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• Solid FFmpeg wrapper for C#/.NET

  31 octobre 2016, par Jacob Poul Richardt

  I have been searching the web for some time for a solid FFmpeg wrapper for C#/.NET. But I have yet to come up with something useful. I have found the following three projects, but all of them apears to be dead in early alpha stage.

  FFmpeg.NET
  ffmpeg-sharp
  FFLIB.NET

  So my question is if anyone knows of a wrapper project that is more mature ?
  I am not looking for a full transcoding engine with job queues and more.
  Just a simple wrapper so I do not have to make a command line call and then parse the console output, but can make method calls and use eventlisteners for progress.

  And please feel free to mention any active projects, even if they are stil in the early stages.

• lavu/hwcontext : Add support for HW -> HW transfers

  24 octobre 2019, par Philip Langdale

  lavu/hwcontext : Add support for HW -> HW transfers
  We are beginning to consider scenarios where a given HW Context
  
  may be able to transfer frames to another HW Context without
  
  passing via system memory - this would usually be when two
  
  contexts represent different APIs on the same device (eg : Vulkan
  
  and CUDA).
  This is modelled as a transfer, as we have today, but where both
  
  the src and the dst are hardware frames with hw contexts. We need
  
  to be careful to ensure the contexts are compatible - particularly,
  
  we cannot do transfers where one of the frames has been mapped via
  
  a derived frames context - we can only do transfers for frames that
  
  were directly allocated by the specified context.
  Additionally, as we have two hardware contexts, the transfer function
  
  could be implemented by either (or indeed both). To handle this
  
  uncertainty, we explicitly look for ENOSYS as an indicator to try
  
  the transfer in the other direction before giving up.
  

  • [DH] libavutil/hwcontext.c

• Adding total duration/enable seeking in mp4 AAC audio stream file with FFMPEG

  12 avril 2016, par lex82

  I’m trying to write an AAC audio stream into an mp4 file using the FFMPEG libraries. I am using a custom IO context that writes directly to a socket so I have to set ioContext->seekable = 0. To make this work I had to add the "movflags" empty_moov and frag_keyframe when writing the header.

  After writing the output to a file on the other end of the socket, I can play the file in VLC or Windows Media Player. However, seeking to a specific position in the file is not working properly in both players. WMP also does not show the total duration and VLC only flashes it shortly when reaching the end of the audio.

  Is there a way to add more metadata when muxing so the players are able to treat the file as if it was not written as a stream ? Transfer via the socket is not interrupted abruptly, so I could write metadata at the end of the file. I also know the total duration in advance, so I could add it to the header of the file if it was possible. I cannot use the faststart flag because this would require output to a seekable file before writing to the socket.

  Update : I learned that I can set the duration in AVFormatContext and I can set nb_frames and avg_frame_rate in AVStream. However, it doesn’t solve my problem. When I set the codecContext flag AV_CODEC_FLAG_QSCALE, VLC seems to be able to estimate the total time. However, seeking still doesn’t work.