplate setup
alias buildah="sudo buildah"
container="$(buildah from scratch)"
alias run="buildah run ${container}"
alias copy="buildah copy ${container}"
alias add="buildah add ${container}"

plkumar

// Package main is a sample macOS-app-bundling program to demonstrate how to
// automate the process described in this tutorial:
//
// https://medium.com/@mattholt/packaging-a-go-application-for-macos-f7084b00f6b5
//
// Bundling the .app is the first thing it does, and creating the DMG is the
// second. Making the DMG is optional, and is only done if you provide
// the template DMG file, which you have to create beforehand.
//
// Example use:

plkumar

/*
  Copyright (c) 2014-2020 Electronic Cats SAPI de CV.  All right reserved.

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of