Why does my 30p video show up as 60i?

I’ve seen some confusion on the online forums regarding shooting in 30p (or 24p) and then importing into a video editor.

Why does my 30p video show up as 60i in <name your editor>?

In an interleaved 60i video (normal old fashioned video), the image is scanned 60 times per second, producing one half frame at each scan (say the odd scan lines, followed by the even scan lines in the next half frame). Because movement can occur between the two half frames, you some times see interlaced jagged edges.

A better way is to take 30 still pictures per second of the entire image.

When your camera records at 30p video, it takes a single image – but splits it into two half frames and stuffs those into two 60i half frames (without any jaggies since its splitting one image in to two pieces whereas 60i creates one image from two separate pieces taken 1/60th of a second apart).

Consequently, a 30p video is stored as a 60i video. And two consecutive half frames, put together, become 30p. Your video software can’t tell the difference between between 60i and 30p.

So why do we have these strange 60i half frames? Historic reasons. The earliest TVs were not able to scan the full image top to bottom before the next image would arrive. The solution then was to draw only half the lines in each interval. Thanks to the persistence of the phosphor image of old TVs, the first lines remained glowing while the TV then scanned the alternate lines.

No one would design a TV like that today – but we’ve lived with it for many decades and it is still supported for compatibility reasons.

I can import 24p video into iMovie (or other editor) but it plays weird – why?

This depends on the camera. But it is common to store the 24p image in half frames, similar to 30p. But since 24 does not evenly divide into 60, the sequence of half frames is a little different.

In 30p, the sequence is basically 2:2:2:2:2:2 and so on where the 2 signifies 2 half frames.

In 24p, the video may be stored in various combinations such as:

2:3:3:2 or 2:3:2:3

In this way, the 24p mode uses up more half frames – consider 2 half frames and then 3 half frames. This slows down the video frames to match the 60i storage of the tape. Consequently, 24p gets mapped into a funky sequence of half frames on the 60i tape.

To a program like iMovie, this 24p footage looks just like 60i. But unfortunately, iMovie (And many other video editors) have no way of knowing that it is not really 60i footage with some frames appearing 3 times. So play back and edits produce strange artifacts.

If you want to convert this to proper 24p footage and then edit in an editor that supports 24 frames per second see these instructions.

Youtube adds 1080p capability

HD videos uploaded in 1920 x 1080/p will – probably – be transcoded by Youtube into 1080p videos. This represents an upgrade from Youtube’s 1280 x 720p maximum HD resolution.  (“Probably” because Youtube says not all videos will be converted just yet.)

The 1080p videos, however, are useless for most computer displays as few have 1920 x 1080 sized displays. The main advantage, probably, is that in a near future world, we will be watching streaming videos over the Internet – on our real HDTVs, arriving via a set top box.

Worse, you’ll need a very fast processor to watch the new 1080/p HD videos. I can’t watch them on a 3.2 Ghz Windows OS computer – and I can watch them on my quad core Mac Pro only if I wait for the video to download entirely, first. The problem is the video stutters badly as the processor cannot keep up with the Flash video decoding.

Recommendation: Upload the HD video but don’t select the HD option during play back.  It looks like the new “normal” is 1280 x 720 – so you don’t need to select HD.

youtube Failed (upload aborted)

uploading Failed upload aborted – YouTube Help.

Just an FYI – this is happening to me, also. It has been impossible to upload videos to YouTube the past couple of days. Actually, I can upload short videos, say 30 seconds long – YouTube gives an error but processes the video anyway. Longer videos, such as 5 minutes, always fail. I suspect this is due to YouTube’s new 1080p upgrade not working.

Nothing changed on my end – or for the many others experiencing this problem. Today is Saturday, November 21, 2009 for reference.

There is a work around, apparently: Use the multi-video or bulk video upload option. This does work for me and others.