HD rendering?

[Todd Schmidt]

Thanks Dave,

So HDTV 1080/29.97. I had it at HDV 1080/29.97. Honestly, what is he big difference?

[Todd Schmidt]

Thanks so much! I seem to have never gotten a straight answer or opinion on that!

[Lars Bunch]

Hi,

I mostly work in HD but frequently provide files in SD. I prefer to work with the largest frame I can (In most cases, 1920×1080, square pixels). If the footage was interlaced, I usually try to remove it if I can before doing any real work. Generally the frame rate of the original footage will dictate the frame rate I work at, although given a preference, I like 24fps or 23.98. If I am working at 23.98 or 24, I stay in that frame rate until I’m ready to output an SD version with interlacing and a 3:2 pulldown.

Generally I try to stay in the HD world and only render to SD as the final step. As my last step, I will usually render an HD file in the Animation codec and then re-import it, modify the output levels to match 601 colorspace and add a 3:2 pulldown to get it up to 29.97 if necessary.

HD gives you more colors to work with than NTSC as well as more pixels. Tracking is easier in HD since you have more detail to work with, although as with SD, you will need to remove interlacing for tracking.

But your render times will be a good deal longer. If your comps start out as SD you can work much faster, but only on fairly simple projects can you easily modify the comp up to HD resolution. If there is a good chance you will need to provide an HD version, then you are best off starting in HD since the time involved in modifying an SD comp up to HD is often longer than the render times.

There are plenty of different comp presets you can choose. I like to stick the the simplest one (for my purposes) which is the 1920×1080 SqPix, 23.98 HD. By working with square pixels, I don’t have to deal with the oddities of different pixel aspect ratios until the final SD render. Since the footage I usually work with is 1920×1080, I work at that size, but if you are getting a smaller HD format (1280×720) you probably won’t see any benefit to working larger. As I mentioned, you’ll probably be best off working at the frame rate of the footage you receive. I prefer 24 partially because it is easy to add a 3:2 pulldown to get it to 29.97fps and also because I don’t have to work with as many frames. Believe me, if you do any rotoscoping, you’ll be happy to not have to deal with 6 extra frames per second.

If you have to provide a 4×3 SD version, you will need to protect the 4×3 area on any 16×9 animations. This usually ends up meaning your compositions don’t look good in either 4×3 or 16×9. Ideally you can work purely in 16×9 and not have to either compromise framing or create two variations of every animation.

For final output, you should render the HD animations with the Animation codec (or Uncompressed 422), re-import them and drop them into a new comp with the output size and pixel aspect ratio and frame rate that you need. In outputting for the web, you may want to just use quicktime pro (or windows media encoder) to export the HD file to whatever format you need.

There is a lot to consider, but I suppose it can be boiled down to keeping everything as large and unmodified from the original format for as long as possible and only shrinking down and changing frame rates as the last step. The only exception is if you have interlaced footage, try to get it deinterlaced as soon as possible.

Okay, this is a bit long winded, but it’s really not that difficult. When I started doing HD, I too was concerned about all the details, but you’ll find it’s pretty straight forward once you get used to the differences between the formats.

Hope this helps,

Lars