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• Video play in slow motion while converting webm file to mp4 using ffmpeg

  14 novembre 2019, par Hardik Kothari

  I am using ffmpeg-static-electron in electron app for converting webm file to mp4 and that file will be play in mobile app as android and ios.

  Here I am using ffmpeg command for converting webm file to mp4.

    await execa(ffmpegPath, [
  
        '-i',
  
        inputPath,
  
        '-f',
  
        'mp4',
  
        '-vcodec','libx264', // video codec
  
        '-acodec','aac', // audio codec
  
        '-b:v', '6400k',  // video bitrate
  
        '-b:a', '4800k',  // audio bitrate
  
        '-strict', 'experimental', // standard
  
        '-r',
  
        '30000/1001',
  
        '-crf',
  
        '26',
  
        '-g',
  
        '16',
  
        '-movflags',
  
        'faststart',
  
        '-preset',
  
        'veryfast',
  
        outputPath,
  
      ])

  I used ’-g’ to 16 for solving a dragging progress issue in android player but it increasing the app size.
  Here you can check it out this https://video.stackexchange.com/questions/21892/why-cant-my-video-play-from-where-i-drag-the-playback-bar

  Some time It is working fine but some time sound coming through garbled and sounded like robot with slow-motion video
  Here is log file for normal video :https://textuploader.com/1o1ml

  I want a best conversion (WebM to Mp4) with lower file size.Anyone please help.

• iPhone slow motion video transcode

  28 septembre 2019, par coverboy

  I’m developing upload video (taken from iPhone) to my server.

  However, I have no idea how to implement.

  Any source code objective-c or swift will be welcomed.

  I have 120fps or 240fps video (It’s a slo-mo).
  When I playback these video on my iPhone6. I can see slo-mo effect.
  (I know playback frame rate is 30fps.)

  I want to convert that video before upload to my server, from 120/240 fps to 30fps video. (I mean not adjusting playback frame rate, it means video transcode to 30fps.)
  Additionally, I want to check slo-mo effect start-point and end-point.
  (Maybe iPhone record this information to video binary(it might be reside in file’s header.)

  Well, I guess if I use ffmpeg library, it should be easy(?).

  So any suggestions will be welcomed.

• FFMPEG - speed up/slow down video, add jitter etc

  27 septembre 2019, par Darrell

  I’m trying to put together a Windows script that will process short videos in a folder.
  The videos will be shot at a high frame rate 60+ fps and be about 4-5 secs long.

  Basically I am looking to make various style clips, using fast/slow effects, back and forth etc.
  So, the script might process a video, make it start normal speed, then slow motion. Next video might be normal speed, slomo, normal speed slomo. Next video might be forwards,back, forwards back, slomo.

  See example : (this is a compliation, I’m looking at processing individual videos in a folder.)

  http://www.youtube.com/watch?v=K03IBQZu8SQ

  I’m guessing there is no way to do this, other than splitting a clip using FFMPEG, processing the bits, then merging back together ? I can’t seem to find a way to do it as one clip.