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In 1999, my DVD player could do this smoothly without any hitches or glitches. In 2020, my Xeon can't render this fast enough to avoid stutters. Either code quality has gone way down or my DVD player had a faster CPU.
To be more specific about why the implementation is bad, it's hardcoded to refresh around every 30ms but not precisely 30ms.
Earlier quoted context omitted.
It didn't even occur to me that this would need to be explained. Up next we should talk about why it was bad to leave VCRs paused for long periods of time.
Why was that bad?
As a historical note, the bouncing logo wasn't just for fun, but was important to prevent screen burn-in on CRTs. If you had a static image on a CRT for a long time, it could damage the phosphor. Sometimes you could even see the image when the screen was off! This was the original purpose of screensavers, which saved your screen from damage. Displaying a dynamic image prevented one part of the screen from being overu…
As to why they are not necessary anymore: we just turn the screen off (some displays, especially OLED, are still prone to burn-in). This was not necessarily wanted in OLD CRTs, where the startup sequence could take a while (and possibly other factors, such as reducing the lifespan, but I'm not sure about this). Funnily, we are starting to see a bit of a comeback of these in OLED smartphone that have an always-on disp…
They suffered terrible burn-in, and I was never sure why they were used. Eventually they ripped them out and replaced them with panels using the same technology (monochrome panels made of amber LEDs) that is used in the rest of the network for displaying information.
The thing about information is that you don't want it to spin or hop about, it needs to remain perfectly still while a potentially large number (tens of thousands of people use the station in an hour, if anything goes wrong all those people want information) stare at the information and so it can't avoid burn in. I can see that for the advertising screens, the opportunity for huge full colour screens is worth the risk of burning in an image, and worst case you could in theory even charge an advertiser who insists on holding a single image for the cost of repairing/ replacing your screens. But the information screens don't much benefit from colour, the pixel-addressable LED screen is only a small improvement over prior electro-mechanical devices which of course couldn't burn in, why allow burn-in just to get a colour screen? Maybe they were cheap?
Earlier quoted context omitted.
Why was that bad?
I remember being told as a child that it "wears out the tape," but I'm going to guess it's specifically because the same section of tape stays wrapped around the capstan (the metal cylinder it loops around to be read) when it would normally be passing through. Keeping the same section of tape under tension for a prolonged period presumably weakens or risks distorting it.
Earlier quoted context omitted.
Why was that bad?
I remember being told as a child that it "wears out the tape," but I'm going to guess it's specifically because the same section of tape stays wrapped around the capstan (the metal cylinder it loops around to be read) when it would normally be passing through. Keeping the same section of tape under tension for a prolonged period presumably weakens or risks distorting it.
¹ It was actually an interlaced field, not a frame, but that too much nitpicking.
As a historical note, the bouncing logo wasn't just for fun, but was important to prevent screen burn-in on CRTs. If you had a static image on a CRT for a long time, it could damage the phosphor. Sometimes you could even see the image when the screen was off! This was the original purpose of screensavers, which saved your screen from damage. Displaying a dynamic image prevented one part of the screen from being overu…
DVD was also popular around the time that Plasmas were being introduced, which also had burn in issues.
Earlier quoted context omitted.
It's not just about speed, it's about timing. With setInterval the alignment of the screen refresh and the code to update will quickly become out of sync and cause periods where 2 frames are the same.
Which causes visual tearing.