IMHO FFmpeg does not change speed/duration of movie. Use MEncoder with -speed option. d r wrote:

I would like to convert my video source, in lenght 07 min 40 sec frame rate 30 per second to a frame rate of 60 per second without adding new frames, that means the duration will be the half.

I did try ffmpeg -r 30 -i input_mjpg.avi -r 60 -vcodec copy -an test.avi and does not change the frame rate.

Can anybody suggest me the correct command line?

thank you D

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The frame rate of your source may be constant or variable. If frame rate of your source is constant, You can just type the following: ffmpeg -r "60" -i "input.avi" -vcodec "copy" "output.avi" Here I assume that that the input video is with the file name of “input.avi” and output video is with the file name of “output.avi”; this video does not have an audio track.Basically, frame rate as an input option will make ffmpeg ignores the original frame rate of the video and use the designated frame rate without adding or dropping frames.If the frame rate of your source is variable, the above method may work but the video may speed up or slow down intermittently due to variable nature of the frame rate. In other words, if you change the frame rate from one to another by adding/dropping frames without changing the playback speed or the length of the video, the video may be out of sync with the audio. One way of mitigating the effect of variable frame rate is to re-encode the video to constant frame rate.Say the average frame rate of the source is 30 FPS; the frame rate is variable. Lossy encoding will inevitably result in “generation loss”. To reduce the quality loss, you can use lossless encoding in the process; then choose the lossy encoding of appropriate level instead of choosing lossy encoding while editing the videos.Basically, converting video to a series of image sequence will force the frame rate to be constant. mkdir "frames" ffmpeg -i "input.avi" -r "30" "frames\f_%%1d.png" ffmpeg -r "60" -i "frames\f_%%1d.png" -vcodec "libx264" -crf "0" "output-crf0.mkv" rmdir /s /q "frames" “output-crf0.mkv” is of lossless encoding. You can choose the appropriate compression level you see fit. -- View this message in context: http://ffmpeg-users.933282.n4.nabble.com/change-frame-rate-tp939542p4660111.... Sent from the FFmpeg-users mailing list archive at Nabble.com.