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• 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 ?

• FFmpeg fourcc Avi codec support list ?

  5 décembre 2013, par Sugrue

  A couple of similar questions are on stackoverflow, but I haven't been able to figure this exact problem out.

  I want to get a list of the fourccs for the avi codecs that FFMpeg can decode.

  I know how to get all the formats ffmpeg -formats and codecs ffmpeg -codecs but neither list gives me an accessible list of fourccs. Neither does the documentation I can find.

  I need this list, so that my application can access the fourcc of an avi file and determine whether to use ffmpeg or VfW (or DirectX) to try decode the file.

  Is there some ffmpeg command that can give me this list ?

• Flash Media Server Recording Delay

  14 novembre 2011, par Corey

  I have an application where a user can record themselves singing along to a song. Once I receive the NetStream status event 'Record.Start' I start playing an audio file. Once the audio completes, I stop recording. Next, I have a script that runs FFMPEG to combine the recorded video/audio with the same music file. The problem I'm finding is that there is a noticeable delay between the recorded audio and the music. It seems also that this delay depends on network speed as it varies depending on the network. Can I determine this delay through the FMS dynamically ?