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**Hacker Public Radio**

Hacker Public Radio is an podcast that releases shows every weekday Monday through Friday. Our shows are produced by the community (you) and can be on any topic that are of interest to hackers and hobbyists.

Latest Episodes:

HPR4251: Dave and MrX turn over a new leaf Nov 18, 2024

This show has been flagged as Explicit by the host.

Introduction

Hosts:

We recorded this on Saturday September 14^th 2024. This time we were at Swanston Farm, a place we had previously visited for lunch in March 2024.

After lunch we adjourned to Dave's car (Studio N) in the car park, and recorded a chat. The details of why it is Studio N instead of Studio C is mentioned in the chat itself!

Preparing this show has taken longer than usual this time - apologies!

Topics discussed

Studio change:
- Sadly, since the last recording Studio C (Dave's 10-year old Citroën C4 Picasso) self-destructed. It was a diesel car and one of the fuel injectors failed and destroyed the engine management system as it died. It wasn't worth repairing!
- The replacement is Studio N, a Nissan Leaf, which is an EV (electric vehicle). The price of nearly new EV cars is fairly good in the UK at this time in 2024, so it seemed like a good opportunity to get one.
- Learning to own and drive an EV can be challenging to some extent:
  - "Range anxiety" and access to charging stations
  - Regenerative braking
  - Fast (DC) charging on the road is relatively expensive (£0.79p per kWh), but is convenient
  - Ideally, a home (AC) charger is required. It will be slower (7 kW per hour) but will be cheaper with a night tariff (£0.085 per kWh versus £0.25 per kWh normal rate)
  - There is potential, with solar panels and a battery, to use free electricity to charge an EV at home
- MrX might like to move to an EV in the future

YouTube channels:
- Dave is subscribed to a channel called "The Post Apocalyptic Inventor (TPAI)" and recently shared one of the latest videos with MrX. The channel owner collects discarded items from scrapyards in Germany, or buys old bits of equipment, and gets them working again.
  - Milling Machine Adventure! Bring her Home! / Gantry Build
  - I built a CNC Plasma Cutting Table from Scrap!

Databases:
- MrX used dBase on DOS in the past, and received some training in databases.
- In 2017 he obtained a large csv (comma-separated values) file from the OFCOM (Office of Communications, UK) website containing their Wireless Legacy Register, which contains licensees and frequencies with longitude and latitude values. A means of interrogating this file was sought, having found that spreadsheets were not really very good at handling files of this size (around 200,000 records).
- MrX used the xsv tool, which was covered in shows hpr2698 and hpr2752 by Mr. Young. It allows a CSV file to be interrogated in quite a lot of detail from the command line. However, with a file of this size it was still quite slow.
- In a discussion with Dave the subject of the SQLite database came up. Using the SQLite Browser it was simple to load this CSV file into a database and gain rapid access to its contents. SQLite databases may also be queried through a command-line interface which can also be run on a Raspberry Pi, phones, tablets and on a ChromeBook.

The textimg tool:
- This is a command to convert from colored text (ANSI or 256) to an image. Dave generates coloured text from his meal database (HPR show hpr3386 :: What's for dinner?, this being a later enhancement), then captures the output and sends it to a Telegram channel shared with his family.
- Dave also exchanges weather data obtained from the site wttr.in with Archer72 on Matrix.
- This is a useful tool for generating images from text, including any text colours. It can be installed from the GitHub copy, and maybe from some package repositories.

Using coloured text in BASH (Dave responding to MrX):
- I have used a function to define variables with colour names:
  - Call a function define_colours which defines (and exports) variables called red, green, etc.
  - Using red=$(tput setaf 1); export red
- I use the colours in two ways:
  - Method 1: use these names in echo "${red}Red text${reset}"
  - Method 2: use another function coloured which takes two arguments, a colour name (as a string) and a message. The script encloses the message argument in a colour variable and a reset. The colour name argument is used in a redirection to turn red into the contents of the variable $red.
- This probably needs a show to explain things fully.

Terminal multiplexers:
- Dave and MrX use GNU screen.
- Both recognise that the alternative tmux might be better to use in terms of features, but are reluctant to learn a new interface!
- Dave has noticed a new open-source alternative called zellij but has not yet used it.

Variable weather:
- Dealing with hot weather: YouTube, Techmoan channel PERSONAL AIRCON - Ranvoo Aice Lite Review
- MrX had recently had a holiday in the Lake District where the weather was good.
- In Scotland the weather has been wet and windy in the same period.

Spectrum24, OggCamp:
- MrX is attending his first OggCamp in Manchester. Dave will be attending too, as will Ken.
  - HPR has a table/booth at OggCamp.
- Ken was recently at Spectrum24, an amateur radio conference in Paris.
  - Meshtastic an open source, off-grid, decentralized, mesh network built to run on affordable, low-power devices

Old inkjet printers:
- MrX has an Epson R300 printer where the black ink seems to have dried up.
- Dave has an old HP Inkjet with the same type of problem. This printer has a scanner and FAX capability. An HPR show was done in 2015 describing how it was set up to use a Raspberry Pi to make it available on the local network.

Propelling or mechanical pencils:
- Dave had a Pentel GraphGear 1000 propelling (aka mechanical) pencil which was mentioned on HPR show 3197. This was dropped onto concrete, and didn't appear damaged at the time, but it apparently received internal damage and eventually fell apart.

Links

Electric cars:
- EV (electric vehicle)
- Regenerative braking

Databases
- SQLite:
  - SQLite
  - SQLite Browser
  - An Easy Way to Master SQLite Fast
  - Open source SQLite Studio available for Linux SQLiteStudio
- SQL:
  - Origins: The Birth of SQL & the Relational Database
  - Intricacies: MySQL JOIN Types Poster (Steve Stedman)
- Design:
  - How to Fake a Database Design - Curtis Poe (Ovid)

The textimg tool:
- GitHub repository: textimg

zellij:
- Website: zellij
- Github repository: zellij
- Quote from the repo: Zellij is a workspace aimed at developers, ops-oriented people and anyone who loves the terminal. Similar programs are sometimes called "Terminal Multiplexers".

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HPR4250: Playing Civilization IV, Part 3 Nov 15, 2024

This show has been flagged as Clean by the host.

Civilization IV made some changes, and in this episode we look at Religion. This is one of the big changes from previous versions of the game and is something that will continue to be important in future versions.

Links:

https://www.palain.com/gaming/civilization-iv/playing-civilization-iv-part-3/

Provide feedback on this episode.

HPR4249: Audio Streams on the Command Line Nov 14, 2024

This show has been flagged as Clean by the host.

TuxJam co-host Kevie has a discussion about playing an audio stream from the command line using VLC and also MPG123 and then ripping the stream to a localised file using the wget command:

Play a stream using VLC:

cvlc https://your.radio.stream

Play a stream using MPG123:

mpg123 https://your.radio.stream

Rip the stream to a local file:

wget -O YourFile.flac "https://your.radio.stream"

Provide feedback on this episode.

HPR4248: Millie Perkins Nov 13, 2024

This show has been flagged as Clean by the host.

Millie Perkins gave a talk "Home automation 🏠 A beginner's foray down the rabbit hole" on Sunday 13 October 2024 between 11:00 and 11:30. The talk was so well received that our HPR Reporters tracked her down for a follow up chat.

Provide feedback on this episode.

HPR4247: Installing GuixSD--Part Deux Nov 12, 2024

This show has been flagged as Clean by the host.

Synopsis

In this episode Rho`n records his further adventures in installing GuixSD onto a Mac Mini computer.

Guix has a graphical text based installer. It is reminiscent of the mid to late 90s Debian installers. Even with its old school feel, the installer is very nice. It is well laid out, has good onscreen description for each step of the installation process, and provides ample configuration selections from language, to to key board layout, to desktop and software selection.

References

Guix website
Instructions for installing Guix as the main OS
Rii 2.4G Mini Wireless Keyboard with Touchpad Mouse,Lightweight Portable Wireless Keyboard Controller with USB Receiver Remote Control for Windows/ Mac/ Android/ PC/Tablets/ TV/Xbox/ PS3. X1-Black - EBay item

Attribution

The transition sound used between audio clips is found on freesound.org:
Name: Harp Transition Music Cue
Author: DanJFilms
License: Creative Commons Zero

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HPR4246: Bytes, Pages and Screens Nov 11, 2024

This show has been flagged as Explicit by the host.

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HPR4245: What's in my bag? Nov 08, 2024

This show has been flagged as Clean by the host.

Just me rambling as I go through my (former) every day carry bag in preparation for a trip.

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HPR4244: Two methods of digitizing photos. Nov 07, 2024

This show has been flagged as Clean by the host.

Today I will talk about digitizing analog photos. I will talk about two methods.

I have scanners from different manufacturers, flat bed scanner and dedicated film scanner. Each scanner is delivered with software. Each software is generally good. But it is a problem to manage several software. Secondly, none of them works for Linux operating system. I wanted to simplify my software learning, so I wanted one software for all my existing and any future scanner. Secondly I intended to migrate to a Linux operating system, which I now have done.

Those two requirements lead me to switch over to VueScan software. I had tested VueScan before and also gotten recommendations from photographic friends. VueScan is a proprietary software made by a small family run company. It’s available for Linux, Windows and macOS. VueScan supports very many hardware scanners. I do not know about any better software for Linux and is maybe also the best choice for any operating system. I do not regret my switch to VueScan.

A second method to digitize photos is reproduction with a camera. That is to use a camera to shoot a photo of the photo.

Some say it is the superior technology. I don’t know. But as I am coming from the scanning technology and starting to explore the repro technology, I will give my early thoughts from that perspective.

My initial plan has been to use repro photography for prints that are glued into albums and therefore difficult to manage in the scanner. It is also an excellent method to digitize other papers in book format. But I have not really started to do that.

However, a while ago I started to look into 6x9 cm negatives. My scanner can just manage 6x9. But I do not have a fixture for 6x9. So it is both somewhat tricky to position the negative as well as to keep it flat. A thin plexiglass plate might be possible to use to keep it flat. Even without plexiglass, I have tested I can get well acceptable result with the scanner.

I started to try out the repro method. I have not come so far in my trials that I can decide which is the best method for me.

My camera is a modest camera compared to state of the art. My flat bed scanner should give better or comparable resolution than my modest digital camera. The fixture I have for repro do not keep the negative fully flat, because 6x9 is a rather big size. So I plan to explore if I can improve quality with a plexiglass plate above the negative.

An issue with the repro method is to keep all angles in control, to mount the camera in exactly correct angle in relation to the object. Focus can also be another issue. I consider it is better to use manual focus rather than auto focus. When I take the repro photos, I have the camera connected to a laptop and I use the Entangle software to control the camera settings. I can use the camera live view to position the object as well as to focus.

I use RawTherapee software to convert the negative photo to a normal photo. RawTherapee comes with pre-installed profiles for this process. The default profile values can be adjusted and also stored as new personal profiles.

A major advantage of the repro method compared to the scanner method is the speed. Once all is configured, it takes one hundred of a second or so to do the digitize itself, while it can take minutes with the scanner.

I use digiKam as my photo catalog software.

All software I currently use with the exception of VueScan are free and open source. I use all on Linux operating system, some of them are available on other platforms. I include links to their websites in the show notes.

If you have any opinion or experience on digitizing analog photos, I will be happy to read your comments or listen to your show.