OK, so I built an Arduino DUE audio IO shield so I can try LIBLTC with a little more horsepower!
I took a differnt aproach this time and used I2S audio IO with the MIKROE-506 codec shield.
I managed to get the Codec connected with this arduino Due I2S library
At the moment the audio is commig in at 48khz 32bit and passthrough is working.
I just found a void ltc_decoder_write_s16 wrapper that accepts 16bit samples, so I'll try that first and report back here with code and wiring diagram if I get this working. I think even Iif I get timcode decoding working it will take longer to make the generator work.
Stay tuned :)