In defense of compression

There’s a certain demographic which seems to sit around thinking of reasons why the Red One can’t possibly be any good. We’ve all run across these arguments. One that has really been bugging me recently is the notion that RedCode compression somehow constitutes, essentially, cheating; that Red shouldn’t really be considered a high-end camera because it shoots compressed footage.

The notion that uncompressed is always better for a professional camera shows a complete lack of understanding of the trade-offs involved with this sort of decision. Sure, uncompressed is better if all other things are equal. But all other things aren’t equal.

What particularly annoys me is the notion that the Red One is somehow less professional than cameras which output uncompressed 1080p as their final product. Modern compression algorithms are extremely smart about what data they discard. The idea that you’re better off with an uncompressed image with a much smaller number of total pixels simply doesn’t hold up to even the most cursory analysis.

Even very low bit-rate consumer formats like HDV, when shooting HD, produce much better looking images than uncompressed SD, despite having far lower bit rates. (And HDV compression for 1080p footage is something like 85:1 or 90:1 compression. RedCode 28 is 12:1, and with a much more advanced algorithm.) You’re far better off capturing lots of detail and having a modern compression algorithm figure out what it can safely get rid of than you are capturing less detail in the first place, or capturing lots of detail but throwing lots of it away immediately using more primitive techniques like downscaling or subsampling chroma.

OK, so why doesn’t Red just record uncompressed 4K bayer, instead of compressed 4K bayer?

I’m quite confident in saying that given today’s technology, the Red One is a far more compelling product because of RedCode than it would be if it only shot uncompressed data. In fact, the camera wouldn’t be nearly as significant to the market if it didn’t shoot to a compressed format.

RedCode is what allows you to shoot to CF cards and Red Drives, rather than being tethered to a RAID the size of a mini-fridge. It’s what allows footage to be downloaded in a practical way on-set. It’s what allows you to play back footage from a single SATA or FireWire 800 hard drive, and store about 10 hours of footage per terabyte, instead of around 50 minutes.

Of course, you don’t get all of this for noting. The Red One probably could probably use less power and run cooler if it didn’t have to do 4K wavelet compression in real-time. And there is some loss of image quality vs. a totally uncompressed 4K image.

But the fact is, the Red One wouldn’t be a remotely practical camera for the vast majority of the projects it’s being used on, if Red had bought into the myth that professional recording must be uncompressed. RedCode is the major factor that makes the Red One usable by low-budget indies. Without RedCode, the data situation would simply be unmanageable for low-budget indies, both on-set and in post. Without Redcode this blog, which after all focuses on the technical issues surrounding low-budget indie filmmaking, probably wouldn’t talk about the Red One at all. As it is, that’s practically all we talk about….

This entry was posted in Tech Commentary and tagged , . Bookmark the permalink.

Leave a Reply