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Comment by mappu | Hacker News Reader

> An encoding family requires a minimum set of resolutions to be made available before we can deliver a video. [...] For example, having one video with all of its VP9 lanes adds more value than 10 videos with incomplete (and therefore, undeliverable) VP9 lanes.

I don't see why this constraint is in place, you can absolutely serve video for certain-res users only with certain codecs (youtube certainly does this).

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I assume Facebook has this requirement for usability reasons. They don’t want a user to receive a video through one of its many share features and then not be able to view it.

You need baseline codecs for baseline visibility, sure. But the article is about selectively choosing which videos to encode with more advanced parameters, and there's no reason to hold back delivering your 1080p VP9 just because the 720p VP9 isn't ready yet - just serve something else.

What if you were streaming 1080 VP9 and then your player decides to downgrade to 720 because your connection became slower? At that point the missing 720 would make you unable to watch the video.

In MPEG-DASH codec is specified at the representation level so with a compliant packager and a compliant player the player should be able to switch down to the "fast h.264" rendition that exists before they start trying to create VP9 renditions.

This is (was?) a big problem with google photos. If you upload a video and immediately share it with someone they'll just see a black screen. A few minutes later they might be able to watch a super-low res encoded version, and only much later does a HD version become available. I started waiting 10 minutes between generating a "share" link before sending it to my family because of all the confusion it was causing.

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