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• unsynchronized graph when h264 stream pause

  24 septembre 2016, par jorp

  Steps to reproduce :

  1.Connect android device to linux PC via USB.
  

  2.Run command on pc :
  adb shell screenrecord --output-format=h264 - | ffplay -analyzeduration 1 -

  3.Screenrecord(an Android system tool) will start to capture Android screen, encode by MediaCodec, generate h264 stream, send stream data to ffplay via pipe.

  4.PC will pop up ffplay window, and start display Android screen graphs

  ---

  If adb command runs when Android screen graph keeps static (no pixel color changes), ffplay window won’t pop up, until I touch somewhere to make Android graph changes.

  Question 1 : how to make ffplay to immidiately display the first frame of video when Android screen keeps static and adb commmand runs ?

  I’m not talking about "latency", if Android graph keeps changing, the graphic latency is within 2 second. It’s fast enough.

  when Android graph is static, run command without ffplay :
  adb shell screenrecord --output-format=h264 -

  screenrecord will output H264 stream data immidiately then pause.(See picture below).
  stream data comes first

  Does the data contain all information of first frame graph ?
  If so, how to make ffplay to display it immidiately ?

  ---

  Question 2 : how to make ffplay to immidiately display the latest frame of video when Android screen suddenly become static ?

  When Android screen start casting and Android graph suddenly become static, H264 data stream transfer will pause, while PC graph is different with Android graph.

  For example, I make a popup menu on Android disappear, there has been a fadeoff animation, PC graph pauses and display a translucent popup menu.(See picture below)

  latest graph on pc

  The first and latest frames of stream doesn’t display in ffplay immidiately, they are "missing".
  when Android screen go on changing, the "missing" frames displays.
  So it seems like the latest frames are always in buffer.

  I’ve tried adding these params to ffplay :
  

  -noinfbuf
-fflags nobuffer
-max_delay 0
-sync ext
-preset ultrafast
-tune zerolatency

  
  They cannot solve the problems

  Modifing Android ROM or screenrecord source, making a pixel color changes every frame, may solve the problems(I guess), but it would enlarge data stream, it’s the last choise.
  Is there any solution by adding params of ffplay, or by modifing screenrecord or ffplay source code ?

  PS : mplayer also has the same problem :
  mplayer -demuxer h264es -

• ffprobe/ffmpeg exec doesn't return result on local machine, but works on production system

  27 juillet 2015, par Kinesias

  I want to get the duration of a movie, using ffprobe (part of ffmpeg).
  The command line I’m using is this :

  ffprobe -v error -show_entries format=duration -of
  
  default=noprint_wrappers=1:nokey=1
  
  path/to/video.mov

  It works perfectly in the shell, gives me a result of 4.5554 (seconds).

  However, if I call this command via exec on my local machine, I get an empty result.

  var_dump( exec("ffprobe -v .......") );
  
  returns string(0) ""

  Now comes the burner : It works perfectly on the production machine, though !!

  These are my configurations :

  Local machine:        Mac OS 10.9.5,      PHP 5.6.11   ffmpeg 2.7.1
  
  Production machine:   Mac OS Server 10.6  PHP 5.3.1    ffmpeg 2.7.2

  Is this kind of a bug in PHP 5.6 or something ???
  Thanks, Matt

• Audi0Segment.from_wav error : OSError : [Errno 2] No such file or directory

  19 mars 2019, par Coder123

  Does anyone know why I am receive a no file or directory error when i execute the code below ? I am using Python 2, FYI. Seems like an easy fix, but I can’t seem to identify it.

  Here is my code that i am using.

  import ffprobe
  
  import ffmpeg
  
  import pydub
  
  from pydub import AudioSegment
  
  
  
  
  
  AudioSegment.from_wav("/home/e136320/sample.wav").export("/output/file.mp3", format="mp3")

  Here is the error message when code is executed :

  OSErrorTraceback (most recent call last)
  
   in <module>()
  
        2 #sound.export("/home/e136320/sample.mp3", format="mp3")
  
        3 
  
  ----> 4 AudioSegment.from_wav("/home/e136320/sample.wav").export("/output/file.mp3", format="mp3")
  
  
  
  /home/e136320/.local/lib/python2.7/site-packages/pydub/audio_segment.pyc in from_wav(cls, file, parameters)
  
      726     @classmethod
  
      727     def from_wav(cls, file, parameters=None):
  
  --> 728         return cls.from_file(file, 'wav', parameters=parameters)
  
      729 
  
      730     @classmethod
  
  
  
  /home/e136320/.local/lib/python2.7/site-packages/pydub/audio_segment.pyc in from_file(cls, file, format, codec, parameters, **kwargs)
  
      663             stdin_data = file.read()
  
      664 
  
  --> 665         info = mediainfo_json(orig_file)
  
      666         if info:
  
      667             audio_streams = [x for x in info['streams']
  
  
  
  /home/e136320/.local/lib/python2.7/site-packages/pydub/utils.pyc in mediainfo_json(filepath)
  
      261 
  
      262     command = [prober, '-of', 'json'] + command_args
  
  --> 263     res = Popen(command, stdin=stdin_parameter, stdout=PIPE, stderr=PIPE)
  
      264     output, stderr = res.communicate(input=stdin_data)
  
      265     output = output.decode("utf-8", 'ignore')
  
  
  
  /opt/cloudera/parcels/Anaconda/lib/python2.7/subprocess.pyc in __init__(self, args, bufsize, executable, stdin, stdout, stderr, preexec_fn, close_fds, shell, cwd, env, universal_newlines, startupinfo, creationflags)
  
      388                                 p2cread, p2cwrite,
  
      389                                 c2pread, c2pwrite,
  
  --> 390                                 errread, errwrite)
  
      391         except Exception:
  
      392             # Preserve original exception in case os.close raises.
  
  
  
  /opt/cloudera/parcels/Anaconda/lib/python2.7/subprocess.pyc in _execute_child(self, args, executable, preexec_fn, close_fds, cwd, env, universal_newlines, startupinfo, creationflags, shell, to_close, p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite)
  
     1023                         raise
  
     1024                 child_exception = pickle.loads(data)
  
  -> 1025                 raise child_exception
  
     1026 
  
     1027 
  
  
  
  OSError: [Errno 2] No such file or directory
  
  </module>