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We started producing shows as Today with a Techie on 2005-09-19, 19 years, 4 months, 3 days ago. Our shows are produced by listeners like you and can be on any topics that "are of interest to hackers". If you listen to HPR then please consider contributing one show a year. If you record your show now it could be released in 6 days.
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My name is Peter Paterson, also known as SolusSpider.
In my spare time I like to watch scifi shows and movies, including
those about superheroes.
I am so looking forward to the new Superman movie by DC, with
James Gunn as showrunner. In that film the actor Nathan Fillion
plays a Green Lantern named Guy Gardner.
Recently I remembered that I owned a Green Lantern Blu-ray
animated movie with Nathan Fillion as the voice of Hal Jordan.
That movie is named Emerald Knights.
These days when I purchase a Blu-ray it normally comes with a
digital code for
Movies Anywhere
. Therefore I often never play the physical disk at all. This
particular disk did not have that option.
I searched the streaming services for where to watch Green
Lantern: Emerald Knights. Seems it is only available for rent or
purchase. Obviously since I own the disk I am not going to do
that.
Therefore, I tried once again to try to play the disk directly on
my Linux system.
We do have dedicated Blu-ray players in the house. One is a
Samsung unit in our living room, but that is where my
Dragon-in-Law Eva lives. The other is a Playstation 3 in our
bedroom. There is also the factor that I wanted to watch while
doing other computer projects in my own room.
My main computer system is a
System76 Thelio desktop running
PCLinuxOS as the operating system.
MakeMKV plugin for VLC
: org.videolan.VLC.Plugin.makemkv
Detailed program names are in the shownotes.
To install these direct from terminal type:
flatpak install (name of program)
These instructions assume that you already have Flatpak installed
on your Linux system.
If you do not, then the Flathub website will give you guidance for
your particular distro.
I did have to uninstall VLC first from PCLinuxOS, which had been
installed from the repo. This enabled all the relevant library
files to be accessible across Flatpak.
MakeMKV is a format converter, or transcoder, that converts
the files on a physical disk to MKV files. Many use this program
to copy their Blu-Rays to a storage medium for their own
home-streaming purposes. I have yet to go down that road, as I
just wanted to play the disk. Plus I don't have that much storage.
I originally purchased MakeMKV for $50 in 2020.
Yes, paid.
It is a proprietary program, but then again so is the Blu-Ray disk
encryption.
These days it costs $60 for a lifetime licence.
That said, MakeMKV is beta software that is free to use, and they
supply a licence key that is good for a month. The only downside
is that you have to visit their
forum page every month to obtain the updated key code.
Once all this was installed, I opened VLC, clicked on 'Open
Disk...' from Media, selected Blu-ray from Disk Selection, then
clicked on Play.
For me it just worked!
Hope it shall do for you also.
It's so great to be able to directly play Blu-rays on my Linux
system again.
Remember the Green Lantern oath:
"In brightest day, in blackest night,
no evil shall escape my sight.
Let those who worship evil's might beware my power…
Green Lantern's light!"
Thank you so much for listening to my latest topic of interest.
Please leave me a comment on the HPR show page.
I look forward to hearing from you.
Now go forth, take care of yourself, also your fellow neighbours,
and record your own HPR show!
Today I would like to talk about the book "Crafting Interpreters" by Robert Nystrom. I have a passion for interpreters and compilers for a long time, and always like to write one. But I never succeed. I read a lot of books about interpreters and compilers but never able to finish it.
Crafting Interpreters is the first book I read cover to cover, and understand it, and I am able to follow through all the coding and build an interpreter as well as a compiler. It is amazing!
The first half of the book is to build a tree-walking interpreter in Java. The 2nd half of the book is to build a bytecode compiler in C. Both of them are for a programming language the author called lox. L-O-X.
The book is smart because it is based on generic Java and C code, and does not specify any IDE or make file to use. You will have to figure out that yourself. That may sound like a hurdle but in fact it is a blessing. That makes the code in the book very portable.
The author has a way to explain compiler concepts in an interesting way. The bytecode compiler in the 2nd half of the book implements the following features: virtual machine, closure, class and methods, garbage collector, etc.
The book cover is already very revealing. It is basically a high-level view of the different passes and types of code generation.
You can buy the book in different places, both physical copy or ebook. However, the book is also available for free at craftinginterpreters.com.
I would say this book is a labour of love by the author. Highly recommended.
TuxJam
co-host
Kevie
follows up on HPR4287 with a bit of a tweak to the Crontab, but still using the ffmpeg command to record.
In the previous episode, the example stream url that was given proved to be unpopular with ffmpeg due to the characters that it contained. A quick work around for this was to put it in a url shortener, for this example I'm using
TinyURL
.
Another issue arose when the stream recorded without first removing the audio file, I could see this being an issue when you want to record a show when you will be away over multiple weeks. To overcome this we simply edit the Crontab file (command
crontab -e
) and add the following to the end of the file, before the extension:
$(date +"%Y_%m_%d")
The Wayback Machine by The Internet Archive is a very good resource for web sites no longer existing or older revisions of them.
However, sometimes I have also found it is nice and useful to have my own copy of a web site. It means I have control over the copy, it can be accessed offline and no world wide wait for the page to load.
My most typical use case if for web sites that I am manager of myself. For one or another reason, I want to keep a snapshot of the site. I have also used it for fact based sites which I want to always have access to, like a reference book. One of my recent use cases was a magazine that has closed down and announced the web site will also soon be terminated. Although it is available in the Wayback machine, I wanted to have a copy myself for a short period of time.
The software I use for this HTTrack. This software is available for Windows, Android, Linux and unix-like systems. It is at least for some platforms available with a graphical user interface. I have myself only used HTTrack with the terminal interface on Linux. HTTrack is a free and open source software.
In its simplest way to operate, it is just to type "httrack" followed by the url to the start page of the site to be copied.
In many cases this works well, I get a perfect copy. In other cases, it works less well. First of all, of course, I do not copy very big websites, both for the amount of time it takes and the disc space. What is stated in the robot textfile can also matter for the result. Another issue can be the folder structure of the site, HTTrack may not find all folders in its default setup, for example how images are stored. I have myself also got issues when menues and links not works normally where I instead have to right click to open the link.
The HTTrack web site has quite a lot of information in the documentation and it also has a forum. And in the terminal, there is also good help about all additional available commands. I have in general for my usage found the simple first attempt to copy sites gives perfect or good enough result directly without need to research details.
So, when I want to preserve snapshot of earlier releases of my own sites or when I want to have an offline and preserved copy of an important site, I consider HTTrack to be an easy to use and yet powerful tool. I am aware other similar tools exist, but this is the one I currently use.
Firefox has add-ons – these are extra features you can download and install to add more functionality to your browser. Add-ons allow you to customize your Firefox browser and enhance the way you use the web.
What happens if one sine wave is modulated with another sine wave?
Similar to sending a pure tone over AM radio.
Apparently the result is two frequencies, one equal to the difference
of the two original frequencies and one equal to the sum.
Creating two tones and multiplying them in Nyquist Prompt in Audacity
then plotting the resulting spectrum concurs.
(mult (sound (hzosc 1000)) (sound (hzosc 500)))
The original tones were 1 kHz and 0.5 kHz.
The result was a peak at 0.5 kHz (the difference) and one at 1.5 kHz
(the sum).
On another note, the manual mentions in practice if one of the tones
is the carrier frequency and one of them is the signal, then the carrier
should not be modulated all the way down to zero or all the way up to
maximum. This avoids distortion and clipping so the quality is better
when received. It is also more power efficient so the transmission can
travel further given the transmitter has a limited power output.
Civilization IV made some changes, and in this episode we look at the
idea of Civics. This is another example of a significant change from
previous versions