Answers.Body: <p>You can use <a href="https://ffmpeg.org/download.html" rel="nofollow">ffmpeg</a>, a free command-line tool, to do this:</p>
  
  <pre><code>ffmpeg -i in.mp4 -vf "select=not(mod(n\,30)),setpts=N/FRAME_RATE/TB" -r 30 out.mp4
  </code></pre>
  
  <p><code>-vf</code> specifies a video filterchain i.e. a sequence of filters applied to a single input.</p>
  
  <p><code>select=not(mod(n\,30))</code> - this filter keeps only each 30th frame from the source.</p>
  
  <p>FFmpeg works primarily within the framework of time-based containers, such as a video, which is a series of images shown in a cycle through time. The PTS is the presentation timestamp of a frame i.e. when the player should present a frame. Due to how ffmpeg works, <code>setpts</code> filter is needed in this case to ensure that no frames are duplicated or dropped other than what the select filter specifies. </p>
  
  <p><code>-r 30</code> is the framerate of the output. To set it to the rate of the source, you can either skip this parameter or set it manually i.e. <code>-r 60</code> for a 60 fps source.</p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2016-05-04T07:31:09.470Z
Answers.LastActivityDate: 2016-05-04T07:31:09.470Z
Answers.UserDisplayName: Gyan
Body: <p>I need to find a way to cut down on the total number of frames in a video I'm editing. Essentially, if it was shot in 60 fps, I'd like to choose to only keep every 20th or 30th frame.</p>
  
  <p>The only programs I have available are Windows MovieMaker and any freeware available. I have a video that is too detailed for the analysis program I'm using which is why I need to be able to keep only every 30th frame.</p>
  
Tags: <framerate><windows-movie-maker>
Title: Decimating files in Moviemaker
UserDisplayName: bizmiard
ThreadText: # Decimating files in Moviemaker
  
  (Asked by: username_0 on 2016-05-04)
  
  I need to find a way to cut down on the total number of frames in a video I'm editing. Essentially, if it was shot in 60 fps, I'd like to choose to only keep every 20th or 30th frame.
  
  The only programs I have available are Windows MovieMaker and any freeware available. I have a video that is too detailed for the analysis program I'm using which is why I need to be able to keep only every 30th frame.
  
  **Tags:** framerate, windows-movie-maker
  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_1 on 2016-05-04. Score: 1
  
  You can use [ffmpeg](https://ffmpeg.org/download.html), a free command-line tool, to do this:
  
  ```
  ffmpeg -i in.mp4 -vf "select=not(mod(n\,30)),setpts=N/FRAME_RATE/TB" -r 30 out.mp4
  
  ```
  
  `-vf` specifies a video filterchain i.e. a sequence of filters applied to a single input.
  
  `select=not(mod(n\,30))` - this filter keeps only each 30th frame from the source.
  
  FFmpeg works primarily within the framework of time-based containers, such as a video, which is a series of images shown in a cycle through time. The PTS is the presentation timestamp of a frame i.e. when the player should present a frame. Due to how ffmpeg works, `setpts` filter is needed in this case to ensure that no frames are duplicated or dropped other than what the select filter specifies.
  
  `-r 30` is the framerate of the output. To set it to the rate of the source, you can either skip this parameter or set it manually i.e. `-r 60` for a 60 fps source.
  
  
  ---
  
  