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• avformat/movenc : use enum values directly for colr atom

  31 mars 2020, par Michael Bradshaw

  avformat/movenc : use enum values directly for colr atom
  The switch cases were missing :
    - Primaries : bt470m, film, smpte428, and ebu3213.
  
    - TRCs : gamma22, gamma28, linear, log, log_sqrt, iec61966_2_4, bt1361,
  
      iec61966_2_1, bt2020_10bit, and bt2020_12bit.
  
    - Space : rgb, fcc, ycgco, bt2020_cl, smpte2085, chroma-derived-nc,
  
      chroma-derived-c, and ictcp.
  They also annoyingly remapped the following (which are functionally
  
  equivalent but can be treated differently by clients) :
    - smpte240m primaries to smpte170m.
  
    - smpte170m TRC to bt709.
  
    - bt470bg color space to smpte170m.
  The enum values in FFmpeg are the same values as ITU-T H.273 and
  
  ISO/IEC 23001-8 so we can just use them directly, which is both simpler
  
  and preserves the user intent.
  Signed-off-by : Michael Bradshaw <mjbshaw@google.com>
  

  • [DH] libavformat/movenc.c

• How to stabilize inverse 360 video using stabilization algorithms ?

  11 août 2020, par Jimmy Leahy

  We have a 12-foot circular ring with about 50 cameras spaced evenly around the perimeter of the circle. These cameras are pointed at the exact center of the circle and are manually aligned. Our application snaps an image from all cameras simultaneously and makes a video from these images creating a matrix-like effect. I believe the effect is called Bullet Time.

  



  This process works well and does a great job of snapping a moment in time from all angles. The problem is that every camera is not perfectly aligned and the video ends up being slightly jerky due to the slightest differences in camera alignments.

  



  We need to stabilize the video. We are using FFmpeg's vidstabdetect and vidstabtransform to do this right now but the results are not desirable. From what I understand, these libraries are meant to be used with a video where the camera angle is static.

  



  Here are the exact commands :

  



  ffmpeg -i "input.mp4" -vf vidstabdetect=stepsize=32:shakiness=5:accuracy=15:result=transform_vectors.trf -f null - 
ffmpeg -i "input.mp4" -y -vf vidstabtransform=input=transform_vectors.trf:zoom=0:relative=1:interpol=bicubic:smoothing=10,unsharp=5:5:0.8:3:3:0.4 -b:v 100M -vcodec hevc_nvenc -tune film -an stabilized.mp4


  



  Are there any algorithms out there for these inverse or negative 260 videos ?

  


• FFmpeg side by side video (widescreen) and play each video one by one

  6 mai 2020, par Knide

  new to ffmpeg, I've already did this to combine 3 or more videos that I have into 1 video :

  



  ffmpeg -i left.mp4 -i center.mp4 -i right.mp4 -filter_complex "[0:v:0][1:v:0][2:v:0]hstack=inputs=3" -c:v libx264 -tune film -crf 16 -b:a 256k output.mp4


  



  Now what I am having trouble with is the videos have different play times (in seconds) what I want to achieve is have them all side by side (working with the code above) then have left.mp4 play first (with it's own audio) once done, center.mp4 plays (has own audio), and when done too, right.mp4 plays (has own audio) as well and the video is over.

  



  Can someone enlighten me on how to achieve this ? Thank you !