[FFmpeg-user] Single-field deinterlace with nnedi

[Alexander Zhang]

>> I'm trying to use nnedi to deinterlace a 29.97 fps video without
>> doubling the frame rate. I added the fields=a option which I thought was
>> supposed to make nnedi only use one of the two fields, but the output is
>> still 59.94 fps. Is this a bug or am I misunderstanding something?
>>
> 
> Filter still produces same number of frames as input in field mode.
> Just every second frame is duplicated in output file because of fixed frame
> rate.

So should I just drop every other frame with an fps filter to get half 
the field rate?