I realise that because of the legacy of PAL vs NTSC our Freeview broadcasts are 1080i/50 vs the US 1080i/60 or 720p/60.

But this is what is not clear to me.

In order to broadcast US shows that probably originate in some 60Hz format, we receive 50Hz frame rate versions. So the framerate is 25fps here and 23.97 or 29.97 (?) in the US. This has the annoying side effect of having the video sped up by about 4%, equivalent to the old PAL vs NTSC speedup in the analogue days. Perhaps I am just being picky but given I watch a fair bit of content on Netflix and then occasionally catch up on the latest versions on FTA, I find the speedup very annoying. It's very clear on a show like The Big Bang Theory where for example Sheldon's voice, which is already quite high pitched normally, pitched up 4% sounds cartoon like to me!

What led me to make this post was the NFL live being broadcast on Freeview 13. I have captured this stream and it looks like it's 25fps but it's not sped up for obvious reasons. So somewhere in the broadcast chain the video is having realtime framerate conversion being performed.

Slightly relevant to this topic was a podcast I listened to recently where the guy in charge of NBC's Olympic's broadcasts was talking about how they covered the London Olympics. He said since England was a technologically advanced nation, they were able to lease much of their OB gear locally. That would presumbly in 25fps standard kit. They then edited the footage locally, inserted whatever graphics etc. they needed and send it to their US locations where realtime framerate version would be done prior to broadcast.

I can't see any downside to NZ sourcing shows in their original framerates since pretty much all HDTV's sold here can display  50Hz and 60Hz. And if they showed the original video stream they would get another 4% of time for ads! When analogue and Freeview coexisted a while ago, that would have meant the two broadcast streams would be out of sync but that issue no longer exists.  Of course the broadcast equipment might not be able to handle a 60hz or 24fps stream?  I don't know.

Alternatively they could perform realtime frame rate conversion to deliver a 50Hz version but with the right speed and pitch.

Probably some technical inaccuracies in the above since I don't profess to be an expert in broadcast video technology but I can certainly hear the results of incorrect playback speeds, even in the HD world and it irks me. Of course I might in a minority of one!