Ok, so I'm new to this site but I have read many of the audio drifting problems already addressed and none of the symptoms completely match my issue. This is a video system for a church...I HAD 3 cameras (just video) going into an Ederol switcher at 1080p and being scaled to 720 60fps...coming out of the switcher and going into a Black Magic ProRecorder H.264 and being recorded onto a PC...The audio from our FOH mixer goes through a 2nd mixer and then out to our A/V distributor and to the Black Magic ProRecorder. Everything (post production wise) worked fine.
We had some compatibility issues with the signal being 720 going to a couple of our overflow rooms over our distribution system so we finally decided (with the help of some consultants) to change everything over to 1024x768 @60hz RGB. We had to get a Kramer VP-420 scaler to go between the switcher and the ProRecorder (converting from RGB to 720). With that everything works fine and the A/V in QuickTime is synced (it may be off by a couple frames but its consistently off) however when I bring it into FCP 6 it is out of sync and drifting with the audio ahead of the video. The first 3 minutes its just slides and background music so i cant compare it, but at about 3 minutes the audio is maybe 10-15 frames ahead and at 30 minutes its almost 3 seconds ahead.
Again the only change we have made that could contribute to this is adding the scaler and changing the output from the Ederol switcher. I haven't messed with any other settings yet because honestly I wouldn't know where to start.
The file info mac pulls up says that its an MPEG-4 Dimensions:180x720; Codecs:H.264,AAC,Timecode; Audio Chanels:2; Total Bit Rate:5,751