Decisions, Decisions

[Fidelio]

I don't know which mode I should choose and what their pros and cons are: 720P versus 1080i. Someone, please, offer me your wisdom.

[andy_starbuck]

That's a complicated question. Here's my approach to making the decisions. I'm sure others have different methods.

Here are my considerations, in order. (Details below)

1. Do I need HD?
2. Output and compatibility requirements
3. Importance of an interlaced look
4. Quality versus workflow tradeoffs


1. Do I need HD?

Always my first question. Because DV is so much easier to work with. If I don't need the extra resolution of HD ... and if I am never going to need an HD version ... then I'll shoot DV to tape because it is convenient and in post the workflow uses resources efficiently (less disk space, less render time, etc.)

Reasons to shoot HD:

a) The project requires HD output.
b) I want to future-proof the project, in case HD is needed one day.
c) I need the extra resolution for special effects.
d) Because I want to learn/practice HD workflow


2. Output and compatibility requirements

If you are shooting for HD broadcast, some broadcasters have standardized on 1080 and some on 720. You will want to check with their requirements. Shooting in their preferred format may avoid conversion costs and issues. If you are working with others, you may want to synch with their chosen format to more easily plug-in to their workflow.

3. Importance of an interlaced look

1080i is recorded "over 60i", which means it is naturally interlaced. 720p is recorded "over 60p" which means it is naturally progressive. 1080i will give you a sharper interlaced video look, which is preferred for some applications.

4. Quality versus workflow tradeoffs

With 1080 you get about 20% more resolution, over 720 for the same progressive frame rate -- but is it worth it?

As with the decision to shoot in HD versus in DV, recording more information is only a good idea when it serves some purpose. There is no sense in gathering more data up front that just has to be carried around and then dropped before output. So if your project is output in 720, you need to consider when the extra information in 1080 is worth the extra work.

1080 is more demanding on resources than 720. Depending on your hardware (cards, disk recorders, computer) and your NLE, working in 1080 may be slower and consume more resources than working in 720. It means less record time on P2 cards, more disk space consumed, and longer rendering times for the same effect.

Because 1080i is interlaced, to get progressive frames you have to remove pulldown, much like working with standard definition DV footage. 720, on the other hand, can be recorded to P2 card in "native" format which means only the 24 frames are recorded with no pulldown.

Clearly, with respect to workflow and resource consumption, 720 is the "sweet spot" for the HVX and an overall more efficient choice.

So then, when is the extra resolution in 1080 worth it? When you need the extra resolution, which for me is primarily effects shots.

For example, I would shoot most of a project in 720. But then I would switch off to 1080 for green screen work where the extra resolution will help hide compositing artifacts. Then I render the 1080 down to 720 for editing.


Summary:
1. Shoot in DV unless you know why you are shooting in HD.
2. Match output format or partner workflow.
3. Decide if I need an interlaced video look, if so 1080i.
4. Decide if I need extra resolution, if not 720p.
5. For effects shots where extra resolution is needed, shoot in 1080 and perform pulldown removal. Then composite. Then render to 720p.

[24fps4ever]

good post, ok and how about if you are going towards 35mm blow up?

[andy_starbuck]

I haven't done 35mm blow-up.

But... DVFilm recommends 1080i 24P because the resulting film will be 15% to 20% sharper than 720p 24PN, but they will transfer either.

[Fidelio]

Andy, you are my saviour. I applaud your excellence!