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• ffmpeg command line for capturing (and recording) audio and video in 720p from decklink card using Windows 7

  24 novembre 2014, par Huron

  I am trying to capture audio and video from a blackmagic decklink capture card using Windows 7 @ 720p, but I cant seem to get the ffmpeg command line settings right.

  ffmpeg -list_devices true -f dshow -i dummy

  [dshow @ 02457a60] DirectShow video devices
  
  [dshow @ 02457a60]  "Blackmagic WDM Capture"
  
  [dshow @ 02457a60]  "Decklink Video Capture"
  
  [dshow @ 02457a60] DirectShow audio devices
  
  [dshow @ 02457a60]  "Decklink Audio Capture"

  ffmpeg -list_options true -f dshow -i video="Decklink Video Capture"

  [dshow @ 03c2ea20] DirectShow video device options
  
  [dshow @ 03c2ea20]  Pin "Capture"
  
  [dshow @ 03c2ea20]   pixel_format=uyvy422  min s=720x486 fps=29.97 max s=720x486 fps=29.97
  
  [dshow @ 03c2ea20]   pixel_format=uyvy422  min s=720x486 fps=23.976 max s=720x486 fps=23.976
  
  [dshow @ 03c2ea20]   pixel_format=uyvy422  min s=720x576 fps=25 max s=720x576 fps=25
  
  [dshow @ 03c2ea20]   pixel_format=uyvy422  min s=720x486 fps=59.9402 max s=720x486 fps=59.9402
  
  [dshow @ 03c2ea20]   pixel_format=uyvy422  min s=720x576 fps=50 max s=720x576 fps=50
  
  [dshow @ 03c2ea20]   pixel_format=uyvy422  min s=1920x1080 fps=23.976 max s=1920x1080 fps=23.976
  
  [dshow @ 03c2ea20]   pixel_format=uyvy422  min s=1920x1080 fps=24 max s=1920x1080 fps=24
  
  [dshow @ 03c2ea20]   pixel_format=uyvy422  min s=1920x1080 fps=25 max s=1920x1080 fps=25
  
  [dshow @ 03c2ea20]   pixel_format=uyvy422  min s=1920x1080 fps=29.97 max s=1920x1080 fps=29.97
  
  [dshow @ 03c2ea20]   pixel_format=uyvy422  min s=1920x1080 fps=30 max s=1920x1080 fps=30
  
  [dshow @ 03c2ea20]   pixel_format=uyvy422  min s=1280x720 fps=50 max s=1280x720fps=50
  
  [dshow @ 03c2ea20]   pixel_format=uyvy422  min s=1280x720 fps=59.9402 max s=1280x720 fps=59.9402
  
  [dshow @ 03c2ea20]   pixel_format=uyvy422  min s=1280x720 fps=60.0002 max s=1280x720 fps=60.0002

  ffmpeg -list_options true -f dshow -i audio="Decklink Audio Capture"

  [dshow @ 047fea20] DirectShow audio device options
  
  [dshow @ 047fea20]  Pin "Capture"
  
  [dshow @ 047fea20]   min ch=1 bits=16 rate= 48000 max ch=1 bits=16 rate= 48000
  
  [dshow @ 047fea20]   min ch=2 bits=16 rate= 48000 max ch=2 bits=16 rate= 48000
  
  [dshow @ 047fea20]   min ch=4 bits=16 rate= 48000 max ch=4 bits=16 rate= 48000
  
  [dshow @ 047fea20]   min ch=6 bits=16 rate= 48000 max ch=6 bits=16 rate= 48000
  
  [dshow @ 047fea20]   min ch=8 bits=16 rate= 48000 max ch=8 bits=16 rate= 48000
  
  [dshow @ 047fea20]   min ch=10 bits=16 rate= 48000 max ch=10 bits=16 rate= 48000
  
  [dshow @ 047fea20]   min ch=12 bits=16 rate= 48000 max ch=12 bits=16 rate= 48000
  
  [dshow @ 047fea20]   min ch=16 bits=16 rate= 48000 max ch=16 bits=16 rate= 48000

  This is the stream information for my current video/audio source, connected to the decklink card’s hdmi port

  Stream #0:0: Video: rawvideo (UYVY / 0x59565955), uyvy422(tv), 1280x720, 59.94 tbr, 10000k tbn, 59.94 tbc
  
  Stream #0:1: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s

  Ultimately I will need to display this video on screen. And simultaneously be able to start and stop recording, while the preview keeps playing.

  My idea was to use ffmpeg to capture the video and audio signal and transmit this to a network stream (eg 127.0.0.1:6666). Then use VLC player to display the stream (the preview). And ultimately start and/or stop another ffmpeg to save that same stream to disk.

  In my mind this works, but I am no audio/video expert so if anyone with more experience could help out, I would appreciate it.

  Update :

  I have been able to display the video using ffplay, with the following command :

  ffplay -f dshow -video_size 1280x720 -rtbufsize 702000k -framerate 60 -i video="Decklink Video Capture":audio="Decklink Audio Capture" -threads 2

  Next step is streaming it so I can view the stream (preview) with VLC.

  Tried to use this command :

  ffmpeg -f dshow -video_size 1280x720 -rtbufsize 702000k -framerate 60 -i video="Decklink Video Capture":audio="Decklink Audio Capture" -threads 2 -f mpegts rtp://127.0.0.1:6666?pkt_size=188?buffer_size=65535

  Which does not give any errors, so appears to work. But when I try to open the stream in VLC I get the following error :

  SDP required :
  A description in SDP format is required to receive the RTP stream. Note that rtp :// URIs cannot work with dynamic RTP payload format (65).

  After a bit of reading it seems I should not be streaming to rtp :// but rather to udp ://

  Command became :

  ffmpeg -f dshow -video_size 1280x720 -rtbufsize 702000k -framerate 60 -i video="Decklink Video Capture":audio="Decklink Audio Capture" -threads 2 -f mpegts udp://127.0.0.1:6666?pkt_size=188?buffer_size=65535

  And when I try to open it now in VLC I get no error, no warning, but also no video.

  Time for some more reading.

• FFMPEG fdk_aac Static Windows Builds

  24 avril 2015, par Benny Chen

  I’m new in FFMPEG. I have download ffmpeg windows build but libfdk_aac is not enabled. Where I can get the ffmpeg build with complete encoder with libfdk enabled ?

• Cannot save animation in matplotlib : Windows permission denied

  13 mai 2015, par Vladimir

  I’ve been trying for a day long to sort this out, checking similar threads but with no success.
  Stretch’s Cannot save matplotlib animation with ffmpeg helped with previous errors (I had ffmpeg path wrong), but I kept getting Access denied after fixing it.

  My ffmpeg binary is on C:\ffmpeg\bin

  A nice alternative would be to able to export gif files, but I keep getting an ascii error with imagemagick. I think both problems are related, so I wanted to sort out the ffmpeg first.

  I think the problem might have to do with the fact I’m working with Canopy (in Windows 8 64bit), which pretty much hegemonized my path variable and broke some things along the way (e.g. I can’t open IDLE since I installed Canopy, didn’t tried to fix that yet). As I fixed things along the way I found at least 3 distinct path variables, all of which I updated : windows advanced settings path (set manually), windows console path (set via console with setx), and sys.path (set or checked at runtime), adding ";C:\ffmpeg\bin", where ffmpeg effectively is. Regardless I sort out the problem or not, I would like to learn which of these environment variables are relevant for what, I find it very confusing.

  The code is the following :

  # -*- coding: utf-8 -*-
  
  import sys
  
  import numpy as np
  
  from matplotlib import pyplot as plt
  
  from matplotlib import animation
  
  plt.rcParams['animation.ffmpeg_path'] = r'C:\ffmpeg\bin'
  
  if r'C:\ffmpeg\bin' not in sys.path: sys.path.append(r'C:\ffmpeg\bin')
  
  
  
  fig = plt.figure()
  
  ax = plt.axes(xlim=(0, 2), ylim=(-2, 2))
  
  line, = ax.plot([], [], lw=2)
  
  
  
  def init():
  
      line.set_data([], [])
  
      return line,
  
  
  
  def animate(i):
  
      x = np.linspace(0, 2, 1000)
  
      y = np.sin(2 * np.pi * (x - 0.01 * i))
  
      line.set_data(x, y)
  
      return line,
  
  
  
  anim = animation.FuncAnimation(fig, animate, init_func=init, frames=200, interval=20, blit=True)
  
  plt.show()
  
  
  
  # This case generates Windows err: Access Denied
  
  FFwriter = animation.FFMpegWriter()
  
  # anim.save(r'C:\basic_animation.mp4', writer = FFwriter, fps=30)
  
  
  
  # This case generates UnicodeDecodeError:'ascii' codec can't decode byte 0xa0 in position 3
  
  # anim.save(r'C:\animation.gif', writer='imagemagick', fps=30)

  The traceback for anim.save(r'C:\basic_animation.mp4', writer = FFwriter, fps=30) :

  %run "C:\Users\Yahveh\Documents\Vlad\Investigacion\animation saving.py"
  
  ---------------------------------------------------------------------------
  
  WindowsError                              Traceback (most recent call last)
  
  C:\Users\Yahveh\Documents\Vlad\Investigacion\animation saving.py in <module>()
  
       27 # This case generates Windows err: Access Denied
  
       28 FFwriter = animation.FFMpegWriter()
  
  ---> 29 anim.save(r'C:\basic_animation.mp4', writer = FFwriter, fps=30)
  
       30 
  
       31 # This case generates UnicodeDecodeError:'ascii' codec can't decode byte 0xa0 in position 3
  
  
  
  C:\Users\Yahveh\AppData\Local\Enthought\Canopy\User\lib\site-packages\matplotlib\animation.pyc in save(self, filename, writer, fps, dpi, codec, bitrate, extra_args, metadata, extra_anim, savefig_kwargs)
  
      759         # since GUI widgets are gone. Either need to remove extra code to
  
      760         # allow for this non-existant use case or find a way to make it work.
  
  --> 761         with writer.saving(self._fig, filename, dpi):
  
      762             for data in zip(*[a.new_saved_frame_seq()
  
      763                               for a in all_anim]):
  
  
  
  C:\Users\Yahveh\AppData\Local\Enthought\Canopy\App\appdata\canopy-1.5.2.2785.win-x86_64\lib\contextlib.pyc in __enter__(self)
  
       15     def __enter__(self):
  
       16         try:
  
  ---> 17             return self.gen.next()
  
       18         except StopIteration:
  
       19             raise RuntimeError("generator didn't yield")
  
  
  
  C:\Users\Yahveh\AppData\Local\Enthought\Canopy\User\lib\site-packages\matplotlib\animation.pyc in saving(self, *args)
  
      184         '''
  
      185         # This particular sequence is what contextlib.contextmanager wants
  
  --> 186         self.setup(*args)
  
      187         yield
  
      188         self.finish()
  
  
  
  C:\Users\Yahveh\AppData\Local\Enthought\Canopy\User\lib\site-packages\matplotlib\animation.pyc in setup(self, fig, outfile, dpi, *args)
  
      174         # Run here so that grab_frame() can write the data to a pipe. This
  
      175         # eliminates the need for temp files.
  
  --> 176         self._run()
  
      177 
  
      178     @contextlib.contextmanager
  
  
  
  C:\Users\Yahveh\AppData\Local\Enthought\Canopy\User\lib\site-packages\matplotlib\animation.pyc in _run(self)
  
      202                                       stdout=output, stderr=output,
  
      203                                       stdin=subprocess.PIPE,
  
  --> 204                                       creationflags=subprocess_creation_flags)
  
      205 
  
      206     def finish(self):
  
  
  
  C:\Users\Yahveh\AppData\Local\Enthought\Canopy\App\appdata\canopy-1.5.2.2785.win-x86_64\lib\subprocess.pyc in __init__(self, args, bufsize, executable, stdin, stdout, stderr, preexec_fn, close_fds, shell, cwd, env, universal_newlines, startupinfo, creationflags)
  
      707                                 p2cread, p2cwrite,
  
      708                                 c2pread, c2pwrite,
  
  --> 709                                 errread, errwrite)
  
      710         except Exception:
  
      711             # Preserve original exception in case os.close raises.
  
  
  
  C:\Users\Yahveh\AppData\Local\Enthought\Canopy\App\appdata\canopy-1.5.2.2785.win-x86_64\lib\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)
  
      955                                          env,
  
      956                                          cwd,
  
  --> 957                                          startupinfo)
  
      958             except pywintypes.error, e:
  
      959                 # Translate pywintypes.error to WindowsError, which is
  
  
  
  WindowsError: [Error 5] Acceso denegado 
  
  </module>

  The traceback for anim.save(r'C:\animation.gif', writer='imagemagick', fps=30) :

  In [8]: %run "C:\Users\Yahveh\Documents\Vlad\Investigacion\animation saving.py"
  
  ---------------------------------------------------------------------------
  
  UnicodeDecodeError                        Traceback (most recent call last)
  
  C:\Users\Yahveh\Documents\Vlad\Investigacion\animation saving.py in <module>()
  
       30 
  
       31 # This case generates UnicodeDecodeError:'ascii' codec can't decode byte 0xa0 in position 3
  
  ---> 32 anim.save(r'C:\animation.gif', writer='imagemagick', fps=30)
  
  
  
  C:\Users\Yahveh\AppData\Local\Enthought\Canopy\User\lib\site-packages\matplotlib\animation.pyc in save(self, filename, writer, fps, dpi, codec, bitrate, extra_args, metadata, extra_anim, savefig_kwargs)
  
      765                     # TODO: Need to see if turning off blit is really necessary
  
      766                     anim._draw_next_frame(d, blit=False)
  
  --> 767                 writer.grab_frame(**savefig_kwargs)
  
      768 
  
      769         # Reconnect signal for first draw if necessary
  
  
  
  C:\Users\Yahveh\AppData\Local\Enthought\Canopy\User\lib\site-packages\matplotlib\animation.pyc in grab_frame(self, **savefig_kwargs)
  
      225             verbose.report('MovieWriter -- Error '
  
      226                            'running proc:\n%s\n%s' % (out,
  
  --> 227                                                       err), level='helpful')
  
      228             raise
  
      229 
  
  
  
  UnicodeDecodeError: 'ascii' codec can't decode byte 0xa0 in position 3: ordinal not in range(128) 
  
  </module>

  Stared at them for a while.

  Thanks for your time !

  UPDATE : I followed the steps in this post for granting access to both C :\ffmpeg and destination folder, but no luck :(