Pierce Brooks PierceLBrooks

iOS NDEF Record Compatibility

Introduction

NDEF (NFC Data exchange format) is a method of transferring (relatively small amounts of) information from a passive or actively emulated tag by way of "records" which specify the type of information is being received and the function it is meant to have.

iPhones do not have a full suite of NDEF compatibility, the reason for this is unknown (to me at least), what this means is the background polling on iPhones will not interpret some specific record types, with compatible NDEF records, a notification will pop up directing the user to follow the received data into its respective app to complete whatever action was intended by the record.

Compatibility Table

Below are the options offered by NFC Tools on IOS for NDEF Encoding, some of the options below are other record types but with a specific function IE social links are just URLs.

Using Xephyr for Secure Docker GUI Access

When working with ROS development in Docker containers, visualizing data using tools like rviz2 can be challenging due to X11 authentication issues, especially after system restarts. The following approach uses Xephyr to securely manage GUI access without compromising the security of your host's X server.

Overview

Challenge: X11 authentication issues and security concerns when using Docker containers with GUI applications.
Solution: Use Xephyr to create a nested X server for Docker container GUI applications.

Steps to Set Up Xephyr for Docker GUI Applications

Start Xephyr:

Building OpenVDB with Python bindings

Locally on a Linux/MacOS machine

Follow one of:

Just make sure to call the cmake command with -DOPENVDB_BUILD_PYTHON_MODULE=ON -DUSE_NUMPY=ON

In a conda/mamba environment (from conda-forge; linux only)

Mastodon Docker Setup

In this guide we will only focus on using the prebuilt images from Docker Hub.

Prerequisites: You have Git, Docker, Docker compose and Nginx pre-installed.

Prepare

Clone Mastodon's repository.

Introduction

A JSON compilation database is a very handy output format which is parsed and used by many development tools. Unfortunately for us Apple Developers, it is not straightforward to generate one from within Xcode, as it is (probably) not Apple's priority and therefore there is no toggle/switch/setting that can be easily enabled to get this information.

There is however a solution, thanks to Apple using Clang/LLVM as their main toolchain.

Implementation

The standard way to generate this with clang would be to use the -MJ flag and give it a file name that typically corresponds to the input file. Using this flag indirectly through Xcode is hard, given that we're not aware of all the other arguments when a compiler call is executed.

However, there is a second hidden/badly documented LLVM flag: -gen-cdb-fragment-path - it is implemented in terms of -MJ and has the same functionality, but it's argument in contrast is an output directory.

	import numpy as np
	import soundfile as sf
	from scipy.fftpack import fft, ifft

	def rotateSignal(signal,flip):
	if flip:
	signal = signal[::-1]

	x = np.concatenate((signal, signal[1:][::-1])) # concatenating the array with a reverse of itself makes it such that the fourier transform doesn't layer over a reversed version of itself in the inverse fft
	rotSig = ifft(x)

	1
	00:00:00,000 --> 00:00:02,500
	Welcome to the Example Subtitle File!

	2
	00:00:03,000 --> 00:00:06,000
	This is a demonstration of SRT subtitles.

	3
	00:00:07,000 --> 00:00:10,500

	1618117522473062401,AmerCrusader,0
	805901211291422720,PatriotGulag,103
	897873361161732098,presidentmeeks,40
	1369024312401870852,obama_baroque,154
	1365839268476645378,vylpill,8705
	1616533685427208192,lpbr0014,102
	1606569725235978240,chitochipper,37
	1530966028221661184,originalpod5,9
	1586008148552212481,TheFaddedGamer,12
	1589871939786620929,Truthyfren,1253

	"""
	To install additional libraries:

	cd /opt/blender/3.2/python/bin
	./python3.10 -m ensurepip
	./python3.10 -m pip install pillow shapely networkx cairosvg

	Python headers are required for compiling nest2d.
	Download the source for your blender python version
	(e.g. 3.10.8) from <https://www.python.org/downloads/source/>

	{
	"name" : "Mixamo",
	"url" : "",

	"bones" : {
	"mixamorig:Hips" : "hips",
	"mixamorig:Spine" : "spine",
	"mixamorig:Spine1" : "spine-1",
	"mixamorig:Spine2" : "chest",
	"mixamorig:Neck" : "neck",