Originally Posted by Ungermann
There is no difference in temporal resolution between 30i (a.k.a. 60i) and 60p.
30i means that the footage contains 30 half frames per second. 60i means that the footage contains 60 half frames per second. 60p means that the footage has 60 full frames per second. So clearly there is a significant difference between 30i, 60i, and 60p. And also clearly 30i is not also known as 60i.
Temporal resolution is determined by how the sensor is scanned, not how the frames are encoded. Some cameras scan their sensor at once (all scan lines in one time interval). Other cameras scan their sensor with alternating scan lines, although these are less common. Each full frame from the sensor can be encoded in the footage either as a single progressive frame or as two interlaced frames. Sometimes frames are doubled, eg., when a sensor is scanned at 24 fps but encoded as 60i then some of the frames must be doubled. When people refer to the footage as 60i, they are not specifying anything about how the frames are scanned from the sensor. It could be 24 full frames per second, 30 full frames per second, 60 half frames per second, and so on. On most modern camcorders with a 60i setting, the sensor is scanned progressively at 30 frames per second and then encoded as 60 interlaced half-frames per second. In that situation, a camera that scans 60 fps and encodes it as 60p has double the temporal resolution of a camera that scans 30 fps and encodes it as 60i.