Invert field order using ffmpeg for NTSC source

[cjdavis83]

Hi,

I was wondering what phase command I should use for inverting the field order of an NTSC video source in ffmpeg captured wrongly as TFF using hardware
It is pure analog NTSC video but TFF was used by default during the capture process.

phase = b or = phase t

??

I was using fieldorder=bff but I understand that some blurring of chroma may be induced.