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• libavutil : Hook up the rest of the gcc specific attributes to clang as well

  21 mars 2017, par Martin Storsjö

  libavutil : Hook up the rest of the gcc specific attributes to clang as well
  Hook up all attributes that don’t have a MSVC specific version at the
  
  moment.
  See f637046d313 for details.
  These don’t seem to be critical for building with clang in MSVC mode
  
  though, and thus haven’t been hooked up until now.
  These seem to build fine with as old clang as 3.3 at least.
  
  (clang 3.3 disguises itself as gcc 4.2 normally, so all of these
  
  have been used for clang before, except for av_cold.)
  The clang version numbers themselves are useless for detecting what
  
  attributes are available, since Apple’s clang builds use a completely
  
  different versioning (presenting itself as e.g. clang 8.0 instead
  
  of 3.8).
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DBH] libavutil/attributes.h

• Video streaming to YouTube using JavaScript and Java

  28 septembre 2020, par user1597121

  I'm trying to stream live video from a user's browser to YouTube Live. I already have the following working :

  


  

  1. Capture video from the webcam using navigator.mediaDevices.getUserMedia

  


  2. Send video data to the server via WebSocket by periodically invoking this function :

  


  


  function getFrame(video)
{
    var canvas = document.createElement('canvas');
    canvas.width = video.videoWidth;
    canvas.height = video.videoHeight;
    canvas.getContext('2d').drawImage(video, 0, 0);

    return canvas.toDataURL('image/png', 1);
}


  


  

  3. Creating a live broadcast and stream on YouTube via their API and receiving the RTMP info where they expect the video stream to be sent.

  


  


  This is where I seem to be stuck. I'm not sure how to send the video data from my Java server to YouTube's RTMP endpoint. I've looked into using Red5 or ffmpeg, but haven't been able to find an example where the data is continually being sent via WebSocket. Rather, there's always some "stream" that is being redirected to YouTube, coming in on a dedicated port, or perhaps from a pre-recorded video file.

  


  I have very limited knowledge of how video streaming works, so that's presumably making things more difficult than they should be. I'd really appreciate some help with getting this figured out. Thank you !

  


• FFMPEG and Matplotlib for animations - strange outputs ?

  27 juin 2020, par user13132640

  I'm trying to create animations using FFMPEG and matplotlib. Using the below code, I am creating the FFMpeg writer, and then using a loop, writing a series of graphs to the animation. However, the outputs I'm getting are very strange ; sometimes, when I watch the .mp4 file, the first 5 seconds are blank, then the video "ends" (the playback time on my media player says that it's complete), and at that point, my animation shows up. Other times, some frames are missing or skipped. I've tried searching around, but frankly I haven't found anyone with similar issues.

  


  I just installed the latest version of FFMpeg today.

  


  FFMpegWriter = manimation.writers['ffmpeg']
metadata = dict(title='Animation test', artist='name')
writer = FFMpegWriter(fps=1, metadata=metadata) # 1 frames per second, each year is 1 second


  


  Then, the plotting part...(I've excluded the code where I setup the fig, ax etc.)

  


  with writer.saving(fig, "animation.mp4", dpi=200):
    year = "2005"
    for i in range(4):

        d1_plot = d1[d1['Year'].str.contains(year, na=False)]
        ax.scatter(d1_plot["Lat"], d1_plot["Long"], c='g', s=d1_plot["Size"], transform=ccrs.PlateCarree())
        ax.set_title(year)
        writer.grab_frame()
        year = str(int(year)+1)