Explain my camera, its insides, and how it does video vs. stills to me?

[tainalewajko]

I figured this would be the best place to go. If it's already been covered elsewhere, that you can think of, please, kindly direct me there.

I have a 60D. That distinction probably won't matter for what I'm asking.

Basically, to get down to the jist of what I'm really longing to know, why can I not record video with the same resolution that I am able to take RAW stills in? (Said differently, why can't I shoot in 5134 x 3456 [18MP] instead of 1920 x 1080?)
Processing power, I'm guessing is the answer, or something in the sensor.

Either way, thanks for your responses ahead of time.

[3pointedit]

Note how long it takes for you to take a sequence of photos in RAW mode. How many can your camera do before it stops clicking away? Just a few? Well the camera memory is full and it is trying to save all that data to the media (CF or SD card). If you could dump that memory out faster perhaps you could record in real time (after all the camera is seeing an image with the entire sensor)? But the RAW image capture enabled by Magic Lantern is a contracted version meant for subsequent processing (into a H264) and for displaying on the back LCD viewer.

I'm not sure that there is a bigger image available to us? And the media port is limited by a bit-rate bottleneck too. Not just the speed of the card (or HDD hack in the CF port).

[nanomad]

There' also the issue of sensor readout speed. The image processing IC can't sample all the sensor's pixels fast enough. Hence line skipping and binning. That's what probably limits the camera at 37 FPS in full hd mode and 60 in 720p.