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I need a software which can blur a scene from a video file. I have thought about VirtualDub and Adobe Premiere but I am not sure if they provide the desired functionality.

My requirement is to blur a some-seconds scene for example blur the scene from 10:12 to 10:45 in a video file.

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3 Answers

You can use ffmpeg, and you currently have a choice of four video filters that can blur: boxblur, sab, smartblur and unsharp. These filters have timeline support, so you can blur just a certain duration or durations if desired.

Example

original image boxblur

ffmpeg -i input.avi -vf "boxblur=enable='between(t,22,113)',boxblur=enable='between(t,(60*4)+35,286)" -codec:a copy output.avi
  • You can enter seconds or have it calculate seconds for you as shown in the example.

  • Expression evaluation is not my best area. You may find a method to declare the filter just once.

  • Note that, since you only want to modify the video, the audio can be copied from the input to the output without re-encoding. This is faster than re-encoding and will preserve the quality.

Preview

If you have ffplay you can get a preview instead of encoding, watching, re-encoding...

ffplay -i input -vf smartblur

Getting ffmpeg

Most Windows users will simply want to visit Zeranoe FFmpeg Windows builds, but of course you can always compile ffmpeg too.

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Premiere can certainly do what you need. You could either cut the clip into sub-clips and apply a blur filter or you could apply a filter and keyframe the level of blur. Note that this would be if you are trying to blur the entire frame. If you want to blur only a portion of the frame, you would probably want something like motion tracking in After Effects that could follow the thing you want to blur and limit the blur to only the area impacted by a mask that follows the motion.

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I want to blur the entire screen, not just a single object. Is it possible –  user1451111 Jul 1 '13 at 8:29
    
@user1451111 - yes, then just use the filter in Premiere like I suggested. I was just mentioning that if you wanted to be more targeted than the whole frame, it would need more advanced software. Blurring the whole frame is trivial. –  AJ Henderson Jul 1 '13 at 13:25
    
Let's say I have a 5 minute video and I want to blur the following two segments within it. 00:00:22 - 00:01:53 and 00:04:35 - 00:04:46 How to proceed? –  user1451111 Jul 2 '13 at 8:42
    
You can either break them in to two subclips using the razor tool (looks like a little razor blade) and apply filters to each of the subclips you want to blur or you can apply blur to the whole thing and then use keyframes on the parameters of the effect to adjust the amount of blur to be 0 during the time you don't want blur. –  AJ Henderson Jul 2 '13 at 13:34
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up vote 0 down vote accepted

I fulfilled my requirement by following the below procedure.

1- Load the complete video in Timeline panel.

2- Using 'Razor' tool cut the section which I need to blur. When we cut using 'Razor' tool, Adobe Premiere Pro marks it as a logical separate clip.

3- Drag the Video-->Blur effect on the desired clip and set the Gaussian blur settings.

4- Repeat the above steps for all other sections of the original video which I need to blur.

5- In the end, Export the complete sequence.

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