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• Recording video in C#

  30 décembre 2022, par pfedotovsky

  I have to do the following : record video from a camera using C#. The camera I use produces video frames (the frame rate is not fixed) and I have to somehow put all the frames together and create a video file. Also I need to use different codecs, such as AVI or MPEG-4 (these codecs are required, others are optional).

  


  The main problem I faced was how to create a video in which the frame rate is not fixed. I have a stream of frames. For example, I can receive the first frame after 1 ms, then after 20 ms, then 36 ms and so on. If I create video with 25 frames/second the result will be wrong because it means that frames are added after 40 ms.

  


  I tried to use Aforge.Video library. It has a method which adds a frame according to a timespan. But this method has problems with setting the bitrate. The bitrate value I pass to the method is simply ignored (About an FFmpeg bitrate and framerate issue).

  


  Is there some C# library which I can use to do video recording ? I have to support AVI and MPEG-4, and also the possibility to set the bitrate and last but not least - record video with a variable framerate.

  


  I can't connect to the camera directly. All I have is a stream of frames and I need to convert this stream to video at run time.

  


  A library I'm looking for should satisfy the following properties. It has to contain a method (or some way how to do the same) to add the next frame with a timestamp, just like in Aforge.Video.FFMPEG :

  


  public void WriteVideoFrame(Bitmap frame, TimeSpan timestamp)


  


  And it should be possible to choose different codecs (at least AVI and MPEG-4) and also to set bitrate.
Are there some alternatives to Aforge.Video.FFMPEG ? Because Aforge doesn't work properly. The bitrate value is ignored, and also some codecs are not supported (MPEG-2 for example).

  


  About the codec license. If I use an open source library, should I worry about the codec license ?

  


• FFMPEG Concat Dropping Frames

  16 mars 2015, par scientiffic

  I’m using FFMPEG to do the following two things :

  • create an mp4 given a set of images
  • compile mp4s to create a longer video (mp4)

  To create mp4s from images, I use the following command :

  ffmpeg -r 5 -i 'img%03d.jpg' output.mp4

  As far as I know, this creates a video with a framerate of 5fps.

  But when I try to compile mp4s, it seems like frames within each mp4 are being dropped.

  To create the compiled footage, I create a text file that points to all the mp4s that should be included in the compilation, e.g.

  file 'set1/output.mp4'
  
  file 'set2/output.mp4'
  
  file 'set3/output.mp4'
  
  file 'set4/output.mp4'
  
  file 'set5/output.mp4'
  
  file 'set6/output.mp4'
  
  file 'set7/output.mp4'

  Then I run the following command :

  ffmpeg -f concat -i input.txt -codec copy compilation.mp4

  The resulting video seems to drop 2-3 frames from each of the output videos.

  How do I ensure that the compiled video doesn’t drop any frames ?

  (For reference, I used the following tutorial : https://trac.ffmpeg.org/wiki/Concatenate)

• compile the ffmpeg3.3 for Mac OS show ERROR : libmp3lame >= 3.98.3 not found

  4 mars 2018, par MR.PJ

  I use my mac to compile the ffmpeg3.3 for Mac OS according to https://trac.ffmpeg.org/wiki/CompilationGuide/macOS.I tried the first(which through Homebrew) and third(which builds it yourself) method,the first method is ok.

  But the third, compiling FFmpeg myself and Installing dependencies with Homebrew.I don’t know the meaning of this sentence enter image description here

  after this step :

  ./configure  --prefix=/usr/local --enable-gpl --enable-nonfree --enable-libass \
--enable-libfdk-aac --enable-libfreetype --enable-libmp3lame \
--enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-libopus --enable-libxvid \
--samples=fate-suite/

  terminal show :

  RROR: libmp3lame >= 3.98.3 not found

  when I use locate libmp3lame.a,it is at ’/usr/local/Cellar/lame/3.99.5/lib/libmp3lame.a’.

  I also try --enable-libmp3lame --extra-ldflags=-L/usr/local/lib to solve,but it is no effect.

  How to solve thisERROR: libmp3lame >= 3.98.3 not found