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• Inconsistent Rotation of Output Video OpenCV

  27 avril 2021, par user530316

  I am reading in mobile videos shot on an iphone (.MOV format). When the video is shot upright, ffmpeg meta data states the video frames are rotated 90 clockwise. When I read the video in with opencv as a .MOV and then outwrite again with opencv as a .mp4, both the input and output videos appear upright. Note I display the video frames using opencv via a while loop :
 cap = cv2.VideoCapture("video.MOV")

  


  ret,frame=cap.read()

  


  while ret:
    cv2.imshow('',frame)
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break
    ret,frame = cap.read()
cap.release()
cv2.destroyAllWindows() 


  


  This is not the problem. The problem is that when the same video is run on another machine with the same os and same virtual environment, the videos come out rotated by 90 degrees. Any reason this should happen ?

  


  Both machines are using opencv-python version 4.5.1, ffmpeg 4.2.2, and ffmpeg-python 0.2.0.

  


• FFmpeg - Transcode video and keep original EXIF metadata in the transcoded file ?

  10 mai 2015, par Paulo

  I am trying to transcode a video from a .mov (recorded with the iPhone) and add the original metadata to transcoded file, how can I achieve that ?

  Here is what I have tried but it does not add the metadata :

  ffmpeg -i input.mov -map 0 -vcodec libx264 -preset superfast -acodec libfaac output.mp4
  
  
  
  ffmpeg -i input.mov -map_metadata 0  -vcodec libx264 -preset superfast -acodec libfaac output.mp4

  I have also tried to transcode to webm but it also does not have the metadata, what am I doing wrong or how can I achieve that with ffmpeg ?

• FFmpeg encoding slow for 4K HDR content

  1er mars 2023, par Geno Diaz

  When processing 4K input with the following configuration it is taking upwards of 2 minutes to process a 35s, 60fps, 4K HDR clip recorded from an iPhone. Is this the expected performance or is there an inefficiency within the configuration that is causing this ?

  


  In comparison, running this configuration on a 35s, 30fps, 4K non-HDR clip, only takes about 20 seconds.

  


  ffmpeg 
-i "input path" 
-y 
-filter:v scale=w=2160:h=3840 
-threads 4 
-r 59.94 
-c:v libx264 
-preset veryfast 
-vsync 1 
-tune film 
-maxrate 6000k 
-bufsize 5400k 
-g 60 
-x264opts no-scenecut 
-c:a aac 
-af aresample=async=1:min_hard_comp=0.100000:first_pts=0 
-ac 2 
-b:a 128k 
-ar 44100 
-vf zscale=transfer=linear:npl=100,
  format=gbrpf32le,
  zscale=primaries=bt709,
  tonemap=tonemap=hable:desat=0,
  zscale=transfer=bt709:matrix=bt709:range=tv,
  format=yuv420p 
-sws_flags full_chroma_int+full_chroma_inp 
-pix_fmt yuv420p 
"outputfile".mp4