Originally Posted by Volitar Prime
Which is going to look better: recording in 1080p and then converting to 1080i or recording in 1080i? If all I want to do is burn AVCHD discs which will work on most Blu-ray players which way should I go?
As most other members agree on so far, 1080p is the way to record first, and then convert down to 60i if needed.
And for a simple mathematical reason:
1080 60i mode scans two FIELDS of 540 horizontal alternating lines each, 60 times per second. Then those two FIELDS are recombined into one complete 1080 lines FRAME when played back, effectively yielding a TRUE playback speed of only 30 FRAMES per second, similar to 1080 30p.
However, if the subject has moved between to field scans, it will appear blurry and stair cased when those two different fields are de-interlaced into a frame. That's one of the possible artifact caused by interlaced scanning, not a problem in 1080 30p mode because all 1080 lines are scanned at once.
On the other hand, 1080 60p mode scans a complete 1080 lines frame, 60 times per second, so it yields a true 60 complete frames per second smooth playback. And that's why it looks so stunning. Because our brain analyzes continuous movements, the higher the number of images per second you can produce, the closer to our natural perception of movement it becomes.
For so many years technology was limited, and trickery was used to fool our brain into thinking it saw continuous movements on screens. First by 24 fps cinema, then 30fps television with all it's interlaced jittering... It's about time that we step the speed up to produce a more convincing result.
The only advantage of interlacing fields, and in fact it was the basis of the invention of this mode of scanning, is the lower bandwidth required because there is less information per second to handle, either by electronic analog signals frequencies or the amount of digital data. Thus allowing lower bit rates and extending record time. That's also the reason why progressive scan will always require a higher bandwidth, because there is more available visual information to deal with.
So to recapitulate, you always want to scale down, not up from original material. Because you can always discard superfluous information, but it's much harder to invent (or extrapolate) convincing data if it's missing in the first place. Although some upconverting players do a remarkable job of it.