Per-title encoding with machine learning is the topic of thie video from MUX.
Nick Chadwick explains that rather than using the same set of parameters to encode every video, the smart money is to find the best balance of bitrate and resolution for each video. By analysing a large number of combinations of bitrate and resolution, Nick shows you can build what he calls a ‘convex hull’ when graphing against quality. This allows you to find the optimal settings.
Doing this en mass is difficult, and Nick spends some time looking at the different ways of implementing it. In the end, Nick and data scientist Ben Dodson built a system which optimses bitrate for each title using neural nets trained on data sets. This resulted in 84% of videos looking better using this method rather than a static ladder.
Many companies would love to be using free codecs, unencumbered by patents, rather than paying for HEVC or AVC. Phil Cluff shows that, contrary to popular belief, it is possible stream with free codecs and get good coverage on mobile and desktop.
Phil starts off by looking at the codecs available and whether they’re patent encumbered with an eye to how much of the market can actually decode them. Free codecs and containers like WebM, VP8 etc. are not supported by Safari which reduces mobile penetration by half. To prove the point, Phil presents the results of his trials in using HEVC, AVC and VP8 on all major browsers.
Whilst this initially leaves a disappointing result for streaming with libre codecs on mobile, there is a solution! Phil explains how an idea from several years ago is being reworked to provide a free streaming protocol MPAG-SASH which avoids using DASH which is itself based on ISO BMFF which is patent encumbered. He then explains how open video players like video.js can be modified to decode libre codecs.
With these two enhancements, we finally see that coverage of up to 80% on mobile is, in principle, possible.
How can we make video more appealing to humans? We’ve evolved to live a certain way and this has defined – and will continue to define – our video technologies. MUX founder Jon Dahl talks to us here about the ways in which human physiology drives viewing habits.
Vertical vs. horizontal video, angular resolution and how the typical viewing distances of computers, TVs and other devices affects what resolution we can perceive are all discussed. Jon moves on to frequencies both of audio and video where frame rates and flicker are important and where physics comes into play alongside biology.
Even for the experienced, this talk is bound to bring something new and is a great tour of the fundamentals of the visual perception that our industry relies on and strives to please day in, day out.
This talk was given at Streaming Tech Sweden which is an annual conference from Eyvinn Technology. Streamed on their own video platform, talks are initially available exclusively to all conference attendees, but are released free-to-view during the subsequent year. Free registration is required to watch the videos.
Mux’s Justin Sanford explains the difference between Quality of Service and Quality of Experience; the latter being about the entire viewer experience. Justin looks at ‘Startup time’ showing that it’s a combination of an number of factors which can include loading a web page showing the dependence of your player on the whole ecosystem.
Justin discusses rebuffering and what ‘quality’ is when we talk about streaming. Quality is a combination of encoding quality, resolution but also whether the playback judders.
“Not every optimisation is a tradeoff, however startup time vs. rebuffering is a canonical tradeoff.”
Finally we look at ways of dealing with this, including gathering analytics, standards for measuring quality of experience, and understanding the types of issues your viewers care most about.