Hi, I want to ask a question about delay frames operation

Hi.

I add dxva2 to decode wmv3 in ffmpeg.exe.In order to increase the speed.I
use 4 surfaces to delay the frame.It means that when the first three
frames,I just decode and return,When decode the forth frame,I got the first
frame from d3d sruface,then encode,So there will be always three decoded
frames in d3d surface.But there is a question.When the decode-encode flow
finished,there will be still three frames in d3d surface.

How can I make ffmpeg to decode the last three frames? I found it is very
complex to modify the primary process.The version I use is
FFmpeg 0.11.1

Thanks