Debian 12 seems not to error-correct corrupted animation
files associated with html web pages.

Weeks ago, I kvetched about screen tearing on Debian 12 -
web pages displayed weirdly-patterned pixellated garbage
with Firefox and Brave browsers.  Those pages displayed
properly on Debian 11, and on (Much) older Ubuntu and
Redhat distros.

My "cure" emerged by accident; I noticed that the Ethernet
switch in-line with the "hot side" (feeding the firewall
machine) of my Ethernet connection was MUCH slower than I
expected after my Comcan't to Ziply internet connection
change (pro tip - if you can, move to Ziply PRONTO).

Connection speed slowed MORE during a 60 second Ethernet
speed test.  The speedometer graphic pointer, displayed
on a hot-side after-switch connected, fast "sacrificial"
Chromebook, dropped from 60 mbps to 40mbps. 

Something was warming up and getting worse, seemingly
inside the hot-side Ethernet switch.  

Connecting the Chromebook (running ChromeOS) directly to
the Ziply optical network terminal, bypassing the Ethernet
switch (and disconnecting my house network from the 'net),
resulted in a 250 mbps speed test. 

So, on a hunch, I replaced the suspect Netgear 308 Ethernet
switch with a new-out-of-box Netgear 308 ... and I got 250
mbps on both sides of the switch.  After that, the pixelated
screen artifacts on web pages vanished on the Deb12 machine.

Finding and fixing my problem still leaves me with a vexing
question - why does Deb 12 display corrupted images if fed
a corrupted data stream, when Deb 11 and other distros do
error correction, and (more slowly) display good images?  

Sadly, this realization occurred AFTER I "destructively
diagnosed" the failed crap-packet-spewing switch.

In the capable hands of a Debian kernel guru, a stream of
crap packets (with some good ones) might help debug the
error-detection-and-correction code that FAILS in Deb 12.

I fixed my corrupted-data-stream problem by replacing the
hardware that corrupted it.  I can afford to, and afford
to keep new-in-the-box ready spares waiting on the shelf.

In a more-fragile network environment, replacing the 
hardware may not be an affordable option.  I imagine a
rural third-world village with an intermittent data
connection, using old hardware culled from first-world
e-waste.  They won't have a noiseless connection and
perfect hardware for comparison debug.

They might blame Debian 12, then switch to bootleg Windoze
instead.  Their kids don't learn Debian, we lose some
future gurus.

I should have kept the borked Ethernet switch; a noisy
packet generator might help developers write and debug and
test more robust code.  In the wrong hands, hell on Earth.

On the other hand, a machine built and coded to produce
INTENTIONAL and REPEATABLE corrupted packets might help
design more robust future versions of Linux.  If "Corrupter"
was open-source code, it might also help marginally-equipped
people become Linux adepts and future contributors.

I'm probably over-thinking this.  However, the first step
towards more robust, data-defect-tolerant Debian 13, 14,
etc. is more-complete automatic testing before release. 
An upgradable device designed to intentionally create
calibrated defective data might be a lucrative product
and test instrument for professional coders everywhere.

Keith L.
-- 
Keith Lofstrom          [email protected]

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