some clarification of the usefulness of 50fps

Cees Mutsaers

Cees Mutsaers

Veteran
I am doing an education "Digital Video Producer" in Amsterdam and to be honest I am the only person who has a cam (HPX300) which is able to shoot at 50 fps. Everybody else has Sony cams which can only do 25 fps. I am learning the whole Final Cut Studio pakkage, AE, PS and a littLe cinema4D. As the course progressed I am slowly coming to the conclusion that 50 fps is something you can not use in practice since one has always to deliver in 25 fps. DVD can only handle 25 fps (SD not even HD), all delivery like you tube, television broadcast is all 25 fps. So did I buy the wrong cam and should I have saved about 6000 euro and have bought a HDV cam. I have seen a lot of HDV footage now at 25fps and to be honest (except from the colour) I could not see any difference with the footage I shoot on my HPX300 in terms of motion artifacts (and I always thought this was the big plus of 50 fps). I always shoot 720/50p because i am afraid to f..k up the footage because of skewing etc. but at the end I always have to compress to 25p (and SD which makes it look like a cam of 500 euro). So maybe someone can me enlight why I made the right choice in picking up a HPX301 in stead of any HDV cam.
 
There are two reasons why you might want to shoot in 50 fps. Firstly, since you're capturing 50 frames per second for 25 fps delivery, you can slow down the footage to 50% of the original speed and still maintain the full 25 fps delivery frame rate. This is called overcranking.
The other reason you might want to shoot 50p is that if your delivery was 50i, you could interlace consecutive 50p frames to conform to the delivery standard.
 
Cees,

I think you are mixing up some terms.

You purchased the HPX-300 because of its image quality and its very nice codec.

"HDV" is a codec just like AVC-Intra. It has no relation to the framerate or the image quality that camera can produce. The HDV codec does throw away a lot of information during its recording process due to its low bitrate.

Your camera can shoot in 50fps and 25 fps. You are not limited to 50fps.

But you also need to separate progressive and interlaced formats.

Sure you can say broadcast television is at 25fps, but it is really at 50i (50 interlaced fields).

There is a different "look" associated with 25p and 50p. Faster framerate means smoother motion and pans.

So why 50p? Well the answer is: what does your content call for?

If you are shooting sports, then 50p. If you are shooting interviews, then 25p might look better.

Another thing about 50p. You can get a very nice HD to SD conversion by shooting in 50p and going to DVD (50i) because each frame of the 50p will be directly translated to a field of 50i.

So you never are hurt by using a "nicer" camera. You will have better images and more choices.

Hope this helps
 
I must admit... I'm still a bit confused by the whole 50p stuff...

I feel the footage looks better in most situations than 25p... but I don't understand how my 25p timeline interprets the footage....

And if I'm editing in 25p and making a DVD with an export from the timeline... won't it just split the fields up anyhow???

Lately I've been outputting my mpegs as progressive... and seems to look alright..

Cheers

PS... I've just dropped a shot into FCP that was done 50p and allowed fcp to adjust the timeline settings and it does now give me
a 50fps timeline... so in a 25fps timeline does FCP discard part of the info to match that timeline??
If so what issues would arise from that....
 
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Lez, I do not use FCP, but I think you should start froma basic point.

50p footage should be edited on a 50p timeline, 25p footage on a 25p timeline.

It is very easy to make a DVD from a 50p timeline as the frames get converted to fields 1:1

It is when you put 50p material on a different timeline that the NLE really decides your fortune as to how it handles the footage.

So, I really think of editing timelines rather than footage so much as your can put different framerate footage on that timeline. The timeline determines how the encoded output will interact with DVD, Blu-ray etc...

At least this is how my editor, Edius works.
 
Cool ... but how would you incorporate variable frame rates in the same project...
isn't all VFR at 720 25pn???...

Cheers
 
True. Variable framerates (most commonly overcranking) has to start at a lower framerate (24p, 25p or 30p) to have a quicker speed (50/60p).

The way most do is shoot in 720p over 60 and put that footage on a 720p or 1080p timeline.

If you want to overcrank, you are pretty much limited to 24p/25p production as 30p is kind of out in the cold for a delivery medium.

I don't know if this helps or not.
 
Lez said:
Cool ... but how would you incorporate variable frame rates in the same project...
isn't all VFR at 720 25pn???...
Click to expand...

Sorry, I'm from another NLE, Adobe Premiere. What you do in that is use the 'interpret footage' option to set the footage to 50 fps. Otherwise it will drop frames to keep real time synchronisation.
 
No I am not mixing up things (more my bad English). Yes one of the advantage is the VFR and the possibility of over/undercrancking. And yes I understand that 50 fps gives a better motion and less artifacts. However the latter only holds if you stay at 50 fps. If you trow away those extra frames in post when you want to make a DVD (the spec of DVD is only 25 fps (and SD)) what is the point in recording them in the first place (I am only talking about progressive).

Bassman2003 said:
Cees,

I think you are mixing up some terms.

You purchased the HPX-300 because of its image quality and its very nice codec.

"HDV" is a codec just like AVC-Intra. It has no relation to the framerate or the image quality that camera can produce. The HDV codec does throw away a lot of information during its recording process due to its low bitrate.

Your camera can shoot in 50fps and 25 fps. You are not limited to 50fps.

But you also need to separate progressive and interlaced formats.

Sure you can say broadcast television is at 25fps, but it is really at 50i (50 interlaced fields).

There is a different "look" associated with 25p and 50p. Faster framerate means smoother motion and pans.

So why 50p? Well the answer is: what does your content call for?

If you are shooting sports, then 50p. If you are shooting interviews, then 25p might look better.

Another thing about 50p. You can get a very nice HD to SD conversion by shooting in 50p and going to DVD (50i) because each frame of the 50p will be directly translated to a field of 50i.

So you never are hurt by using a "nicer" camera. You will have better images and more choices.

Hope this helps
Click to expand...
 
Cees, this all depends upon your DVD player format, Progressive or interlaced.

A 25fps (interlaced) DVD uses 50 fields. A 25fps (progressive) DVD uses 25 frames.

In the US, interlaced DVD players are more common than progressive DVD players. So it is safer to make an interlaced DVD product.

True, if you are going to a 25p progressive DVD, then your should not need to shoot 50p unless you want some slo-motion.

Your original post said a lot of different concepts, and a few were mixed up a bit. Not a problem, but your camera will take care of whatever you need to do. I would keep on reading posts here and learning.

Everybody would favor your HPX-301 to an "HDV" cam as you called them :)
 
Bassman2003 said:
In the US, interlaced DVD players are more common than progressive DVD players. So it is safer to make an interlaced DVD product.
Click to expand...
Not true. Every DVD player ever manufactured has always had support for 24p. You are always 100% safe in mastering a 24p DVD, and every player will play it.

The early DVD players would always add 2:3 pulldown on their own to create a 60i data stream, later progressive players can either do that or output the 24p content progressively.

But there is no good reason or valid reason to author your 24p-footage DVD as 60i.
 
I did a project recently where the main camera was a 300 shooting 720 50p and the b cam was a hdv shooting 1080i, the timeline was 720 50p in fcp and although not ideal they worked fine together. Really not sure what fcp did to be honest, maybe it did terrible things to the interlaced hdv.

I prefer working with the 300 in 720 50p. I avoid HDV as much as I can.
 
Barry_Green said:
Not true. Every DVD player ever manufactured has always had support for 24p. You are always 100% safe in mastering a 24p DVD, and every player will play it.

The early DVD players would always add 2:3 pulldown on their own to create a 60i data stream, later progressive players can either do that or output the 24p content progressively.

But there is no good reason or valid reason to author your 24p-footage DVD as 60i.
Click to expand...

Sorry for my mis-information. I do not work in 24p so I do not have the familiarity.

I was thinking about the 60i vs 30p framerates.

I guess this is somewhat of a myth left over from the "early days"? I thought progressive players were a smaller portion of the DVD install base. Does this apply to 30p as well?
 
It's good to bear in mind that if someone plays your DVD in a computer it's unlikely that it will deinterlace the footage. Progressive formats will always look good on computer.
 
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