Answers.Body: <p>Commands allow you to change the parameters <em>during</em> execution of the command. This is primarily useful when working with streaming media e.g. if the volume gets too loud during a broadcast, send a command to the volume filter to lower it.</p>
  
  <p>To issue commands to filters which support it from outside, ffmpeg has to be compiled with libzmq support. See the <a href="https://ffmpeg.org/ffmpeg-filters.html#zmq_002c-azmq" rel="nofollow noreferrer">docs</a> for the zmq filter for details.</p>
  
  <p>To issue commands from the terminal, press <kbd>c</kbd></p>
  
  <p>The 'command prompt' will be shown :</p>
  
  <pre><code>Enter command: &lt;target&gt;|all &lt;time&gt;|-1 &lt;command&gt;[ &lt;argument&gt;]
  </code></pre>
  
  <p>Enter a command as per the given format and press <kbd>Enter</kbd>.</p>
  
  <p>e.g. <code>overlay@logo -1 x 100</code></p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2017-04-27T08:12:12.640Z
Answers.Text: Thank you very much, I intensively searched for it without a success.
Answers.UserDisplayName: MarianD
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2017-04-27T07:45:29.893Z
Answers.LastActivityDate: 2018-11-18T15:09:51.117Z
Answers.LastEditDate: 2018-11-18T15:09:51.117Z
Answers.UserDisplayName: Gyan
Body: <p>In the <a href="http://ffmpeg.org/ffmpeg-filters.html" rel="nofollow noreferrer">FFmpeg Filters Documentation</a> some filters have a subsection "Commands" which begins with the sentence</p>
  
  <blockquote>
    <p>This filter supports the following commands:</p>
  </blockquote>
  
  <p>e. g. in the section <a href="http://ffmpeg.org/ffmpeg-filters.html#volume" rel="nofollow noreferrer">6.68 volume</a>.</p>
  
  <p>Filters have <em>parameters</em>; it is understandable. But what is the meaning of filter <em>commands</em> and how and when are they used?</p>
  
Tags: <ffmpeg>
Title: What does it mean "This filter supports the following commands"?
UserDisplayName: MarianD
ThreadText: # What does it mean "This filter supports the following commands"?
  
  (Asked by: username_0 on 2017-04-27)
  
  In the [FFmpeg Filters Documentation](http://ffmpeg.org/ffmpeg-filters.html) some filters have a subsection "Commands" which begins with the sentence
  
  > This filter supports the following commands:
  
  e. g. in the section [6.68 volume](http://ffmpeg.org/ffmpeg-filters.html#volume).
  
  Filters have *parameters*; it is understandable. But what is the meaning of filter *commands* and how and when are they used?
  
  **Tags:** ffmpeg
  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_1 on 2017-04-27. Score: 3 | Accepted answer
  
  Commands allow you to change the parameters *during* execution of the command. This is primarily useful when working with streaming media e.g. if the volume gets too loud during a broadcast, send a command to the volume filter to lower it.
  
  To issue commands to filters which support it from outside, ffmpeg has to be compiled with libzmq support. See the [docs](https://ffmpeg.org/ffmpeg-filters.html#zmq_002c-azmq) for the zmq filter for details.
  
  To issue commands from the terminal, press `c`
  
  The 'command prompt' will be shown :
  
  ```
  Enter command: <target>|all <time>|-1 <command>[ <argument>]
  
  ```
  
  Enter a command as per the given format and press `Enter`.
  
  e.g. `overlay@logo -1 x 100`
  
  > **Comments:**
  > **username_0**: Thank you very much, I intensively searched for it without a success.  
  
  ---
  
  