File Size Question

[Dentrassi_BBQ]

The program works so beautifully that i've never felt the need to post before, even though i've been using it for more than a year. Now i've got a question that i didn't see answered in any of the fora:

I recently encoded "Mary Poppins" and noticed that the resulting file is significantly larger than other movies of similar length. For comparison purposes using the "AppleTV" default, "Harry Potter and the Prisoner of Azkaban" the 2:22 run time renders as a 1.8 GB file. "Mary Poppins"'s 2:19 run time renders as over 2 GB, for more than a 10% size difference against the longer movie. Is this simply due to the nature of the movie, i.e. that it combines live action and animation, or is there something else at work here. Do you guys get similar results from, let's say, "Who Framed Roger Rabbit?"

[dynaflash]

Assuming its the original Mary Poppins its due to the graininess. Constant quality encoding can compress a very clean source much more efficiently and get good quality. Grainy complex sources require much more bitrate/file size to achieve the same quality.

You really want to see file size balloon use crf on a mid 80's live concert video.

That said constant quality (even given the file size caveat for old grainy sources ) is still preferable imho to some arbitrary bitrate.

[creamyhorror]

Could be any of various factors, but the basic reason is that Mary Poppins is more complex to encode. Some old, grainy movies (even animation!) can go to 3+GB. If you don't want to spend so much bitrate/size on those specimens, then use 2-pass to set a bitrate, or increase the CRF value.

[Dentrassi_BBQ]

Okeh, i see that now. FWIW, this morning i encoded National Velvet. That came out to be almost 2.5 GB. Interestingly, an even older movie [Casablanca] came out well under 2 GB. Maybe that was due to the fact that it was B&W, while National Velvet was Turnerized.

On the subject of old animations bloating up: I was just thinking that most or all of those would have only a few colors and no delicate shading. Wouldn't it be pretty easy to posterize out the grain in those cases? Or probably get the same results by just setting target quality lower...