View Full Version : creating a true progressive stream


Adam Krawczyk
January 20th, 2008, 05:49 PM
Hey,

From my understanding, my v1p shoots in 25p but converts it to a 50i stream. Is there any way to convert this 50i stream into a 25p stream?

It shouldbe as simple as adding the 2 identical 50i fields into one 25p frame. But I havent yet seen a method of conversion that doesnt drop one field and interpolate the other.

I have premier cs3 and gives me the option of starting a project as 25p or 50i - whgich one should I be using given that my footage on the v1p is shot in progressive but output in interlaced?

thanks,

Adam

Sorry if this has been covered b4, I did a search but the discussions didnt really adress this issue.

Carl Middleton
January 20th, 2008, 05:58 PM
I think Cineform would be able to accomplish this?

C

Adam Krawczyk
January 21st, 2008, 07:52 PM
Ok, well in the meantime should I be using 25p or 50i projects in Premiere cs3? Is there any difference? Does it end up capturing differently? I'm really not sure what to call somthing captured in 25p on an 50i stream like the v1p does.

thanks,

Adam

I think Cineform would be able to accomplish this?

C

Piotr Wozniacki
January 22nd, 2008, 03:05 AM
Adam,

It doesn't make any difference how you capture the 25PsF (progressive segmented frames) stream - in fact, some NLEs will recognize it as 25 progressive (Vegas), most as interlaced - upper filed first (like Premiere or Edius). But after you render it from the 1080/50i (or 1080/25p - really doesn't matter) timeline into the 1080/25p MPEG-2, i's already what you are after -i.e. the 2 fields are weaved into a frame.

Which doesn't change the fact that when you feed such a file using component to your monitor, it's sent within the interlaced 50i stream again ...

Adam Krawczyk
January 23rd, 2008, 12:04 AM
Adam,

It doesn't make any difference how you capture the 25PsF (progressive segmented frames) stream - in fact, some NLEs will recognize it as 25 progressive (Vegas), most as interlaced - upper filed first (like Premiere or Edius). But after you render it from the 1080/50i (or 1080/25p - really doesn't matter) timeline into the 1080/25p MPEG-2, i's already what you are after -i.e. the 2 fields are weaved into a frame.

Which doesn't change the fact that when you feed such a file using component to your monitor, it's sent within the interlaced 50i stream again ...

I think I get this... I was thinking about it last night- The whole reason u get a comb effect playing back on the comp is because the 2 fields are diplayed at the same time anyway. U can go frame by frame and its 25 frames even on interlaced video. So progressive will be displayed like true progressive because the 2 alternate but identical in time fields are shown at the same time.

I hope I got that right.