1080i/25p

B

BWyldeck

Well-known member
I dont understand these codecs that list frame size with an 'i' and frame rate with a 'p'. eg 1080i/24p. It's either interlaced or progressive......not both. Whats it all about. Very confusing, especially since I own an HVX now.:thumbdown
 
25p mode shoot 25 fps in progressive mode. For output and recording the 25 fps signal is converted to 50-field-per-second interlace (see Operating Instructions page E-36).
 
I suppose its to do with the broadcast standards for 1080 that are broadcast in 1080i currently. The fact is you still have a progressive picture stored in there, its just stored and broadcast in 50i.

The NLE you use to edit will reform the 25P picture from the two fields stored in the 50i stream. You don't lose any resolution, its just a way its stored. You still have the same great 1080p image.

Its like the DVX, it shoots 25P over the 50i fields. Its all there ready to be retrieved.

Enjoy your new baby and worry ye-not !

Richard
 
majormorgan said:
I suppose its to do with the broadcast standards for 1080 that are broadcast in 1080i currently.
Click to expand...

It doesn't have to do with anything other than the DVCProHD codec and the way it is designed - which is what jjb was getting at in his post.

DVCProHD 1080 is always interlaced footage with 60 fields per second (or 50 in PAL land)
DVCProHD 720 is always progressive with 60 frames per second (or 50 in PAL land)

When shooting progressive, it is still laid down in an interlaced stream (like others have mentioned, this is how the DVX is able to record 24 progressive frames per second). In 720 when shooting variable frame rates, duplicate frames are recorded to pad the signal to 60 frames per second.

This has become a bit more confusing since the advent of tapeless workflows because we are no longer held to the restrictions that came with using tape based media.
 
I understand the progressive / interlace thing, but my Avid doesn't. When I import 1080 25p footage I have to use the 1080 50i setting else I get the "Mixing interlaced and progressive warning".
Should I continue to use 108050i or the 1080 25p and ignore the warning? I dont want to loose the progressive agvantage, but don't want to loose resolution either.
Thanks in advance,
Dave
 
It doesn't have to do with anything other than the DVCProHD codec and the way it is designed - which is what jjb was getting at in his post.
Click to expand...
Ah but the codec was designed that way for a reason. What I should have explicitly said was that I thought they had designed the DVCProHD codec for 1080 as 1080i instead of 1080P as that is what broadcasters were using until they create and broadcast a new codec different to MPEG2.

So coming back to BWvldeck's original confusion if its easy for them to store a progressive frame in the 1080i stream much like they proved when they produced progressive DV on the DVX100 then its a more flexible option for filmmakers and fits with TV standards.

Thanks for the opportunity to clarify Luis.

As this article says:
"Broadcasts -Various television networks in the world broadcast HDTV programming in 1080i and 720p; no 1080p broadcasting exists at this time.
"
quoted from http://en.wikipedia.org/wiki/1080p

Richard
The Major
 
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