Most streaming producers know that dif- ferent video clips encode with more or less efficiency depending on the mo- tion in the video, the level of detail, and other factors. Still, most producers use a fixed encoding ladder because it’s
simple to implement and because they don’t
feel that they have other options.
Well, whether you’re encoding in the cloud or
on premise, with a commercially available encoder or your own do-it-yourself FFmpeg-based
encoding farm, you do have options. In this article, I’ll discuss four: One is for the DIY crowd,
and the others are available as features of pre-packaged software programs.
1. DIY: Capped constant rate factor, or CRF
2. Pre-packaged: Capella Systems’ Source
Adaptive Bitrate Ladder, or SABL
3. OVP or cloud encoder: Brightcove
Context Aware Encoding, or CAE
4. Cloud service: FASTech.io Video Optimizer
To be clear, this article is not a head-to-head
comparison of these products and services, but
rather an exploration of their features and capabilities, and an attempt to create a structure
to gauge their effectiveness. It will help you understand how these products and services function, and it will identify questions you can ask to
tell them apart.
Rather than jumping right in, let’s start at
the beginning, which in this case extends all
the way back to December 2015.
Netflix Per-Title Encode Optimization
On Dec. 14, 2015, Netflix published a blog
post entitled “Per-Title Encode Optimization.” It
stated, “To deliver the best quality video to our
members, each title should receive a unique bit-
rate ladder, tailored to its specific complexity
Netflix describes its approach, which involves
multiple test encodes at different data rates
and resolutions to identify the optimum qual-
ity at each data rate/resolution pair. Original-
ly, Netflix used the peak signal-to-noise ra-
tio metric (PSNR) to measure quality, but later
changed to its own Video Multimethod Assess-
ment Fusion (VMAF) approach.
By Jan Ozer