[opendtv] Re: Frames Per Second of 720P

  • From: "Hoffmann, Hans" <hoffmann@xxxxxx>
  • To: <opendtv@xxxxxxxxxxxxx>
  • Date: Fri, 18 Jul 2008 14:49:31 +0200

John,

This kind of confusion is why the EBU has decided for a different
nomenclature 

Active_lines    scanning / frame rate
1080                    i          / 25
720               p        / 50

The small "i" characterises whether it is an interlaced format which means
each frame is divided into 2 fields. But I understand that marketing people
don't like smaller numbers if they compare format;-)

Regards,
Hans 

> -----Original Message-----
> From: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-
> bounce@xxxxxxxxxxxxx] On Behalf Of John Shutt
> Sent: 18 July 2008 14:37
> To: opendtv@xxxxxxxxxxxxx
> Subject: [opendtv] Re: Frames Per Second of 720P
> 
> The Sony brochure
> http://bssc.sel.sony.com/Professional/docs/brochures/mvs8000.pdf states
> that
> the switcher operates at 1080i60, 1080i59.94, and 1080i50.  This is
> probably
> where the Sony rep got confused, because 1080i60 is indeed 30 unique
> frames
> per second, and 1080i59.94 averages out to 29.97 unique frames per
> second.
> 
> This is exactly why I don't understand the nomenclature that seemed to
> only
> come into fashion with the advent of HD, of calling 1920x1080 thirty
> frames
> per second interlaced as "i60"  Read the timecode, there are 30 frames
> per
> second in the timecode, therefore it is a thirty frames per second
> (ignoring
> the 1.001 for the moment) format, and should be called "i30" which
> clearly
> states 30 fps, presented interlaced.
> 
> When recording "1080i59.94", you can frame advance through the timecode
> and
> watch the time change from 00:00:03:29 to 00:00:04:00.  In contrast,
> with
> 720p59.94, you can watch the timecode change from 00:00:03:59 to
> 00:00:04:00.
> 
> "1080i60" looks better on paper next to "720p60" I suppose.
> 
> John
> 
> ----- Original Message -----
> From: <dan.grimes@xxxxxxxx>
> 
> 
> >I just attended a demonstration of a Sony MVS8000 production switcher.
> The
> >switcher can output 720 at 59.94 P and 1080 at 29.97 I.
> >
> > As I we discussed frame stores, I asked if it took 60 frames to store
> a
> > one second motion clip (120 with a key) and they said no, only 30.
> They
> > (multiple Sony reps) were telling me all video is 30 frames per
> second, no
> > matter what the format.
> 
> 
> 
> 
> 
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