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• Stream microphone from iOS and Android to ffmpeg on server [on hold]

  22 août 2019, par Demosthenes

  To be perfectly clear : The problem here is that ffserver has been dropped, and I find all alternatives proposed (such as gstreamer) too complicated to get into. If anybody wants to propose ffserver, it has been removed from ffmpeg, years ago actually, and is no longer maintained, and thus no option anymore.

  I want something simple : I want to stream the microphone from a mobile device to an ffmpeg process. So, the device encodes audio (let’s say aac but it really doesn’t matter), and I have the data ready for sending. I can send it somewhere, but I cannot open a server on the phone hosting a stream.

  What I want to be done : The data shall be processed, in real time, by an ffmpeg process running on a server. That process can be spawned on demand when needed, the handshake for this is not a problem.

  My problem : It seems to me that ffmpeg cannot listen on a port for a stream as input, but only actively connect to another server to retrieve the input stream.

  I’m looking for a simple solution to get this done. Writing a small program (almost any language, really) is not an issue. One solution I’ve been thinking about was writing a Python script or C++ program as the server and linking that against ffmpeg and feeding the audio data inside this program to ffmpeg. That’s not actually what I want, I would like to just pipe the data through the ffmpeg executable, but would be a last resort.

  Does anybody have an idea for a simple solution for this ?

• Having trouble obtaining the time from RTP Timestamps obtained through OpenCV

  24 août 2019, par Fr0sty

  I am finding it a bit difficult trying to understand whether or not the hack around with FFmpeg and OpenCV really provided a RTP timestamp. My last post helped a little bit but got me stuck in trying to validate the timestamps obtained through this work around by modifying ffmpeg and opencv.

  FFmpeg version : 4.1.0
  OpenCV version : 3.4.1

  import cv2
  
  import time
  
  from datetime import datetime, date
  
  
  
  uri = 'rtsp://admin:password@192.168.1.66:554/Streaming/Channels/101'
  
  cap = cv2.VideoCapture(uri)
  
  '''One is the offset between the two epochs. Unix uses an epoch located at 1/1/1970-00:00h (UTC) and NTP uses 1/1/1900-00:00h.
  
  This leads to an offset equivalent to 70 years in seconds (there are 17 leap years between the two dates so the offset is'''
  
  time_offset = 2208988800 # (70*365 + 17)*86400 = 2208988800 (in seconds)
  
  # offset = 3775484294
  
  days = 43697
  
  pdat = "1900-01-01 00:00:00:00"
  
  mdat = "2019-08-23 22:02:44:00" # str(datetime.now()) + str(datetime.now().time())
  
  pdate = datetime.strptime(pdat, "%Y-%m-%d %H:%M:%S:%f").date()
  
  mdate = datetime.strptime(mdat, "%Y-%m-%d %H:%M:%S:%f").date()
  
  delta = (mdate - pdate).days
  
  offset = delta * 86400
  
  def time_delta(s):
  
      return (s - time_offset)
  
  
  
  while True:
  
      frame_exists, curr_frame = cap.read()
  
      if frame_exists:
  
          seconds = cap.getRTPTimeStampSeconds()
  
          fraction = cap.getRTPTimeStampFraction()
  
          timestamp = cap.getRTPTimeStampTs()
  
          unix_offset = seconds - time_offset
  
          msec = int((int(fraction) / 0xFFFFFFFF) * 1000.0)
  
          ts = float(str(unix_offset) + "." + str(msec))
  
          # print("Timestamp per Frame:%i" % timestamp)
  
          print((datetime.fromtimestamp(float(ts) + offset)))
  
  cap.release()

  My Output :

  On August 23, 2019 at 22:02

  ...
  
  2019-08-23 13:59:52.781000
  
  2019-08-23 13:59:52.726000
  
  2019-08-23 13:59:52.671000
  
  2019-08-23 13:59:52.616000
  
  2019-08-23 13:59:52.561000
  
  2019-08-23 13:59:52.506000
  
  2019-08-23 13:59:52.451000
  
  2019-08-23 13:59:52.396000
  
  2019-08-23 13:59:52.342000
  
  2019-08-23 13:59:52.287000
  
  2019-08-23 13:59:52.232000
  
  2019-08-23 13:59:52.177000
  
  2019-08-23 13:59:52.122000
  
  2019-08-23 13:59:52.067000
  
  2019-08-23 13:59:52.012000
  
  2019-08-23 13:59:53.570000
  
  2019-08-23 13:59:53.020000
  
  2019-08-23 13:59:53.847000
  
  2019-08-23 13:59:53.792000

  I’ve noticed how the time increments weirdly (that’s not suppose to happen in the real, current time), such as the last two lines and a few others in between in the output. A bit flabbergasted as to what went wrong. Also trying this out on multiple IP cameras, with each showing a different timestamp probably related to when they were turned on.

• RTP Timestamps Are Not Monotonically increasing

  25 août 2019, par Fr0sty

  I am finding it a bit difficult trying to understand whether or not the hack around with FFmpeg and OpenCV really provided a RTP timestamp. My last post helped a little bit but got me stuck in trying to validate the timestamps obtained through this work around by modifying ffmpeg and opencv.

  FFmpeg version : 4.1.0
  OpenCV version : 3.4.1

  import cv2
  
  import time
  
  from datetime import datetime, date
  
  
  
  uri = 'rtsp://admin:password@192.168.1.66:554/Streaming/Channels/101'
  
  cap = cv2.VideoCapture(uri)
  
  '''One is the offset between the two epochs. Unix uses an epoch located at 1/1/1970-00:00h (UTC) and NTP uses 1/1/1900-00:00h.
  
  This leads to an offset equivalent to 70 years in seconds (there are 17 leap years between the two dates so the offset is'''
  
  time_offset = 2208988800 # (70*365 + 17)*86400 = 2208988800 (in seconds)
  
  # offset = 3775484294
  
  days = 43697
  
  pdat = "1900-01-01 00:00:00:00"
  
  mdat = "2019-08-23 22:02:44:00" # str(datetime.now()) + str(datetime.now().time())
  
  pdate = datetime.strptime(pdat, "%Y-%m-%d %H:%M:%S:%f").date()
  
  mdate = datetime.strptime(mdat, "%Y-%m-%d %H:%M:%S:%f").date()
  
  delta = (mdate - pdate).days
  
  offset = delta * 86400
  
  def time_delta(s):
  
      return (s - time_offset)
  
  
  
  while True:
  
      frame_exists, curr_frame = cap.read()
  
      if frame_exists:
  
          seconds = cap.getRTPTimeStampSeconds()
  
          fraction = cap.getRTPTimeStampFraction()
  
          timestamp = cap.getRTPTimeStampTs()
  
          unix_offset = seconds - time_offset
  
          msec = int((int(fraction) / 0xFFFFFFFF) * 1000.0)
  
          ts = float(str(unix_offset) + "." + str(msec))
  
          # print("Timestamp per Frame:%i" % timestamp)
  
          print((datetime.fromtimestamp(float(ts) + offset)))
  
  cap.release()

  My Output :

  On August 23, 2019 at 22:02

  ...
  
  2019-08-23 13:59:52.781000
  
  2019-08-23 13:59:52.726000
  
  2019-08-23 13:59:52.671000
  
  2019-08-23 13:59:52.616000
  
  2019-08-23 13:59:52.561000
  
  2019-08-23 13:59:52.506000
  
  2019-08-23 13:59:52.451000
  
  2019-08-23 13:59:52.396000
  
  2019-08-23 13:59:52.342000
  
  2019-08-23 13:59:52.287000
  
  2019-08-23 13:59:52.232000
  
  2019-08-23 13:59:52.177000
  
  2019-08-23 13:59:52.122000
  
  2019-08-23 13:59:52.067000
  
  2019-08-23 13:59:52.012000
  
  2019-08-23 13:59:53.570000
  
  2019-08-23 13:59:53.020000
  
  2019-08-23 13:59:53.847000
  
  2019-08-23 13:59:53.792000

  I’ve noticed how the time increments weirdly (that’s not suppose to happen in the real, current time), such as the last two lines and a few others in between in the output. A bit flabbergasted as to what went wrong. Also trying this out on multiple IP cameras, with each showing a different timestamp probably related to when they were turned on.