Lair Of The Multimedia Guru

I was playing around with a VM remotely. Without much thinking i setup a VPN and hit enter after the connect command.
It worked fine, or rather i suspect it did because it blocked the connection to the router through which i accessed it.

Now I could have gotten in the car and driven over to the thing or just ignored it as it had no real use anyway. But it turns out it was too hard for me to just ignore it. That had to be fixable remotely.
I would have expected virtualbox to have some sort of serial console or something like that. And iam sure it has a host of ways to recover this nicer but what i found first and that worked was this:

vboxmanage  controlvm (name) screenshotpng this.png ; ffplay this.png
vboxmanage  controlvm (name) keyboardputstring "foobar"
vboxmanage  controlvm (name) keyboardputscancode 12 34 56

With these we can look at the screen and we can enter things, thats more than enough to recover it. One thing to keep in mind is that the keyboardputstring commend seems to assume a us keyboard layout.
The 2nd thing to keep in mind if you use this for a similar case, you want to make sure you do not put any passwords into any shell history files. At least not without realizing it and changing the password then

A few days ago i wanted to print a page, nothing special here thats a common thing. But this time was different, my Samsung CLP-365 color laser printer did not print, its main LED red, the 4 toner leds all the same and lighting. On the linux side no error message or anything. Paper was in it, no paper stuck anywhere, power cycling did not help. None of the button combinations i could find that where intended to print debug information did print anything. Searching the wide net lead to a service manual and the tip to look at the display which my printer did not had and some windows software which required a windows machine. A youtube video pointed to the waste toner container but that was not the reason for the failure though it was messy.
What finally helped was connecting the printer to a mac, its printer drivers finally provided a useful error message, namely that the yellow toner cartridge was incompatible. It of course was not a original samsung one because the originals cost as much as a new printer. The other 3 cartridges where still the originals, the yellow one was bought from amazon a bit less than a year ago and it worked fine for a few months. (and this seemed not related to a firmware update)
The final confirmation that this was the issue came today as i received a replacement yellow toner cartridge again non original of course. And putting that in the printer, it came back to life, for now at least.
Iam not sure what i should think about this, but this is uncool. First samsung WTF, why if theres a fatal issue with a toner cartridge why do the LEDs for the toners all light up equally that gives 0 hope to one finding the issue. And iam not commenting about the whole toner original vs compatibility thing except id like the CEOs of all th e printer manufacteurs that make it hard to produce compatible toner cartridges to cleanup all the avoidable waste this creates. Go with a row boat please to the Great Pacific Garbage Patch and pick your incompatible toners and still good but misdiagnosed printers out and recycle them properly.

Thanks

What i write here is going to be outdated in a few days or weeks likely but anyway, some thoughts about this …
Ive been following the information updates in the last few days, less the mainstream news. And normally i do not pay much attention to either the mainstream news nor any non mainstream stuff. But since about the 13th or so ive the feeling from what iam reading that this might turn into a pandemic. I hope iam wrong, this is not my area of expertise at all.
I hope the dumb extrapolation of numbers one can do is wrong because if this virus is anywhere as deadly as currently predicted and if it spreads widely. A worst case scenario could have many dead. Basically if this infects a significant fraction the world population, and the current fraction of seriously ill patients would apply in that scenario. There would not be enough hospitals, ICUs, … . People could be dieing because of the medical system being overwhelmed by the cases of serious illness.
So, i hope iam wrong. I hope this is successfully contained, people are quarantined everywhere and the virus dies instead of people. And from what iam reading it seems china is successful in containing it, but i have difficulty imagining all countries will.
I hope by isolating the most severe cases the virus will evolve to become more benign. A virus which causes severe disease which causes quick detection and isolation doesnt spread well, one that produces minor or no symptoms spreads much better. This can push the virus to evolve toward being milder. Of course that only works if a milder variant still spreads equally well, evolution is survival of the fittest after all, it has nothing do do with the hosts survival.
I hope a working vaccine is quickly found, tested and becomes widely available.
I hope there will be enough antiviral medications for the people who need them.
I hope that if it does spread, the politicans will direct resources toward preparing the medical system of their country and teaching citizens about Hygiene.
In some countries wearing a mask to protect against spreading diseases is even outlawed currently. (like the one i am in for example)
Also its socially not particularly accepted, people here rather cough each other in the face, or if they are more polite cough in their hand and then touch everything and everyone from food to other people with that hand. Yeah thats why the flu and the cold spreads so well and why this one might too.
And i dont even want to think or be reminded of the general gen-tech-phobia. Without that more laboratories and researchers would exist who could now work on finding a vaccine or other treatments or just testing samples from patients if they have the virus. It is AFAIK very simple to do a PCR and gel electrophoresis or realtime PCR which is AFAIK how this is detected currently. There are YouTube channels where you can see hobbyists doing PCR and electrophoresis in a garage, shed or similar. Sure for the virus one needs a negative pressure glove box and some additional saftey but still it puzzles me a bit when i read that various countries cant test or cant test as many samples as they need.
Enough off topic talk, I hope this virus disappears, and everyone gets well and no more people die from it or any other virus.

Update 2020-03-14: You can donate to WHO to fight COVID-19 via covid19responsefund.org

A few days ago i noticed a missing mail from james in my ffmpeg-devel folder. Checking my local logs, checking the servers logs it appeared as if it was sent to me and that i never received it locally. I saw some bounce but mailman doesnt seem to keep track of bounce details. James said it might be a fluke and i put it asside. But shortly later another 2 mails that reached the Archives and others did not reach me. So i opened an issue on gandi.net about this which iam using for my mail. A long while ago i switched to gandi as gmx was just a pain if something did not work …

Until this issue was looked into by gandi, i used a 2nd email address to receive mails from ffmpeg-devel reliably. I also as a precaution changed my password and then later went over most of my email setup to check for any potential bad configuration. In the meantime another mail, one from Andreas failed to reach me over gandi but received me over gmx. So i reported that to gandi with all the headers. On the 24th gandi after a bit of back and forth found the email. It was in a Junk folder that one can see in their webmail but which is inaccessible via POP3. There in fact where almost exactly 1000 mails in the Junk folder.
So i switched from POP3 to IMAP and fetched all, sending them through my own spam filtering i have locally. I have to shockingly say that a substantial number of these “Junk” mails, as in 5-10% where miss-classified and where not junk. Mails from the IETF list, from the debian lists, from ffmpeg, some buisness/finance related mails and many IRC logs, just to list what i remember now off the top of my head. The recovered mails seemed to cover a Timespan since july 2019. I do not know if mails prior to july 2019 “expired” in the Junk folder or if that was when this issue started. From my memory gandi did longer ago reject mails on reception so the sender would always get an error and know. Also it feels as if their spam filters where orders of magnitude more accurate in the past. I was a bit foolish to fail to guess that the well working mail service that gandi had wouldnt be “improved”.

Either way, the things of note are

1. If you sent me a mail of importance and i didnt react, send it again, especially if it was prior 2019 mid july
2. Avoid POP3, use IMAP, make sure you fetch all folders the times where companies cared about features working are over. In the past if one fetched mails via POP3 from a webmail thingy that had a spam folder one could get these mails with a “SPAM” header or SPAM keyword added to the subject.

Everyone on youtube, well all the science channels at least are collaborating on planting trees #teamtrees.
So i donated too because well. I like forests :). And in fact Trees are very important, life as we know it maybe would not exist without trees. Without trees all the carbon now locked up in coal might instead be CO₂ in the atmosphere. Also so many lifeforms depend on trees …
Ahh and they are a great way to turn CO₂ from the atmosphere into wood, the later does not cause global warming.

Here are some forest related pictures i took in 2019

I just managed to order 15 euro worth of office stuff on amazon for 1 euro 22 cent. And together with buying my first 30 euro giftcard i should theoretically get a 5 euro coupon. So if that worked that means amazon will pay me 3 euro 78 cent for doing probably 2 separate free deliveries of things to me.
2 Deliveries because mysteriously it was out of stock so the gift card would come separate and first i assume.
Not as cool as that case where amazon recently managed to sell 13k USD equipment for less than 100, i wish i knew about that one in time :(
But still cool.

PS: The price already changed back to normal by the time iam writing this

Some random pictures from my cameras sd card in chronological order (this is from end 2017)

Dont focus on me.

Dont step on me.

You shall not pass.

The way oil radiators work is that the oil inside is heated by electricity flowing through some resistive heating element. The heated up oil then raises due to lower density and that way circulates in the radiator which then gets hot and heats the air.
Noise is produced by either mechanical thermostats or relays, so every time the set temperature is exceeded by some fixed amount some mechanical switch or relay switches which makes a click. That can be annoying if one tries to use a device like this in an otherwise silent bed room.
The Device:

To get it open one has to remove 2 screws and slide teh front down:

The top can be removed too after that and after removing the handle.

Three more screws later the next front layer can be taken off, that is as much as we need to disassemble to access all parts we need to access:

Removing the lower board is trivial, just remove screws and disconnect cables:

Next the 2 noisy relays are desoldered:

To replace the relays 2 solid state relays from ali express are added, they are rated at several times the needed current (i expected the rating to be exaggerated when i ordered and wanted to make sure they arent underrated but it seems the seller actually was honest with the rating). Careful attention is also paid to their heat-sinking requirement (which is none at the currents they would be used with).

And a quick tests shows they are working fine and also have a pretty red led indicating that they are on:
btw, they are lacking their top cover because the heater could not be closed with it on, and it serves no purpose in this case

And now i have a silent electric oil heater radiator thing … click …WTF
Was there some part expanding from the heat and making a noise ? something on the 2nd board i didnt look at ?
I had it already reassembled and had to disassemble it again to trace where that came from. The radiator is rated for 2000W, one circuit 700 W or so and the other the rest to get to 2000W. It contains a fixed mechanical thermostat that disables both heating elements in case of overheat. and the 1300W heater has its own mechanical thermostat which disables just it at 85°C. The surprising thing here (to me) was that 85°C is easily exceeded by the 700W element alone. So the heater rating of 2000W is misleading at best because the heater under normal conditions will only heat with the 700W element continuously. The 2000W will just be used for a short period. After learning about that ive checked the shop where it was bought long ago and looking at heaters rated at 700W (which they have too and which are smaller) one quickly finds customer complaints that the 700W units switch off and are unable to sustain heating at 700W. This is Europa not China :( I did not expect to find this …
Ok back to the silencing, the solution here is in fact very simple. As the 2000W and 1300W modes are fake and only sustain 700W anyway and i have to assume for a good reason. The solution is to simply disable the 1300W part.

With that change the radiator is now actually silent and also looks cooler with the relay led shining through the front. Looking at the images i regret a bit that i hadnt thought about replacing the front by a transparent polycarbonate window. it would have looked cooler ;)

The chinese negative ion generator i used in 3d-printer-particles-air-pollution made me a bit curious about what voltage it outputs. The page from the seller mentions several different values, 2-5kv, 5-8kv, 5kv and other things. So one wonders what it actually is. This sadly cannot be directly tested by just using a normal DMM as its a bit outside the supported voltage range of the average DMM. High voltage probes for DMMs exist but even chinese ones seem to cost at least ~70€ and i wouldn’t trust them safety wise. So lets make one for 1€ which we can trust to be unsafe.
We start out with a inappropriate high voltage probe enclosure, which we disassemble and remove the unneeded parts:

The innards of our HV probe is simply a 90MΩ resistor, which will together with the internal 10MΩ resistance of the DMM form a 10:1 voltage divider, extending its input range.

Lets try:

1470V, hmm
Checking what output saftey resistance this device uses:

It seems its something around 20MΩ, maybe 2 10MΩ resistors ? Its potted so no easy way to tell exactly. But this changes our output voltage estimate as now our probe effectively is 110MΩ instead of 90MΩ. That raises it to 1764V, but it still feels a bit lowish to me. Also the 120MΩ to ground would draw 15uA, which could pull the voltage down by an unknown amount. This ionizer thing after all is not intended for producing any current.
To test for this we can use a higher value resistor. I do have a 1GΩ resistor (though it cost more than 1€), with it we get:

Aha, 4270V, so the 15uA does in deed quite significantly pull the voltage down. Now with 1GΩ we still pull 4uA here so this is likely still a too low estimate. Sadly i do not have a higher value resistor ATM.
What remains is to check that the 2 HV probe setups actually work at all, we must test this as we cannot be sure the DMM behaves as expected in this setup.

Both produce expected values at a 1kV test input, the voltage appears to be slightly below 1kV though.

at a 500V test input the value matches much better indicating that indeed the 1kV test output seems lowish

disclaimer: high voltage is dangerous, do not play with it or replicate anything described above. If you do anyway you do so at your own risk.

A while ago i bought a quite cheap flashlight/”worklight” from aliexpress. Not the best quality but it worked.

About 3 days later its button started to work only intermittently. A few days later it basically didnt work anymore.
I wonder why these items have so many 5 star reviews.
Yesterday after putting some food in the oven in the morning i had some time while waiting for it.
After disassembly, it looks like this:

The button is a standard SMD button, i had some equivalent replacement.

After exchanging it, it works again. Lets see for how long …

Almost forgot, the failed button after gentle disassembly: