NDF/DF SMPTE timecode, frame number w/ FFmpeg

smptetc.c

// gcc -std=c99 -I/usr/include/ffmpeg ndf.c -lavutil
#include <stdio.h>
#include <libavutil/timecode.h>

int main() {
  AVRational fps = { 30000, 1001 };
  AVTimecode tc1, tc2;
  av_timecode_init(&tc1, fps, 0,                          0, NULL);  // NDF TC
  av_timecode_init(&tc2, fps, AV_TIMECODE_FLAG_DROPFRAME, 0, NULL);  // DF TC

  int prev_fn_df = 0;
  for (int fn = 0; ; fn++) {
    uint32_t tc_ndf = av_timecode_get_smpte_from_framenum(&tc1, fn);  // SMPTE 12M(NDF)
    uint32_t tc_df  = av_timecode_get_smpte_from_framenum(&tc2, fn);  // SMPTE 12M(DF)
    int fn_df = av_timecode_adjust_ntsc_framenum2(fn, tc1.fps);       // frame number (for DF)
    
    char buf1[AV_TIMECODE_STR_SIZE], buf2[AV_TIMECODE_STR_SIZE];
    printf("%8d %s  %8d %s%s\n",
      fn,    av_timecode_make_smpte_tc_string(buf1, tc_ndf, 0),
      fn_df, av_timecode_make_smpte_tc_string(buf2, tc_df,  0),
      (prev_fn_df + 1 == fn_df) ? "" : " *");
    prev_fn_df = fn_df;
  }
}