720p or 1080i ??

[Ian McElroy]

Okay - simple question - should I film 720P or 1080i with my Sony NX5?

I've done a wedding in 720P and loved everything - the footage - the edit - the output. Output for this particular film was for mostly a PC environment - hence opting for the 50P.

My next wedding film will be output initially on SD DVD, but I will retain the whole finished film for later output on Bluray. I've done some filming for me with the camera at 1080i, and I just don't like the footage as much on my PC screen (can't really say why - could simply be because my PC screen does not interlace and is not 1920 pixels wide...)

I've heard it said that 720p down converts better than 1080i - but can not find out why!! Also, can you publish 720p to bluray?

Help please - the wedding is this weekend (and although I will make a decision tomorrow - I'd love to know it is the right one - so please reply if you have an opinion!!)

Thanks

ian

[Wacharapong Chiowanich]

For outputting to SD DVD and Blu-ray, final IQ will be close depending more on certain factors you can't control i.e. the disc player and, more critically, the display you clients use to watch the video. As you have to pick one, I suggest 720/50p for a few reasons:
-Not having to deal with deinterlacing to make a cleaner looking progressive scan SD DVD (though the disc format is still the standard PAL interlaced 50i but with a 2:2 pulldown removal flag)
-Downscaling to SD DVD with simple conversion from 50p-50i while maintaining all the temporal (frame rate) data to output to Blu-ray in the original 720/50p format
As I said, a lot will depend on the end user's equipment factor but generally speaking, picking either format over another will give you a comparable viewing quality under the current laypeople's digital display chain. Computer and theatrical viewings are another matter and these are where a progressive format is always preferred.

[Peter Manojlovic]

Yes, since it's part of BD specs, and yes, since it downconverts much nicer than interlaced, and yes, since it's better for web output...

[David Heath]

Originally Posted by Ian McElroy

I've heard it said that 720p down converts better than 1080i - but can not find out why!! Also, can you publish 720p to bluray?

The theory is that each PAL field is obtained from a unique 720p/50 frame, which is relatively straightforward processing. Start off with 1080i/25, and it's necessary to de-interlace before the downconversion. That's the theory, in practice a lot will depend on the software that does the conversion, but in general, then yes, if the primary end product is to be downconverted SD, 720p/50 is arguably the way to go.

It's important to note that it's assuming you want "smooth motion". If you actively want "film look" motion - the 25fps look - then 1080p/25 becomes the obvious choice.

Note that in the case of most HD cameras the limiting factor is likely to be the camera front end in resolution terms. In the sub £10,000 range the majority are likely to have 1 megapixel chips or even 0.5 megapixel - hence making a 1080 recording is unlikely to give the difference over 720 you may expect anyway. The notable exceptions are the EX cameras and the new Canon, which do have 2 megapixel chips - full 1920x1080.

[Ian McElroy]

Thanks everyone. Completely reinforcing my thoughts - I have a Sony NX5, so the chips are around the 1 megapixel mark.

Decision made / concern removed. Thanks for the help!