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• Convert FLV video with alpha channel to PNGs with transparency

  8 octobre 2012, par AZAR

  I have some FLV videos with alpha channels, and I want to convert each of them to PNG images using ffmpeg but keep the transparency.

  So far, I've tried this :

  ffmpeg -i input.flv -an -y %d.png

  But this outputs the PNG files with black background.

  Is there any way to do this ?

  Alternate acceptable solution : If I can output the images and give the alpha channel a certain color of my choice. I can then remove it later via imagemagick and convert that color to transparency.

• ffmpeg fade filter installed but not working ?

  4 novembre 2011, par Astha

  I have php 5.1.6 running on my CentOS 5 server running Apache 2.2.3

  I installed ffmpeg library and my aim is to covert a set of images into a slideshow with the fadein/fade out effect per image swap.

  Command ffmpeg says :

  `FFmpeg version SVN-r26402, Copyright (c) 2000-2011 the FFmpeg developers
  
    built on Sep 12 2011 03:37:39 with gcc 4.1.2 20080704 (Red Hat 4.1.2-50)
  
    configuration:
  
    libavutil     50.36. 0 / 50.36. 0
  
    libavcore      0.16. 1 /  0.16. 1
  
    libavcodec    52.108. 0 / 52.108. 0
  
    libavformat   52.93. 0 / 52.93. 0
  
    libavdevice   52. 2. 3 / 52. 2. 3
  
    libavfilter    1.74. 0 /  1.74. 0
  
    libswscale     0.12. 0 /  0.12. 0
  
  Hyper fast Audio and Video encoder
  
  usage: ffmpeg [options] [[infile options] -i infile]... {[outfile options] outfile}...
  
  
  
  Use -h to get full help or, even better, run 'man ffmpeg'

  and command ffmpeg -filters prints :

  FFmpeg version SVN-r26402, Copyright (c) 2000-2011 the FFmpeg developers
  
    built on Sep 12 2011 03:37:39 with gcc 4.1.2 20080704 (Red Hat 4.1.2-50)
  
    configuration:
  
    libavutil     50.36. 0 / 50.36. 0
  
    libavcore      0.16. 1 /  0.16. 1
  
    libavcodec    52.108. 0 / 52.108. 0
  
    libavformat   52.93. 0 / 52.93. 0
  
    libavdevice   52. 2. 3 / 52. 2. 3
  
    libavfilter    1.74. 0 /  1.74. 0
  
    libswscale     0.12. 0 /  0.12. 0
  
  Filters:
  
  anull            Pass the source unchanged to the output.
  
  anullsrc         Null audio source, never return audio frames.
  
  anullsink        Do absolutely nothing with the input audio.
  
  copy             Copy the input video unchanged to the output.
  
  crop             Crop the input video to width:height:x:y.
  
  drawbox          Draw a colored box on the input video.
  
  fifo             Buffer input images and send them when they are requested.
  
  format           Convert the input video to one of the specified pixel formats.
  
  gradfun          Debands video quickly using gradients.
  
  hflip            Horizontally flip the input video.
  
  noformat         Force libavfilter not to use any of the specified pixel formats for the input to the next filter.
  
  null             Pass the source unchanged to the output.
  
  overlay          Overlay a video source on top of the input.
  
  pad              Pad input image to width:height[:x:y[:color]] (default x and y: 0, default color: black).
  
  pixdesctest      Test pixel format definitions.
  
  scale            Scale the input video to width:height size and/or convert the image format.
  
  setdar           Set the frame display aspect ratio.
  
  setpts           Set PTS for the output video frame.
  
  setsar           Set the pixel sample aspect ratio.
  
  settb            Set timebase for the output link.
  
  slicify          Pass the images of input video on to next video filter as multiple slices.
  
  transpose        Transpose input video.
  
  unsharp          Sharpen or blur the input video.
  
  vflip            Flip the input video vertically.
  
  buffer           Buffer video frames, and make them accessible to the filterchain.
  
  color            Provide an uniformly colored input, syntax is: [color[:size[:rate]]]
  
  nullsrc          Null video source, never return images.
  
  nullsink         Do absolutely nothing with the input video.`

  firstly my ffmpeg was not having fade filter because it was giving error

  fade: filter not found

  so i installed the patch created vf_fade.c and made corresponding changes to Makefile and allfilters.c file of directory libavfilters in ffmpeg. configured it again then also ran commands 'make' and 'make install' Restarted the server but still its showing the same error

  fade: filter not found

  what should i do next ? if any more details needed please ask and all the helps and ideas and links will be appreciated.

• Rotating videos with FFmpeg

  19 février 2016, par jocull

  I have been trying to figure out how to rotate videos with FFmpeg. I am working with iPhone videos taken in portrait mode. I know how to determine the current degrees of rotation using MediaInfo (excellent library, btw) but I’m stuck on FFmpeg now.

  From what I’ve read, what you need to use is a vfilter option. According to what I see, it should look like this :

  ffmpeg -vfilters "rotate=90" -i input.mp4 output.mp4

  However, I can’t get this to work. First, -vfilters doesn’t exist anymore, it’s now just -vf. Second, I get this error :

  No such filter: 'rotate'
  
  Error opening filters!

  As far as I know, I have an all-options-on build of FFmpeg. Running ffmpeg -filters shows this :

  Filters:
  
  anull            Pass the source unchanged to the output.
  
  aspect           Set the frame aspect ratio.
  
  crop             Crop the input video to x:y:width:height.
  
  fifo             Buffer input images and send them when they are requested.
  
  format           Convert the input video to one of the specified pixel formats.
  
  hflip            Horizontally flip the input video.
  
  noformat         Force libavfilter not to use any of the specified pixel formats
  
   for the input to the next filter.
  
  null             Pass the source unchanged to the output.
  
  pad              Pad input image to width:height[:x:y[:color]] (default x and y:
  
   0, default color: black).
  
  pixdesctest      Test pixel format definitions.
  
  pixelaspect      Set the pixel aspect ratio.
  
  scale            Scale the input video to width:height size and/or convert the i
  
  mage format.
  
  slicify          Pass the images of input video on to next video filter as multi
  
  ple slices.
  
  unsharp          Sharpen or blur the input video.
  
  vflip            Flip the input video vertically.
  
  buffer           Buffer video frames, and make them accessible to the filterchai
  
  n.
  
  color            Provide an uniformly colored input, syntax is: [color[:size[:ra
  
  te]]]
  
  nullsrc          Null video source, never return images.
  
  nullsink         Do absolutely nothing with the input video.

  Having the options for vflip and hflip are great and all, but they just won’t get me where I need to go. I need to the ability to rotate videos 90 degrees at the very least. 270 degrees would be an excellent option to have as well. Where have the rotate options gone ?