Aside from the codec and frame size, the most important factor in determining the quality of the finished product when rendering video is bitrate.
The term bitrate refers to the number of bits per second used to encode a given clip. Just as the quality of a still image is measured in resolution, the quality of a video file is measured by the bitrate.
For video destined for the web, you don’t want to encode with the bitrate set too high for several reasons:
1. You will make your viewers wait unnecessarily long before they can start viewing your video.
2. Higher bitrate videos put an extra strain on your server and will cost you more money in extra bandwidth.
3. Older computers will have a hard time decoding very high bitrate codecs in real time, leading to dropped frames and jerky appearing motion.
4. Uploading will be slower.
5. You’ll use up unnecessary room on your server and local drives.
On the other hand, you don’t want to encode video with bitrate too low either otherwise the visual quality will suffer - there will be pixelization and blockiness, especially in any areas with motion.
Let’s Get Progressive
“Progressive download” means, as soon as your viewers click to view a particular video, the video starts downloading to a hidden cache file on the users machine.
As soon as enough of the video has downloaded to provide the user with an uninterrupted viewing experience, the video begins playing (as long as it’s set to: autoplay = “true”).
With a video that is encoded at a lower bitrate than the total bandwidth of the connection between the video server and the viewer, the video will start playing within a second or two, and continue without stopping. This is obviously the goal to aspire to for most purposes.
Fortunately, choosing the best bitrate to achieve this goal while retaining visual fidelity is no longer just a matter of luck.
The video bitrate calculator in DV Kitchen will give you the video bitrate that satisfies whatever criteria you set.
