ltcdump start TC not match decode from other tools

[RNLgit]

Hi, it's a great lib and tool to use really appreciate. I'm trying to decode LTC time code from pre-recorded audio wave file. (which is generated by a hardware timecode generator, then feed into camera. Then take LTC audio track from clip file and decode the timecode use ltcdump).

I can get timecode back from ltcdump however when I use the same wav file and load it in other tools like 'Tentacle Sync Studio', 'LTCconvert', they all see same timecode which is 1 frame ahead of ltcdump decode. Following are the details:

The sound file example
30fps_wave.zip

ltcdump vs LTCconvert.app vs Tentacle Sync Studio.app decode ltc

sample rate: 48,000, 30fps, ltc on ch1

As can see there ltcdump shows timecode start at 00:00:26:20 where as other two tools shows it starts at 00:00:26:19. This is just one of many examples. I've tried other fps like 23.98, 24, 25, 29.97 and also convert to other bit depth like 8bit 16bit, seems ltcdump always shows 1 frame behind those tools. Any idea of this inconsistency?