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• Where is moviepy getting the video fps from ?

  7 février 2017, par Gloin

  I am using the Python 3 moviepy module for video editing, and I have a few videos that are taken in slow motion. When imported into moviepy, they are massively sped up, and then sit on the last frame for the rest of their duration. Note that, the videos are supposed to be normal for the first couple and last couple of seconds, then slow in the middle.

  Unfortunately, I cannot provide the actual video for you to test with, but here is the relevant metadata (fetched with the command ffprobe -v quiet -print_format json -show_format -show_streams slo-mo_movie.mov)

  "r_frame_rate": "240/1",                               
  
  "avg_frame_rate": "1679400/39481",
  
  "time_base": "1/2400",

  For comparison, here is the equivalent metadata from a video taken, I think, from the same phone, but without slo-mo :

  "r_frame_rate": "30/1",
  
  "avg_frame_rate": "143160/4771",
  
  "time_base": "1/600",

  I can import the videos in to moviepy with clip = VideoFileClip("path/to/file.mp4"), and then for each run print(clip.fps). The first video prints 2400 (not a typo from me !), and the second 30.

  Here is the moviepy code (in moviepy/video/io/ffmpeg_reader.py) at line 293) that gets the fps :

  # Get the frame rate. Sometimes it's 'tbr', sometimes 'fps', sometimes
  
  # tbc, and sometimes tbc/2...
  
  # Current policy: Trust tbr first, then fps. If result is near from x*1000/1001
  
  # where x is 23,24,25,50, replace by x*1000/1001 (very common case for the fps).
  
  
  
  try:
  
      match = re.search("( [0-9]*.| )[0-9]* tbr", line)
  
      tbr = float(line[match.start():match.end()].split(' ')[1])
  
      result['video_fps'] = tbr
  
  
  
  except:
  
      match = re.search("( [0-9]*.| )[0-9]* fps", line)
  
      result['video_fps'] = float(line[match.start():match.end()].split(' ')[1])
  
  
  
  
  
  # It is known that a fps of 24 is often written as 24000/1001
  
  # but then ffmpeg nicely rounds it to 23.98, which we hate.
  
  coef = 1000.0/1001.0
  
  fps = result['video_fps']
  
  for x in [23,24,25,30,50]:
  
      if (fps!=x) and abs(fps - x*coef) < .01:
  
          result['video_fps'] = x*coef
  
  
  
  if check_duration:
  
      result['video_nframes'] = int(result['duration']*result['video_fps'])+1
  
      result['video_duration'] = result['duration']
  
  else:
  
      result['video_nframes'] = 1
  
      result['video_duration'] = None
  
  # We could have also recomputed the duration from the number
  
  # of frames, as follows:
  
  # >>> result['video_duration'] = result['video_nframes'] / result['video_fps']

  If I set the slo-mo video’s fps using moviepy to 24, it outputs it the same (very fast, then still on the last frame), but if I set the slo-mo video’s fps to 20, then it outputs it correctly.

  Obviously video players like VLC player and Quicktime can correctly work out what frame speed to play, but moviepy/ffmpeg fails. Moviepy/ffmpeg is getting the wrong fps from somewhere.

  So, how can I get moviepy to automatically output them as they are supposed to be without human trial and error like above ?

• Inconsistant rendering in libmelt XML and C interface and 'hold' producer and avformat consumer

  14 octobre 2016, par Leif Andersen

  I am trying to create a short video that is just a single image. (I know its a bit silly, but its a test for something bigger).

  The code I have for rendering it is :

  #include <framework></framework>mlt.h>
  
  #include 
  
  #include 
  
  
  
  int main() {
  
    if(mlt_factory_init(NULL)) {
  
      mlt_profile p = mlt_profile_init(NULL);
  
      mlt_consumer target = mlt_factory_consumer(p, "avformat", 
  
      mlt_producer source = mlt_factory_producer(p, "hold", "/Users/leif/logo.png");
  
      mlt_producer_set_in_and_out(source, 0, 10);
  
      mlt_consumer_connect(target, mlt_producer_service(source));
  
      mlt_consumer_start(target);
  
  
  
      sleep(5);
  
      mlt_consumer_stop(target);
  
  
  
      mlt_consumer_close(target);
  
      mlt_producer_close(source);
  
      mlt_factory_close();
  
    } else {
  
      printf("No\n");
  
    }
  
  
  
    return 0;
  
  }

  Where logo.png is this file.

  When I run this code and play output.mp4, the picture comes out all garbelled. There is a green line in the middle and the logo is superimposed on itself a lot.

  On the other hand, if I change the consumer to be SDL, the image plays just fine.

  And finally, if I change the consumer to be XML, and then use the melt command line application to render it :

  melt -consumer avformat:xmlout.mp4 output.xml

  and play the video, it also plays fine.

  Is there something I am missing in the avformat consumer that I should be setting ? Or something else that I am missing here ?

  Edit : For reference, the outputted xml file : output.xml is :

  <?xml version="1.0" encoding="utf-8"?>
  
  <mlt version="6.2.0" root="/Users/leif/src/video/private" title="Anonymous Submission" parent="producer0" in="0" out="10">
  
        <profile description="DV/DVD PAL" width="720" height="576" progressive="0" colorspace="601"></profile>
  
    <producer title="Anonymous Submission" in="0" out="10">
  
      <property>15000</property>
  
      <property>pause</property>
  
      <property>/Users/leif/logo.png</property>
  
      <property>1.06667</property>
  
      <property>0</property>
  
      <property>onefield</property>
  
      <property>hold</property>
  
      <property>1</property>
  
    </producer>
  
  </mlt>

• Inconsistant rendering in mlt XML and C interface and 'hold' producer and avformat consumer

  14 octobre 2016, par Leif Andersen

  I am trying to create a short video that is just a single image. (I know its a bit silly, but its a test for something bigger).

  The code I have for rendering it is :

  #include <framework></framework>mlt.h>
  
  #include 
  
  #include 
  
  
  
  int main() {
  
    if(mlt_factory_init(NULL)) {
  
      mlt_profile p = mlt_profile_init(NULL);
  
      mlt_consumer target = mlt_factory_consumer(p, "avformat", 
  
      mlt_producer source = mlt_factory_producer(p, "hold", "/Users/leif/logo.png");
  
      mlt_producer_set_in_and_out(source, 0, 10);
  
      mlt_consumer_connect(target, mlt_producer_service(source));
  
      mlt_consumer_start(target);
  
  
  
      sleep(5);
  
      mlt_consumer_stop(target);
  
  
  
      mlt_consumer_close(target);
  
      mlt_producer_close(source);
  
      mlt_factory_close();
  
    } else {
  
      printf("No\n");
  
    }
  
  
  
    return 0;
  
  }

  Where logo.png is this file.

  When I run this code and play output.mp4, the picture comes out all garbelled. There is a green line in the middle and the logo is superimposed on itself a lot.

  On the other hand, if I change the consumer to be SDL, the image plays just fine.

  And finally, if I change the consumer to be XML, and then use the melt command line application to render it :

  melt -consumer avformat:xmlout.mp4 output.xml

  and play the video, it also plays fine.

  Is there something I am missing in the avformat consumer that I should be setting ? Or something else that I am missing here ?

  Edit : For reference, the outputted xml file : output.xml is :

  <?xml version="1.0" encoding="utf-8"?>
  
  <mlt version="6.2.0" root="/Users/leif/src/video/private" title="Anonymous Submission" parent="producer0" in="0" out="10">
  
        <profile description="DV/DVD PAL" width="720" height="576" progressive="0" colorspace="601"></profile>
  
    <producer title="Anonymous Submission" in="0" out="10">
  
      <property>15000</property>
  
      <property>pause</property>
  
      <property>/Users/leif/logo.png</property>
  
      <property>1.06667</property>
  
      <property>0</property>
  
      <property>onefield</property>
  
      <property>hold</property>
  
      <property>1</property>
  
    </producer>
  
  </mlt>