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• avformat/mxfenc : set/force channelcount in MXF D-10

  25 juin 2014, par Gaullier Nicolas

  avformat/mxfenc : set/force channelcount in MXF D-10
  There are interoperability issues with D-10 related to the channelcount property in the generic sound essence descriptor.
  On one side, SMPTE 386M requires channel count to be 4 or 8, other values being prohibited.
  
  The most widespread value is 8, which seems straightforward as it is the actual size of the allocated structure/disk space.
  
  At the end, it appears that some vendors or workflows do require this descriptor to be 8, and otherwise just "fail".
  On the other side, at least AVID and ffmpeg do write/set the channel count to the exact number of channels really "used",
  
  usually 2 or 4, or any other value. And on the decoding side, ffmpeg (for example) make use of the channel count for probing
  
  and only expose this limited number of audio streams
  
  (which make sense but has strong impact on ffmpeg command line usage, output, and downstream workflow).
  At the end, I find it pretty usefull to simply give ffmpeg the ability to force/set the channel count to any value the user wants.
  
  (there are turnaround using complex filters, pans, amerge etc., but it is quite boring and requires the command line to be adapted to the input file properties)
  Reviewed-by : Matthieu Bouron <matthieu.bouron@gmail.com>
  
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavformat/mxfenc.c

• Get all bytes of stream from webcam after being compressed by codec with ffmpeg ?

  26 octobre 2015, par vantrung -cuncon

  I need to capture every single byte of the video stream from webcam -after using commandline-ffmpeg to compress it with codec.

  So can you please light me up with somewhat the ffmpeg commandline look like and the strategy to get the output stream into my program written by VB6 or VB.net ? (I need to manipulate with every single byte !) Highly appreciate any suggestion.

  ---

  Update : I wonder if it’s possible to save the output as "avi" file on hard disk and at the same time use my program to read content of the saving file. Can I playback the "part of avi file" that I retrieve while the file is being saved (appended) ? Is there any better file format for writting & reading (recording & playing) at the same time other than "avi" ?

  Or any better/faster solution ?

• Is it possible to read a Video from POST request into python-ffmpeg or OpenCV ?

  16 janvier 2021, par PhyDev

  I've been thinking of a way to read the uploaded Video from POST request with ffmpeg-python or OpenCV so I can process it before saving, so is it possible ?
And if not, then is it safe to save the video into disk and then do all the processing required ? the main point that is bothering me is that I would want to read Video length so I can verify it's valid, so is it also a good idea to save it into disk, check length, and then keep it if its length is in the permitted range, and otherwise I delete it.

  


  Thanks in advance.

  


  Note : I've noticed that the tags don't contain ffmpeg-python, so answers regarding pyffmpeg are also accepted.