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• WebM Decoding Improvements in Google Chrome 6

  10 septembre 2010, par noreply@blogger.com (John Luther)

  Google Chrome 6 for Windows, Mac and Linux was released last week. We want to congratulate the Chrome team and thank them for their contributions to the WebM project.

  Making the web faster is a core goal of Chrome, and we are happy to report that across a set of test clips Chrome 6 decodes VP8 video significantly faster than the developer version that was released at our launch in May. On single-core Intel machines the average improvement is about 20% ; on multicore processors it ranges from 15% (two cores) to 50% (four cores). If you want to try it for yourself, get Chrome 6 and then follow our instructions for playing WebM videos on Youtube.

  We’ve made further decoding speed gains in Chrome 7 dev channel, and are working on better video rendering to further improve the WebM user experience.

  

• Can pyAudioAnalysis be used on a live http audio stream ?

  30 mars 2022, par Tompo

  I am trying to use pyAudioAnalysis to analyse an audio stream in real-time from a HTTP stream. My goal is to use the Zero Crossing Rate (ZCR) and other methods in this library to identify events in the stream.

  


  pyAudioAnalysis only supports input from a file but converting a http stream to a .wav will create a large overhead and temporary file management I would like to avoid.

  


  My method is as follows :

  


  Using ffmpeg I was able to get the raw audio bytes into a subprocess pipe.

  


  try:
    song = subprocess.Popen(["ffmpeg", "-i", "https://media-url/example", "-acodec", "pcm_s16le", "-ac", "1", "-f", "wav", "pipe:1"],
                            stdout=subprocess.PIPE)


  


  I then buffered this data using pyAudio with the hope of being able to use the bytes in pyAudioAnalysis

  


  CHUNK = 65536

p = pyaudio.PyAudio()

stream = p.open(format=pyaudio.paInt16,
                channels=1,
                rate=44100,
                output=True)

data = song.stdout.read(CHUNK)

while len(data) > 0:
    stream.write(data)
    data = song.stdout.read(CHUNK)


  


  However, inputting this data output into AudioBasicIO.read_audio_generic() produces an empty numpy array.

  


  Is there a valid solution to this problem without temporary file creation ?

  


• How to decode RTSP h264 stream from IP camera using C# and EMGUCV ?

  9 janvier 2020, par xor31four

  I am trying to access a H.264 stream on an IP camera within my LAN via EmguCV Video Capture. There is an RTSP URL containing the h.264 stream and an HTTP URL that transmits MJPEG.

  The goal is to perform perform some EmguCV video processing operations on a live stream in as close to real-time as possible.

  I have a bandwidth limitation of 10Mbps.

  The problem is that Emgu.CV is unable to open the rtsp(h264) stream but perfectly capable of opening the http(mjpeg) stream..

  I can’t use the mjpeg stream as it consumes too much bandwidth and I drastically lose picture quality and fps.

  I need to access the h.264 stream in order to meet my bandwidth requirements

  Here is the code that I use to check whether the capture has been created :

              string MJPEG_URL = "http://192.168.0.11:35271/image1"; //returns true
  
              string RTSP_URL = "rtsp://192.168.0.11/stream1.sdp"; //returns false
  
  
  
              _cam1 = new VideoCapture(RTSP_URL, VideoCapture.API.Any);
  
              var flag = _cam1.IsOpened;
  
              Console.WriteLine(flag);

  RTSP_URL returns false. But when I enter the exact same URL in VLC Player, or if I use VLCSharp library to access the stream it works.

  Any suggestions ?