Answers.Body: <p>Your source is variable frame-rate with a peak rate of 120 and an average rate of close to 60. Editors tend to want constant frame rate streams. If you can interpret your whole transcoded file as 120 fps, then you should get the expected result. Alternatively, you can preserve the original variable frame rate,</p>
  
  <pre><code>ffmpeg -i test-source.mov -vsync vfr test-result.mov
  </code></pre>
  
  <p>or transcode to a constant 60 fps,</p>
  
  <pre><code>ffmpeg -i test-source.mov -r 60 test-result.mov
  </code></pre>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2018-08-01T11:54:14.877Z
Answers.Text: This definitely worked, but left me with the same questions as I had before and stated in question - is it a feature (I guess so, because it has a specific interface), what is this feature called and what it is used for. Also why the original does not observe the slow motion part, while the file processed does...
Answers.UserDisplayName: techraf
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2018-08-01T12:54:46.673Z
Answers.Text: This has more to do with Apple's AV backend rather than the file or ffmpeg. My guess is that in a VFR file, it slows down regions with higher-than-avg rate. Just a guess.
Answers.UserDisplayName: Gyan
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-04-22T14:22:06.357Z
Answers.Text: If anyone is still interested in the answer. This kind of video is created when you record it in "slow motion" (at least iPhone does this). In this mode, your camera just slows the video down after first 10% of paly time or so and then speeds it up again before the end. It looks pretty cool when you record playing fetch with your dog I suppose. I was looking for a way to get rid of it and none of these two commands did it =/
Answers.UserDisplayName: kub1x
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2018-07-29T04:56:26.007Z
Answers.LastActivityDate: 2018-07-29T04:56:26.007Z
Answers.UserDisplayName: Gyan
Body: <p><strong>Source video</strong></p>
  
  <p>I have a screencast recorded from iPad with QuickTime Player on macOS.</p>
  
  <p>When I open the original recording in QuickTime Player for playback, I can see the playback controls as below:</p>
  
  <p><a href="https://i.sstatic.net/8zpUJ.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/8zpUJ.png" alt="enter image description here"></a></p>
  
  <hr>
  
  <p><strong>Processing</strong></p>
  
  <p>I processed the video with the following command (<a href="https://pastebin.com/mDQK4RE1" rel="nofollow noreferrer">full log</a>):</p>
  
  <pre><code>ffmpeg -i test-source.mov test-result.mov
  </code></pre>
  
  <hr>
  
  <p><strong>Resulting video in QuickTime Player</strong> </p>
  
  <p>Then, when I open the result in QuickTime Player, I see the controls as below:</p>
  
  <p><a href="https://i.sstatic.net/DDPi2.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/DDPi2.png" alt="enter image description here"></a></p>
  
  <p>The part with more sparse "dots" plays in slow motion, I can drag the bars to change the start and end of this part and minimise it to zero-length (the overall length changes from 03:06 to 01:00 then and full video plays at normal speed).</p>
  
  <hr>
  
  <p><strong>Resulting video in iMovie 10</strong> </p>
  
  <p>Similarly, when add the video in iMovie with Import Media, I see "Speed"-control already applied on the source:</p>
  
  <p><a href="https://i.sstatic.net/lW6t8.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/lW6t8.png" alt="enter image description here"></a></p>
  
  <p>I can turn it off before adding to the timeline, but if I don't, the clip shows with the following decorators indicating normal speed (left and right) and slow (the middle section with the turtle):</p>
  
  <p><sup>(for this screenshot I added a black overlay to hide the video)</sup></p>
  
  <p><a href="https://i.sstatic.net/tIZqP.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/tIZqP.png" alt="enter image description here"></a></p>
  
  <p>Both the limits of the speed sections and slowdown rate differ between QuickTime Player (1 min. movie expanded to 3:06) and iMovie (expanded to 1:30).</p>
  
  <hr>
  
  <p>VLC does not notice it, plays the video at normal speed.</p>
  
  <hr>
  
  <p><strong>Questions</strong></p>
  
  <ul>
  <li><p>What is this feature called?</p></li>
  <li><p>How to avoid this slow motion part in the output of FFmpeg?</p></li>
  </ul>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2018-07-28T19:46:46.650Z
Comments.Text: Share the log of `ffmpeg -i test-source.mov -i test-result.mov`. How does the file play in other players like VLC?
Comments.UserDisplayName: Gyan
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2018-07-28T21:12:52.157Z
Comments.Text: I uploaded the log to the [pastebin](https://pastebin.com/mDQK4RE1). As I mentioned in my previous comment, VLC plays it at normal speed.
Comments.UserDisplayName: techraf
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2020-05-15T16:00:49.543Z
Comments.Text: I'm here a couple of years after you asked this, and it's perfectly answered what I was looking for.  Thanks!
Comments.UserDisplayName: benjaminbenben
Tags: <ffmpeg><quicktime>
Title: Output of FFmpeg has a "slow motion" part - what is it and how to avoid?
UserDisplayName: techraf
ThreadText: # Output of FFmpeg has a "slow motion" part - what is it and how to avoid?
  
  (Asked by: username_0 on 2018-07-28)
  
  **Source video**
  
  I have a screencast recorded from iPad with QuickTime Player on macOS.
  
  When I open the original recording in QuickTime Player for playback, I can see the playback controls as below:
  
  [![enter image description here](https://i.sstatic.net/8zpUJ.png)](https://i.sstatic.net/8zpUJ.png)
  
  ---
  
  **Processing**
  
  I processed the video with the following command ([full log](https://pastebin.com/mDQK4RE1)):
  
  ```
  ffmpeg -i test-source.mov test-result.mov
  
  ```
  
  ---
  
  **Resulting video in QuickTime Player**
  
  Then, when I open the result in QuickTime Player, I see the controls as below:
  
  [![enter image description here](https://i.sstatic.net/DDPi2.png)](https://i.sstatic.net/DDPi2.png)
  
  The part with more sparse "dots" plays in slow motion, I can drag the bars to change the start and end of this part and minimise it to zero-length (the overall length changes from 03:06 to 01:00 then and full video plays at normal speed).
  
  ---
  
  **Resulting video in iMovie 10**
  
  Similarly, when add the video in iMovie with Import Media, I see "Speed"-control already applied on the source:
  
  [![enter image description here](https://i.sstatic.net/lW6t8.png)](https://i.sstatic.net/lW6t8.png)
  
  I can turn it off before adding to the timeline, but if I don't, the clip shows with the following decorators indicating normal speed (left and right) and slow (the middle section with the turtle):
  
  (for this screenshot I added a black overlay to hide the video)
  
  [![enter image description here](https://i.sstatic.net/tIZqP.png)](https://i.sstatic.net/tIZqP.png)
  
  Both the limits of the speed sections and slowdown rate differ between QuickTime Player (1 min. movie expanded to 3:06) and iMovie (expanded to 1:30).
  
  ---
  
  VLC does not notice it, plays the video at normal speed.
  
  ---
  
  **Questions**
  
  * What is this feature called?
  * How to avoid this slow motion part in the output of FFmpeg?
  
  **Tags:** ffmpeg, quicktime
  
  > **Comments:**
  > **username_1**: Share the log of `ffmpeg -i test-source.mov -i test-result.mov`. How does the file play in other players like VLC?  
  > **username_0**: I uploaded the log to the [pastebin](https://pastebin.com/mDQK4RE1). As I mentioned in my previous comment, VLC plays it at normal speed.  
  > **username_2**: I'm here a couple of years after you asked this, and it's perfectly answered what I was looking for.  Thanks!  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_1 on 2018-07-29. Score: 3 | Accepted answer
  
  Your source is variable frame-rate with a peak rate of 120 and an average rate of close to 60. Editors tend to want constant frame rate streams. If you can interpret your whole transcoded file as 120 fps, then you should get the expected result. Alternatively, you can preserve the original variable frame rate,
  
  ```
  ffmpeg -i test-source.mov -vsync vfr test-result.mov
  
  ```
  
  or transcode to a constant 60 fps,
  
  ```
  ffmpeg -i test-source.mov -r 60 test-result.mov
  
  ```
  
  > **Comments:**
  > **username_0**: This definitely worked, but left me with the same questions as I had before and stated in question - is it a feature (I guess so, because it has a specific interface), what is this feature called and what it is used for. Also why the original does not observe the slow motion part, while the file processed does...  
  > **username_1**: This has more to do with Apple's AV backend rather than the file or ffmpeg. My guess is that in a VFR file, it slows down regions with higher-than-avg rate. Just a guess.  
  > **username_3**: If anyone is still interested in the answer. This kind of video is created when you record it in "slow motion" (at least iPhone does this). In this mode, your camera just slows the video down after first 10% of paly time or so and then speeds it up again before the end. It looks pretty cool when you record playing fetch with your dog I suppose. I was looking for a way to get rid of it and none of these two commands did it =/  
  
  ---
  
  