[noggin]

@noggin
but then how will you detect the correct frame rate? Just sniffing the metadata of the container hoping they are correct
this is Kodi with one of those hevc from Elecard website:

V/Kodi ( 1373): Debug Print: int CDVDPlayerVideo::OutputPicture(const DVDVideoPicture*, double) - change configuration. 1920x1080. framerate: 24.08. format: BYPASS
V/Kodi ( 1373): Debug Print: Resolution 1920x1080 @ 24.00 - Full Screen (26) not a very good match for fps 24.083 (weight: 0.003), trying 2:3 cadence
V/Kodi ( 1373): Debug Print: Resolution 1920x1080 @ 60.00 - Full Screen (22) not a very good match for fps 24.083 with 2:3 cadence (weight: 0.003), choosing 60 hertz
V/Kodi ( 1373): Debug Print: Display resolution ADJUST : 1920x1080 @ 60.00 - Full Screen (22) (weight: 0.246)

For broadcast use the HEVC encoder will receive baseband uncompressed (or mezzanine compressed using something like VC-2) video (SDI for SD, HD-SDI for HD and either a new form of HD-SDI like 12G, or Quad 3G HD-SDI, or SMPTE 2022 video over IP or similar)

This will have a fixed frame rate, but the encoder will detect the duplicate frames (e.g. 2:2 for 25p in a 50p format) as part of the encoding scheme. You wouldn't use broadcast metadata as that is likely to cover the whole show, and you could easily expect a show to contain content sourced in multiple frame rates. (Perfectly normal to have 25p, 50p content mixed in a show)

When it comes to decoding - doesn't HEVC have both a 'source frame rate' and an 'actual frame rate' header? (i.e. it tells you what the decoder should output as part of the stream?) The issue with 24p 3:2 stuff is that this will be 60p (or 60i) not 24p - because the encoder was fed 60i/60p not 24p. (The VFR is supposed to be 'hidden' from the end user) If you want to detect 24p 3:2 content that needs to be downstream of the encoder - you can't 'trust' the VFR stuff to accurately tell you this. This is because you can expect TV shows to have a mix of 24p and 60p content in some cases, and the last thing you want is your display re-syncing on a cut from the studio to a film clip...

VFR is unlikely to be used in the production chain - we're pretty much standardised on Intra-frame for post-production (AVCi, DNXHD, ProRes etc.) and almost all the Long GOP acquisition codecs use a fixed GOP (and cameras run at fixed frame rates so VFR no use there)