[mythtvnz] Recordings without audio

[Austin Green]

Occasionally shows are recorded without any sound. Others on the same channel are fine. E.g.: TV3, recording 'Graham Norton' and (immediately following) '7 Days' - the first is OK, the second silent. I have two tuner cards; perhaps MythTV switches from one to the other between shows? The 'silent' problem only happens infrequently, maybe one show per month, so if it was a faulty tuner, I would expect to see it a lot more often. Anyone have any ideas?