17

I don't want to use a player like vlc to speedup the playback. I want to actually speedup playback in the original file; I want the video to be played 2 times faster.

19

mencoder has a -speed option you can use, e.g. -speed 2 to double the speed. It's described in the man page. Example:

mencoder -speed 2 -o output.avi -ovc lavc input.avi
  • 2
    To make this work I had to add -oac mp3lame – Freedom_Ben Jul 28 '14 at 2:41
  • I should add -srate 8000 too. – Soorena Nov 20 '18 at 7:11
7

After doing some research on this I found that the following command line option works well with ffmpeg:

ffmpeg -i input.mp4 -filter_complex "[0:v]setpts=0.5*PTS[v];[0:a]atempo=2[a]" -map "[v]" -map "[a]" -c:v libx264 -c:a aac output.mp4
  • First install ffmpeg.

  • setpts is for video speed (.5 means twice as fast).

  • atempo is for audio speed (2 means twice as fast).

  • The native FFmpeg AAC encoder used to be considered experimental, but this is no longer the case. If your ffmpeg is old, you will need to add -strict experimental to enable this encoder (the console output will mention this if you don't).

  • Control video quality and encoding speed with -crf and -preset as described in FFmpeg Wiki: H.264 Video Encoding Guide. Or just use the defaults if it looks acceptable to you.

  • Control audio quality with -b:a as described in FFmpeg Wiki: AAC Audio Encoding Guide.

Reference: FFmpeg Wiki: MP3 Audio Encoding Guide.

4

slowmoVideo is able to speed up and slow down video

slowmoVideo is an OpenSource program that creates slow-motion videos from your footage.

But it does not simply make your videos play at 0.01× speed. You can smoothly slow down and speed up your footage, optionally with motion blur.

How does slow motion work? slowmoVideo tries to find out where pixels move in the video (this information is called Optical Flow), and then uses this information to calculate the additional frames.

First download and install the program. When it is loaded go to File > New and select your video file.

enter image description here

With your video loaded draw you curves (by clicking on an empty area) to describe how the video should speed up and slow down.

enter image description here

When you have finished go to File > Render (Ctrl + R) and choose a directory to save your video

enter image description here

0

Kdenlive is a video editor for KDE that also can do it and even has a GUI.

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