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• How do I get duration of an In Memory Video in Python / Django ?

  21 novembre 2019, par Lucas Tonon

  So I was successfully using the following code to get the duration of a saved video in Django.

  def get_video_length(file_path):
  
  command = [
  
      'ffprobe',
  
      '-v',
  
      'error',
  
      '-show_entries',
  
      'format=duration',
  
      '-of',
  
      'default=noprint_wrappers=1:nokey=1',
  
      file_path
  
    ]
  
  
  
  try:
  
      output = check_output( command, stderr=STDOUT ).decode()
  
  except CalledProcessError as e:
  
      output = e.output.decode()
  
  
  
  return output

  But now I need to get the duration of an uploaded file before saving it.
  I have a serializer with a FileField and on validate method I should check the video duration.
  For instance :

  class VideoSerializer(serializers.Serializer):
  
  video = serializers.FileField(required=True, validators=[validate_media_extension, validate_video_duration])

  Then on validate_video_duration I needed to call some method like get_video_length, but I need an alternative to get the duration from the video in memory. The object that I have is an instance of InMemoryUploadedFile (https://docs.djangoproject.com/en/2.2/_modules/django/core/files/uploadedfile/)

• releases doc formating

  13 février 2013, par jonrohan

  m docs/releases.md
  

  releases doc formating

• ffmpeg : avfilter's anull says "Rematrix is needed between stereo and 0 channels but there is not enough information to do it"

  12 juillet 2017, par kuanyui

  I’m trying to write a transcoder according to FFMpeg’s official example with ffmpeg 3.2.4 (official prebuild Win32), and try to transcode a video with stereo audio stream source (from avformat’s dshow).

  In the example code, which passes anull into avfilter_graph_parse_ptr() for audio stream, and "time_base=1/44100:sample_rate=44100:sample_fmt=s16:channels=2:channel_layout=0x3" is passed into avfilter_graph_create_filter(), occurs error in the following avfilter_graph_config() :

  [auto-inserted scaler 0 @ 32f77600] w:iw h:ih flags:'bilinear' interl:0
  
  [Parsed_null_0 @ 2e9d79a0] auto-inserting filter 'auto-inserted scaler 0' between the filter 'in' and the filter 'Parsed_null_0'
  
  [swscaler @ 3331bfe0] deprecated pixel format used, make sure you did set range correctly
  
  [auto-inserted scaler 0 @ 32f77600] w:1920 h:1080 fmt:yuvj422p sar:1/1 -> w:1920 h:1080 fmt:yuv420p sar:1/1 flags:0x2
  
  [libmp3lame @ 2e90a360] Channel layout not specified
  
  [in @ 3866e8a0] tb:1/44100 samplefmt:s16 samplerate:44100 chlayout:0x3
  
  [Parsed_anull_0 @ 330e8820] auto-inserting filter 'auto-inserted resampler 0' between the filter 'in' and the filter 'Parsed_anull_0'
  
  [auto-inserted resampler 0 @ 330e8dc0] [SWR @ 3809b620] Rematrix is needed between stereo and 0 channels but there is not enough information to do it
  
  [auto-inserted resampler 0 @ 330e8dc0] Failed to configure output pad on auto-inserted resampler 0

  I’ve googled for days but didn’t find any clue for it. Doesn’t what anull do is only "Pass the audio source unchanged to the output", why libav want to resample stereo to 0 channel ? What’s going wrong ?