There can be several things that can interfere with Transcoding.
One of the first, available HDD space, has been ruled out, with your 800GB defragmented free-space.
Another, that gets many, is an uncovered gap in the Video. Often, the error message thrown, will be "Failed to Return Video Frame," but unfortunately, not always. This ARTICLE goes into more detail on gaps.
Another cause can be "odd" Assets, at points in the Timeline. Those usually do not yield any specific errors.
If, after a very careful search for uncovered gaps in the Video, you cannot find any, then it might be time to list the Assets on the Timeline, to see if there are any, that are unlike the other Video, or Audio Assets.
Thanks for getting back, i have gone frame by frame through the time line and i cant find any gaps.
How do i list Assets on a Timeline?
Sorry that it was not a simple gap. Those are easy to fix, though can be a pain to track down.
I'd look at the Assets in your Timeline, and then see if any are different. It could well be something like having four DV-AVI's, and then a MOV file, or perhaps having PCM/WAV Audio for most, and then one MP3 Audio file.What you are looking for here will be something that is different, and especially around the point in the Timeline, where Transcoding fails - though you indicate that the failure is not common, and that makes things tougher. If you got a failure at the same spot, and there had an odd Asset, things are much more simple.
Whole video is made out of one original file, only duplicated for bluring purposes, few key frames etc.
There is no other audio or video imported rather then original file.
OK,and thanks for that info.
I have not encountered, nor have I read of such problems.
There have been a few issues with Track Matte Keying (pointed out in older versions of PrE), but they have affected the behavior of Track Matte Keying, and not Transcoding.
I am now out of ideas, as what you describe should NOT be an issue. Maybe others can come up with some other ideas, as to why you cannot Transcode.
Good luck, and sorry that my "quick fixes" did not help,
I think i have narrowed the problem to duplicate clip.
If you delete duplicate clip and leave a mask track works ok, only problem is you ending up with white oval instead nice blured area. So i guess problem is somwhere in duplicate clip.
I have tried to get rid of track mate and mosaic leaving duplicate clip on however its failing as well.
So not really sure whats going on.