hellagrant wrote:I honestly don't really even know what bitrate means and what number I should use.
Bitrate itself isn't complicated. Just like when you save an image to .jpg you know that there are variable levels of compression. If you add more compression you'll get smaller files, but at some point they will start to fall apart.
Jpeg compression is destructive and data gets discarded. But as it turns out, normally we can do quite a bit of compression before visually losing image quality.
Bitrate is "data over time". If you have a bitrate of 10.000 kb/s and you have a clip that is 25 fps, you'll have 400 kb per frame at your disposal. OK, this is simplified since codecs typically don't distribute data perfectly per frame like that, but you get the idea.
As codecs become increasingly sophisticated, they can deliver the same quality with less data thanks to advanced algorithms, The flip side is that they become more computationally intensive.
If you look at the iTunes Store you'll see that a typical movie is around 5-6GB for full HD. The movie 'Venom' is 1h52min and 5.67GB. This boils down to an average bitrate of approximately 7077 kb/s. Let's assume Apple is being "aggressive but not going overboard" with compression. I think 8000-10.000 is a good target for HD if you want to actually compress the files.
Some users might freak out saying that any 2h-ish movie that is less than 15GB is trash, so it's all subjective.