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Old February 28th, 2010, 07:51 PM   #1
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True 24p

One of the biggest disappointments I have in the Sony EX-3 is that it does not shoot in true 24p but uses the drop-frame 23.98p, the legacy of old analog television that I wish had died already.

I noticed the
Blackmagic Design Sync Generator
can produce true 24p. Does anyone know if this could make the EX-3 shoot in true 24p? And if so, will the files till be marked as drop frame? And if so, is it possible to change their headers to reflect their true non-drop-frame nature?
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Old February 28th, 2010, 08:08 PM   #2
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Geez... speed the video and audio up 0.1%. Problem solved. Unless you are doing film-out there is practically no other good use to shoot at 24.000.
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Old February 28th, 2010, 08:21 PM   #3
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Quote:
Originally Posted by Found on Another Forum
NTSC is broadcast over airwaves, and is interlaced to achieve the proper speed, engineering wise. That means for standard def TV, you don't actually have "frames", you have 60 interlaced "fields" per second. This was developed back in the old days, when there was no "digital" anything, and "industry standard" meant something useful.

Think this way, each "frame" you use in film is a full image. In broadcast TV, that same frame must be made up of "scan lines" (how TV sets display images fast enough to look real) on the NTSC CRT screen (not the same as a computer CRT monitor). It displays one "field" at a time, not a full "frame". Each field is made up of either all even numbered lines, or all odd numbered lines (upper or lower dominance means which field is shown first). In effect, it shows half of a "frame" at a time. The TV set can't show two fields at once. But you can put two fields together to make up a full progressive frame, which is necessary in an NLE to display on a computer monitor.

Interlacing does not mathematically (in the engineer of NTSC signals) work out to an even number per second when converted to frames, and thus we have "drop frame" time code when working with interlaced footage.

Since NLE's use frames, not fields, to display, we have to convert that 60i rate to "frames", which works out to not 30fps, but technically 29.97fps. If you worked visually with separate fields, you'd never see a full image, you'd go insane, and kill people.
Quote:
Originally Posted by Perrone Ford View Post
Unless you are doing film-out there is practically no other good use to shoot at 24.000.
If you are outputting to DVD or even Blu-Ray, even if you shoot true 24p it will be converted to 23.97p anyways. It's just the way digital tv works. Like Perrone said, the only reason to really shoot 24p would be if you're outputting to film, otherwise it seems to be a moot point.
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Old February 28th, 2010, 08:25 PM   #4
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The EX3 is an EX1 with an interchangeable lens and a few extra buttons.

It shoots the same flavors the EX1 does.
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Old February 28th, 2010, 08:44 PM   #5
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You could switch from NTSC to PAL in the menus, and shoot a hard 25fps then slow that down. But if you are using any NLE in the NTSC world you will never get the audio to sync if you shoot a hard 24 or 25 or 30fps and not a decimal framerate.

The first Sony HD F900/3 had a hard 24fps setting and it really played audio havoc in post if a camera person was unaware and shot with that setting instead of 23.98. It's a legacy of analog days, you are right, but until we are off the 110v / 60hz (actually 59.97 hz hence the decimal having to do with color sub-carrier delay) not much is going to change on this side of the pond. Over on the other PAL side, they have 220v / 50hz which is why PAL is 25fps (remember 50% interlace time division?) with no decimal, as well as HD and their NLE systems have no decimal issues.

So either shoot 25fps and slow it down, shoot 23.98fps and speed it up, or move to France.

Lastly, all PsF recordings are non-drop frame, all of them.
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Old February 28th, 2010, 08:51 PM   #6
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The question was whether using the Blackmagic Design Sync Generator with the EX-3 would produce true 24p.
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Old February 28th, 2010, 09:56 PM   #7
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so your going to try and feed it a 24.00 genlock signal , to attempt to defy the video frame thing?
then get the 59.97i signal out of the SDI-HD (or will it be 60.00 then), and then do what with it?

it sounds possible as genlocks can offset the frequency to the sync signal they are recieveing, they can bend a bit. but to me there are to many factors involved, like what will record it? how will you get it back out from the pulldown?

i just checked a bunch of dvd movies none of them use 24.00 all of them use the 23.9?? . so i agree with the above, unless the intended output is to FILM with sprockets , not digital film i cant see the purpose of it. and if i was going to go to FILM, i wouldnt want that Video SDI output??
i donno, because its all so confusing and crasy. I Sync Therfore i am.

They are using video FOR films often now, so dont the Cine converting people who are going to transfer to FILM itself know how to deal with video they are getting? i think i would ask them (or mabey you did). Back when the cams wouldnt even DO a psudo 24, the film people wanted the 60i of all things for the conversion? does it get more cinefusing than that?
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Last edited by Marty Welk; February 28th, 2010 at 11:23 PM.
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Old February 28th, 2010, 10:53 PM   #8
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Originally Posted by Marty Welk View Post
its all so confusing and crasy.
Indeed, it is. Computers mostly cannot handle 23.94 or 29.98, etc. The typical computer monitor can have the refresh rate of 60 Hz or some other integer value. So, it is indeed crazy to stick to the analog standards in the digital age. Not just when you want to go to film.

Another problem is when editing with an NLE. The sound is usually 48 kHz or 96 kHz, so with an integer video frame rate you have a specific number of audio samples per video frame (e.g., 2000 audio samples per video frame at 24 fps video and 48 kHz audio) and you can easily split your video at any frame boundary while splitting the audio accordingly. And you can reassemble it all nicely.

But when you are using the non-integer video frame rate, suddenly your audio and your video cannot be perfectly spliced. And when you reassemble it, you get your video out of sync with your frame rate unless you always cut at a multiple of 1001 seconds, which is not what we do.

The way I see it, if you shoot at the integer 24 fps, you can edit your video any way you want. Then to convert it to the 24000/1001 rate, you just drop a frame (well, your software does) when needed, preferably at a place of a cut, so no one will ever notice it.

And if you need to go to film, you do not drop the frames.

But to go the other way, you need to insert a frame every so often.

Then there is the problem of mixing video with computer generated graphics. It is much easier to produce true 24p with graphics software than the other way.

So, to me at least, it makes more sense to shoot and edit at the film rate because that allows you to do anything you want with it.

I do shoot at 23.94 because that is all I can do with my EX-3 right now. But if I could get it genlocked to 24 even, I would not hesitate.
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Old February 28th, 2010, 11:01 PM   #9
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if they would interleave the audio every single frame some of this out of sync stuff wouldnt be happening.
i dont totally understand, or know which formats are capable of 1 frame interleaving, but once i interleave audio in Virtual-Dub for every frame, the audio locks on and never falls off again. on the other hand with most of the files i am working with they give us as "pros" can fall out of sync when there is a frame differential or a capture issue, or a glitch or whatever.
SOOO many things could be done sooo much better even given the same technology.
i still want 120FPS digital frame motion for my high motion videos.
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Old February 28th, 2010, 11:23 PM   #10
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Yes, and the only way to interleave the audio (after editing) with the video and stay in sync is if the audio rate is an integer multiple of the video rate. The professional audio rate is 48 kHz or sometimes 96 kHz. Both numbers are integer multiples of 24, 25, and 30, but not 23.94, etc.

The consumer audio rate can also be 44.1 kHz (same as CD), which is an integer multiple of 25 and 30 but not 24. Even then, 44100 / 24 = 1837.5, so it is aligned on every other video frame, a limitation one could live with.
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Old March 1st, 2010, 05:45 AM   #11
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Quote:
Yes, and the only way to interleave the audio (after editing) with the video and stay in sync is if the audio rate is an integer multiple of the video rate.
I don't see how this is correct. The data block that contains one frame of vision does not have to contain exactly that frame's audio. In fact in some systems it doesn't contain any of that frame's audio. Admittedly in extreme cases that poses some challenges for vision switching but not keeping sync.
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Old March 3rd, 2010, 04:34 AM   #12
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a thought on 24p

This is just a thought: if you really want to shoot 24p with an EX3/1, maybe you could consider undercranking 24p/25p and recording sound seperately. In the edit just interpret the 25p as 24p and then sync the sound in a 24p timeline.

I know this is a lot more work, but it's just a thought....
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Old March 6th, 2010, 09:19 PM   #13
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Interesting suggestion, Walter, thanks.
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Old March 7th, 2010, 07:33 AM   #14
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You're welcome!
Your question let me to the idea.

Just let us know whether it really works or not.
And offcourse I would like to see the endresult!
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Old March 7th, 2010, 09:27 PM   #15
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Quote:
Originally Posted by Adam Stanislav View Post
One of the biggest disappointments I have in the Sony EX-3 is that it does not shoot in true 24p but uses the drop-frame 23.98p, the legacy of old analog television that I wish had died already.

I noticed the Blackmagic Design Sync Generator can produce true 24p. Does anyone know if this could make the EX-3 shoot in true 24p? And if so, will the files till be marked as drop frame? And if so, is it possible to change their headers to reflect their true non-drop-frame nature?
It's all about backward-compatibility, my man. 23.98p was a good trade-off for equipment compatibility. We'd have to buy a bunch of new stuff along with our viewers if it wasn't otherwise. Not cool...not cool at all. If you want to lose the legacy buy everyone in America a new TV!

Ironically, the EX3 does capture true 24p. It's those "other" cameras (including ones with the Sony logo on them) that record 24p onto 60i. Again, for compatibility!

The EX3/1 could have easily recorded what you call "true 24p" but to save everyone the after-the-fact headache they stuck with the typical delivery format. Your film-out house can/should easily be able to deal with a conversion. For DVD/Blu-ray/editing you should go with 1080/23.976 yada yada progressive goodness.
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