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HD resolutions... Correct forum?

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Jason Brown
HD resolutions... Correct forum?
on Dec 8, 2009 at 8:50:17 pm

Hey Guys,

I have a generic resolution question and not sure if this is the best place for it.

I've been editing in HDV 1440x1080 1.33 PAR @ 60i for a long time now...I don't get too fancy with frame rates and 24p or anything like that.

I'm trying to understand the 720 world...why is 720 listed in many places as: 1280 x 720 - 59.94? I'm not referring to the decimal value...just why isn't it 29.97? Does this mean that the 720 is played back at halfspeed at this framerate? Or are there double the amount of frames per second?

Can someone help me understand?

-Jason


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Micah McDowell
Re: HD resolutions... Correct forum?
on Dec 8, 2009 at 10:21:59 pm

720 at 59.94 would mean likely mean 720p, which is 59.94 full progressive frames per second.

The 1080i HDV you've been working in is 60i, meaning 59.94 interlaced fields per second, which corresponds to a "framerate" of 29.97. Does that answer your question?


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john sharaf
Re: HD resolutions... Correct forum?
on Dec 8, 2009 at 10:29:10 pm

Jason,

Because progressive frame rates do not have "half" frames (otherwise known as "fields") there are now 60 frames per second instead of 30 frames. This is why some observers think that 720/60p creates a "smoother" action than interlaced formats.

When you specify 720/30p, each of the distinct 30 frames are repeated one time to create the 60 frames that are consumed each second. At this frame rate the "action" looks more "filmic" because it includes a 2:2 pull down cadance.

Hope this helps,

JS



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Jason Brown
Re: HD resolutions... Correct forum?
on Dec 9, 2009 at 1:41:14 am

OK...I think I got it...I've worked with NTSC D1 interlaced Betacam SD video for a LONG time...so I fully understand interlacing.

Question about 720p...so I can do 720p at 29.97...right? I know I've naively rendered things to the 720 resolution at 29.97 progressive. (played back on a media box...worked correctly)

I think I was mosly confused by the fact that 1080 is listed at 60i sometimes...but I've never heard the listing 60p...wouldn't that be the correct way to refer to 720p footage?

1920x1080 60i would be 30 frames per second interlaced.
1280x720p could be called 60p? Correct?

Thanks for helping me understand this guys...

-Jason


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Bram Desmet
Re: HD resolutions... Correct forum?
on Dec 9, 2009 at 3:35:39 am

To avoid confusion it is generally a really good idea to list both the native resolution and native frame rate. You would not want to refer to 1280x720p60 as just 60p because there is also a 1920x1080p60 broadcast format, albeit at almost 3Gbps bandwidth. You also have the less common 480p60 (flavor of EDTV) formats so 60p could be misleading as it does not necessarily imply 1280x720p60.

Bram Desmet
FSI (Flanders Scientific, Inc.)
http://www.FlandersScientific.com


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Jason Brown
Re: HD resolutions... Correct forum?
on Dec 9, 2009 at 3:52:17 am

Does the 720 format come in other flavors or is the standard 60fps?

I may be asking a loaded question, because I'm guessing that delivery is dependent upon "standard" ... I'm not referring to broadcast...only blu-ray and what monitors would support playing back from a media box type of delivery.

-Jason


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Bram Desmet
Re: HD resolutions... Correct forum?
on Dec 9, 2009 at 4:11:44 am

Yes, 720 does come in other flavors. 720p24/25/30/50/60. If we were talking about broadcast this would actually be simpler as the number of transmission formats are generally much more limited, but when we start talking about playback from DVD, BluRay, digital media players, etc. these other formats may be more prevalent. Also, you are much more likely to run into 1080p60 with the type of equipment you describe, which again reinforces the idea that it is quite important to list the native resolution along with the frame rate to avoid confusion.

Bram Desmet
FSI (Flanders Scientific, Inc.)
http://www.FlandersScientific.com


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Jason Brown
Re: HD resolutions... Correct forum?
on Dec 9, 2009 at 1:36:09 pm

OK...GREAT information...I appreciate it!

My experience and understanding was that 720p @ 60fps was intended as slo motion footage...it can be played back like that, correct?

If you play back 60 fps video at 30 (29.97) it will be half speed at 30p, right? That's always how I've seen it used.

-Jason


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Richard Herd
Re: HD resolutions... Correct forum?
on Dec 10, 2009 at 12:02:16 am

It's also worth keeping in mind the difference between:
-- electronic signal processing &
-- computer programming

There's so much information on all of it, it's hard to know exactly where to start, so here's a place: http://lurkertech.com/lg/fields/ It's written from the point of view of a computer programming trying to make software to turn a video signal into a video editing platform (like Final Cut Pro). This guy Mr. Lurkertech wrote specs for QuickTime. He's an authority worth reading.


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Jason Brown
Re: HD resolutions... Correct forum?
on Dec 10, 2009 at 1:41:11 am

wow...that's a pretty good read! I'll take a look at work tomorrow...that may be well above my head! :)

Thanks for the good information...

Can anyone speak to the idea of using 720 60p as half speed footage? That's the only application I've ever seen it used in...I don't think I've ever seen anyone (editing) with 720 at 60 frames per second. (In my small circle of video professionals)

-Jason


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Bram Desmet
Re: HD resolutions... Correct forum?
on Dec 10, 2009 at 1:53:04 am

"I don't think I've ever seen anyone (editing) with 720 at 60 frames per second."
That really surprises me. 1280x720p60 is very common. It is the broadcast standard adopted by many of the largest networks and a lot of material is edited/delivered, etc. as such...

1080p60 doesn't 'kill' 720p60 because the storage/bandwidth needs increase substantially so there is the very real issue of cost to deal with...also, keep in mind that most transmission systems don't currently support 1080p60 so adoption of this format at all levels is seriously hampered. In terms of performance though 1080p60 is the best of all worlds b/c you have both the high resolution and the high progressive frame rate.

Bram Desmet
FSI (Flanders Scientific, Inc.)
http://www.FlandersScientific.com


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john sharaf
Re: HD resolutions... Correct forum?
on Dec 10, 2009 at 2:11:52 am

Bram,

I am (unfortunately) editing a project in 720 60p at the moment and I can tell you that it uses a lot of storage.

I shot a documentary this past summer using the first generation of the Sony PDW700 camera. At the time 1080/24p had not been implemented (although it is now with v1.5 software and an optional software "key" upgrade), but at the time the camera contained a "24 over 60" speed, essentially writing a 2:3 pulldown over the 60 frames, "like the Varicam does" I was told and thought.

Unfortunately it did not work like the Varicam, as it did not write "A" frames in the user bit to identify the beginning of the cadence nor did it even conform to the SMPTE RP188 standard which aligns the 00 frames of time code to the beginning of the cadence. As a result, even though I still have the 24p "effect" I could not use FCP nor AJA Kona to "pull the 24's" and create a 24p timeline which would use only 40% of the storage space I must use at 60p.

As a work around, if we end up going to a filmmout at the end we can use a fancy box called "Alcemist" to jigger the frames back and forth to find the cadence and create a "reverse telecine" in on-line.

Needless to say in the latest software Sony has fixed this problem, at least as conforming to RP188 and all my cameras have the 1080/24 option installed which of course is the preferred method.

Long story, but yes, sometimes (once in my life), I've edited in 60p.

Also consider the "Showscan" experiment of Dulton Trumble many years ago where they shot tests of shooting film and projecting it at 60 fps. It was an incredible experience to view on a large screen (as I did one day long ago in Westwood Village) where film actually looked like television. Obviously the expense of shooting, processing and printing 2.5 times as much stock as conventional 24fps cinema and the conversion of the projectors doomed this experiment because of economics.

JS



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Jason Brown
Re: HD resolutions...
on Dec 10, 2009 at 2:31:19 am

[Bram Desmet] "That really surprises me. 1280x720p60 is very common. It is the broadcast standard adopted by many of the largest networks and a lot of material is edited/delivered, etc. as such... "

I was speaking about my "small circle of friends" who are mostly lower end HDV users. The EX3 is the camera I've seen most of them use and in 720 they use the 60 frames played back at half speed. Everything they produce is almost always for web delivery or iphone...or possibly some sort of media player.

That's great information Bram...I don't produce things for broadcast...so I'm really interested in how to maximize quality and formats...

Do you know if there are limitations on Blu-Ray? I've heard the reference to 1080p in regards to blu-ray playback, is that 60p or 30p?

Thanks for your continued answers...I'm getting alot from this discussion.

-Jason


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john sharaf
Re: HD resolutions...
on Dec 10, 2009 at 2:36:07 am

Jason,

Blu-Ray would necessarily leverage the same rational if editing in a 24p timeline (of material shot that way like 100% of movies) so that it wcould fit feature length material (90-120 minutes or more) within it's storage capacity. The player hardware then does the telecine out to 60p were it repeates 2 then three frames in cadence to "stretch" 24 frames into 60 frames per second whilst retaining the "filmic" motion.

JS



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Bram Desmet
Re: HD resolutions...
on Dec 10, 2009 at 2:23:33 pm

Yep, absolutely correct. Add to that the fact that BluRay 1080p format support is limited to 24p on most (if not all-I believe a limit of the BluRay encoding spec, might have been updated at some point, not really sure) players so this isn't really the realm you'd find native 1080p60 content in. As a production/cinematography standard 24 frames is of course the prevailing standard so you probably should not concern yourself to much with the in/outs of 1080p60. However, on the broadcast level you do see a good deal of acquisition and archiving, especially of sports, starting to be very focused on 1080p60...but that isn't what you're doing.

Bram Desmet
FSI (Flanders Scientific, Inc.)
http://www.FlandersScientific.com


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Jason Brown
Re: HD resolutions... Correct forum?
on Dec 10, 2009 at 1:39:17 am

Bram mentions later that the format exists of 1080p60 which would be 1920x1080 frame size at 60 progressive frames per second...wouldn't that essentially kill 720p?

-Jason


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john sharaf
Re: HD resolutions... Correct forum?
on Dec 10, 2009 at 1:50:02 am

Jason,

Very astute question. Problem is that at 1920x1080 60p is a massive amount of data, capable of being recorded only in the HDCAM-SR format which records 880mbs (and also slo-mo disc recorders like those used for pro sports broadcasts). Essentially this frame rate has been referred to up until now as "the holy grail". 720 can and does run at this rate because it uses less bandwidth, but 1080 would clog all means of broadcast and other forms of distribution and playback.

That is not to say that in the future (Moore's Law) methods of recording and transmitting this much data will not be possible. Until then the viability of 720p continues.

JS



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Jason Brown
Re: HD resolutions... Correct forum?
on Dec 11, 2009 at 4:11:16 am

I don't know if any of you guys use After Effects or not...but I was looking at that for the 720 composition setting and the 720 option is defaulted at 29.97fps. I was expecting it to be 59.94. I can change it...but from the discussion we had, I was expecting 59.94 to be the default.

Thoughts?

-Jason


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john sharaf
Re: HD resolutions... Correct forum?
on Dec 11, 2009 at 1:24:16 pm

Jason,

Remember 29.97fps = 59.94 fields per second.

JS



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Jason Brown
Re: HD resolutions... Correct forum?
on Dec 11, 2009 at 1:30:26 pm

Yes...I got that.

But from the discussion we've been having 720p is NOT interlaced. And runs at 60 (59.94) progressive frames per second.

If that is the case, then the preset for 720p in AE should be a frame rate of 59.94.

Correct?


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Joey Burnham
Re: HD resolutions... Correct forum?
on Dec 14, 2009 at 6:53:57 pm

[Jason Brown] "If that is the case, then the preset for 720p in AE should be a frame rate of 59.94."

Where do you see a preset for 720p? I'm looking through the presets now and none of them are listed as p or i. Are you in CS4?

Joey



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Jason Brown
720p 60 or 30fps?
on Dec 14, 2009 at 7:25:33 pm

There is no frame progressive or interlaced setting until you render.

BUT there is no option for 59.94...only 29.97. If the "standard" or "normal" 720p setting is 60 frames per second, then why doesn't AE have a setting according to that specification?

http://www.jbtwist.com/CC/ae.png

-Jason


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Richard Herd
Re: 720p 60 or 30fps?
on Dec 14, 2009 at 9:06:39 pm

You can change that setting and then save it as a preset if you want. The AE Help menu has the answers you're looking for.





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Bob Pierce
Re: 720p 60 or 30fps?
on Dec 18, 2009 at 1:59:55 pm

I find that very strange too (AE's default 29.97 preset). Why on earth would they do that? Personally, I've never understood why anyone would bother with 720p30.
Bob

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