It is possible to decode SMPTE using a 8051 many low cost SMPTE to MIDI timcode units do this. is it done by using a timer to determin the long and short pulse widths in SMPTE, ie a pulse width of less than 2/3 of the previous pulse is considered a long to short tansition a pulse of greater than 3/2 of the previous pulse is coniderd a short to long transition, you need to read the SMPTE spec to understand this but I hope this gives a pointer to making a decoder which handles varible playback speed. Some time ago (and for a different employer) I wanted to implement a decoder in 8051 but it was against comapny poilcy to use distributed micro,s but I acolu use as many PLD's as I liked