<p>The above command line was copied from <a href="https://superuser.com/a/901705">FFmpeg - Apply blur over face</a> which also provides a good explanation:</p>

<blockquote>
  <p>Note: The x and y offset numbers in overlay (60 and 30 in this
  example) must match the crop offsets.</p>
  
  <p>What this example does:</p>
  
  <ul>
  <li>Crop the copy to be the size of the area to be blurred. In this example: a 200x200 pixel box that is 60 pixels to the right (x axis)
  and 30 pixels down (y axis) from the top left corner.</li>
  <li>Blur the cropped area.</li>
  <li>Overlay the blurred area using the same x and y parameters from the crop filter.</li>
  </ul>
</blockquote>

<p>So: the <code>200:200</code> is the size of the blurred area and <code>60:30</code> its position relative to the top-left corner. The input <code>v</code> is split into two streams <code>v0</code> and <code>v1</code> where <code>v0</code> is blurred and the result is named <code>fg</code>. Streams <code>v1</code> and <code>fg</code> are composed to the final stream <code>v</code>.</p>

CC BY-SA 4.0
2019-05-21T17:04:51.480Z
2019-05-21T17:04:51.480Z
Christian Lindig
<p>I searched for a FFmpeg command to blur part of a video, and found the following:</p>

<pre><code>ffmpeg -i short.mp4 -filter_complex 
       "[0:v]split=2[v0][v1]; 
        [v0]crop=200:200:60:30,boxblur=10[fg]; 
        [v1][fg]overlay=60:30[v]" -map "[v]" 
    -map 0:a -c:v libx264 -c:a copy -movflags +faststart filtered.mp4
</code></pre>

<p>(<a href="http://www.hildstrom.com/projects/cut-cat/ffmpeg_notes.txt" rel="nofollow noreferrer">cut-cat minimal video editing bash script</a>)</p>

<p>Unfortunately, I can't blur the part of the video that I want to blur. So, I took a picture with the same resolution and color so that someone may help me understand what to do, and perhaps even explain what the numbers in the code above mean or refer to.</p>

<p>Here's the picture: </p>

<p><a href="https://i.sstatic.net/fQX4a.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/fQX4a.png" alt="enter image description here"></a></p>

<p><a href="https://i.ibb.co/4fZNcgN/ask-368-X320-WHITE-BLURED.png" rel="nofollow noreferrer">https://i.ibb.co/4fZNcgN/ask-368-X320-WHITE-BLURED.png</a></p>

CC BY-SA 4.0
2019-04-28T18:45:57.103Z
Welcome! Please share your answer so that others may benefit. There is nothing wrong with answering your own question and marking it as accepted.
Michael Liebman
<ffmpeg>
Understanding an FFmpeg command (blurring a video)
newbi
# Understanding an FFmpeg command (blurring a video)

(Asked by: username_0 on 2019-04-28)

I searched for a FFmpeg command to blur part of a video, and found the following:
ffmpeg -i short.mp4 -filter_complex 
       "[0:v]split=2[v0][v1]; 
        [v0]crop=200:200:60:30,boxblur=10[fg]; 
        [v1][fg]overlay=60:30[v]" -map "[v]" 
    -map 0:a -c:v libx264 -c:a copy -movflags +faststart filtered.mp4

(cut-cat minimal video editing bash script)
Unfortunately, I can't blur the part of the video that I want to blur. So, I took a picture with the same resolution and color so that someone may help me understand what to do, and perhaps even explain what the numbers in the code above mean or refer to.
Here's the picture: 

https://i.ibb.co/4fZNcgN/ask-368-X320-WHITE-BLURED.png

**Tags:** ffmpeg

> **Comments:**
> **username_1**: Welcome! Please share your answer so that others may benefit. There is nothing wrong with answering your own question and marking it as accepted.  

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## 1 answers

### Answer by username_2 on 2019-05-21. Score: 2

The above command line was copied from [FFmpeg - Apply blur over face](https://superuser.com/a/901705) which also provides a good explanation:

> Note: The x and y offset numbers in overlay (60 and 30 in this
> example) must match the crop offsets.
>
> What this example does:
>
> * Crop the copy to be the size of the area to be blurred. In this example: a 200x200 pixel box that is 60 pixels to the right (x axis)
>   and 30 pixels down (y axis) from the top left corner.
> * Blur the cropped area.
> * Overlay the blurred area using the same x and y parameters from the crop filter.

So: the `200:200` is the size of the blurred area and `60:30` its position relative to the top-left corner. The input `v` is split into two streams `v0` and `v1` where `v0` is blurred and the result is named `fg`. Streams `v1` and `fg` are composed to the final stream `v`.


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