Is this camera going to have higher video quality than the C300? It's 4k output but the C300 is only 1080 output.
Read the specs more carefully: the two are probably very similar in photosites count, but described differently. Each of those 1920x1080 pixels in the HD frames from the C300 come from four photsites: one each rad and blue, two green. This is almost certainly aggregating a 2x2 block from a Bayer CFA sensor with 3840x2080 photosites. When Canon talks of 4K in the future camera, it is counting the way RED does: every photosites, so an array with roughly 4000 single color photosites in the horizontal direction.
So it's 3840 vs about 4000 really.
P.S. the numbers for this future Canon video DSLR fit with the sensor having the same pixel count and size as the D1X, once you note the crop to 80% of frame width for that 4000 pixel wide video frame.
My guess Is that the 1080p model is aimed at the needs of HD television, while 4K fits better for making movies intended for digital projection in cinemas. The digital projectors are mostly 2K now, with Sony pushing new 4K models. (but that is 2000 and 4000 full three-color pixels wide, not the dodgy 4K spec used to describe many digital video cameras with Bayer CFA's.)
