What is the advantage of 24P over a 30 frame per second?

[ljCharlie]

Can anyone explain the advantage of a 24P versus a 30 frame per second video?

Many thanks in advance!

ljCharlie

[freebird73717]

the way i understand it 23.976 is NTSCfilm used on most commercial dvds and 29.97 is NTSC used for most cable and tv broadcast. as to an advantage of either i'm honestly not sure. if i'm wrong on any of the above info someone will correct me.

good luck!

[ljCharlie]

Many thanks for your contribution. I have heard many people rave about the new Panosonic camcorder that can take video at 24P. However, I have not idea the advantages of a 24P version 30p. Not to mention that not many program will actually capture a 24P video either.

ljCharlie

[teegee420]

I do a lot of Divx encoding and if the source is film or animation(both being 23.976fps) and I encode to 29.97 and the quality suffers a bit. You can easily see a ghosting effect, particularly when the camera pans from side to side. Duplicate frames are created in order to get 29.97 frames where there are only aproximately 24. Encoding at 23.976 eliminates this completely. If your source is "video" and not film, leave the frame rate as is. As long as you can tell the difference and use the correct frame rate you'll be fine.

[adam]

There's two main advantages. The first is that you only have ~24fps every second instead of ~30. This means your bitrate is being spread out over 20% less frames, so essentially its like you increased your bitrate by 20%. Now realistically this doesn't translate into 20% better quality, but its definitely a noticable improvement.

The more important benefit is that you are working with progressive frames rather than interlaced fields. Interlaced material is inherantly more complex and much much more difficult for encoders to work with. It also generally requires more bitrate to look as good as a progressive source. Most encoders do very poorly with interlaced footage.

Another thing to consider is the elusive "film look" that alot of DV shooters are always trying to achieve. Going progressive definitely gets you much closer to this, though this is a very subjective thing.

[DivXExpert]

When I compare 24fps to 30. I think First off 24 is progressive, twice the resoltion. The second thing I think is the film look which can only be achived by that framerate. If you shoot film at 60fps and play it back so, it looks like video.

[Nilfennasion]

Some facts:

PAL and NTSC are both interlaced. This system was adopted when TV was first invented because technology wasn't advanced enough to broadcast a whole picture at a time. When the picture is interlaced, it basically means it is being updated one half at a time. First all the odd lines are updated, then the even ones.

This is the sole cause of the most irritating and visible artefacting in film-to-video transfer on any format - aliasing. Instead of smooth lines that move reasonably smoothly, we get jagged lines that shimmer when they move unless some video processing is applied (and even after then). Every time you see something flicker (swords and greenery are prone to this), that's because of interlacing.

Film was and always has been progressive. This means that the whole picture is updated each time. It means motion is smoother, and there are no interlacing artefacts whatsover. It is totally irrespective of frame rate, and mostly irrespective of resolution. The only difference resolution makes is that display devices may not be able to update that many vertical pixels at a time in the one go. The old CRT devices can't handle progressive material very well. So in essence, interlacing should have been ditched at least twenty years ago, but legacy technology is holding us back.

NTSC discs are all encoded at the same framerate you get in the cinema - 24 frames per second. They have special coding to let the player know which half-frames to repeat in order to match the 60 fields per second requirements of an NTSC display. Ergo, it is an easy matter to create a player that will convert an NTSC disc into 24fps. However, the 60 fields per second, contrary to what you have been told, do not require any more compression at all.

If only they'd make HDTV progressive and 24fps (or better yet, multisync), then we could put all of this framerate and interlacing nonsense behind us.

[CaseyComb]

I guess it all depends on what you want to shoot with the camera. The 24p gives a film look to the footage because of the 24 Progressive frames while most video cameras shoot 29.97 FPS which is interlaced. If you ever want to transfer to film shoot with 24p. Plus I think it looks amazing myself.

[Nilfennasion]

It is also worth pointing out that film has a resolution considered by most experts to be about 4000 vertical pixels. The type of video available to the public is doing well to reach an eighth of that. Digital video, or HDTV, can do 1080I, but you're welcome to try getting your hands on the camera.

[ljCharlie]

Thank you very much for all your responses. I learned quite a bit from your ideas and suggestions. Yes, I really like that Panasonic camcorder but like I said, first, I'm not sure what the advantage is, second, I'm not sure if any video editing program will capture at 24P, third, I'm not sure if the current DVD+R media will handle or able to take 24P resolution assuming that I have the right encoder.

But from your responses, I now understand some of the advantages. Again, thanks!

ljCharlie

[adam]

We are talking about a DV camcorder here right? DV is digital, its doesn't matter what framerate it is filmed at, it is going to be "captured" correctly to your computer as is. You are doing nothing more than transferring the digital data from the tape to your pc.

Any encoder will accept progressive 24fps material. Any DVD authoring software should accept ~24fps material perfectly fine if you encode it correctly. For NTSC, you simply encode it to 23.976fps and include 3:2 pulldown flags. Then just author as normal. This is most certainly perfectly DVD compliant and will play on any DVD player. The vast majority of commercial NTSC DVDs are in fact encoded at 23.976fps.

Working with progressive material will actually be much easier. You don't have to worry about field order or interlacing artifacts and it won't have to be deinterlaced for progressive scan playback devices, ie: pc monitors.

If its in your budget go for it. A camcorder that records at TRUE progressive 24fps should give much better quality output then one that records at interlaced 29.97fps, though I admit there is alot of subjectivity to it.

[Nilfennasion]

No subjectivity involved. Progressive will always be better than interlaced. Anyone who's seen the last two Star Wars DVDs on a display that is larger than 80cm can tell you that.

Not to mention that when you're working with progressive source material, you can always keep it in progressive format as a backup for the day when they finally get their finger out and bring us a consumer video solution that allows progressive playback.

How exactly do 3:2 pulldown flags work?

[DivXExpert]

Actually, Camcorders are recording at 60fps. you see the information inbetween the 30fps everytime your television refreshes, which makes it look like it has un-naturally smooth motion, thus giving it the video feel. 30 progresssive looks tons better than 30 interlaced, even if only have the res is being showed on screen, but you don't have that inbetween information.

[ljCharlie]

Well, if everyone don't mind I like to introduce a new issue into this conversation. Now that I understand the advantages of the 24P, how about the a high definition camcorder? JVC introduce its first high definition camcorder and appearantly the cost is the same as the Panasonic camcorder. How's a high definition different from a 24P camcorder and is the quality better than a 24P or are they the same thing? Would it be harder to edit and find a media that will hold a high definition video?

Again, thank you for your help.

ljCharlie

[DivXExpert]

HD Cams are expensive, the media is expensive, and the harddrive storage is expensive, but you get over twice the resolution.

[DivXExpert]

And the editing software that handles HD is expensive too. And the computers that can handle it are expensive too. And a HD monitor is expensive too.

HD is a super expensive buisness. Might as well shoot film.

[ljCharlie]

I saw a JVC model for around 3 grand...it wasn't too bad..however, I was concern about the media storage. I don't think current 4.7GB DVD+R media will hold much, will they? Does anyone know how much hard drive space will one hour of HD content requires? I have a HDTV already...that's why I'm also interested in the HD cam. However, knowing that I do much with it...especially limited to media space, I might hold back on that.

ljCharlie

[DivXExpert]

its like 19.3 megabytes every second.

[DivXExpert]

and thats for a compressed MPEG-2 stream. I don't even know about raw video that you would use for editing. It is very rare that people edit in a MPEG format.

[ljCharlie]

I see. Thank you for the information. When I make my decision I will certain certainly take all that into consideration.

ljCharlie

[bugster]

Some facts:

NTSC discs are all encoded at the same framerate you get in the cinema - 24 frames per second.

Wrong

The vast majority of commercial NTSC DVDs are in fact encoded at 23.976fps.

Correct

[Nilfennasion]

Practical difference? Minimal.

(Pictures a display unit slowed down to a frame per second, and showing a single incomplete frame just because the specification says 23.976...)

[adam]

Maybe he was talking about those DVDs which are hard telecined to 29.97fps, and just commenting that not all DVDs are stored as NTSCfilm.

NTSC has to use 29.97fps playback (23.976fps internal) because of drop frame.

BTW: cinemas actually play film at 48frames per sec. They double each frame to prevent flicker. But I know what you meant.

[CaseyComb]

Well I know for a fact that Final Cut Pro 4 will capture a 24p DV stream. I also read somewhere that one of the big 3 editing programs (I forget which one)for windows is going to incorporate 24p capture. And if not the camera does an automatic pull down anyway.

[adam]

If its DV then any program that can capture DV, will be able to capture it at 24fps just fine. DV is digital. Its no different then copying a file from one hard drive to another. The framerate is irrellevant.

[bugster]

Maybe he was talking about those DVDs which are hard telecined to 29.97fps, and just commenting that not all DVDs are stored as NTSCfilm.

You seem to understand what I was getting at Adam, not all NTSC DVD's are 23.976fps with 3:2 pulldown, some are true 29.976fps. I believe this is the case if the original source was a 29.976fps video such as is commonly used for TV programs. Anything that originated as film will be encoded at 23.976fps. What is the proportion of movies to Tv shows on DVD in NTSC land though I have no idea!

[DivXExpert]

If its DV then any program that can capture DV, will be able to capture it at 24fps just fine. DV is digital. Its no different then copying a file from one hard drive to another. The framerate is irrellevant.

You cannot record DV at 23.976fps, it is always hard telecined to 29.97. Always, the DV format won't alow otherwise.
Some editing programs recognize the 2:3 of progressive cameras. More advanced editing programs recognize the 2:3:3:2 pulldown of some cameras that have an "advanced" progressive mode, this is for better recovery of the original 23.976fps. But either way it is hard telecined.

[DivXExpert]

So if you capture video that was recorded with a 24p camera with a simple transfer program like DVIO, then it will come out the normal 29.97fps. It only comes out 24p with software that recognizes the pulldown methods.

[adam]

I stand corrected. I guess worst case scenario you'd just have to do an IVTC with a good filter though.

BTW DivXExpert, you can edit your posts.