I've captured a load of footage using the Sony Nex-5, which is in (AVCHD 1080 50i) I believe.

I've constructed a movie out of this in Sony Vegas, with background music and the preview plays flawlessly. But, whenever I render to a file on my pc choosing the options :

Save as type - Sony AVC (m2ts)

Template - AVCHD 1920x1080 50i

The resulting video plays fine for about half of it and then I get slowdowns in the video at various points and then it speeds up towards the end but is too fast! The music remains constant throughout.

Not sure what's going on here? Can anyone help me please, I've tried rendering about three times now with the same problem