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• A ffmpeg comman canwork in cmd but not in Python using subprocess.call() or os.system()

  6 juin 2018, par Starrysky

  I wanna transfer a .mp3 to .wav. This is my command :
  ffmpeg -i a.mp3 -ar 16000 -ac 1 -acodec pcm_s16le a.wav

  It worked well in cmd

  C:\Users\starrysky\Documents\GitHub\bing_pic\html>ffmpeg -i a.mp3 -ar 16000 -ac 1 -acodec pcm_s16le a.wav
  
  ffmpeg version N-86482-gbc40674 Copyright (c) 2000-2017 the FFmpeg developers
  
    built with gcc 7.1.0 (GCC)
  
    configuration: --enable-gpl --enable-version3 --enable-cuda --enable-cuvid --enable-d3d11va --enable-dxva2 --enable-libmfx --enable-nvenc --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-libzimg --enable-lzma --enable-zlib
  
    libavutil      55. 66.100 / 55. 66.100
  
    libavcodec     57. 99.100 / 57. 99.100
  
    libavformat    57. 73.100 / 57. 73.100
  
    libavdevice    57.  7.100 / 57.  7.100
  
    libavfilter     6. 92.100 /  6. 92.100
  
    libswscale      4.  7.101 /  4.  7.101
  
    libswresample   2.  8.100 /  2.  8.100
  
    libpostproc    54.  6.100 / 54.  6.100
  
  Input #0, mp3, from 'a.mp3':
  
    Metadata:
  
      encoder         : Lavf54.6.100
  
    Duration: 00:00:01.87, start: 0.000000, bitrate: 8 kb/s
  
      Stream #0:0: Audio: mp3, 8000 Hz, mono, s16p, 8 kb/s
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (mp3 (native) -> pcm_s16le (native))
  
  Press [q] to stop, [?] for help
  
  Output #0, wav, to 'a.wav':
  
    Metadata:
  
      ISFT            : Lavf57.73.100
  
      Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 16000 Hz, mono, s16, 256 kb/s
  
      Metadata:
  
        encoder         : Lavc57.99.100 pcm_s16le
  
  size=      59kB time=00:00:01.87 bitrate= 256.3kbits/s speed= 187x
  
  video:0kB audio:58kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.130208%

  but when I moved it into my python program, something strange happened.

  >>> C:\Users\starrysky\Documents\GitHub\bing_pic\html\
  
  'ffmpeg' �����ڲ����ⲿ���Ҳ���ǿ����еij���
  
  ���������ļ���
  
  1 Command 'ffmpeg -i a.mp3 -ar 16000 -ac 1 -acodec pcm_s16le a.wav' returned non-zero exit status 1.
  
  文件错误啊，亲
  
  [WinError 2] 系统找不到指定的文件。: 'a.wav'

  This is part of my python code :

  @bot.register(wife, RECORDING)
  
  def translate_sound(msg):
  
      msg.get_file(save_path='a.mp3')
  
      path = os.path.abspath('.')+'\\'
  
      print(path)
  
      try:
  
          subprocess.check_call('ffmpeg -i a.mp3 -ar 16000 -ac 1 -acodec pcm_s16le a.wav', shell=True)
  
          # ''
  
      except Exception as e:
  
          print(1, e)
  
      wav_to_text('a.wav')
  
      try:
  
          os.remove('a.wav')
  
      except Exception as e:
  
          print(e)

  ---

  # 调用百度语音识别API
  
  def get_token():
  
      URL = 'http://openapi.baidu.com/oauth/2.0/token'
  
      _params = urllib.parse.urlencode({'grant_type': b'client_credentials',
  
                                        'client_id': b''
  
                                        'client_secret': b''})
  
      _res = urllib.request.Request(URL, _params.encode())
  
      _response = urllib.request.urlopen(_res)
  
      _data = _response.read()
  
      _data = json.loads(_data)
  
      return _data['access_token']
  
  
  
  
  
  def wav_to_text(wav_file):
  
      try:
  
          wav_file = open(wav_file, 'rb')
  
      except IOError:
  
          print('文件错误啊，亲')
  
          return
  
      wav_file = wave.open(wav_file)
  
      n_frames = wav_file.getnframes()
  
      print('n_frames ', n_frames)
  
      frame_rate = wav_file.getframerate()
  
      print("frame_rate ", frame_rate)
  
      if n_frames == 1 or frame_rate not in (8000, 16000):
  
          print('不符合格式')
  
          return
  
      audio = wav_file.readframes(n_frames)
  
      seconds = n_frames/frame_rate+1
  
      minute = int(seconds/60 + 1)
  
      for i in range(0, minute):
  
          sub_audio = audio[i*60*frame_rate:(i+1)*60*frame_rate]
  
          base_data = base64.b64encode(sub_audio)
  
          data = {"format": "wav",
  
                  "token": get_token(),
  
                  "len": len(sub_audio),
  
                  "rate": frame_rate,
  
                  "speech": base_data.decode(),
  
                  "cuid": "B8-AC-6F-2D-7A-94",
  
                  "channel": 1}
  
          data = json.dumps(data)
  
          res = urllib.request.Request('http://vop.baidu.com/server_api',
  
                                data.encode(),
  
                                {'content-type': 'application/json'})
  
          response = urllib.request.urlopen(res)
  
          res_data = json.loads(response.read())
  
          try:
  
              print(res_data['result'][0])
  
          except Exception as e:
  
              print(e)

  What happened ?

• Google’s YouTube Uses FFmpeg

  9 février 2011, par Multimedia Mike — General

  Controversy arose last week when Google accused Microsoft of stealing search engine results for their Bing search engine. It was a pretty novel sting operation and Google did a good job of visually illustrating their side of the story on their official blog.

  This reminds me of the fact that Google’s YouTube video hosting site uses FFmpeg for converting videos. Not that this is in the same league as the search engine shenanigans (it’s perfectly legit to use FFmpeg in this capacity, but to my knowledge, Google/YouTube has never confirmed FFmpeg usage), but I thought I would revisit this item and illustrate it with screenshots. This is not new information— I first empirically tested this fact 4 years ago. However, a lot of people wonder how exactly I can identify FFmpeg on the backend when I claim that I’ve written code that helps power YouTube.

  Short Answer
  How do I know YouTube uses FFmpeg to convert multimedia ? Because :

  1. FFmpeg can decode a number of impossibly obscure multimedia formats using code I wrote
  2. YouTube can transcode many of the same formats
  3. I screwed up when I wrote the code to support some of these weird formats
  4. My mistakes are still present when YouTube transcodes certain fringe formats

  Longer Answer (With Pictures !)
  Let’s take a video format named RoQ, developed by noted game designer Graeme Devine. Originated for use in the FMV-heavy game The 11th Hour, the format eventually found its way into the Quake 3 engine as well as many games derived from the same technology.

  Dr. Tim Ferguson reverse engineered the format (though it would later be open sourced along with the rest of the Q3 engine). I wrote a RoQ playback system for FFmpeg, and I messed up in doing so. I believe my coding error helps demonstrate the case I’m trying to make here.

  Observe what happened when I pushed the jk02.roq sample through YouTube in my original experiment 4 years ago :

  
  
  

  Do you see how the canyon walls bleed into the sky ? That’s not supposed to happen. FFmpeg doesn’t do that anymore but I was able to go back into the source code history to find when it did do that :

  
  
  

  Academic Answer
  FFmpeg fixed this bug in June of 2007 (thanks to Eric Lasota). The problem had to do with premature colorspace conversion in my original decoder.

  Leftovers
  I tried uploading the video again to see if the problem persists in YouTube’s transcoder. First bit of trivia : YouTube detects when you have uploaded the same video twice and rejects the subsequent attempts. So I created a double concatenation of the video and uploaded it. The problem is gone, illustrating that the backend is actually using a newer version of FFmpeg. This surprises me for somewhat esoteric reasons.

  Here’s another interesting bit of trivia for those who don’t do a lot of YouTube uploading— YouTube reports format details when you upload a video :

  
  
  

  So, yep, RoQ format. And you can wager that this will prompt me to go back through the litany of unusual formats that FFmpeg supports to see how YouTube responds.

• Permissions issue with Python and ffmpeg on a Mac

  13 avril 2020, par EventHorizon

  I am fairly new to Python ( 4 weeks), and I have been struggling with this all day.

  



  I am using MacOS 10.13, Python 3.7 via Anaconda Navigator 1.9.12 and Spyder 4.0.1.

  



  Somehow (only a noob, remember) I had 2 Anaconda environments. I don't do production code, just research, so I figured I would make life simple and just use the base environment. I deleted the other environment.

  



  I had previously got FFmpeg working and was able to do frame grabs, build mpeg animations, and convert them to gifs for blog posts and such. I had FFmpeg installed in the directories associated with the deleted environment, so it went away.

  



  No worries, I got the git URL, used Terminal to install it in /opt/anaconda3/bin. It's all there and I can run FFmpeg from the Terminal.

  



  My problem : When I attempt to run a module that previously worked fine, I get the following message :

  



  [Errno 13] Permission denied : '/opt/anaconda3/bin/ffmpeg'

  



  In my module I set the default location of FFmpeg : plt.rcParams['animation.ffmpeg_path'] = '/opt/anaconda3/bin/ffmpeg'

  



  In my module I have the following lines :

  



  writer = animation.FFMpegWriter(fps=frameRate, metadata=metadata)
writer.setup(fig, "animation.mp4", 100)


  



  This calls matplotlib's 'animation.py', which runs the following :

  



  def setup(self, fig, outfile, dpi=None):
    '''
    Perform setup for writing the movie file.

    Parameters
    ----------
    fig : `~matplotlib.figure.Figure`
        The figure object that contains the information for frames
    outfile : str
        The filename of the resulting movie file
    dpi : int, optional
        The DPI (or resolution) for the file.  This controls the size
        in pixels of the resulting movie file. Default is fig.dpi.
    '''
    self.outfile = outfile
    self.fig = fig
    if dpi is None:
        dpi = self.fig.dpi
    self.dpi = dpi
    self._w, self._h = self._adjust_frame_size()

    # Run here so that grab_frame() can write the data to a pipe. This
    # eliminates the need for temp files.
    self._run()

def _run(self):
    # Uses subprocess to call the program for assembling frames into a
    # movie file.  *args* returns the sequence of command line arguments
    # from a few configuration options.
    command = self._args()
    _log.info('MovieWriter.run: running command: %s', command)
    PIPE = subprocess.PIPE
    self._proc = subprocess.Popen(
        command, stdin=PIPE, stdout=PIPE, stderr=PIPE,
        creationflags=subprocess_creation_flags)


  



  Everything works fine up to the last line (i.e. 'command' looks like a well-formatted FFmpeg command line, PIPE returns -1) but subprocess.Popen() bombs out with the error message above.

  



  I have tried changing file permissions - taking a sledgehammer approach and setting everything in /opt/anaconda3/bin/ffmpeg to 777, read, write, and execute. But that doesn't seem to make any difference. I really am clueless when it comes to Apple's OS, file permissions, etc. Any suggestions ?