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Microscopes can see video on a laserdisc

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Re: Microscopes can see video on a laserdisc

#21

Post by Retr0id »

EvanAnderson wrote: post #18
csours wrote: post #15

Not nearly as cool, but I was able to show a colleague the letters in a raster image section of a pdf using xxd by varying the output width

I wrote a simple tool, when I was a kid, that dumped binaries into VGA mode 0x13 and allowed me to vary the width. Mode 0x13 is one byte per pixel so it was just a simple REP MOVSB to put data into the buffer (no worrying about bitplanes). It was so useful in reverse engineering software. Besides raster data, regular data structures often jump out.

Fun fact, if you load a file with extension ".data" into GIMP there's a UI where you can set the pixel format and adjust the width/height with sliders

Re: Microscopes can see video on a laserdisc

#22

Post by mh- »

a-dub wrote: post #19
oofbey wrote: post #17

Fun fact about laser discs. They are analogue not digital. CD’s store digital information with the presence or absence of pits. Fairly ancient but still fundamentally feels like a very old version of a thumb drive. Laser discs are not digital. They encode the analogue video signal’s value as the length of the pit. It is digitized in the time domain - sampled at some frequency, but the “vertical” signal value is store…

yeah i remember learning this as a kid and being surprised. i originally thought laserdiscs were modern high tech, but then they turned out to actually be from the late 70s/early 80s with the primitive analog video encoding where red book audio cds of the mid to late 80s were actually digital.

I just learned this in my 40s and am surprised. Very cool.

Re: Microscopes can see video on a laserdisc

#24

Post by VerifiedReports »

smusamashah wrote: post #5

So CAV (constant angular velocity) is an encoding format for laser disks. When something is written with CAV, it is basically analogue data and therefore repeating patterns can be recognized on the disk.

No; it's strictly a reference to constant RPM or variable RPM.

CAV discs contained one frame per rotation. While this meant you could only fit half an hour on one side of a disc, it did give you perfect slow-motion and freeze-frames.

I worked in a video store and loved LaserDiscs. The Duran Duran video album was CAV, and the Pioneer LD-700 had such a fast transport mechanism and remote control that I could to DJ-style "scratching" with it.

Re: Microscopes can see video on a laserdisc

#25

Post by VerifiedReports »

a-dub wrote: post #19
oofbey wrote: post #17

Fun fact about laser discs. They are analogue not digital. CD’s store digital information with the presence or absence of pits. Fairly ancient but still fundamentally feels like a very old version of a thumb drive. Laser discs are not digital. They encode the analogue video signal’s value as the length of the pit. It is digitized in the time domain - sampled at some frequency, but the “vertical” signal value is store…

yeah i remember learning this as a kid and being surprised. i originally thought laserdiscs were modern high tech, but then they turned out to actually be from the late 70s/early 80s with the primitive analog video encoding where red book audio cds of the mid to late 80s were actually digital.

BUT... Pioneer put AC-3 (Dolby Digital) surround on LaserDiscs before DVDs came out. So LaserDiscs were the first video medium to offer digital sound at home.

And at that point, most players sold were combo players that could also play CDs.

And there was one more disc format: CD Video. It was a CD-sized digital single that also had a LaserDisc section for the (analog) music video. I have a couple; one is Bon Jovi.

Re: Microscopes can see video on a laserdisc

#29

Post by userbinator »

Retr0id wrote: post #21
EvanAnderson wrote: post #18

Earlier quoted context omitted.

I wrote a simple tool, when I was a kid, that dumped binaries into VGA mode 0x13 and allowed me to vary the width. Mode 0x13 is one byte per pixel so it was just a simple REP MOVSB to put data into the buffer (no worrying about bitplanes). It was so useful in reverse engineering software. Besides raster data, regular data structures often jump out.

Fun fact, if you load a file with extension ".data" into GIMP there's a UI where you can set the pixel format and adjust the width/height with sliders

Photoshop does the same with the .raw extension.
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