Practicals: Video Compression and Data Rates

Cannon C100 camera on stand
Zack Gross

Camera Video Compression

Often, I’ll hear newer shooters or filmmakers complain about having trouble manipulating and refining their footage in post, especially DSLR footage or more affordable cinema cameras. This is mainly due to video compression. Think of it like a funnel. In order for a useful amount of video footage to fit onto small memory cards like SD cards, a digital cameras computer has to constrict the amount of information that’s saved.

A camera’s video compression is described by a ratio, such as 2:1 or 50:1. The greater the first number, the higher the compression will be. During the compression process, the camera throws out extra information such as color depth and detail. It’s that extra information that higher end cameras retain, that allows you to better color grade and refine your footage. On a DSLR, no matter if you shoot in a saturated or flat color profile, your ability to manipulate your footage is limited because the footage is so compressed.

Camera's Codec

Your camera's codec often determines the compression and data rate.  For example, the Canon C100 records 1080 footage with an 8-bit, 4:2:0 (color space) video codec using H.264 compression.  The more expensive C300ii has a few recording options, but uses a 10-bit, 4:2:2 video codec at a higher data rate than the C100.  Codecs are a balance between file size (compression) and quality.  The goal is to have the highest quality file for the recording media designed to work with the camera.  Less expensive cameras will use less expensive recording media, such as SD cards, while higher end cameras will require faster and more robust media, such as CF and XQD cards.

Transfer Speed = Data Rate

Another factor that plays into this is your camera and media’s data rate, also called “transfer speed”. Your data rate describes how much and how fast your footage can be compressed and stored to your media. To lower the data rate of your footage, your camera’s computer must compress more. Higher end cameras usually have higher data rates because they compress much less, and so retain much more information, leading to larger video files. You must always make sure that your media’s data rate can handle your camera’s data rate.

Just for Reference

Creative Liquid’s C100 shoots HD footage to SD cards at 24 Mbps. Our Panasonic 270 can shoot HD footage at 100 & 200 Mbps. Our Sony F5 can shoot full 4K footage at around 400 Mbps.

Why Your Budget Matters

Before you select a camera for your next project figure out the best option for your budget.  This goes well beyond just the cost of renting or buying a camera.  You need to consider the cost of the media you'll need, how much storage do you have for post production, will your computer be able to edit the type of footage you're going to capture and how comfortable are you with media management.  All of these things factor into total costs.