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• cpu.c:253 : x264_cpu_detect : Assertion

  12 octobre 2017, par user6341251

  environment :
  ubuntu 16.04_x64 server
  install ffmpeg through apt-get install
  python 3
  

  when I try

  from moviepy.editor import *
clip = VideoFileClip("/root/video.mp4")
clip.ipython_display(width=280)

  Traceback (most recent call last) :
  File "", line 1, in
  File "/usr/local/lib/python2.7/dist-packages/moviepy/video/io/html_tools.py", line 219, in ipython_display
  center=center, rd_kwargs=rd_kwargs, **html_kwargs))
  File "/usr/local/lib/python2.7/dist-packages/moviepy/video/io/html_tools.py", line 97, in html_embed
  clip.write_videofile(**kwargs)
  File "", line 2, in write_videofile
  File "/usr/local/lib/python2.7/dist-packages/moviepy/decorators.py", line 54, in requires_duration
  return f(clip, *a, **k)
  File "", line 2, in write_videofile
  File "/usr/local/lib/python2.7/dist-packages/moviepy/decorators.py", line 137, in use_clip_fps_by_default
  return f(clip, *new_a, **new_kw)
  File "", line 2, in write_videofile
  File "/usr/local/lib/python2.7/dist-packages/moviepy/decorators.py", line 22, in convert_masks_to_RGB
  return f(clip, *a, **k)
  File "/usr/local/lib/python2.7/dist-packages/moviepy/video/VideoClip.py", line 349, in write_videofile
  progress_bar=progress_bar)
  File "/usr/local/lib/python2.7/dist-packages/moviepy/video/io/ffmpeg_writer.py", line 216, in ffmpeg_write_video
  writer.write_frame(frame)
  File "/usr/local/lib/python2.7/dist-packages/moviepy/video/io/ffmpeg_writer.py", line 178, in write_frame
  raise IOError(error)
  IOError : [Errno 32] Broken pipe

  MoviePy error : FFMPEG encountered the following error while writing file temp.mp4 :

  ffmpeg : common/cpu.c:253 : x264_cpu_detect : Assertion ` !(cpu&(0x0000040|0x0000080))’ failed.

  what happend ?

  ---

  @Ronald S. Bultje
  

  I am using a virtual machine

  processor : 0
  vendor_id : GenuineIntel
  cpu family : 6
  model : 13
  model name : QEMU Virtual CPU version (cpu64-rhel6)
  stepping : 3
  microcode : 0x1
  cpu MHz : 3504.000
  cache size : 4096 KB
  physical id : 0
  siblings : 1
  core id : 0
  cpu cores : 1
  apicid : 0
  initial apicid : 0
  fpu : yes
  fpu_exception : yes
  cpuid level : 13
  wp : yes
  flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pse36 clflush mmx fxsr sse sse2 ss syscall nx pdpe1gb rdtscp lm rep_good nopl eagerfpu pni pclmulqdq ssse3 fma cx16 pcid sse4_1 sse4_2 x2apic movbe popcnt aes xsave avx f16c rdrand hypervisor lahf_lm abm fsgsbase bmi1 avx2 smep bmi2 xsaveopt
  bugs :
  bogomips : 7008.00
  clflush size : 64
  cache_alignment : 64
  address sizes : 39 bits physical, 48 bits virtual
  power management :
  

• Killing python ffmpeg subprocess breaks cli output

  27 septembre 2017, par JayLev

  I’m trying to execute a system command with subprocess and reading the output.

  But if the command takes more than 10 seconds I want to kill the subprocess.

  I’ve tried doing this in several ways.

  My last try was inspired by this post : https://stackoverflow.com/a/3326559/969208

  Example :

  import os
  
  import signal
  
  from subprocess import Popen, PIPE
  
  
  
  class Alarm(Exception):
  
      pass
  
  
  
  def alarm_handler(signum, frame):
  
      raise Alarm
  
  
  
  def pexec(args):
  
  
  
      p = Popen(args, stdout=PIPE, stderr=PIPE)
  
  
  
      signal.signal(signal.SIGALRM, alarm_handler)
  
      signal.alarm(10)
  
  
  
      stdout = stderr = ''
  
      try:
  
          stdout, stderr = p.communicate()
  
          signal.alarm(0)
  
      except Alarm:
  
          try:
  
              os.kill(p.pid, signal.SIGKILL)
  
          except:
  
              pass
  
  
  
      return (stdout, stderr)

  The problem is : After the program exits no chars are shown in the cli until I hit return. And hitting return will not give me a new line.

  I suppose this has something to do with the stdout and stderr pipe.

  I’ve tried flushing and reading from the pipe (p.stdout.flush())

  I’ve also tried with different Popen args, but might’ve missed something. Just thought I’d keep it simple here.

  I’m running this on a Debian server.

  Am I missing something here ?

  EDIT :

  It seems this is only the case when killing an ongoing ffmpeg process. If the ffmpeg process exits normally before 10 seconds, there is no problem at all.

  I’ve tried executing a couple of different command that take longer than 10 seconds, one who prints output, one who doesn’t and a ffmpeg command to check the integrity of a file.

  args = ['sleep', '12s'] # Works fine
  
  args = ['ls', '-R', '/var'] # Works fine, prints lots for a long time
  
  args = ['ffmpeg', '-v', '1', '-i', 'large_file.mov','-f', 'null', '-'] # Breaks cli output

  I believe ffmpeg prints using \r and prints everything on the strerr pipe. Can this be the cause ? Any ideas how to fix it ?

• FFmpeg what exactly is the filtergraph pipeline like during transcoding ?

  8 septembre 2017, par Jeff Gong

  I have been studying the source code for FFmpeg to attempt to understand its threading model and how it processes inputs. For example, when I run a command like :

  ffmpeg -i video.mp4 -s hd720 -c:v libx264 --preset medium -c:a aac -profile:v main -r 60 -f null /dev/null

  The input itself is irrelevant, but I am trying to understand how the transcoding pipeline works. In the source code, I see that the main steps occur in the functions transcode and transcode_step.

  It seems like for a single input, a single frame is read in, decoded, encoded, and written out. The process is obviously very complex but what I am really not understanding is what FFmpeg is doing when it attempts to build out a filtergraph. For example, in transcode_step of ffmpeg.c, there is the following code that happens right after an output stream has been selected :

  if (ost->filter && !ost->filter->graph->graph) {
  
      if (ifilter_has_all_input_formats(ost->filter->graph)) {
  
          ret = configure_filtergraph(ost->filter->graph);
  
          if (ret < 0) {
  
              av_log(NULL, AV_LOG_ERROR, "Error reinitializing filters!\n");
  
              return ret;
  
          }
  
      }
  
  }

  Does this only apply if I specify a specific series of filtering options to FFmpeg, like the one in this link ? For the sample command I input above, is this code still executed ?

  One last other question I had was for the case where I run an FFmpeg instance with a single input but multiple outputs (perhaps different variants for transcoding). In this scenario, does a single phase of transcode_step take in an input frame and send that frame through decoding and encoding for only a single one of the outputs ? Or does it take a frame at a time and process this frame for each of the outputs we have specified ?