I have a 2h multichannel-recording with two people in Mumble, where one resulting file is 3 seconds shorter than the other. In the beginning everything is ok, but after 30 minutes there were some UDP transmission problems caused by one user doing heavy uploads on his side. Right after the transmission error, the channels were heavily out-of-sync.
By looking at the source, I found some code generating silent samples when there are missing samples - but only when the silence period is larger than 100ms. Do you think that our silence period was shorter? BTW, I used WAV for recording.
Our settings are shown on the screenshots found here: