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Scroll Slow. Have Fun

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Re: Scroll Slow. Have Fun

#51

Post by phaker »

Aardwolf wrote: post #5

This somehow manages my monitor to make a high pitched sound. It's an LCD monitor. It's the actual monitor making the sound. Switching to a different window or tab makes the sound top. Taking a screenshot of the tab, and closing the tab but viewing the screenshot, produces the sound.

It's because of these horizontal bars, you can get the same effect with similar graphics:

All video interfaces we use transmit data serially, line by line, pixel by pixel. The bars are 16px tall (black + white) so at 60Hz and 1920×1080px they'll produce a tone with fundamental frequency of 4.05kHz (60Hz × 1080 lines / 16 lines) and harmonics.

Re: Scroll Slow. Have Fun

#52

Post by chc »

lukashed wrote: post #24
fauria wrote: post #11

Earlier quoted context omitted.

Same here on a MBP.

Mine doesn't (Retina without ghosting). Though, when scrolling on the site, _something_ (it's not the screen) is making weird noises, almost like the sound when accessing a HDD. I have an SSD though. I had the same issues with other sites / applications when scrolling in general as well. Even more noticeable with the MacBook Air I had before. Is there any rational explanation for this?

I used to have a computer that did that a long while back. It made a whistle whenever I'd scroll. IIRC I decided it was the video card, though I'm not sure I ever confirmed it.

Re: Scroll Slow. Have Fun

#53

Post by TazeTSchnitzel »

AlphaGeekZulu wrote: post #33

We just produced a children book with this technology in Germany: http://www.amazon.de/Ulff-Backenh%C3%B6rnchen-eine-irre-Verf... Will be released in the next 4 weeks. It was fun to make, but also quite nightmarish in the technical details. It is a hell of work (we have roughly 30 animations in the book, very small and very big ones). It requires extremely accurate measurements for the grid-foil and a sophisticated w…

Isn't this how those "3D" panels work as well? It's the same thing printed, but with a plastic prism-esque thing on top showing different views from different angles.

Re: Scroll Slow. Have Fun

#54

Post by ashmud »

Aardwolf wrote: post #5

This somehow manages my monitor to make a high pitched sound. It's an LCD monitor. It's the actual monitor making the sound. Switching to a different window or tab makes the sound top. Taking a screenshot of the tab, and closing the tab but viewing the screenshot, produces the sound.

Same on my work LCD. Dell E207WFP.

I also tried test patterns at http://www.lagom.nl/lcd-test/ and http://www.testufo.com/. None of those made caused my screen to make an audible sound.

Re: Scroll Slow. Have Fun

#55

Post by userbinator »

lukashed wrote: post #24
fauria wrote: post #11

Earlier quoted context omitted.

Same here on a MBP.

Mine doesn't (Retina without ghosting). Though, when scrolling on the site, _something_ (it's not the screen) is making weird noises, almost like the sound when accessing a HDD. I have an SSD though. I had the same issues with other sites / applications when scrolling in general as well. Even more noticeable with the MacBook Air I had before. Is there any rational explanation for this?

The first thing to know is that the power consumption of modern CPUs varies hugely between idle and full-speed; from a few watts to several dozen.

When you are just looking at the screen, and the machine is otherwise idle, the CPU is not doing much, so it goes into low-power low-frequency mode and "sleeps" until some event occurs. When you put fingers on the trackpad and scroll, it sends an "interrupt" to the CPU, telling it that a scroll event has occurred; in a few microseconds the CPU goes from idle to full power to process that scroll event, then goes back to sleep again. The GPU might also be involved in the same way. Every little scroll movement results in an interrupt, so when you are scrolling at a constant rate interrupts occur at a fixed frequency, and the system is going from idle to full power many times a second. The pulses of power draw that this creates, happening at audible frequencies, causes various components like inductors and capacitors to emit sound.

Re: Scroll Slow. Have Fun

#57

Post by ashmud »

drivers99 wrote: post #35
Aardwolf wrote: post #5

This somehow manages my monitor to make a high pitched sound. It's an LCD monitor. It's the actual monitor making the sound. Switching to a different window or tab makes the sound top. Taking a screenshot of the tab, and closing the tab but viewing the screenshot, produces the sound.

"Some surface-mount capacitors exhibit acoustic noise when operated at frequencies in the audio range." [1] I see that this screen has alternating black and white lines. I count 43 black lines on my monitor. Assuming 60 Hz refresh rate, that is 2580 Hz in terms of the pixels being off or on, which is a perfectly audible frequency. Even with 120 Hz refresh rate, that would be 5160 which is still easily audible. Withou…

Zooming in and out does produce different audible frequencies on my screen.

Re: Scroll Slow. Have Fun

#58

Post by tricolon »

Aardwolf wrote: post #5

This somehow manages my monitor to make a high pitched sound. It's an LCD monitor. It's the actual monitor making the sound. Switching to a different window or tab makes the sound top. Taking a screenshot of the tab, and closing the tab but viewing the screenshot, produces the sound.

Same here on my Monoprice 27" IPS LED monitor: http://www.monoprice.com/Product?p_id=10489
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