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• Checkinstall equivalent on Red Hat (Santiago)

  29 octobre 2013, par Dalius

  I'm not familiar with Red Hat, never used it before.

  I'm installing ffmpeg from source, following this guide https://trac.ffmpeg.org/wiki/CentosCompilationGuide

  On Debian, after using make to compile ffmpeg, I would use checkinstall to install ffmpeg for all users. How can I do the same on Red Hat ?

• matplotlib 3D linecollection animation gets slower over time

  15 juin 2021, par Vignesh Desmond

  I'm trying to animate a 3d line plot for attractors, using Line3DCollection. The animation is initally fast but it gets progressively slower over time. A minimal example of my code :

  


  def generate_video(nframes):

    fig = plt.figure(figsize=(16, 9), dpi=120)
    canvas_width, canvas_height = fig.canvas.get_width_height()
    ax = fig.add_axes([0, 0, 1, 1], projection='3d')

    X = np.random.random(nframes)
    Y = np.random.random(nframes)
    Z = np.random.random(nframes)

    cmap = plt.cm.get_cmap("hsv")
    line = Line3DCollection([], cmap=cmap)
    ax.add_collection3d(line)
    line.set_segments([])

    def update(frame):
        i = frame % len(vect.X)
        points = np.array([vect.X[:i], vect.Y[:i], vect.Z[:i]]).transpose().reshape(-1,1,3)
        segs = np.concatenate([points[:-1],points[1:]],axis=1)
        line.set_segments(segs)
        line.set_array(np.array(vect.Y)) # Color gradient
        ax.elev += 0.0001
        ax.azim += 0.1

    outf = 'test.mp4'
    cmdstring = ('ffmpeg', 
                    '-y', '-r', '60', # overwrite, 1fps
                    '-s', '%dx%d' % (canvas_width, canvas_height),
                    '-pix_fmt', 'argb',
                    '-f', 'rawvideo',  '-i', '-',
                    '-b:v', '5000k','-vcodec', 'mpeg4', outf)
    p = subprocess.Popen(cmdstring, stdin=subprocess.PIPE)

    for frame in range(nframes):
        update(frame)
        fig.canvas.draw()
        string = fig.canvas.tostring_argb()
        p.stdin.write(string)

    p.communicate()

generate_video(nframes=10000)


  


  I used the code from this answer to save the animation to mp4 using ffmpeg instead of anim.FuncAnimation as its much faster for me. But both methods get slower over time and I'm not sure how to make the animation not become slower. Any advice is welcome.

  


  Versions :
Matplotlib : 3.4.2
FFMpeg : 4.2.4-1ubuntu0.1

  


• JSMpeg not able to get stream from RTSP

  20 octobre 2023, par Q.Rey

  i'm trying to get a RTSP stream inside a webpage, but with no success actually.

  



  For this I followed exactly the tutorial of JSMpeg : https://github.com/phoboslab/jsmpeg

  



  With a custom FFMPEG command :

  



  ffmpeg -i "rtsp://myurl/media.smp" \
 -vcodec h264 -f mpegts -codec:v mpeg1video -s 1290x980 -b:v 8000k \
 -r 25 -max_muxing_queue_size 9999 http://localhost:8081/supersecret


  



  My websocket well receive my connection on it.

  



  But my canvas is still a white square :


  



  The weird thing is when I change the websocket url with a false one, in my code, the canvas turn to black.

  



  So I guess that it turn WHITE when it receive something.

  



  Thansk for help