Shooting HD with the 5D but outputting in SD: Why?

J

jimbee

Member
I'm new to the 5D MKII so maybe this is a dumb question, but I'm puzzling over it. I just shot my first short film on the 5D, and I see the data rate is about 40 megabits per second, or roughly 5 megabytes per second. I transcode the 5D's H.264 files to Apple ProRes 422 (LT) for editing in Final Cut and the data rate goes up to 10.6 megabytes per second.

Then when I output my final version through Apple's compressor, my only choice to make a playable DVD is to use the Standard Definition settings because my DVD player will not play an HD disc. And the SD data rate in compressor is about 7 megabits per second, or roughly 1 megabyte per second.

If I have the math right, I am going from the beautiful 5-megabytes-per-second HD footage of the 5D down to 1-megabyte-per-second viewing on a DVD.

What is the point of shooting at higher data rates if you have to compress it down to much lower rates? If you shot the footage at 7 megabits per second to begin with and just kept it there, wouldn't it look the same in the end?

Or am I missing some important detail? Is starting with more data to begin with better, even though you throw 80 percent of it away when you output to SD?

Any illumination on this topic is much appreciated,

Jim
 
jimbee said:
I'm new to the 5D MKII so maybe this is a dumb question, but I'm puzzling over it. I just shot my first short film on the 5D, and I see the data rate is about 40 megabits per second, or roughly 5 megabytes per second. I transcode the 5D's H.264 files to Apple ProRes 422 (LT) for editing in Final Cut and the data rate goes up to 10.6 megabytes per second.

Then when I output my final version through Apple's compressor, my only choice to make a playable DVD is to use the Standard Definition settings because my DVD player will not play an HD disc. And the SD data rate in compressor is about 7 megabits per second, or roughly 1 megabyte per second.

If I have the math right, I am going from the beautiful 5-megabytes-per-second HD footage of the 5D down to 1-megabyte-per-second viewing on a DVD.

What is the point of shooting at higher data rates if you have to compress it down to much lower rates? If you shot the footage at 7 megabits per second to begin with and just kept it there, wouldn't it look the same in the end?

Or am I missing some important detail? Is starting with more data to begin with better, even though you throw 80 percent of it away when you output to SD?

Any illumination on this topic is much appreciated,

Jim
Click to expand...


Oversampling.
If you start off with more resolution then even when you downrez to SD 'some' of the quality remains. Movies shot on 35mm and then broadcast in NTSC SD still look good.
 
Two other reasons to shoot HD:

1) DVD might not be the only destination for your video. Many film festivals want the highest-quality, highest-resolution version of your movie for exhibition. Many video sharing Web sites (e.g. YouTube, Vimeo, ExposureRoom) don't limit you to SD quality. And if have a PS3, you can encode H.264 files for it and play them at full 1080p resolution on your HDTV, without the need to burn Blu-ray discs.

2) The SD mode is not widescreen.
 
jimbee said:
Or am I missing some important detail? Is starting with more data to begin with better, even though you throw 80 percent of it away when you output to SD?

Any illumination on this topic is much appreciated,

Jim
Click to expand...
Hi Jim. Yes. The important point you are missing is that filmmaking is not and should not be about data rates.

That's why I always laugh when we geek out over the latest this or the hottest that. Audiences don't care or better yet, don't know what you shot your project on. They just want to be engaged.

Concentrate on that and everything else will fall into place.

With that said, let me geek out a bit. Unless you are going to Blu-Ray. All HD and Film projects will be much higher resolution than you would ever be able to play back on a DVD. Same even goes for shooting 1920x1080. Most cable companies or networks don't broadcast in 1080 HD. They do 720. So you go through all that trouble of getting the best image possible only to go downrez from there.

The bottom line is you have a great camera that will be capabale of giving you amazing images that will impress chicks and make your neighbors jealous. So go out there and use it wisely.

G.
 
what everyone said about oversampling. Recently shot a film on HVX-200 w/Letus Extreme....the film looks better on DVD on a large LCD than in the full res pro res file...I was pretty stoked. The opposite has also happened to me...I've hated the way some of my GH1 stuff has looked down resed to DVD...
 
You must log in or register to reply here.
Back
Top