XPost: alt.comp.os.windows-10, rec.photo.digital   
   From: ollie@invalid.net   
      
   After the sig is a series of video conversion commands I'm using on Windows   
   10 to fix videos uploaded to Amazon for product reviews - which are great.   
      
   But today I have a video that is too long as it's a video of how a water   
   pump will self start when the water level gets high & stop when it's low.   
      
   Meanwhile the pump goes through stages, so I had to video the entire five   
   minute process - but three or more of the five minutes are just waiting.   
      
   Rather than chop the video (which leads the reader to think it's fudged), I   
   would just like to speed it up (somehow) during the interim periods.   
      
   How do you normally go about speeding up a section of a five minute MP4?   
      
   I don't even know what the proper term to google for is but I found this:   
   https://shotstack.io/learn/ffmpeg-speed-up-video-slow-down-videos/   
      
   According to that article, this command will double the video's speed.   
   ffmpeg -i input.mp4 -filter:v "setpts=0.5*PTS" -an output.mp4   
   But I need the humming of the motor so I'll remove the audio none option.   
   ffmpeg -i input.mp4 -filter:v "setpts=0.5*PTS" output.mp4   
   But you still need to speed up the audio so they add the atempo option.   
   ffmpeg -i input.mp4 -vf "setpts=0.5*PTS" -af "atempo=2.0" output.mp4   
      
   But how do you speed up just a disjoint section or two of a video clip?   
   --   
   1. Create a copy of your MP4 (just in case)   
       C:\> copy amazon.mp4 amazon1.mp4   
      
   2. Remove metadata (spaces matter in the command below!)   
       C:\> exiftool -all= amazon1.mp4   
      
      (prolly should use ffmpeg for this step)   
      
   3. Test that the metadata was removed   
       Rightclick on the video review > Open With... > Media Info   
      
      (again, prolly should use ffmpeg)   
      
   4. Deshake the video (if needed)   
       C:\> ffmpeg -i amazon1.mp4 -vf deshake amazon2.mp4   
      
   5. Create captions if needed (assume a 68-second video below)   
       C:\> gVim amazon2.srt   
      1   
      00:00:05,000 --> 00:00:15,000   
      I think this product is crummy   
      Because it failed all my tests   
      
      2   
      00:00:20,000 --> 00:00:30,000   
      Even the cat didn't like this product   
      
      3   
      00:00:40,000 --> 00:00:50,000   
      But there was one saving grace   
      
      4   
      00:00:55,000 --> 00:00:68,000   
      The product didn't cost all that much   
      
   6. Merge captions into the file for upload to Amazon   
       C:\> ffmpeg -i amazon2.mp4 -vf subtitles=vine.srt amazon3.mp4   
      
   The result is a single stead(ier) file with burned-in captions.   
   If you can make ALL the steps using ffmpeg, that would be better.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)