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• Python, Flask, ffmpeg video streaming : Video does not work in Firefox

  12 avril 2018, par user3187926

  I am writing a preview portion for video management system, it works like a charm in chrome with standard tag but firefox does not recognize MIME type for some reason and it bugs me a lot.

  Here is my stream class :

  class Stream:
  
      run = False
  
      FNULL = open(os.devnull, 'w')
  
      overlay = ffmpeg.input("somelogo.png")
  
  
  
      def __init__(self, camid):
  
          camUtil = CameraUtil()
  
          self.camid = camid
  
          self.streamurl = camUtil.get_stream_from_id(self.camid)['streamURL']
  
          print(self.streamurl)
  
          self.args = ffmpeg.input(self.streamurl)
  
          # vcodec="libvpx",
  
          # acodec="libvorbis",
  
          self.args = ffmpeg.output(self.args, "-",
  
                                    f="matroska",
  
                                    vcodec="copy",
  
                                    acodec="copy",
  
                                    blocksize="1024",
  
                                    # strftime="1",
  
                                    # segment_time="60",
  
                                    # segment_format="matroska"
  
                                    preset="ultrafast",
  
                                    metadata="title='test'"
  
                                    )
  
          self.args = ffmpeg.get_args(self.args)
  
          print(self.args)
  
          self.pipe = subprocess.Popen(['ffmpeg'] + self.args,
  
                                       stdout=subprocess.PIPE,)
  
                                       #stderr=self.FNULL)
  
  
  
      def dep_stream(self):
  
          def gen():
  
              try:
  
                  f = self.pipe.stdout
  
                  byte = f.read(1024)
  
                  while byte:
  
                      yield byte
  
                      byte = f.read(1024)
  
              finally:
  
                  self.pipe.kill()
  
  
  
          return Response(gen(), status=200,
  
                          mimetype='video/webm',
  
                          headers={'Access-Control-Allow-Origin': '*',
  
                                   "Content-Type": "video/webm",
  
                                   })

  My html playback portion :

     <video preload="auto" autoplay="autoplay" width="1280" height="720">
     <source src="/stream/{{ camid }}" type="video/webm;codecs=&quot;vp8, vorbis&quot;"></source>
     YOUR BROWSER DOES NOT SUPPORT HTML5, WHAT YEAR ARE YOU FROM?!
   </video>

  Firefox says "No video with supported format and MIME type found" and in console it says

  error : Error Code : NS_ERROR_DOM_MEDIA_METADATA_ERR (0x806e0006)

  Did I do something dumb ?! Or am I missing something, because it works google chrome like a charm

  I need fresh eyes.

  Help plez

• Encoding MJPEG from webcam in UWP development with C#

  24 avril 2018, par Federico Parra

  this is my first question in StackOverflow.

  How can I encode video being captured from webcam as a MJPEG using C# in UWP enviroment (Visual Studio 2017) ?
  Perhaps using FFMPEG or DirectShow ? Any particular bindings required to use them in UWP ?

  I’ve been through these walk-throughs trying to go the official way using MediaCapture :

  https://docs.microsoft.com/en-us/windows/uwp/audio-video-camera/basic-photo-video-and-audio-capture-with-mediacapture
  https://docs.microsoft.com/en-us/uwp/api/windows.media.capture.mediacapture

  According to Microsoft though, there is no MJPEG encoder included in MediaEncoder (only decoder) : https://docs.microsoft.com/en-us/windows/uwp/audio-video-camera/supported-codecs

  About FFMPEG UWP integration, I found this :
  https://github.com/Microsoft/FFmpegInterop
  https://blogs.windows.com/buildingapps/2015/06/05/using-ffmpeg-in-windows-applications/#HHYbWAVcM7LhkvYZ.97

  But it’s geared towards decoding, and I want to encode.

  Just in case someone is wondering, I want to use MJPEG for Two reasons :
  1) less CPU intensive (much less) because it doesn’t do inter-frame compression, means my Surface Pro (and other similar computers) will keep quiet without fans running like crazy
  2) I need all frames (i.e. not one every 30) to be crystal clear because of an algorithm I need to run on each of them after

  Any pointers would be greatly appreciated.

  Thank you,
  Federico

• avformat/matroskaenc : do not write timebase as framerate

  28 avril 2018, par wm4

  avformat/matroskaenc : do not write timebase as framerate
  If the API user doesn't set avg_frame_rate, matroskaenc will write the
  
  current timebase as "default duration" for the video track. This makes
  
  no sense, because the "default duration" implies the framerate of the
  
  video. Since the timebase is forced to 1/1000, this will make the
  
  resulting file claim 1000fps.
  Drop it and don't write the element. It's optional, so it's better not
  
  to write it if the framerate is unknown.
  Strangely does not require FATE changes.
  

  • [DH] libavformat/matroskaenc.c