[FFmpeg-user] Converting a 23.98p source to 29.97i ProRes w/interlaced 3:2 pulldown?

[Mel Matsuoka]

> On Oct 25, 2015, at 4:47 AM, Marcelo Boufleur <mboufleur at gmail.com> wrote:
> 
>> Why is "-r 30000/1001" necessary?
>> Is there a bug?
> 
> "-r 30000/1001" in not necessary, and there aren't any bugs related to this
> code/syntax.


Just for my newbie-enlightenment, is there a reason why people seem to prefer using the "frame_rate_num/frame_rate_den" syntax for defining the frame rate, rather than--as in my case--simply defining the framerate as a float number like "29.97"?

In my world, the only frame rates that matter are 23.976 (aka "23.98") and 29.97 (either interlaced or progressive), so is there a reason why I shouldn't be using these specific numbers (or even "ntsc" or "ntsc-film"?)