Interlaced mode, a still needed legacy ?

[Alexey Eromenko]

Hello,

From what I read, things like 1080i mode (as opposed to 1080p), or interlaced mode seems to offer little to no advantage over 720p video,  and compilcating codec design, introducing potential bugs.

Do you think this feature is useful or should be axed from future codecs ?

-Alexey

[Jai Krishnan]

Hi Alexey,

Interlaced wasn't a priority for vp9, and as we've been focusing on video for the web, I don't see that changing for future codecs.

Thanks,
Jai

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[Alberto Vigata]

Hello Alexey!, 

I worked extensively in the past with interlaced codec support so I may have something to add.  

Interlaced support mode made sense in an era where interlaced displays were commonplace. These days, virtually all displays out there are natively progressive. Old codecs (<h265) had deep support for interlaced video, all the way down to the transform sometimes, and it was an enormous engineering headache to go around supporting this, specially as we swiftly moved to progressive. 

I think interlaced support will linger around for sometime to support the massive amounts of content produced in 480i or 1080i, but it will be minimally supported in broadcast codecs by simply flagging the frame as an odd/even field with the appropiate resolution. Web/Streaming oriented codecs don't need to keep this sort of backward compatibility and can happily be progressive only. The future is progressive only and we must move on.

Alberto