25p doesnt exist?

S

ST_

Well-known member
I have heard that 25p recording is not really 25p, it is something like 720p/50p or 25/50p... but i cant find information about this anywhere. can anyone explain? (im talking about SD and HD?)

does it record at 50i then convert it to 25p at the camera level, or 50p then convert it to 25p?
 
Barry_Green said:
25pN is shot and recorded as 25fps.

25P mode is shot at 25fps and recorded as 50fps (each frame being duplicated once).
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Actually there is no such thing as a 25pN mode on the DVX100, it's easier than that.

As Barry pointed out the camera shoots at 25fps (full frames per second, meaning both fields at once) and then each frame is divided into two fields (50 fields per second) to be compatible with the PAL video standard. That's it! No pulldowns no anything.

720P is a HD format and the numbers refer to the number of vertical pixels used for it. In this case 1280x720 pixels, where standard definition PAL is 720x576. 25P is progressive video and 50i is interlaced video. The two HD standards mostly talked about are 720P (P for progressive) and 1081i (i for interlaced), meaning 720P uses 25 whole frames per second where 1080i use 50 fields (half frames) per second.

Hope this helps!

/Johan

edit: changed the explaination a little to avoid confusion - it now makes more sense i think :)
 
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thanks guys.

so with the dvx100pal for example it records at 25fps then converts it to 50fps by doubling the frames because thats how pal tv's work at 50hz, so 25p does not exist? as it is 50p. so while 50p will look filmic in comparision to 50i, 25p and 24p will look different as there is not just 1 frame different there is actually 26. or does the use of repeated frames keep it looking like 24p.

and in the new cameras i have seen frame rates of 25p recording and 50p recording, i take it the difference is that all the 50 frames in 50p will be different, where as in 25p, the 50 frames will be doubled...
 
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PAL is not 50P. PAL is 50i.

Not 50 frames per second, it's 50 fields per second. There is no such thing as progressive-scan PAL; PAL is always 50 fields.

So 25p from the DVX results in each frame being converted to two fields (which works nicely, as each field is 1/2 the resolution of a frame).

So 50i = "video look", 25p = "film look".

In the HVX you can actually record 50p or 25p, and yes they'll look very different -- 50p = "video look", 25p = "film look".
 
25p PAL is recorded on tape as two interlaced fields exposed at the same instant, in normal 50i those fields are exposed 1/50 sec apart. Thus 25p is a real progressive, this is just a conveninet and easy way to record it using a standard video system. What you see on television is 25 discrete pictures/sec, but of course shown as 2 interlaced (identical) fields, as that is the way televisions always work.

This progressive PAL recording system is waaaay more simple than fitting 24 frames on 29,97 frames (or 59,94 interlaced frames) with pulldown in NTSC. I could say in my part that how can THAT concotion be progressive?

But those are just workarounds to put the non-standard video format on a standard designed-for-interlaced-TV tape using standard tapes and drives. If the video is shot as 24 or 25 discrete pictures/sec and not as two half fieds it is called progressive, how the data is recorded is totally a different matter. It is still progressive even if you would write down the bit values on a piece of paper...
 
So then how about editing DVX originated footage as progressive 25fps in FCP?

So then how about editing DVX originated footage as progressive 25fps in FCP?

Here's a question that has me baffled. I'm originally from the States and used to shooting on an NTSC DVX100A and doing the pulldown for 24P (FCP has settings now for all that to be taken care of). Now I'm doin' a masters degree in Australia (PAL) and shooting with DVX100AEs.

In FCP 5, is there a special way to keep the 25fps progressive throughout the capture to edit to DVD? Or am I not understanding properly and it just stays 50i and thats fine and dandy? It looks good, but it says on the timeline settings that it is interlaced.

So, I'm just wondering if I were to somehow keep it 'progressive' throughout the process, would it look even smoother (as it did for NTSC and the 24P stuff I did)? And then, is there a way to make progressive scan PAL DVDs from the DVX footage?

Does any of this make sense? I can find no answers to these "PAL progressive scan in FCP" type questions....only 24p answers!!
 
bwilson2 said:
In FCP 5, is there a special way to keep the 25fps progressive throughout the capture to edit to DVD? Or am I not understanding properly and it just stays 50i and thats fine and dandy? It looks good, but it says on the timeline settings that it is interlaced.

And then, is there a way to make progressive scan PAL DVDs from the DVX footage?
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about the first question, i confirm you just leave it 50i and everything is fine. as said before in the thread, couple of consecutive fields are taken from the same (progressive) original image, so it's just technically interlaced, but without using the features of the interlacing (where usually the two fields are captured in different time instants). so what you get is progressive-like.

i don't know how to answer to the second question, and i'm moderately (since i'm sure it would look the same anyway) interested in the answer.

Andrea
 
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