Today, poorly drawn Calvin's dad will teach you about constant angular velocity and constant linear velocity. This depends on the kind of spinny music in question.
Vinyl records have constant angular velocity. They spin at the same number of revolutions per minute regardless of where the needle is. This means the surface passes under the needle faster at the edges than in the middle, because the outer edge of the disk is longer than the inner edge, but an entire revolution goes by in the same amount of time. "Surely," you say, "This must mean that the record technically has higher fidelity at the edges than at the center?" This is absolutely correct.
CDs have constant linear velocity. The surface must pass by the laser at the same rate all the time, because the interval of the ones and zeroes (it's slightly more complicated than that, yes, quiet in the back there) must remain the same. Unbeknownst to you unless you're a hyper nerd, your CD player speeds up and slows down its spindle depending where on the disk it's reading.
And LaserDiscs can do either! Each one has advantages/disadvantages. CLV has longer runtime, but CAV has better quality and crosstalk properties --- one frame is one revolution, so crosstalk from adjacent track is just crosstalk from +/- 1 frame, and it's "the same part of the frame" in a sense.
CAV also allows for clean pauses, as it just keeps reading the same frame over and over again, with no need for a fancy buffer.
9 Comments
dual_sport_dork@lemmy.world · 42 pts · 151d
Today, poorly drawn Calvin's dad will teach you about constant angular velocity and constant linear velocity. This depends on the kind of spinny music in question.
Vinyl records have constant angular velocity. They spin at the same number of revolutions per minute regardless of where the needle is. This means the surface passes under the needle faster at the edges than in the middle, because the outer edge of the disk is longer than the inner edge, but an entire revolution goes by in the same amount of time. "Surely," you say, "This must mean that the record technically has higher fidelity at the edges than at the center?" This is absolutely correct.
CDs have constant linear velocity. The surface must pass by the laser at the same rate all the time, because the interval of the ones and zeroes (it's slightly more complicated than that, yes, quiet in the back there) must remain the same. Unbeknownst to you unless you're a hyper nerd, your CD player speeds up and slows down its spindle depending where on the disk it's reading.
redhorsejacket@lemmy.world · 15 pts · 151d
aeronmelon@lemmy.world · 5 pts · 151d
Current mood.
sharkfucker420@lemmy.ml · 8 pts · 151d
That's really cool thank you
qjkxbmwvz@startrek.website · 8 pts · 151d
And LaserDiscs can do either! Each one has advantages/disadvantages. CLV has longer runtime, but CAV has better quality and crosstalk properties --- one frame is one revolution, so crosstalk from adjacent track is just crosstalk from +/- 1 frame, and it's "the same part of the frame" in a sense.
CAV also allows for clean pauses, as it just keeps reading the same frame over and over again, with no need for a fancy buffer.
vaionko@sopuli.xyz · 3 pts · 150d
You watched Shelby's video didn't you?
qjkxbmwvz@startrek.website · 2 pts · 150d
Hah nope, but I picked up a used Laserdisc player in grad school --- an old school HeNe type :)
Scubus@sh.itjust.works · 7 pts · 151d
Mom: we have technology connections at home
Technology connections at home:
threelonmusketeers@sh.itjust.works · 5 pts · 151d
TL;DR: v = ωr