Saturday, December 12, 2015

Netflix: The Challenges of Preparing Video for Best QoE

Anne Aaron [pictured], Manager, Video Algorithms, and David Ronca, Director, Encoding Technology, explain in a post to Netflix Techblog how Netflix prepares its video content and "encode them to the best video streams possible for a given member’s viewing device and bandwidth capabilities" which turns out to be a bigger challenge than what most people think.

Related posts
  • How does Netflix Optimize Video? - here
  • Sandvine: Streaming Video is 70% (Netflix 37%) of NA Fixed Traffic" - here.
"The video encoding pipeline runs EC2 Linux cloud instances. The elasticity of the cloud enables us to seamlessly scale up when more titles need to be processed, and scale down to free up resources .. Long processing jobs are divided into smaller tasks and parallelized to reduce end-to-end delay and local storage requirements .. A modern 4K source file can be quite large. Larger, in fact, than a typical drive on an EC2 instance. In order to efficiently support these large source files, we must run the inspection on the file in smaller chunks .. Before we implemented parallel chunked encoding, a 1080p movie could take days to encode, and a failure occurring late in the process would delay the encode even further"

"..At Netflix we stream to a heterogeneous set of viewing devices. This requires a number of codec profiles: VC1, H.264/AVC Baseline, H.264/AVC Main and HEVC. We also support varying bandwidth scenarios for our members, all the way from sub-0.5 Mbps cellular to 100+ Mbps high-speed Internet. To deliver the best experience, we generate multiple quality representations at different bitrates (ranging from 100 kbps to 16 Mbps) and the Netflix client adaptively selects the optimal stream given the instantaneous bandwidth" 

See "High Quality Video Encoding at Scale" - here.

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