False frame rates and a genius down under

[gillianren]

You don't; your camera just doesn't worry about seconds.

[smartcooky]

So it's the average then, because how do you display a fraction of a frame?
That's really what I was asking.

You don't. Its a close approximation

25 frames per second is really 40 milliseconds per frame

29.7 frames per second is really 33.67 milliseconds per frame

[raven]

Derp, silly brain. Thanks, that makes a lot more sense.

[dwight]

Something else I have noticed about these hoax theorists ist that they dont understand the proper TV terminology. For example, they will argue to the bitter end that "Live" cannot possibly be live if a camera is pointing at a screen. They also cant grasp the fact that every third frame of the sstv tv camera was indeed live, while the other 2 were buffered. So Apollo 11 TV was live when it was telecast.

No different to racecam footage which is run through a frame store and strangely no claims the buffered feed isnt live.

[ka9q]

This brings back a memory for me. Do NTSC and PAL not have the same Hscan frequency, 15625 KHz?

PAL uses 625 lines/frame which yields a frame rate of 15625/625 = 25 fps
NTSC uses 525 lines/frame which yields a frame rate of 15625/525 = 29.7 fps

No, but they're close. NTSC's horizontal sweep rate is 15 750/1.001 = 15 734.26 Hz and its frame rate is 30/1.001 = 29.97 Hz. PAL's horizontal sweep rate is 15 625 Hz, and its frame rate is 25 Hz.

The Wikipedia articles on both are pretty complete.

During my first summer in TV broadcasting, the 15 kHz squeal from the monitors really bugged me. The next summer, it didn't. Maybe too many loud concerts?
 

[JayUtah]

So it's the average then, because how do you display a fraction of a frame?
That's really what I was asking.

You don't display fractions of frames; yes, it's an artifact of the way the rate is expressed.  You just get one (whole) frame after the other, in sequence.  How that relates to some arbitrary yardstick like "seconds" or "minutes" may be a fractional ratio.

[Tedward]

During my first summer in TV broadcasting, the 15 kHz squeal from the monitors really bugged me. The next summer, it didn't. Maybe too many loud concerts?

Or you got older and it was above your threshold......


I heard an interesting anecdote, when they were testing humans for MP3 compression, the frequency checks on audio engineers hearing showed they tended to blank out 1K. Standard test tone so its there but you learn to ignore it. Be nice if that were a true observation but it fits.

[ka9q]

I heard a very similar claim about 15 kHz from the other TV engineers, that many develop a "notch" at that frequency. But it probably wouldn't take long until you lose everything above 15 kHz anyway. Sigh.

400 Hz was our standard audio test tone. 1 kHz was also used but much less often. I can still hear both quite well, and on airplanes I often wish I couldn't.

[Allan F]

You learn how to "tune out" certain sounds. My parent have a grandfather clock, which goes tick-tock quite loudly, and when my brother-in-law visits, he always sneaks over and stop it. I, myself simply cannot hear it, unless I focus on hearing that sound. And I have excellent hearing - even though the 15.000 Hz and above is long gone.

[dwight]

For me, 1khz tone is like the angels themselves singing.

[JayUtah]

I actually had a nurse friend of mine measure my heart rate higher when hearing 440 Hz -- the pitch orchestras tune to.  For me as a musician, that signals the start of a concert and the occasional onset of performance anxiety.

[Andromeda]

I think I'm tone deaf

[JayUtah]

I think I'm tone deaf

What makes you say that?

[Tedward]

Used to work in a rather noisy equipment room, electro mechanical switches, all motors and relays and pawls and racthets and so on. In that cacophoney of audio audible assault on your ear 'oles you could pick out a switch mis stepping or a motor on its last legs. Funny how sounds works.

[Luke Pemberton]

Funny how sounds works.

Exactly. It's more proof of a hoax. There is no air on the moon, but you can still hear the astronauts talk.  Yes, I've heard that argument.