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• Overlay Image on moving object in Video (Argumented Reality / OpenCv)

  30 juillet 2017, par Karandeep Atwal

  I am using FFmpeg to overlay image/emoji on video by this command -

  "-i "+inputfilePath+" -filter_complex "+"[0][1]overlay=enable='between(t,"+startTime+","+endTime+")'[v1]"+" -map [v0] -map 0:a "+OutputfilePath;  

  But above command only overlay image over video and stays still.

  In Instagram and Snapchat there is New pin feature. I want exactly same ,eg blur on moving faces or as in below videos -

  

  Here is link.

  Is it possible via FFmpeg ?

  I think someone with OPENCV or Argumented Reality knowledge can help in this. It is quiet similar to AR as we need to move/zoom emoji exactly where we want to on video/live cam.

• Is there a Heroku-supported method for getting the length of an audio file in seconds ?

  12 juillet 2013, par Ben West

  I'm trying to implement

  http://blog.firmhouse.com/validate-length-of-an-audio-file-when-using-paperclip-and-s3

  But I'm unsure what gem provided FFMpegWrapper, and I'd like to use Heroku to deploy my app for testing. Does heroku support something that will work for this ?

  full Rails Application source :

  https://github.com/mrgenixus/sound-byte

  Relevant Model :

  https://github.com/mrgenixus/sound-byte/blob/master/app/models/episode.rb

• ffmpeg - less frames getting extracted than expected

  20 juin 2021, par Vrajesh Doshi

  


  ffmpeg -i instagram.mp4 -vf fps=29.97 thumb%06d.jpg -hide_banner

  
 


  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'instagram.mp4' : Metadata :
 major_brand : isom
 minor_version : 512
 compatible_brands : isomiso2avc1mp41
 encoder : Lavf55.19.104 Duration : 00:00:13.61, start : 0.000000, bitrate : 1163 kb/s
 Stream #0:0(und) : Video : h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p, 640x640 [SAR 1:1 DAR 1:1], 1099 kb/s, 29.97 fps,
 29.97 tbr, 11988 tbn, 59.94 tbc (default)
 Metadata :
 handler_name : VideoHandler
 Stream #0:1(und) : Audio : aac (LC) (mp4a / 0x6134706D), 44100 Hz, mono, fltp, 64 kb/s (default)
 Metadata :
 handler_name : SoundHandler Stream mapping : Stream #0:0 -> #0:0 (h264 (native) -> mjpeg (native)) Press [q] to stop, [?] for help [swscaler @ 0x55b2b53cf440] deprecated pixel format used, make sure
 you did set range correctly Output #0, image2, to 'thumb%06d.jpg' :
  
 Metadata :
 major_brand : isom
 minor_version : 512
 compatible_brands : isomiso2avc1mp41
 encoder : Lavf57.83.100
 Stream #0:0(und) : Video : mjpeg, yuvj420p(pc), 640x640 [SAR 1:1 DAR 1:1], q=2-31, 200 kb/s, 29.97 fps, 29.97 tbn, 29.97 tbc (default)
 Metadata :
 handler_name : VideoHandler
 encoder : Lavc57.107.100 mjpeg
 Side data :
 cpb : bitrate max/min/avg : 0/0/200000 buffer size : 0 vbv_delay : -1 frame= 405 fps=231 q=24.8 Lsize=N/A time=00:00:13.51 bitrate=N/A speed=7.72x video:5961kB audio:0kB subtitle:0kB other streams:0kB
 global headers:0kB muxing overhead : unknown

  


  



  The video duration is 13.61 seconds and frame rate is 29.97. So I was expecting 13.61 * 29.97 = 407.8917 i.e. 407 frames. But have got 405 frames. I am new to ffmpeg, need help to correctly get all 407 frames.

  



  I had also tried following command,

  



  ffmpeg -i instagram.mp4 thumb%06d.jpg -hide_banner


  



  but the output was same 405 frames.

  



  Possibly the start 2 frames are missing.

  



  I need to display the frames generated in the base video timeline. And on clicking on the frame I need to exactly seek the video to the frame position using HTML5 currentTime. Since the first 2 frames are not getting available, exact mapping is not getting possible.

  



  Please guide.