Wednesday, March 05, 2008

High Definition Video

Hello Reel Grrls,

It's an exciting era for us as we are all learning about High Definition Video for the first time here. I'm beginning to pull together some info that we can all share and am going to start posting it up right here on our Reel Grrls blog. I'd love to invite all of you to do the same. Post to our blog with info you find or glean, questions or thoughts or observances about using the new HD format. This is a big technology jump and I for one am confused and a bit intimidated by all the new stuff we have to learn about it. So let's figure it out together. Here's my first crack at it (a lot of this is taken from various internet sites and a lot of it is reworded by me because rewording helps me understand):

What is High Definition Video?
HD is more than just "better quality than SD (standard definition)" or "wider than SD." SD records in interlaced frames in 720x480 pixels at 29.97 frames per second in NTSC video countries like ours. One abbreviation for this that you may have seen is 480i, which means 480 scan lines with interlaced frames. When SD shoots in "widescreen" it's actually not changing the resolution at all but simply uses a "wide pixel" mode for 16:9 recording. The overal resolution in SD is fixed and universal.

On the other hand, High Definition Video can be defined by three different characteristics:
1. The number of lines in the vertical display resolution. In HD it's generally 1080 lines (versus SD's 480)
2. The scanning system: progressive vs. interlaced. Progressive scanning redraws an image frame (the lines of the image) each time it refreshes that image. Interlaced scanning draws the image FIELD (every other line or "odd numbered" lines) during the first image refresh, then draws the remaining "even numbered" lines during the second refreshing. Interlaced scanning gives us greater image resolution if the subject isn't moving BUT can lose a lot of resolution and can gain digital artifacts when filming fast moving subjects/images.
3. The number of frames per second or fields per second. The 720p60 format is 1280x720 pixels, progressive encoding with 60 frames per second.

So what does all this mean for us and our new Canon XH-A1? Well now we can interpret some of the settings we've been figuring out:
24f means 24 frames per second and 24p means 24 progressive scan frames per second (and 24 is what we want to be shooting in because it's closest to film)
1080i mean 1080 lines of horizontal resolution, shot in interlaced frames
60i means 30 interlaced frames per second, consisting of 60 interlaced fields per second

Is all of this starting to make some sense? Or are you more confused than when you started reading this post?? Personally I haven't decided yet. Let's keep on workin on it.

Also, I found these great forums where you can read and post about HDV (high definition video). They even have a thread just for our very own Canon camera! Check it out grrls: