HMC150 1080/30p (over 60i) & 720/30p (over 60p)
 

Hi All,

HMC 150 question, these are the recording formats listed in the instructions:

1080 1080/60i

1080 (only PH mode) 1080/30p (over 60i)

1080/24p (Native)*2

720 (only PH mode) 720/60p

720/30p (over 60p)

720/24p (Native)*

What is the deal with the (over 60i) and (over 60p) stuff? I read about some people having problems with this and having clips moves double fast after transcoding. Is this a problem? What does it mean?

What does native mean?

Thanks for any help,

TL

Tim,

There is nothing to worry about. All of these recording formats work perfectly, and none will play back at the wrong speed with standard NLEs.

Cineform was recently having problems transcoding 720P60 footage correctly - I think it was playing back half-speed. They issued a reg fix for that a couple of months ago.

I, too, am a bit puzzled by the references to "over" 60P and 60i.

24p native: each progressive frame is stored separately (modulo compression), and the video is marked as 24fps.

30p over 60i: each progressive frame is split into two interlaced frames corresponding to even and odd fields. These are then stored in the video file instead of the original progressive frame. The resultant video has 60 interlaced frames per second or 60i.

However, unlike true 60i video, both fields refer to the same instant in time, not two instants 1/60th of a second apart.

I think for 30p over 60p each progressive frame is repeated twice in the recorded stream.

As Guy mentioned above, the files are usually marked and most NLEs recognize these formats and can deal with them without any action on the user's part.