24p vs 25p
 

Hi,
Just ordered my Hd101 and have to wait 2 weeks, in the mean time i've been thinking (always a bad idea) and I was curious - is there any advantage to shooting 24p over shooting 25p? Bear in mind I live in a Pal environment. My long term intention is to shoot low budget features, and obviously 24 would be the best rate if I ever hoped to transfer to a film print, but... thats the last stage in a long process, and I just find it easier dealing in a 25 frame environment, everything from working out in my head how many frames make up 30 seconds to making VHS tapes (yes, some people still use them). So, any comments?

There is little benefit to shooting 24p if you're in a PAL environment. You can always slow the 25p down to 24 as well.
Bear in mind that in PAL-land, many DVD players still can't play 24p, so they speed it up to 25 anyway. Should you come time to do a film out, it's no big thing at all to convert 25 to 24. People have been doing it for years.

Thanks Douglas - I've always suspected that there is little advantage to shooting 24p, although capability to shoot 24p seems to be the gold standard for modern Dv/Hdv cameras. I suppose its more useful in an NTSC environment

The PAL version of the new XL H1 doesn't even shoot 24p (f). Only 25.

Much more useful in a PAL environment. Many film projects in the past have been shot in the US using 50i and then converted later to 24p. The irony is, a LOT more video projects have been produced this way than have been produced using the newer 24p cameras, but folks seem to forget that when they're beating up on anything that isn't 24. This was the only way to come close to the 24p cadence, and after the 24p cams came out, I'm aware of at least 2 relatively well-known producers that liked the 50/25p better still both for look and cadence. And anyone who tells you they can immediately observe whether a project was shot in 24p vs 25p, well.....

But it can be 'unlocked' by the factory to do both for an additional $500USD. Same for the NTSC version.

-gb-

Thanks greg, I was aware of that. But I think the thing Douglas is describing (difference in look 24p 25p) is the reason its not standard on the camera.

He's right, of course... the human eye cannot discern any difference between 24p and 25p.

i think one of the reasons alot of NTSC shooters use PAL 50i/25p for film out, is due to resolution more than anything (SD cameras.. with HDV, that problem doesnt exist.. ).
Frame rates can always change...

In the past, this isn't correct. It's due to framerate. Resolution plays a small part in it, but it's about the framerate.
One good source if you want this sort of information, is to read Scott Billups excellent information on digital film production.

But not at DVCPRO-HD 1080 for PAL regions where the horizontal resolution is 1440 and for NTSC regions where is 1280, if I'm not wrong.

That would be incorrect.
All HD falls into one of two categories.
1-1920 x 1080
2-1280 x 720

There are various framerates for either format, and the 1080 flavor can be either interlaced or progressive.
Other than framerate standards (25p/50i or 30p/60i) the format for all regions is identical once you get into the HD game.

Leuname Ereh is right. The recorded framesize for DVCProHD is 1280x1080 for 1080i60, 1440x1080 for 1080i50 and 960x720 for 720p. The image is scaled to 1920x1080 or 1280x720 on output.

Thanks Ben De Rydt. I'm not an engineer or other technical professional, I'm just working in filmmaking. But I thought exactly what you are saying. That's why I posted it. Because if we are posting without a complete info, it can occur in error to any reader and to be harmful.

The output image is what is the determining factor, unless I'm misunderstanding what you're asking/saying. In other words, all cameras pixel shift to some extent, at some resolution or another. The transport image size is all that anyone is interested in with regards to this particular thread.

What you quote are the 'square pixel' resolutions for the two HD formats, not necessarily what gets recorded, especially in the case of 1080. Whilst for each category the vertical resolution remains constant with differing framerates and recording formats, the horizontal resolution is often compromised to cope with the high data rates involved - so fewer than 1920 samples per line get recorded to ease the job of the compressor. In the case of HDCAM it's 1440, same for DVCPRO HD in the 50Hz world, BUT in the 60Hz world it's 1280 for DVCPRO HD. Hence I'd agree with Leuname that under certain circumstances the format can and does change between 50 and 60 Hz regions, and under some circumstances a 50Hz HD camera may be capable of somewhat higher horizontal resolution than a 60Hz model.

Note these figures are for recording formats, the actual camera performance will depend in practice upon lens, chips, processing etc. The term 'pixel shift' is normally used quite specifically to refer to the front end of the camera, and a technique used in some cases (eg Z1, HVX200) to improve the luminance resolution over that which may be expected from simply looking at the pixel counts of the individual R,G,B sensors.

And in the end, it still doesn't matter on the display. Whether the PAR is 1.0 (which nothing sub 100k records) or 1.333 (HDV) or any variance thereof, the viewer only sees one of two resolutions on their screen, and that....is the point. Either it's pixel shifted in the camera, or it's resampled at the display.
Maybe someone somewhere, including me, missed the point of the original question. The reason that footage in the US was/is shot at 50i in the past was more a film cadence option than a resolution option. Taking the thread into the nether world of imager size and pixel shift isn't part of the original topic, so that's where the thread has gone awry.

It's not really about 24p vs. 25p, as some of the posts have suggested it's easy to convert between the two simply by using a 4% time stretch in audio.

Completely agreed. The original comment, which seems to have gotten lost in the discussion, is WHY many digital film makers started using PAL to shoot with 10 years ago in the first place. The reason it was used in the first place, was because of the framerate. The resolution wasn't as important, and actually caused problems for some folks 10 years ago when they started shooting PAL.
The extra resolution is an added bonus, but it wasn't of much help to those shooting PAL for broadcast when they had to downconvert the res, given the tools available at the time. If they were doing film out, it was great. Some guys are still doing this.
Additionally, the original question is regarding HDV camcorders, in which case there is no additional resolution, as there is no PAL or NTSC to contend with.

I recently did a test converting Z1 footage shot in 50i/CineFrame 25 to 24p and honestly, there wasn't much difference in appearance--it's one frame away from each other, except my DVD player wouldn't play back 50i footage. So for me, converting to 23.98 is best.

heath

Thanks for all the comments - the original post could actually be summed up as "Is there any point in shooting 24P?" If I have a 25P option I can't see myself ever needing 24P, and I don't entirely understand why it exists and why it seems to be a requirement of modern cameras.

Simple: marketing for digital/HD filmmakers.

hwm