Beamr Blog’s Dror Gill provides an easily accessible guide to understanding Adaptive Bitrate Streaming recipes and best practices for encoding video for different bandwidths.
He writes, “There is one thing in common to all ABR recipes used today across the industry: They are fixed. The same bitrates and resolutions are being used across the whole content repository, for each and every title. For example, if your 720p layer is 3 Megabits per second, all of your movie titles, regardless of their content, would be encoded at this bitrate. But the reality is that some titles “need” more bits for encoding, while others need less – this is related to the nature of video encoding. For example, a 720p animated movie that has smooth surfaces and textures, and relatively little content, can be encoded at 1.5 Mbps and will retain the same quality of the 3 Mbps encode, since the additional bits do not contribute to added quality.
“On the other hand, action movies with a lot of rapid scene changes, high motion and special effects will require the full 3 Mbps at 720p to reach the same quality. Therefore, when you encode all of your titles at the same bitrates, you are actually “wasting” bits on titles that don’t need them. Why do you care? For two reasons: first, because you pay for those bits, and if you didn’t stream them, you would reduce your CDN costs. And second, your users can enjoy a better user experience with a faster stream start and less re-buffering events if the bitrate you stream to them for a particular ABR layer is lower.”