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• Input seeking for frame at specified timestamp with Py-AV

  9 décembre 2019, par neonScarecrow

  I have a project already using Py-AV and am trying to replicate a specific ffmpeg command. The goal is to get a frame roughly around the specified timestamp.

  Here’s the ffmpeg commmand :
  https://trac.ffmpeg.org/wiki/Seeking

  ffmpeg -ss 14 -i https://some_url.mp4 -frames:v 1 frame_at_14_seconds.jpg

  Here’s my code :

      #return one frame around 14 seconds into the movie
  
      target_sec = 14 
  
      container = av.open('https://some_url.mp4', 'r')
  
      container.streams.video[0].thread_type = 'AUTO'
  
      video_stream = next(s for s in container.streams if s.type == 'video')
  
      time_base = float(video_stream.time_base)
  
      target_timestamp = int(target_sec / time_base) + video_stream.start_time
  
      video_stream.seek(target_timestamp)
  
      for frame in container.decode(video_stream):
  
          frame.to_image().save('frame_at_14_seconds.jpg')
  
          break

  Additionally, I have found any documentation about this, but does anyone know if either command (ffmpeg/av.open) is downloading the entire file to a tmp file behind the scenes. I’m looking for a less memory-intensive way to read a frame for every second in an up to 60 second video.

• Remove watermark by merging two videos

  29 septembre 2019, par LoStack

  I have actually two videos, one in high quality but with watermark and the other in poor quality without watermark. They are not synchronized.

  I would like to do something like the removelogo filter of ffmpeg but instead to simply interpolate like removelogo I would like to extract a part of a frame of the poor quality video to put it on the highest quality video with a mask to hide the watermark.

  Unfortunately the two videos are not synchronized and I would like to synchronize with the audio stream.

  Is it possible to do that with ffmpeg ?
  Thank you very much.

• Mix original clip audio with audio of an overlay clip

  28 octobre 2019, par Mr. Messy

  I have a video clip on which I want to add commentary videos (someone talking in a bubble).
  I have 3 commentary videos I need to insert in specific times.

  The video rendering is working well, but I can’t seem to add the audio tracks.
  I tried both amix and amerge, but I got the same issue.

  When I added "[0:1][2:1]amerge ;" I get the follwing :

  

  and the process freezes.

  The full ffmpeg command is as follows :

  ffmpeg -y   -i story.mp4
  
          -loop 1 -i mask.png
  
          -itsoffset 10 -i commentary1.mp4
  
          -itsoffset 22 -i commentary2.mp4
  
          -itsoffset 34 -i commentary3.mp4
  
          -filter_complex "[0:v]scale=w=1/2*in_w:h=1/2*in_h[vid1],
  
                          [2:v]crop=w=480:h=480:x=0:y=120[vid2in],
  
                              [1:v]fifo[2af],[2af]alphaextract[alf2],[vid2in][alf2]alphamerge[vid2alf],
  
                              [vid2alf]format=yuva420p,fade=in:st=10:d=0.5:alpha=1,fade=out:st=22.7294:d=0.5:alpha=1[vid2fade],
  
                              [vid2fade]scale=w=-1:h=160[vid2],
  
                              [vid1][vid2]overlay=790:10:enable='between(t\,10,21)'[out2],
  
                          [3:v]crop=w=480:h=480:x=0:y=120[vid3in],
  
                              [1:v]fifo[3af],[3af]alphaextract[alf3],[vid3in][alf3]alphamerge[vid3alf],
  
                              [vid3alf]format=yuva420p,fade=in:st=22:d=0.5:alpha=1,fade=out:st=32.768733:d=0.5:alpha=1[vid3fade],
  
                              [vid3fade]scale=w=-1:h=160[vid3],
  
                              [out2][vid3]overlay=790:10:enable='between(t\,22,33)'[out3],
  
                          [4:v]crop=w=480:h=480:x=0:y=120[vid4in],
  
                              [1:v]fifo[4af],[4af]alphaextract[alf4],[vid4in][alf4]alphamerge[vid4alf],
  
                              [vid4alf]format=yuva420p,fade=in:st=34:d=0.5:alpha=1,fade=out:st=44.598189:d=0.5:alpha=1[vid4fade],
  
                              [vid4fade]scale=w=-1:h=160[vid4],
  
                              [out3][vid4]overlay=790:10:enable='between(t\,34,45)'[out4]"
  
          -map [out4] -pix_fmt yuv420p -c:v libx264 -crf 18
  
          final_video.mp4

  (mask.png is a circle on a transparent image that crops the video to a bubble)

  Thank you for your help.