Slow motion with ffmpeg?

[charlesdavison]

Is this possible to do? I started some tests by playing with the -r framerate option but it hasn't actually slowed the video.

I'd like to be able to do 1/2x and 1/4x slow motion, and possible 2x speed too. Any ideas?

[Case]

The "ffmpeg -r <rate>" option will set the target framerate, but keeps the duration. So it adds frames or removes frames, but does not speed up or slow down the video. Similar for mencoder "-ofps".

Mencoder has a "-speed" option that you may want to play with. "-speed 1" is realtime. Try 0.5 and 2 for testing. Not in the GUI, so you'll have to go command line. But that doesn't seem to be a problem, as you talk about command line options already.

[SpectateSwamp]

Here's how the slow motion feature works for GOLF - It works just as well for Football and other action sports.

The initial plan was to shoot video of each golfer from behind and across; then play these short (4 to 6 secs) videos in SLO-MO and NORMAL speed before the awards luncheon started.

This was ACCOMPLISHED and the 180+ videos were playing on a large screen within 10 minutes of leaving the course. The only PROBLEMS were: that a few golf swings took far more time than others (10 to 15 secs) and when played back in slow motion; the audience would lose interest. As well; in attempting to capture just the "golf swing" we missed some completely.

The SOLUTION was a program fix that allowed for just the FINAL 3 secs of video (the swing) to be played in slow motion. With this change; we can start recording when the golfer addressed the ball and shut it off on completion of the swing. No more missed swings or bored viewers.

Now they see each video clip followed by the final 3 seconds in Slo-Mo, as a screen saver.

One FINAL problem: After the meal there was a silent auction. Golfers wanted to see their swing (2 clips out of nearly 200). Again the solution comes from the record on/off button. To achieve this and not lose any time by having to manually edit the catalog text file. An extremely short video clip is created (as each group comes to the T) of a white-board with the golfers name and flight#. The software uses these small files as break point indicators in the catalog file. The golfer identifies which group they were in, from the tournament sheet and we play that foursome's videos. Upon viewing those videos we determine the golfers sequence # and select it (ie "Grp#12" "Seq#3"). Their videos from camcorder #1 then camcorder #2 play over and over again.

The 180+ videos fit on 2 GigaByte USB sticks. These sticks can be quickly loaded with the videos & software before the golfers leave. They just LOVED the immediacy.

http://www.telusplanet.net/public/stonedan/osoyoos_golf.htm

SEE the above link; for video clips from those 2 tournaments. 20 of the 360+ videos are being switched out daily.

This method is extremely easy; because NO EDITING is required. Just off-load the MPEG video from the 2 camcorders (5 to 10 mins). Catalog the video to play normal speed and Slo-mo (mere seconds). Then start the replay. VERY timely. All golfers from the rank amateur to the seasoned pro; want to see golf swings in Slo-Mo. Having hundreds of dual-speed golf swings playing randomly on the clubhouse screen is far more interesting to the patrons.