1080i vs 720p

Thanks Dean, I do remember your spot when you posted about it earlier in the year... great job!

One final test to share and then I put this resolution difference issue to bed forever in my mind.

This test doesn't tell you WHAT rez the HVX can do, but in one glance shows both the vertical and horizontal differences compared to each other... each set of lines is 25% different in size that the one before or after it... in addition, the 720p side seems downshifted physically, this is not my fault, that is what comes from the camera.

http://ftp.datausa.com/imageshoppe/outgoing/HVX_TESTS/STILLS/REZ_DIFFERENCE_EXTRACT_FROM_1080.png

Regards,
 
Thanks for all the pictures, Jim. In case anyone had any lingering doubts this should settle it now and forever. 1080 is better. Not a LOT better, just a tad better, but definitely better, not just in the resolved detail but also in the compression. It just looks better.

However, for those wanting to take advantage of the 2.5x as much extra storage space, now you can see just what you'd be giving up. And it isn't all that much!
 
It seems like if the resolved detail reports from the various test are to be trusted, none of the under 10k cameras is all that impressive in 1080p. According to the reports, XLH1 may do some amazing things in 60i, but try it's 1080 in simulated progressive mode and you ultimatly get quiet a bit less resolved detail than the 720p only HD100 or Varicam.

I've been constantly experimenting with 1080p over the last week or so and it really is difficult not to get it to look a bit soft at full resolution. I shrink it down to 720p and it looks fantastic but, in 1080, it's still not quite up to par. That said, when I first heard about the HVX200 all I ever wanted was good 720p performance. I've been shooting DVX for awhile and it's more than enough for me.
 
Hey all!

I'm shooting a feature and decided now to shoot 720 25p. Avid say their bringing out a new version that will support us PAL users in December.

I'm just wondering whats the best format I can shoot to get the best quality and best look.

Were using two HVX's, one with a firestore and the other with a P2 dump which has four P2 cards with it.

Should I be shooting Native, im not really sure what the difference is. HELP!!!

Also should I shoot sutff at a slower speed that has no dialogue that I want to look smoother. Like shooting with a glidecam and shooting in a moving vehicle??

What if you shoot some 1080p stuff and some 720p stuff. will it matter??

Appreciate any help from anyone.
 
Kudos to the work that Jim put into viewing the differences between 1080 & 720PN.

Here are a few of my observations. I recently completed a 36 minute HD project of very rare Napoleon French Clocks. The details on these clocks are amazing. I shot the entire project in 720P with great lighting. I will pretty much guarantee you that if I were to show this project to 99% of the public and asked them if this were shot in 1080 or 720 it would have been a crap shoot.


It now just boils down to what you're going to use it for. For the vast majority of my work, I will continue to use 720PN, not just for the 2-1/2 recording times, but for over and undercranking.

eric
 
^
I on the other hand am gonna stick with 720p unless I've got some keying to do and save my cash. The 720p image still looks amazing and is enough for most projects (especially if you are ending on an SD DVD).
 
Hi Antoine... maybe I need a sales cut from Panasonic on their larger cards now :)

Guys, up 'til now I've pretty much shot exclusively with 720p myself. Recorded 720p is a nice format, exactly twice the surface area of SD, and very useful. I will keep shooting it for most live action stuff. But it's not the best choice for key work, 1080 is much better, mainly because of the smaller and more pleasing compression artifacts.

Doing tests like these help inform me of where and when the need for 1080 is important or desired. Now, if P2 was huge and cheap, we'd never think twice about recording HVX 1080, but unfortunately there are trade-offs that have to be considered. More information makes making those decisions easier, and more precise.

Regards,
 
Okay, I've thought about this, and now that I see the answer, it's so painfully obvious that I feel silly for not thinking of it before.

The question is why does the 1080 show so much milder compression? Both 1080 and 720 use the same 6.7:1 compression ratio, so why would 1080 be less compressed?

The answer is: while 1080 does indeed retain more detail than 720, it doesn't fully saturate its frame with detail. Principally on the vertical direction. The chips are capable of delivering about 1400x810 to the recorded frame, which can record (PAL) 1440x1080 or (NTSC) 1280x1080. So it's saturated on the horizontal, but not nearly so on the vertical! Contrast that with 720p, where the 1440x810 gets scaled to 960x720 -- there's more than enough detail to fully saturate the frame.

But in 1080, there's about 33% of vertical space more than is necessary to store the frame. So DV-based compression algorithms can intelligently reallocate bits from underused macroblocks to macroblocks where they're necessary. The result is dramatically milder compression. Which is exactly what we're seeing in the results. Gentler compression. Could it be said that 720p = the "DV" of high-def modes, and 1080p = the "DVCPRO50" of high-def modes? Probably not, but the concept at least gets someone thinking in the right direction!

Which further clarifies to the superiority of 1080. No the small 1/3" chips can't generate enough detail to fully saturate the frame, but that doesn't mean the bandwidth goes to waste! It's used to create a milder/less-compressed image. More detail with less compression...
 
Interesting theory... and ironic, because who would have thought there would be a "benefit" to less that full saturation of recorded resolution?

I'm sure there's a really neat real-world analogy for this, it's just too early in the morning for me to come up with one...
 
Great thread this. I missed it all together and found it earlier today after Barry mentioned to check it out in another thread pertaining to film transfers.

Thanks Jim, your comparisons are just what I wanted to observe. That wipe mov file seems to fit in with Barry's theory above, you can see the improved "under-used macroblocks", observed particularly in between the text paragraphs of the book footage, where the 720p is really blocky and the 1080p wipe reveals much better compression applied to the 1080p footage. Is that analogy correct Barry?
 
Whew!
I'm glad i saw this thread as I had bee about to post a similar question myself
I had thought that 720p, being closer to the "native" resolution of the pickup, ( Whaterver that is) would give a better picture ( Whatever that is ).
So, the outcome appears to be, that unless one is doing variframe work, to stick to 1080.
Now, I assume (Dangerous thing), that the 1080 off the sensor is 1080p25, split over 50i for recording. is this correct? If so, it may make the Firestore / Cineporter decision fo rme.

Dave
 
The signal off the sensor is about 1400x800, sampled into a 1920x1080 grid, at up to 50p (EU/Aus) or 60p (US/Japan). It's always progressive, all the time.

It then gets converted to whatever recording format you're using. So for 1080 you can split the 50p frames into fields and record as 50i, or you can sample at 25fps and record directly the 25p frames (again, segmenting into fields to record as 50i). The difference would be the motion sampling; 25p will look like film, 50i (created from the internal 50p) will look like "video".
 
Hans Moleman said:
so, would shooting 108024pa, and converting to 720x1280 with cineform yield a result with less artifacting?
Click to expand...

Yes, without question. This is almost a "perfect" workflow for the HVX... you get the benefits of shooting 1080 with the editing benefits of full raster 720p. You loose a tiny, tiny bit of vertical resolution, but if you look at my stills from earlier in the thread, you'll see it's not significant. You gain the better compression characteristics of the 1080 original and all the horizontal resolution improvements.

Let's see you do that with a Varicam... :)

Regards,
 
Christopher Barry said:
Thanks Jim, your comparisons are just what I wanted to observe. That wipe mov file seems to fit in with Barry's theory above, you can see the improved "under-used macroblocks", observed particularly in between the text paragraphs of the book footage, where the 720p is really blocky and the 1080p wipe reveals much better compression applied to the 1080p footage. Is that analogy correct Barry?
Click to expand...

Off topic, but are you the same Christopher Barry that purchased a copy of my time-lapse cloud stock footage CD "Colorado Altitudes" back in the late 90's? If so, PM me so we can catch up!
 
Will there be any difference in the motion between 720pN clips and 1080pa clips? Interlace won't show its ugly face, will it?
 
No worries, progressive frames are just stored in the interlaced format and fully retrievable without issues... just like a 24fps film to tape transfer (albeit with the "original style" 3:2 pulldown order) or the good old DVX with 24fps stored in 480i...
 
Hans, David Newman, CTO of CineForm, has discussed this in his blog. It is a very good option for the ConnectHD and AspectHD users. ProspectHD CineForm users can stay at 1080p and 10-bit, if desired, and still very reasonable data rates. Very cool, imo.
 
Hey Jim. Yes, I am the CB who purchased "Colorado Altitudes" and "Cirrus", plugging away in this game over the years. You continue to do amazing things. I will PM you my details. :thumbsup:
 
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