We demonstrate a characterisation of short optical pulses using dual comb spectroscopy where one comb is a well characterized, stable frequency comb and the second is the pulse source to be measured. This technique enables to extract the amplitude and phase of any pulse and is tested with relatively long (80 ps) pulses generated by an active mode locked semiconductor laser as well as with a fiber laser emitting 2 ps wide pulses. The method is generalized for weak pulses with arbitrary repetition rates. The limitations due to the fluctuation of the carrier envelope offset and the repetition rate, are addressed and are overcome by implementing non-uniform sampling of measured inferferograms by computational means.