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• Android mp4 remove rotation and rotate the video stream

  4 mars 2015, par Mathijs Segers

  I’m having some issues trying to remove the rotation value of Android video’s.
  For some reason convertion tools in the cloud cannot seem to handle android’s rotation value correctly. f/e I have a portrait video recorded in 1080x1920 (so the file’s headers tell me it’s actually 1920x1080 with rotation : 90).

  So now I’m trying to convert these video’s to an actual 1080x1920 format when they have this rotation value but i’m kind of stuck, probably using the wrong search terms on SO and Google.

  In the hope of making things clear I’ve actually added some ffmpeg libs to android following these steps, of course with some changes to parameters. I’m building this on a Mac and this all works fine now.
  http://www.roman10.net/how-to-build-ffmpeg-with-ndk-r9/

  Now the following, I have no real clue how these libs work and how to use them or which I actually need or if I even need them at all.

  Is there anyone who can point me in the right direction of solving my issue ? Basicly the video’s are on my android filesystem and I can access them fully, before uploading I want to check the values and remove and rotate the video’s if needed.

• Flash player seek not working when ffmpeg encoded with gop(-g) = 1 [migrated]

  3 mars 2015, par Brian

  I am trying to deliver video content with frame-by-frame viewing via the SMP Flash player. For encoding, I am using FFMPEG with the x264 video codec for files with .mp4 containers. I am using the latest ffmpeg build and using the OSMF SMP flash video player.

  I am taking a series of png files and creating a .mp4 file :

  ffmpeg -nostdin -loglevel warning  -i out.%d.png -g 1 -crf 15 -c:v libx264 -movflags faststart -pix_fmt yuv420p -r 24 out.mp4

  By encoding with the gop(-g) flag = 1, I am encoding to make each frame a keyframe. When I seek using the scrub bar of the SMP flash player, it always seeks to the start of the video. If I play and scrub/seek the video using the default HTML player, it works perfectly.

  When I encode with the gop(-g) flag = 2, the SMP Flash player scrubs/seeks and plays correctly.

  It looks like there may be some kind of bug or incompatibility with the Flash player. I have found this problem mentioned back in 2009. I think my only hope is to find a work around. Any suggestions ?

• Upscale the key frames while decoding in H.264

  25 janvier 2023, par Monaco

  I would like to just upscale the keyframes in an H.264 video. I've been trying to see where can I hold the key frame, in the C src code, in order to scale it. I'm confused whether to apply the scaling in the parsing packet part, or in the decoding part.

  


  I also don't know if upscaling the B & P frames would be enough to not damage the video frames.

  


  I hope you guide me as there are no sufficient documentation about FFmpeg. If you have any suggestions please let me know.