Why is it 60i

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PunkMetalDrummer17

Carbonite Member
I've been think recently about frame rate names and I'm just wondering why it's called 60i. Isn't it 60 de-interlaced fields?, so shouldn't it be 60d or 60 de-interlaced frames? Because in actuallity its 30 interlaced frames, right? Video doesn't run at 120 de-interlaced frames. Interlaced means to tie together. Does anyone have any information on why it was given the name 60i?
 
60i because it is actually 30 odd fields Interlaced with 30 even fields. If you could see this interlacing with the naked eye, and took a snapshot of a single frame, it would look somewhat like the red and white stripes on the Amercian flag, each field alternating between one and the other.

After 1 second, you actually have 30 FRAMES, but since EACH frame is made up of TWO fields, its considered 60i, or 60interlaced frames. The alternate to interlaced footage would be progressive. Each frame is made up of ONE field. So, 1 second of 30p footage, would yield 30 frames of single field footage.

Make sense?
 
rlm7189 said:
60i because it is actually 30 odd fields Interlaced with 30 even fields. If you could see this interlacing with the naked eye, and took a snapshot of a single frame, it would look somewhat like the red and white stripes on the Amercian flag, each field alternating between one and the other.

After 1 second, you actually have 30 FRAMES, but since EACH frame is made up of TWO fields, its considered 60i, or 60interlaced frames. The alternate to interlaced footage would be progressive. Each frame is made up of ONE field. So, 1 second of 30p footage, would yield 30 frames of single field footage.

Make sense?
Click to expand...

Right but it's still 60 deinterlaced frames a second...

The odd Fields are scanned down 1,3,5,7,9,11, ect..... and then the even fields are scanned up. Since it takes 60 fields to make one second.... fields mean de-interlaced, there's still 60 de-interlaced fields, which to me should mean 60d or even 60f for fields. Interlaced material would make 30 complete frames but 60 de-interlaced frames.... Frames with every other line.
 
They are not deinterlaced. They are simply interlaced. If they were deinterlaced, it would be a pseudo 30p (like the frame modes on some cameras).
 
Yeah... the 'de' in de-interlaced assumes that they were interlaced at some point. Meaning that the camera would have to interlace, then de-interlace. It doesn't do that.

As long as we're throwing stuff out, would un-interlaced be progressive? :grin:
 
okay.. so its 30P just scanned every other line? odd down for 1/60th of a second, even up for 1/60th of a second..... creating 60I, at 1 full frame at 1/30th of a second, right? Also, this could make 24P, 48I? Makes sense.... it's just a book I have confused me, it said things as 30i and 25i; instead of 60i and 50i.
 
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True 30p is one solid frame, 30 times per second, there is no interlacing. Same for 24p (except 24 times per second). 60i is 30 frames per second, but with two interlaced fields instead of the solid progressive frame.
 
Hey, I knew what you were getting at. Just wanted to make sure that he's understanding it. :costumed-smiley-047
 
Yep, we could have given you a masters in 6 months... think of all the wasted time.

:grin:
 
technically 24p is still 60i coming out of the dvx it's just...welll this is the dvx user forum so everyone should know how it works, right?
 
the reason they went with interlacing at alll was to eliminate the TV screen from flickering. 30 htz, isnt fast enough to trigger persistence of vision. ( neither is 24p BTW, they actually flash each frame of film twice so youre seeing 48 flashes of light per sec) so to help keep the TV from flickering the engineers in the 20's and 30's settled on an interlaced signal, to make the screen flash twice as fast.

i can actually see the flicker in PAL tvsets. its at 50 HTZ, and its just detectable to me. so i have trouble watching TV in europe, it gives me a headache.

( the set not the programming, italian TV is where life begins... especally after 10PM..... )
 
I get confused by the issue myself, when I went to school video was 30 frames per sec and was comprised of two fields. However, when I went on a search for the best setting for slow motion I saw posts saying shoot at 30i and others saying to shoot at 60i. Should not 30i be refered to as ntsc video and 60i refer to the full gamut of the resulting footage i.e 60i?
 
Wait, since when is there a 30i?

Now I'm confused. Where the hell is Mr. Green?
 
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