NF/NDF flag in SMPTE 12M timecode standard

SMPTE 12M timecode

31...28 27...24 23...20 19...16 15...12 11...8 7...4 3...0
   h       h       m       m       s       s     f     f

It’s encoded like BCD.

Example )
01:28:17:18

      31...28 27...24 23...20 19...16 15...12 11...8 7...4 3...0
NDF :    0       1       2       8       1       7     1     8
       0000    0001    0010    1000    0001    0111  0001  1000

DF  :    0       1       2       8       1       7     5     8
       0000    0001    0010    1000    0001    0111  0101  1000

The high 2 bit of second nibble from the right is for DF/NDF.

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