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• Can't save matplotlib animation

  19 novembre 2014, par renger

  I am trying to get a simple animation saved using ffmpeg. I followed a tutorial to install ffmpeg, and I can now access it from the command prompt.

  Now I run this piece of code :

  import numpy as np
  
  from matplotlib import pyplot as plt
  
  from matplotlib import animation
  
  
  
  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)
  
  
  
  mywriter = animation.FFMpegWriter()
  
  anim.save('mymovie.mp4',writer=mywriter)
  
  
  
  plt.show()

  I get this error :

  Traceback (most recent call last):
  
    File "<stdin>", line 1, in <module>
  
     File "C:\Python27\lib\site-packages\spyderlib\widgets\externalshell\sitecustomize.py", line 523, in runfile
  
      execfile(filename, namespace)
  
    File "C:\Users\Renger\.xy\startups\b.py", line 23, in <module>
  
      anim.save('mymovie.mp4',writer=mywriter)
  
    File "C:\Python27\lib\site-packages\matplotlib\animation.py", line 609, in save
  
      with writer.saving(self._fig, filename, dpi):
  
    File "C:\Python27\lib\contextlib.py", line 17, in __enter__
  
      return self.gen.next()
  
    File "C:\Python27\lib\site-packages\matplotlib\animation.py", line 166, in saving
  
      self.setup(*args)
  
    File "C:\Python27\lib\site-packages\matplotlib\animation.py", line 156, in setup
  
      self._run()
  
    File "C:\Python27\lib\site-packages\matplotlib\animation.py", line 183, in _run
  
      stdin=subprocess.PIPE)
  
    File "C:\Python27\lib\subprocess.py", line 711, in __init__
  
      errread, errwrite)
  
    File "C:\Python27\lib\subprocess.py", line 948, in _execute_child
  
      startupinfo)
  
  WindowsError: [Error 2] Het systeem kan het opgegeven bestand niet vinden
  
  </module></module></stdin>

  The last dutch sentence does mean something like : The system can’t find the specified file.

  What do these errors mean, and how can I solve them ?

• Buffering without transcoding with FFMPEG CLI Linux

  3 juillet 2017, par Deex

  I’m currently using ffmpeg on my server to transcode a 13Mbit stream down to 6Mbit. For my other broadcasts i’m using the NGINX RTMP module. Sometimes i got some bandwith breakdowns from my internet provider and i saw that the transcoded stream is much more stable, so i would ask you if its possible to use ffmpeg for buffering and to clean out bandwith issues without transcoding the whole video again.

• ffmpeg and pulse audio creating buzzy speech

  17 juin 2017, par flashape

  I’m attempting to record video and audio from an ec2 instance (Ubuntu 16.04), using xvfb and pulse audio. Everything works fine, except that the output file contains "buzzy" speech (not sure if this is what "clipping" is ?). This happens using either aac or mp3 audio codecs.

  Sample audio file : http://s000.tinyupload.com/index.php?file_id=86237391396073526211

  ffmpeg command :

  ffmpeg \
  
  -f x11grab -framerate 30 -video_size ${SCREEN_WIDTH}x${SCREEN_HEIGHT} -i :1.0 \
  
  -f pulse -i default \
  
  -c:v libx264 -preset veryfast -maxrate 2500k -bufsize 2500k -vf "format=yuv420p" -g 60 \
  
  -c:a aac -strict -2 -channel_layout stereo  -ab 256k -ar 48000 -bufsize 512k -ac 2  \
  
  -flags +global_header -f flv "test.mp4"

  The output from ffmpeg when I run the command :

  Input #0, x11grab, from ':1.0':
  
    Duration: N/A, start: 1497567394.762052, bitrate: N/A
  
      Stream #0:0: Video: rawvideo (BGR[0] / 0x524742), bgr0, 1360x764, 30 fps, 30 tbr, 1000k tbn, 30 tbc
  
  Guessed Channel Layout for  Input Stream #1.0 : stereo
  
  Input #1, pulse, from 'default':
  
    Duration: N/A, start: 1497567396.743667, bitrate: 1536 kb/s
  
      Stream #1:0: Audio: pcm_s16le, 48000 Hz, 2 channels, s16, 1536 kb/s
  
  [libx264 @ 0x1977d20] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 AVX2 LZCNT BMI2
  
  [libx264 @ 0x1977d20] profile High, level 3.2
  
  [libx264 @ 0x1977d20] 264 - core 148 r2643 5c65704 - H.264/MPEG-4 AVC codec - Copyleft 2003-2015 - http://www.videolan.org/x264.html - options: cabac=1 ref=1 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=2 psy=1 psy_rd=1.00:0.00 mixed_ref=0 me_range=16 chroma_me=1 trellis=0 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=0 threads=3 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=1 keyint=60 keyint_min=6 scenecut=40 intra_refresh=0 rc_lookahead=10 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 vbv_maxrate=2500 vbv_bufsize=512 crf_max=0.0 nal_hrd=none filler=0 ip_ratio=1.40 aq=1:1.00
  
  Output #0, flv, to 'test.mp4':
  
    Metadata:
  
      encoder         : Lavf56.40.101
  
      Stream #0:0: Video: h264 (libx264) ([7][0][0][0] / 0x0007), yuv420p, 1360x764, q=-1--1, max. 2500 kb/s, 30 fps, 1k tbn, 30 tbc
  
      Metadata:
  
        encoder         : Lavc56.60.100 libx264
  
      Stream #0:1: Audio: aac ([10][0][0][0] / 0x000A), 48000 Hz, stereo, fltp, 256 kb/s
  
      Metadata:
  
        encoder         : Lavc56.60.100 aac
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (rawvideo (native) -> h264 (libx264))
  
    Stream #1:0 -> #0:1 (pcm_s16le (native) -> aac (native))

  Based on various posts, I thought it might be something in the pulse config, particularly the "resample-method" setting, but that doesn’t appear to do anything. Here is how the /etc/pulse/daemon.conf config file currently stands :

  ; daemonize = no
  
  ; fail = yes
  
  ; allow-module-loading = yes
  
  ; allow-exit = yes
  
  ; use-pid-file = yes
  
  ; system-instance = no
  
  ; local-server-type = user
  
  ; enable-shm = yes
  
  ; shm-size-bytes = 0 # setting this 0 will use the system-default, usually 64 MiB
  
  ; lock-memory = no
  
  ; cpu-limit = no
  
  
  
  ; high-priority = yes
  
  ; nice-level = -11
  
  
  
  ; realtime-scheduling = yes
  
  ; realtime-priority = 5
  
  
  
  ; exit-idle-time = 20
  
  ; scache-idle-time = 20
  
  
  
  ; dl-search-path = (depends on architecture)
  
  
  
  ; load-default-script-file = yes
  
  ; default-script-file = /etc/pulse/default.pa
  
  
  
  ; log-target = auto
  
  ; log-level = notice
  
  ; log-meta = no
  
  ; log-time = no
  
  ; log-backtrace = 0
  
  
  
  ; resample-method = speex-float-1
  
  ; resample-method = speex-float-10
  
  resample-method = speex-fixed-10
  
  ; enable-remixing = yes
  
  enable-lfe-remixing = yes
  
  ; lfe-crossover-freq = 120
  
  
  
  flat-volumes = no
  
  
  
  ; rlimit-fsize = -1
  
  ; rlimit-data = -1
  
  ; rlimit-stack = -1
  
  ; rlimit-core = -1
  
  ; rlimit-as = -1
  
  ; rlimit-rss = -1
  
  ; rlimit-nproc = -1
  
  ; rlimit-nofile = 256
  
  ; rlimit-memlock = -1
  
  ; rlimit-locks = -1
  
  ; rlimit-sigpending = -1
  
  ; rlimit-msgqueue = -1
  
  ; rlimit-nice = 31
  
  ; rlimit-rtprio = 9
  
  ; rlimit-rttime = 200000
  
  
  
  ; default-sample-format = s16le
  
  default-sample-format = s32le
  
  default-sample-rate = 44100
  
  ; default-sample-rate = 48000
  
  ; alternate-sample-rate = 48000
  
  alternate-sample-rate = 44100
  
  ; default-sample-channels = 2
  
  ; default-channel-map = front-left,front-right
  
  
  
  ; default-fragments = 4
  
  ; default-fragment-size-msec = 25
  
  ; default-fragments = 4
  
  ; default-fragment-size-msec = 25
  
  
  
  
  
  ; enable-deferred-volume = yes
  
  deferred-volume-safety-margin-usec = 1
  
  ; deferred-volume-extra-delay-usec = 0

  Edit :

  Ok, updated the ffmpeg command to capture only the audio, but still have the same issue :

  ffmpeg \
  
  -f pulse -i default \
  
  -c:a aac -strict -2 -channel_layout stereo  -ab 256k -ar 48000 -bufsize 512k -ac 2  \
  
  test.aac

  I do get some interesting messages in the output about timestamps being off :

  [aac @ 0x12a4900] Queue input is backward in timeits/s
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 182857 >= 175924
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 182857 >= 176948
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 182857 >= 177972
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 182857 >= 178996
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 182857 >= 180020
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 182857 >= 181044
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 182857 >= 182068
  
  [aac @ 0x12a4900] Queue input is backward in time
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 183406
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 184430
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 185454
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 186478
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 187502
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 188526
  
  [aac @ 0x12a4900] Queue input is backward in time
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 189550
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 190574
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 169622
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 170646
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 171670
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 172694
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 173718
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 174742
  
  [aac @ 0x12a4900] Queue input is backward in time
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 175766
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 176790
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 157020
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 158083
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 159107
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 160131
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 161155
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 162179
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 163203
  
  [aac @ 0x12a4900] Queue input is backward in time
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 164227
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 165251
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 154697
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 159400
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 160424
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 161448
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 162472
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 163496
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 164520
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 165544
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 166568
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 171795
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 172819
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 173843
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 174867
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 175891
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 176915
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 177939
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 178963
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 187279
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 189829
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 190853
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 191877
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 193354 >= 192901
  
  [aac @ 0x12a4900] Queue input is backward in time
  
      Last message repeated 2 times
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 216609 >= 216172
  
  [aac @ 0x12a4900] Queue input is backward in time
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 216609 >= 214950
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 216609 >= 214933
  
  [adts @ 0x12a35a0] Application provided invalid, non monotonically increasing dts to muxer in stream 0: 216609 >= 214836