24p vs 25p

[David Heath]

Originally Posted by Douglas Spotted Eagle

That would be incorrect.
All HD falls into one of two categories.
1-1920 x 1080
2-1280 x 720
<.....>
Other than framerate standards (25p/50i or 30p/60i) the format for all regions is identical once you get into the HD game.

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.

[Douglas Spotted Eagle]

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.

[Dennis Hingsberg]

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.

[Douglas Spotted Eagle]

Originally Posted by Dennis Hingsberg

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.

[Heath McKnight]

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

[Paul Jefferies]

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.

[Heath McKnight]

Simple: marketing for digital/HD filmmakers.

hwm