Answers.Body: <p>Documentation for ffmpeg is at <a href="http://www.ffmpeg.org/documentation.html" rel="nofollow noreferrer">http://www.ffmpeg.org/documentation.html</a></p>
  <p><code>scale</code> here refers to the scale filter, whose documentation is at <a href="http://www.ffmpeg.org/ffmpeg-filters.html#scale-1" rel="nofollow noreferrer">http://www.ffmpeg.org/ffmpeg-filters.html#scale-1</a></p>
  <p>The list of variables available in this filter is listed at the bottom of the <a href="http://www.ffmpeg.org/ffmpeg-filters.html#Options-1" rel="nofollow noreferrer">Options</a> section.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-06-14T09:58:24.190Z
Answers.Text: I did try the documentation, but it was difficult to find the values. Are the values for scaling the only variables of this kind?  I was hoping for one that would give the frame rate of the video being read, or the bit rates of the video and audio of the file being read.
Answers.UserDisplayName: Bart Lederman
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-06-14T14:59:33.100Z
Answers.Text: The variables available in a filter are specific to it. By convention, filters will use similar names for a parameter. But you need to consult an filter's doc for that info.
Answers.UserDisplayName: Gyan
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-06-13T17:37:34.787Z
Answers.LastActivityDate: 2021-06-13T17:37:34.787Z
Answers.UserDisplayName: Gyan
Body: <p>There is an article that says you can scale a video to be a multiple or fraction of the input size like this:</p>
  <pre><code>-vf &quot;scale=iw/2:ih/2&quot; to scale by half
  </code></pre>
  <p>Are there any other symbols for input variables in addition to <code>iw</code> and <code>ih</code>?</p>
  <p>I've done multiple web searches and forum searches and I can't find anything that says what list of input values there are that are like <code>ih</code> and <code>iw</code>.</p>
  <p>Thanks.</p>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-06-16T08:16:17.423Z
Comments.Text: Welcome to Video Production! [What should I do when someone answers my question?](https://video.stackexchange.com/help/someone-answers)
Comments.UserDisplayName: MarianD
Tags: <ffmpeg>
Title: Is there a list of input variables?
UserDisplayName: Bart Lederman
ThreadText: # Is there a list of input variables?
  
  (Asked by: username_0 on 2021-06-13)
  
  There is an article that says you can scale a video to be a multiple or fraction of the input size like this:
  
  ```
  -vf "scale=iw/2:ih/2" to scale by half
  
  ```
  
  Are there any other symbols for input variables in addition to `iw` and `ih`?
  
  I've done multiple web searches and forum searches and I can't find anything that says what list of input values there are that are like `ih` and `iw`.
  
  Thanks.
  
  **Tags:** ffmpeg
  
  > **Comments:**
  > **username_1**: Welcome to Video Production! [What should I do when someone answers my question?](https://video.stackexchange.com/help/someone-answers)  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_2 on 2021-06-13. Score: 1
  
  Documentation for ffmpeg is at <http://www.ffmpeg.org/documentation.html>
  
  `scale` here refers to the scale filter, whose documentation is at <http://www.ffmpeg.org/ffmpeg-filters.html#scale-1>
  
  The list of variables available in this filter is listed at the bottom of the [Options](http://www.ffmpeg.org/ffmpeg-filters.html#Options-1) section.
  
  > **Comments:**
  > **username_0**: I did try the documentation, but it was difficult to find the values. Are the values for scaling the only variables of this kind?  I was hoping for one that would give the frame rate of the video being read, or the bit rates of the video and audio of the file being read.  
  > **username_2**: The variables available in a filter are specific to it. By convention, filters will use similar names for a parameter. But you need to consult an filter's doc for that info.  
  
  ---
  
  