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• FFmpeg - Rotating at angle

  23 septembre 2017, par connor

  I’ve been working through FFmpeg, but I have been unable to get a rotation to run from the examples they have on their site. I am trying to "wiggle" a video back and forth at a fixed point on the bottom - think a head moving left to right (and so on).

  I am attempting to do this with the filter "rotate" (https://ffmpeg.org/ffmpeg-filters.html#rotate). Attempting to use their examples, I get an error.

  This is what I have so far :

  ffmpeg -i vid1.mp4 -i vid2.mov -loop 1 -i image.png -filter_complex "\
  
      [2:v]alphaextract, scale=240x160[mask];\
  
      [0:v] scale=240x160, rotate=A*sin(2*PI/T*t) [ascaled];\
  
      [ascaled][mask]alphamerge[masked];\
  
      [1:v]scale=480x360[background];\
  
      [background][masked]overlay=120:20"\
  
      -c:a copy 65B6354F61B4AF02_HD_sq.MOV

  I am using "rotate" directly from an example in an attempt to get something to run at all.

  The error I get back is :

  [Parsed_rotate_3 @ 0x7ff4476045e0] [Eval @ 0x7fff5b3e3f00] Undefined constant or missing '(' in 'T*t)'
  
  [Parsed_rotate_3 @ 0x7ff4476045e0] Error occurred parsing angle expression 'A*sin(2*PI/T*t)'
  
  [Parsed_rotate_3 @ 0x7ff4476045e0] Failed to configure output pad on Parsed_rotate_3
  
  Error reinitializing filters!
  
  Failed to inject frame into filter network: Invalid argument
  
  Error while processing the decoded data for stream #1:0

  If I remove ’A’, ’T’, ’sin’, etc, rotate does actually work, but far from the desired behavior.

  Am I missing something to expose those params ?

• Using ffmpeg in asp.net

  23 avril 2014, par pessi

  I needed a audio conversion library. After already pulling my hair..I have given up on the fact that there is no such audio library out there..every library out there has some or the other problem.

  The only option left is ffmpeg which is the best but unfortunately you cannot use it in asp.net (not directly I mean). Every user on the website that will convert a file ; will launch an exe ? ; I think I will hit the server memory max soon.

  Bottom Line : I will try using ffmpeg.exe and see how many users it can support simultaneously.

  I went to the ffmpeg website and in the windows download section I found 3 different version ; static, shared and dev.

  Does any one know which would be the best ? All packed in one exe (static) or dll’s separely and exe small, wrt using it in asp.net ?

  PS : any one has a good library out there..would be great if you can share.

  Static builds provide one self-contained .exe file for each program (ffmpeg, ffprobe, ffplay).

  Shared builds provide each library as a separate .dll file (avcodec, avdevice, avfilter, etc.), and .exe files that depend on those libraries for each program

  Dev packages provide the headers and .lib/.dll.a files required to use the .dll files in other programs.

• scaling a video captured in portrait mode using FFMPEG

  24 octobre 2016, par Ahmed Mujtaba

  I’m trying to rotate a video on my android app using FFMPEG and then uploading it to the server. The following command does the job for me :

  -y -noautorotate -i inputPath -vf transpose=1,scale=360:640,setsar=1 -metadata:s:v rotate=0

  The aspect ratio of the original video is 16:9. I’m trying to maintain the aspect ratio after rotation so I add padding on either side of the video to scale it properly with the following command :

  -y -noautorotate -i inputPath -vf transpose=1,scale=iw*min(360/iw\,640/ih):ih*min(360/iw\,640/ih),pad=640:360:(360-iw)/2:(640-ih)/2,setsar=1 -metadata:s:v rotate=0

  The video scales perfectly on the website but now the issue is that I can see the black bit when I play it on the android app which I don’t want. I don’t mind the black bits when I play the video on the website but on the app, it looks terrible. The container of the video on the app has height "280dp" and width of "380dp". How can I scale the video so the black sides don’t show when I play a video on the app.
  Any solutions/suggestions ?

  This is what the video looks like when I play on the website :

  

  This is what it looks like on the app