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• FFMPEG spoils the extreme pixels when converting and cropping images [closed]

  20 décembre 2024, par Jacob

  I have a side image processing task in my work.
I am using the following command to translate a spherical panorama into a cubemap :

  


  Path/ffmpeg.exe -i "Path/PanoImageInput.png" -vf v360=equirect:c6x1:fin_pad=64:out_frot=002200,scale=-1:2048:flags=neighbor "Path/CubemapOutput.png"

  


  And then I slice it into separate images, 1 face for example :

  


  Path/ffmpeg.exe -i "Path/CubemapOutput.png" -vf crop=2048:2048:0:0 -sws_flags neighbor "Path/face_1.png"

  


  I get artifacts on both cubemap and images of this kind that really bother me :

  


  Cubemap image junction
The junction and part of the edge of the cubemap image

  


  The pixels at the junctions of the 6 images in cubemap and the outermost pixels of any images change their color slightly. This eventually leads to the appearance of visible seams in the scene assembled from the images.

  


  Is there any way I can get rid of them ?

  


  I have tried different interpolation methods in both functions : fast, bicubric, gauss, etc. It doesn't seem to have any effect.

  


  I also tried to crop a couple of pixels less, something like : crop=2040:2040:4:4

  


  I thought it was all because of cubemap and its distortions. Anyway, at the edges of the image, the extreme pixels change their hue.

  


  I also hoped that with the help of pad, during the conversion, I could somehow control the area where the pixels deteriorate, but it absolutely does not matter what I put there - fin_pad, fout_pad and any numbers for them, remove scale, set scale - neither the final image size changes, nor any extra fields appear. Most likely, I just don't understand what this function is really supposed to mean.

  


• Put remaining pieces of CODEC_FLAG_EMU_EDGE under FF_API_EMU_EDGE.

  17 août 2015, par Ronald S. Bultje

  Put remaining pieces of CODEC_FLAG_EMU_EDGE under FF_API_EMU_EDGE.
  The amv one probably looks suspicious, but since it’s an intra-only
  
  codec, I couldn’t possibly imagine what it would use the edge for,
  
  and the vsynth fate result doesn’t change, so it’s probably OK.
  

  • [DH] ffmpeg_opt.c
  • [DH] ffplay.c
  • [DH] libavcodec/mjpegenc.c
  • [DH] libavcodec/snowenc.c
  • [DH] libavcodec/wmv2dec.c

• How to create video and audio files for the Media Source Extension API ?

  5 décembre 2018, par Aman

  I have created a video player from the Media Source Extension API. I have split the video and audio from the original.mp4 (1 minute duration). I have split the video and audio into small 5 second files (12 files in total). I’m getting each one of them and playing them together. But the video stops playing at around 45-47 seconds. I cannot understand to why the video is stopping/buffering. I cannot understand whether the problem is in the javascript code or the video files ?

  I have uploaded all the resources here (https://drive.google.com/file/d/1NHc_yNRU0tvaU18aohLy74Js3y7UHD4N/view?usp=sharing). And written the commands I used to construct my video and audio files below. I have also noticed that this problem only occurs with Google Chrome and works perfectly and smoothly on Microsoft Edge. Thanks

  Making the Media files:

  Extracting video from original.mp4: MP4Box -single 1 original.mp4

  Extracting audio from original.mp4: MP4Box -single 2 original.mp4

  Splitting the video and audio into 5 second parts: ffmpeg -ss starting-time -to end-time -i (video.mp4 OR audio.mp4) (video_part.mp4 OR audio_part.mp4)

  Fragmenting all the video and audio parts: MP4Box -dash 1000 -rap -frag-rap(video_part.mp4 OR audio_part.mp4)

  Then using the fragmented video and audio files to be played via the Media Source Extension API video player. e.g. (video_part_dashinit.mp4 OR audio_part_dashinit.mp4)