[LEAPSECS] TV frame-rate in 60Hz countries

[Stephen Scott]

  On 2014-01-18 16:14, Peter Vince wrote:

> Stephen Scott has just mentioned his involvement in the TV industry in 

> the USA, with its problematical 29.97 Hz frame-rate.  I also work in 

> the TV industry, but in the UK where we are lucky to have a nice 

> integer 25 Hz rate.  Although historically we still had a problem with 

> leap seconds, as the 625 PAL system had a 4-frame ("8-field") sequence 

> (due to the exact colour subcarrier frequency being offset from a 

> multiple of line frequency to avoid static patterning on monochrome 

> displays), and so there were three and one-eighth of these 4-frame 

> sequences per second.  When editing, this frame-sequence had to be 

> maintained, else there would be a small sideways jump when the replay 

> machine kept the signal synchronous with the colour subcarrier phase.

> Anyway... those problems have largely gone away now that we have 

> stopped broadcasting the analogue PAL signal.

Is there any attempt to maintain the PAL 8-field sequence when aligning 
the timestamps with clock time?

>  I was wondering if Stephen, or anyone else, has any information about 

> the possibility of 60 Hz countries changing the nasty NTSC-based 29.97 

> Hz frame rate to a nice integer 30 Hz rate, as I believe analogue has 

> also all but been switched off in the USA too (no knowledge of other 

> 60 Hz countries.)

This would be one of my fondest dreams. However there is an enormous 
reluctance to do so. With the advent of higher frame rates 60/1.001 Hz 
has been adopted for UHDTV and there is a proposal for 120/1.001 Hz 
being proposed.

Regards
Stephen

>

>      Regards,

>

>           Peter Vince

>



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