seek to frame

Seeking to a frame using ffmpeg ...

I knew this was a bit of a pain since I'd tried it before, but oh boy - there went my weekend. And i still don't have a 100% reliable solution. Ho hum.

Some of the issues I found with only a handful of videos I have at hand:

1. An mpeg ts which will wont seek via timestamp. Only byte seeking works.
   
2. An avi in which byte seeking never works. Only timestamp seeking does.
   
3. An avi in which the DTS increments forever - so although you can seek by timestamp to a keyframe, you cannot use it to identify specific frames thereafter.
   
4. A mov file in which byte seeking never works.
   
5. A mov file which ends with an EPIPE error rather than end of file. It must be closed and re-opened to perform any further operations.
   

I have something which mostly works now, but I suspect it will never be reliable enough.