Evaluate accuracy of per buffer timestamps

[Era-Dorta]

The accuracy of the method to generate timestamps in #18 has not been tested. See discussion in #18 (comment), we need to check whether the buffers are released when we think they are and just check if the timestamps make sense.

To test this a good approach is to play an LTC signal on a speaker, record it with the midge, decode it and compare the time stamps.