Answers.Body: <p>It's a <em>warning,</em> not an error (if it would be an error, FFmpeg would abort).</p>
  
  <p>“Non-monotonous DTS” means that the DTS (Display Time Stamp) of some frame <em>is less than</em> the DTS of the <em>previous frame.</em> </p>
  
  <p>This situation may cause many problems (with playback, seeking, etc.), so 
  FFmpeg fixes timestamps by rewriting some of them.</p>
  
  <p>Here are your 3 warning messages: </p>
  
  <blockquote>
  <pre><code>[...] Non-monotonous DTS ... ; previous: 86, current: 73; changing to 87. This may ...
  [...] Non-monotonous DTS ... ; previous: 87, current: 74; changing to 88. This may ...
  [...] Non-monotonous DTS ... ; previous: 88, current: 75; changing to 89. This may ...
  </code></pre>
  </blockquote>
  
  <p>in a graphical form:
  <a href="https://i.sstatic.net/2yRyS.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/2yRyS.jpg" alt="enter image description here"></a></p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2019-09-07T20:52:11.467Z
Answers.LastActivityDate: 2019-09-14T23:46:13.523Z
Answers.LastEditDate: 2019-09-14T23:46:13.523Z
Answers.UserDisplayName: MarianD
Body: <p>I'm trying to record segments using a webcam and save these segments with a lower fps. I've tried this command, but it keeps giving me an error:</p>
  
  <pre><code>ffmpeg -f v4l2 -input_format mjpeg -video_size 800x600 -i /dev/video0 -c:v copy -c:a copy -f segment -segment_time 10 -reset_timestamps 1 -r 10 -strict -2 test_%04d.avi
  </code></pre>
  
  <p>The errors I get is:</p>
  
  <pre><code>[segment @ 0x15bf0e0] Non-monotonous DTS in output stream 0:0; previous: 86, current: 73; changing to 87. This may result in incorrect timestamps in the output file.
  [segment @ 0x15bf0e0] Non-monotonous DTS in output stream 0:0; previous: 87, current: 74; changing to 88. This may result in incorrect timestamps in the output file.
  [segment @ 0x15bf0e0] Non-monotonous DTS in output stream 0:0; previous: 88, current: 75; changing to 89. This may result in incorrect timestamps in the output file.
  </code></pre>
  
  <p>Anyone know how to do it right?</p>
  
Tags: <ffmpeg>
Title: How to change frame rate of MJPEG segments with/without re-encoding?
UserDisplayName: John M.
ThreadText: # How to change frame rate of MJPEG segments with/without re-encoding?
  
  (Asked by: username_0 on 2019-09-07)
  
  I'm trying to record segments using a webcam and save these segments with a lower fps. I've tried this command, but it keeps giving me an error:
  
  ```
  ffmpeg -f v4l2 -input_format mjpeg -video_size 800x600 -i /dev/video0 -c:v copy -c:a copy -f segment -segment_time 10 -reset_timestamps 1 -r 10 -strict -2 test_%04d.avi
  
  ```
  
  The errors I get is:
  
  ```
  [segment @ 0x15bf0e0] Non-monotonous DTS in output stream 0:0; previous: 86, current: 73; changing to 87. This may result in incorrect timestamps in the output file.
  [segment @ 0x15bf0e0] Non-monotonous DTS in output stream 0:0; previous: 87, current: 74; changing to 88. This may result in incorrect timestamps in the output file.
  [segment @ 0x15bf0e0] Non-monotonous DTS in output stream 0:0; previous: 88, current: 75; changing to 89. This may result in incorrect timestamps in the output file.
  
  ```
  
  Anyone know how to do it right?
  
  **Tags:** ffmpeg
  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_1 on 2019-09-07. Score: 2
  
  It's a *warning,* not an error (if it would be an error, FFmpeg would abort).
  
  “Non-monotonous DTS” means that the DTS (Display Time Stamp) of some frame *is less than* the DTS of the *previous frame.*
  
  This situation may cause many problems (with playback, seeking, etc.), so
  FFmpeg fixes timestamps by rewriting some of them.
  
  Here are your 3 warning messages:
  
  > ```
  > [...] Non-monotonous DTS ... ; previous: 86, current: 73; changing to 87. This may ...
  > [...] Non-monotonous DTS ... ; previous: 87, current: 74; changing to 88. This may ...
  > [...] Non-monotonous DTS ... ; previous: 88, current: 75; changing to 89. This may ...
  >
  > ```
  
  in a graphical form:
  [![enter image description here](https://i.sstatic.net/2yRyS.jpg)](https://i.sstatic.net/2yRyS.jpg)
  
  
  ---
  
  