[Gettting Started with FFEncoder]
0. create instance
   add FFEncoder component to the form of your applcation, or you can create it in run-time. We name the instance as FFEncoder for presentation.
1. load libraries
   FFEncoder.LoadAVLib('libraries path')
   failed if return False
2. add a task with options just like ffmpeg cmd line
   TaskIndex := FFEncoder.AddTask([options] [[infile options] -i infile]... {[outfile options] outfile}...)
   failed if TaskIndex < 0
3. add event handler of OnProgress
   add progress information showing code
4. add event handler of OnTerminate
   add termination controlling code
5. if you need the log message, please add a FFLogger component
   add the log message showing code in OnLog event
6. start transcoding
   FFEncoder.Start(1)
7. wait for done
