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• DXGI Desktop Duplication : encoding frames to send them over the network

  13 novembre 2016, par prazuber

  I’m trying to write an app which will capture a video stream of the screen and send it to a remote client. I’ve found out that the best way to capture a screen on Windows is to use DXGI Desktop Duplication API (available since Windows 8). Microsoft provides a neat sample which streams duplicated frames to screen. Now, I’ve been wondering what is the easiest, but still relatively fast way to encode those frames and send them over the network.

  The frames come from AcquireNextFrame with a surface that contains the desktop bitmap and metadata which contains dirty and move regions that were updated. From here, I have a couple of options :

  1. Extract a bitmap from a DirectX surface and then use an external library like ffmpeg to encode series of bitmaps to H.264 and send it over RTSP. While straightforward, I fear that this method will be too slow as it isn’t taking advantage of any native Windows methods. Converting D3D texture to a ffmpeg-compatible bitmap seems like unnecessary work.
  2. From this answer : convert D3D texture to IMFSample and use MediaFoundation’s SinkWriter to encode the frame. I found this tutorial of video encoding, but I haven’t yet found a way to immediately get the encoded frame and send it instead of dumping all of them to a video file.

  Since I haven’t done anything like this before, I’m asking if I’m moving in the right direction. In the end, I want to have a simple, preferably low latency desktop capture video stream, which I can view from a remote device.

  Also, I’m wondering if I can make use of dirty and move regions provided by Desktop Duplication. Instead of encoding the frame, I can send them over the network and do the processing on the client side, but this means that my client has to have DirectX 11.1 or higher available, which is impossible if I would want to stream to a mobile platform.

• Anomalie #2472 : Compagnon : un bug dans un des boutons de fermeture

  2 janvier 2012, par marcimat -

  C’est vrai qu’on avait mis ce define pour ça effectivement. C’est relou parce qu’on va l’avoir pour d’autres cas ça. Suhosin est assez présent. De mémoire Cédric tu disais qu’on pouvait difficilement activer le define d’office parce que

  si un navigateur à une url ajax et que le cache est vidé, on (...)

• Why is ffmpeg-python throwing a codec error here ?

  15 octobre 2019, par TwentyPenguins

  I’m trying out ffmpeg-python for the first time and I’m hitting what looks like a complex error surprisingly early on.

  Here’s my complete code as it stands :

  from tkinter import filedialog
  
  import ffmpeg
  
  
  
  sourceFile = filedialog.askopenfile()
  
  targetFile = filedialog.asksaveasfilename()
  
  
  
  stream = ffmpeg.input(sourceFile, ss=0, format='mov')
  
  stream = ffmpeg.output(stream, targetFile, format='mp4')
  
  ffmpeg.run(stream)

  In my head, this ought to be simple. The user browses to an existing MOV file (a standard h264 file which ’normal’ FFmpeg.exe can handle no problem on a Windows command line), then selects an output file for an MP4 to be saved, then FFmpeg is called and an MP4 file is converted from the MOV.

  However, regardless of what source file I choose, I am always hitting this error :

    File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Python37_64\lib\site-packages\ffmpeg\_ffmpeg.py", line 85, in output
  
    File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Python37_64\lib\site-packages\ffmpeg\_run.py", line 285, in run_async
  
      args, stdin=stdin_stream, stdout=stdout_stream, stderr=stderr_stream
  
    File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Python37_64\lib\subprocess.py", line 775, in __init__
  
      restore_signals, start_new_session)
  
    File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Python37_64\lib\subprocess.py", line 1119, in _execute_child
  
      args = list2cmdline(args)
  
    File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Python37_64\lib\subprocess.py", line 530, in list2cmdline
  
      needquote = (" " in arg) or ("\t" in arg) or not arg
  
    File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Python37_64\lib\encodings\cp1252.py", line 23, in decode
  
      return codecs.charmap_decode(input,self.errors,decoding_table)[0]
  
  UnicodeDecodeError: 'charmap' codec can't decode byte 0x90 in position 41: character maps to <undefined>
  
  </undefined>

  The position number changes depending on the file but the error is always ’charmap’ codec can’t decode byte 0x90 in position [x] : character maps to < undefined >

  Please can somebody point me to where I may be going wrong on this one ? I feel the answer is staring me in the face but I’m not seeing it.