How to double video frames without any duplicate frames My video details : DV-PAL 720x576i , 25FPS , duration=20s , frames=500

I need to increase (double) the video frames without any duplicate frame.

I used the following commands to increase (double) frame rate of the video.

ffmpeg -i in.avi -r 50 out.avi
ffmpeg -i in.avi -r 50 -filter:v setpts=2*PTS out.avi


But not works properly.

Please tell me How to double video frames without any duplicate frames?

Note : tool (ffmpeg or mencoder or etc.) and the duration and speed are not matter for me, Because I want to extract frames.
(Sorry for my English)
Use

ffmpeg -i in.avi -r 50 -filter:v "setpts=0.5*PTS" out.avi


or

ffmpeg -i in.avi -r 50 -filter:v "setpts=N/50/TB" out.avi




If you want to interpolate new frames, use

ffmpeg -i in.avi -r 50 -filter:v "yadif,framerate=50" out.avi


yadif is a deinterlacing filter, which is needed since the framerate filter does not operate on interlaced media.