October 8 2024 Image sharing, Python, SD cards, SDR, AAX, Proxmox, Ventoy
Steve asked about photodisplay software; John mentioned that David had done a session on that many years ago when he had mentioned Panoramio [acquired by Google in 2007 and closed in 2016], Picasa [acquired by Google in 2004 and closed in 2016] and the bargain basement ImageShack [moved to a subscription based service in 2016] and Photobucket [moved to a subscription based service in 2017] but he did not know how many were still in action. [There is a list of active image-sharing websites on Wikipedia].
Darren noted that, to specify a particular version of Python, you can change the shebang line; Bernie added that ‘python’ just goes to Python3 now. Steve commented on the many different ways of embedding strings in Python and Bernie said that using f strings is the modern way.
Darren has started a new Open University course which uses JupyterLab running in a Docker container. He has found it easy to build a program but difficult to throw it away!
Bernie confirmed what had been queried at the previous meeting: the Raspberry Pi shop in the Victoria Centre has vanished. He mentioned that a test of a lot of SD cards which say they are A2 SD card standard had shown that they aren’t — only high spec. Sandisk ones really meet the standard.
Darren asked if it was possible to access software-defined radio (SDR) over the Internet, for example, using websdr. Brian said that you need to spend a lot of money to get a decent SDR; you cannot use the tuner they show on a webpage. If you want to have your own SDR you’ll have to spend money. Steve said that, if you only wanted to receive, you could get a receiver for about £20. This had worked with an aerial attached; he could even pick up data from a neighbour’s weather station which he was able to decrypt to find out about the weather.
Brian and Steve had got into a discussion about the Proxmox server which Steve uses because Brian would like to run an iso in a virtual machine. Steve explained that you can built a virtual NAS server inside Proxmox and, while you can run LXC containers within Proxmox, you can run a Docker container inside LXC.
So Steve gave a demo of his Proxmox server running on a Dell Precision 4-core i7 with 24GB RAM. On the left was a list of the machines, most of them running in LXC. You can see the CPU usage, memory usage, etc.
Proxmox can run on bare metal with an iso or run on Debian 12. However, installing with an iso is very slick.
The iso images on a NAS are mounted on Proxmox as a share; you can download isos, select an iso and upload it onto a Proxmox machine.
In response to a question from Brian, Steve explained that he has a subset of IP addresses which have to be hard coded but ones with 5 in the third octet are set by DHCP. He uses pfSense on a gateway machine. You can start a machine with DHCP and then map Mac address to a static address which is picked up when it is next loaded. He has a container running MediaWiki; for this you specify the network address in the config file as in LXC.
The main factor in Proxmox is the amount of RAM, not the CPU speed.
Brian asked if anyone knew how to convert the AAX audio format. The FFmpeg Formats Documentation says that:
Audible AAX files are encrypted M4B files, and they can be decrypted by specifying a 4 byte activation secret.
ffmpeg -activation_bytes 1CEB00DA -i test.aax -vn -c:a copy output.mp4
You therefore need the activation code to decrypt them.
David mentioned the chap using a cigarette lighter to inject stuff into a memory bus, though it was pointed out that you have to have physical access to the machine.
He also mentioned the AI researchers who have been awarded the Nobel Prize for physics and wondered what connection AI has to physics; apparently it relates to their use of statistical methods in physics in the 1980s to begin their work on AI.
Steve mentioned Ventoy which offers multi-boot for iso images; you don’t have to create a bootable USB; you simply install Ventoy on the USB and then only copy isos for bare-metal machines onto the USB; you then select the iso which you want to boot from a list provided by Ventoy. It will accept anything, even Windows 10. Whether the iso will boot will depend on the hardware.