Is viewing a compressed video more processor intensive?

Question

If, when viewing a raw video, the computer basically maps pixel information to pixels on the screen, then wouldn't viewing a compressed video use more processing power, because the computer has to decompress the video as well?

Or have I got it all wrong? I still somehow suspect that watching a raw video is more processor intensive.

Answer 1

Raw video will use less processing power, but that doesn't mean it's faster.

Modern CPUs are quite remarkable, and they keep getting faster. Storage, OTOH, hasn't really kept up—especially if you're talking about rotational media. So, let's say you want to watch a video with a resolution of 1280×720, at 24 frames per second, and 24 bits per pixel… that is ((1280 * 720 * 3 * 24) / 1048576) = 63.28125 MiB per second of video that you have to read from your hard slow hard drive instead of doing a little bit of math on your fast CPU.

Futhermore, most video these days is decoded on the GPU or dedicated hardware (which is often integrated into either the GPU or CPU), so it probably isn't even competing for resources which you are using.

So yes, raw video uses less processing power, but the question is whether it makes sense to sacrifice a significant amount of scarce resources (I/O and disk space) in order to avoid using a resource which you probalby have more than enough of.