[FFmpeg-user] Copied Video and Audio Way Out of Sync

[Wayne]

Here's the simple command line I'm using to copy part of an mp4 file to 
a new file.

ffmpeg -ss 6.6401 -i inFile.mp4 -to 17.6679 -c copy outFile.mp4

Since the seek position does not fall on a keyframe, the video stream of 
the copied file starts on the preceding keyframe which is OK.  However, 
the audio stream begins at the actual seek time in the command line.   
The result is a file which is way out of sync.

What am I doing wrong?  How do I make sure that the audio stream begins 
copying at the same point as the start of the video stream?

Wayne