Answers.Body: <p>Use</p>
  
  <p><code>-filter_complex [0:v]trim=0:12,setpts=(PTS-STARTPTS)[sv];[0:a]atrim=0:12,asetpts=(PTS-STARTPTS)[sa];[0:v]trim=12:50,setpts=0.50*(PTS-STARTPTS)[v0];[0:a]atrim=12:50,asetpts=(PTS-STARTPTS),atempo=2.00[a0];[0:v]trim=50:57,setpts=(PTS-STARTPTS)[ev];[0:a]atrim=50:57,asetpts=(PTS-STARTPTS)[ea];[sv][sa][v0][a0][ev][ea]concat=n=3:v=1:a=1</code></p>
  
  <p>concat filter expects all inputs to start from 0, so each instance of PTS should be replaced with PTS-STARTPTS.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2019-06-11T09:54:29.027Z
Answers.LastActivityDate: 2019-06-11T09:54:29.027Z
Answers.UserDisplayName: Gyan
Body: <p>I try speed up a part of video but when completed, the output has the wrong duration video, and it contain some freeze frames. My command:</p>
  
  <pre><code>ffmpeg -i /storage/emulated/0/Screen_Recorder/ScreenRecord/Audio_VD_1560242359654.mp4 -preset ultrafast \
    -filter_complex \
       [0:v]trim=0:12,setpts=PTS[sv]; \
       [0:a]atrim=0:12,asetpts=PTS[sa]; \
       [0:v]trim=12:50,setpts=0.50*(PTS)[v0]; \
       [0:a]atrim=12:50,atempo=2.00[a0]; \
       [0:v]trim=50:57,setpts=PTS[ev]; \
       [0:a]atrim=50:57,asetpts=PTS[ea]; \
       [sv][sa][v0][a0][ev][ea]concat=n=3:v=1:a=1 \
    -profile:v baseline -c:a aac \
    /storage/emulated/0/Screen_Recorder/ScreenRecord/Speed_VD_1560242925087.mp4
  </code></pre>
  
  <p>and when I try <code>atrim</code> audio, and merge it to video if trim form more than zero frame before of video after trim can't play. How can I fix it?</p>
  
Tags: <ffmpeg><android>
Title: Speed multi part of video
UserDisplayName: van nguyen
ThreadText: # Speed multi part of video
  
  (Asked by: username_0 on 2019-06-11)
  
  I try speed up a part of video but when completed, the output has the wrong duration video, and it contain some freeze frames. My command:
  
  ```
  ffmpeg -i /storage/emulated/0/Screen_Recorder/ScreenRecord/Audio_VD_1560242359654.mp4 -preset ultrafast \
    -filter_complex \
       [0:v]trim=0:12,setpts=PTS[sv]; \
       [0:a]atrim=0:12,asetpts=PTS[sa]; \
       [0:v]trim=12:50,setpts=0.50*(PTS)[v0]; \
       [0:a]atrim=12:50,atempo=2.00[a0]; \
       [0:v]trim=50:57,setpts=PTS[ev]; \
       [0:a]atrim=50:57,asetpts=PTS[ea]; \
       [sv][sa][v0][a0][ev][ea]concat=n=3:v=1:a=1 \
    -profile:v baseline -c:a aac \
    /storage/emulated/0/Screen_Recorder/ScreenRecord/Speed_VD_1560242925087.mp4
  
  ```
  
  and when I try `atrim` audio, and merge it to video if trim form more than zero frame before of video after trim can't play. How can I fix it?
  
  **Tags:** ffmpeg, android
  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_1 on 2019-06-11. Score: 2
  
  Use
  
  `-filter_complex [0:v]trim=0:12,setpts=(PTS-STARTPTS)[sv];[0:a]atrim=0:12,asetpts=(PTS-STARTPTS)[sa];[0:v]trim=12:50,setpts=0.50*(PTS-STARTPTS)[v0];[0:a]atrim=12:50,asetpts=(PTS-STARTPTS),atempo=2.00[a0];[0:v]trim=50:57,setpts=(PTS-STARTPTS)[ev];[0:a]atrim=50:57,asetpts=(PTS-STARTPTS)[ea];[sv][sa][v0][a0][ev][ea]concat=n=3:v=1:a=1`
  
  concat filter expects all inputs to start from 0, so each instance of PTS should be replaced with PTS-STARTPTS.
  
  
  ---
  
  