720p VS 1080i - Which one?

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filmguy123

Veteran
Which one do you prefer, and why? How much better is 1080i than 720p? Any benefits to the 720 being progressive, and 1080i only being interlaced? Quality differences? Pros/Cons?

Trying to decide what my HD shooting format should be...
 
Hi Barry, thanks for the article. Reading that raised a few questions for me:

1.) Can it be said, then, that the image quality on the HVX-200 between the 1080i mode and 720p is very close, and in fact, the 720p mode should be considered superior due to the progressive scanning and thus better handling of moving images?

2.) When, where, and why would someone want to choose the 1080i mode on the HVX200?

3.) The article mentioned that many cameras are only capable of 1440x1080 rather than 1920x1080 at the current time. I noticed that my 1080 footage in FCP was only showing to have a resolition of 1280x1080. Why is this?

4.) If in fact that HVX is only capable of 1280x1080, doesn't that bring the the image quality differenc between the 1080i mode and 720p even closer? Does this make one more reason to always choose 720p shooting mode?

5.) What does it mean when a format includes a mix of interlaced and progressive... I am a little confused about this. For example, on the HVX, there is 480i/30p which is what I have shot a lot of footage in. Is this interlaced footage, or progressive? How does the 30p and 480i play into this, and how do they relate. In FCP, should my timeline settings be set to interlaced or progressive when shooting 480i/30p?

Thanks so much!
 
filmguy123 said:
1.) Can it be said, then, that the image quality on the HVX-200 between the 1080i mode and 720p is very close, and in fact, the 720p mode should be considered superior due to the progressive scanning and thus better handling of moving images?
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Depends on what frame rate you're shooting. 1080/24p is better than 720/24p, and 1080/30p is better than 720/30p. But yes I'd say 720/60p is better than 1080/60i. They are very close, as you suggest, but for fast motion a 60p frame rate is just better than 60i.

2.) When, where, and why would someone want to choose the 1080i mode on the HVX200?
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If you're displaying on a 1080/60i monitor, or sending your footage to a network that broadcasts in 1080/60i, or doing stock footage for a footage house that sells 1080/60i, etc.

3.) The article mentioned that many cameras are only capable of 1440x1080 rather than 1920x1080 at the current time. I noticed that my 1080 footage in FCP was only showing to have a resolition of 1280x1080. Why is this?
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No recording format in common use records 1920x1080. HDCAM, DVCPRO-HD (50i) and HDV, and even most implementations of AVC-HD, all prefilter the footage down to 1440x1080. 60i DVCPRO-HD goes a little further, prefiltering down to 1280x1080. Compression comes in many forms, and that prefilter is one of the ways footage gets compressed before recording.

4.) If in fact that HVX is only capable of 1280x1080, doesn't that bring the the image quality differenc between the 1080i mode and 720p even closer? Does this make one more reason to always choose 720p shooting mode?
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No, because 720p gets prefiltered down to 960x720. 1080p is just plain better on the HVX than 720p. The only time I think 720 is unqualifiedly "better" on the HVX is when comparing 720/60p vs. 1080/60i (or 720/50p vs. 1080/50i). Or for slow-mo, of course.

5.) What does it mean when a format includes a mix of interlaced and progressive... I am a little confused about this. For example, on the HVX, there is 480i/30p which is what I have shot a lot of footage in. Is this interlaced footage, or progressive?
Click to expand...
Progressive footage, carried in an interlaced "basket."

In FCP, should my timeline settings be set to interlaced or progressive when shooting 480i/30p?
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I don't use FCP, but I would presume you'd set it to progressive 480/30p.
 
It means "interlace." On the 170/200, it refers to how the footage is recorded, whether or not it's inherently progressive or interlaced. As Barry says above, in 1080 or 480, progressive footage is "carried in an interlaced 'basket'." It has to be, because that's what the recording standard for the codecs is. You restore the to progressive in post by stitching the progressive frames back together from interlace fields. (This is not, just to head off any confusion, the same as deinterlacing. Deinterlacing is taking inherently interlaced footage and changing it.)
 
interlacing

interlacing

So in the 480i and 1080i modes the fields are scanned odd and even (at 60 fields per second for 30P and 24P? then 120 or 60 fields per second for 60i?) then combined as a progressive frame conforming to whichever frame rate you choose. I am trying to combat/understand the interlacing stair case/combing effects with motion blur due to slow shutter/frame rate. Is this the case in 720P or is that truely progressive scanning, more resembling a film exposure?

My initial understanding after reading this thread was that it always shoots 60 progressive fields per second and when interlacing it combines odd from field 1 and dumps even, and vice versa for field 2 making frame 1 (the interlaced "basket"), but still allows you to somehow use all information from all fields, I guess via some mxf transfer process. I think most of this is a misconception though. I'm still confused.
 
BPistone said:
So in the 480i and 1080i modes the fields are scanned odd and even
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No. The CCDs are scanned at the frame rate you select, progressively. They're recorded as interlaced where the codec requires it (1080 DVCPRO HD or 480, all flavors).

(at 60 fields per second for 30P and 24P? then 120 or 60 fields per second for 60i?) then combined as a progressive frame conforming to whichever frame rate you choose. I am trying to combat/understand the interlacing stair case/combing effects with motion blur due to slow shutter/frame rate. Is this the case in 720P or is that truely progressive scanning, more resembling a film exposure?
Click to expand...

You will see no interlace artifacts at any time in 720 mode. It's never interlaced.


My initial understanding after reading this thread was that it always shoots 60 progressive fields per second and when interlacing it combines odd from field 1 and dumps even, and vice versa for field 2 making frame 1 (the interlaced "basket"), but still allows you to somehow use all information from all fields, I guess via some mxf transfer process. I think most of this is a misconception though. I'm still confused.
Click to expand...

In 24p mode, it shoots 24 progressive frames per second. Then, if shooting in 1080 or 480, the progressive frames are split up into interlace fields. Some fields are duplicated to fill out the pattern (once you split the 24 frames into 48 fields, you need 12 more fields per second to reach 60). Then, it's recorded in an interlaced stream. You reconstruct the original 24 progressive frames in post.

In 30p mode, no extra fields are necessary; the 30 frames are split into 60 fields and recorded. Then, you reconstruct the frames in post, or just edit as 60i.
 
If it always scans progressive frames, why not have progressive modes for 480/1080? Do those codecs not exist (I guess in terms of final output)?
 
It's not how those codecs work. Other codecs do exist, but the codecs in the 200/170 were chosen because they're standards.
 
What I've always wondered it this. I know standard are standards, but when you import a 1080i 24pa (60i) DVCPROHD clip, it's saved as a 1080p 24p native DVCPROHD file. I mean you can basically save a DVCPROHD clip in whatever framerate you want. Why can't this be done in camera? 1080p 24p native should technically be possible no? I understood why it couldn't be done on tape with the DVX, but with P2, we shouldn't "need" to use "containers."
 
David Jimerson said:
In 24p mode, it shoots 24 progressive frames per second. Then, if shooting in 1080 or 480, the progressive frames are split up into interlace fields. Some fields are duplicated to fill out the pattern (once you split the 24 frames into 48 fields, you need 12 more fields per second to reach 60). Then, it's recorded in an interlaced stream. You reconstruct the original 24 progressive frames in post.

In 30p mode, no extra fields are necessary; the 30 frames are split into 60 fields and recorded. Then, you reconstruct the frames in post, or just edit as 60i.
Click to expand...

How do you reconstruct the frames in Premiere to make it progressive? I've seen the 24p and 30p modes for 1080, but I always got 1440x1080 (upper fields) from MiniDV, and I thought it was always interlaced.

Most people seem to prefer progressive over interlaced, same for 24p. An editor told me he would always shoot in 24p, even if the output was broadcast TV. Is this true? Can a 720x480 progressive video be used for NTSC TV without any problems?
 
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