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• Artifacts after HEVC 10-bit encoding using NVENC

  18 juillet 2017, par Cryman

  Recently I purchased a brand new GPU - AORUS GeForce GTX 1080 Ti. I found out that it supports HEVC 10-bit encoding, so I wanted to give that a try. Unfortunately, after encoding I noticed some artifacts, which occur in dark scenes and last one frame of the video. You can see them on these screenshots :

  

  

  I was wondering if someone could help me figure out what might be the cause of these artifacts and how I can get rid of them.

  Here is the MI of the source video :

  ID                                       : 1
  
  Format                                   : AVC
  
  Format/Info                              : Advanced Video Codec
  
  Format profile                           : High@L4.1
  
  Format settings, CABAC                   : Yes
  
  Format settings, ReFrames                : 4 frames
  
  Codec ID                                 : V_MPEG4/ISO/AVC
  
  Duration                                 : 2 h 2 min
  
  Bit rate mode                            : Variable
  
  Bit rate                                 : 29.5 Mb/s
  
  Maximum bit rate                         : 37.0 Mb/s
  
  Width                                    : 1 920 pixels
  
  Height                                   : 1 080 pixels
  
  Display aspect ratio                     : 16:9
  
  Frame rate mode                          : Constant
  
  Frame rate                               : 23.976 (24000/1001) FPS
  
  Color space                              : YUV
  
  Chroma subsampling                       : 4:2:0
  
  Bit depth                                : 8 bits
  
  Scan type                                : Progressive
  
  Bits/(Pixel*Frame)                       : 0.593
  
  Stream size                              : 25.2 GiB (66%)
  
  Language                                 : English
  
  Default                                  : Yes
  
  Forced                                   : No

  And here is the MI of the encoded video :

  ID                                       : 1
  
  Format                                   : HEVC
  
  Format/Info                              : High Efficiency Video Coding
  
  Format profile                           : Main 10@L4@Main
  
  Codec ID                                 : V_MPEGH/ISO/HEVC
  
  Duration                                 : 2 h 2 min
  
  Bit rate                                 : 3 689 kb/s
  
  Width                                    : 1 920 pixels
  
  Height                                   : 800 pixels
  
  Display aspect ratio                     : 2.40:1
  
  Frame rate mode                          : Constant
  
  Frame rate                               : 23.976 (24000/1001) FPS
  
  Standard                                 : Component
  
  Color space                              : YUV
  
  Chroma subsampling                       : 4:2:0
  
  Bit depth                                : 10 bits
  
  Bits/(Pixel*Frame)                       : 0.100
  
  Stream size                              : 3.15 GiB (95%)
  
  Default                                  : Yes
  
  Forced                                   : No
  
  Color range                              : Limited

  The command I’m using for encoding :

  ffmpeg -hide_banner -i "" -map 0:v:0 -map_chapters -1 -map_metadata -1 -vf "crop=1920:800:0:140" -vcodec hevc_nvenc -pix_fmt p010le -preset hq -profile:v main10 -rc constqp -global_quality 21 -rc-lookahead 32 -g 240 -f matroska Video_CQP21_LAF32_GOP240.mkv

• Unable to convert mov to mp4 using ffmpeg carrierwave in ruby

  9 avril 2021, par LearningROR

  I am unable to convert MOV files to MP4 using carrierwave and FFmpeg.

  


  It does upload mp4 file but does not convert it to mp4 and so on browser only sound gets played not the video.

  


  What I am missing here ? I tried most of the solutions.

  


  Code :

  


  class VideoUploader < CarrierWave::Uploader::Base
  include CarrierWave::MiniMagick
  include CarrierWave::Video
  include CarrierWave::Video::Thumbnailer
  include CarrierWave::FFmpeg
  # Choose what kind of storage to use for this uploader:
  storage :file
  # Override the directory where uploaded files will be stored.
  # This is a sensible default for uploaders that are meant to be mounted:
  def store_dir
    "uploads/#{model.class.to_s.underscore}/#{mounted_as}/#{model.id}"
  end
  version :video, :if => :video? do
    process :encode
  end
  version :thumb do
    process thumbnail: [{format: 'jpg', quality: 8, size: 360, logger: Rails.logger, square: false}]
    def full_filename for_file
      jpg_name for_file, version_name
    end
  end
  def encode
    tmp_path = File.join( File.dirname(current_path), "tmpfile.mp4" )
    movie = FFMPEG::Movie.new(current_path)
    movie.transcode(tmp_path, custom: %w(-c:v libx264 -c:a aac -vf format=yuv420p -movflags +faststart)) do |progress|
      puts progress
    end
    File.rename tmp_path, current_path
  end
  protected
  def video?(new_file)
    new_file.content_type.include? 'video'
  end
end


  


  Logs :

  


  I, [2021-04-09T15:33:24.783337 #9397]  INFO -- : Running transcoding...
["/usr/local/bin/ffmpeg", "-y", "-i", "/Users/osx/workspace_ror/xxx-react/tmp/1617964403-459168728101935-0021-9213/video/sample_iTunes__1_.mov", "-c:v", "libx264", "-c:a", "aac", "-vf", "format=yuv420p", "-movflags", "+faststart", "/Users/osx/workspace_ror/xxx-react/tmp/1617964403-459168728101935-0021-9213/video/tmpfile.mp4"]

0.0
0.08304093567251461
0.1672514619883041
0.2327485380116959
0.3229239766081871
0.4008187134502924
0.45426900584795327
0.5033918128654971
0.5403508771929825
0.6100584795321637
0.663859649122807
0.711812865497076
0.7657309941520468
0.8196491228070175
0.87953216374269
0.9394152046783625
1.0
1.0
I, [2021-04-09T15:33:33.555508 #9397]  INFO -- : Transcoding of /Users/osx/workspace_ror/xxx-react/tmp/1617964403-459168728101935-0021-9213/video/sample_iTunes__1_.mov to /Users/osx/workspace_ror/xxx-react/tmp/1617964403-459168728101935-0021-9213/video/tmpfile.mp4 succeeded

Running....ffmpegthumbnailer -i /Users/osx/workspace_ror/xxx-react/tmp/1617964403-459168728101935-0021-9213/thumb/sample_iTunes__1_.mov -o /Users/osx/workspace_ror/xxx-react/tmp/1617964403-459168728101935-0021-9213/thumb/tmpfile.jpg -c jpg -q 8 -s 360
Success!


  


• Audio extracted using ffmpeg giving nan and very low/high (2.6283893e-37) values

  17 février 2023, par Shreya Gupta

  I'm extracting raw audio from a .flac file(youtube link - https://youtu.be/—BfvyPmVMo , extracting 10sec from this) and storing it as np-array float32. Getting nan, and extremely low and high values = [-8.63468980e+30 -9.76911766e+34 -1.93298665e+37 -2.69400132e+38 .... 2.33467619e-38  5.71834450e-39  6.70703932e-38  7.58865403e-36].

  


  On this when I try to get melspectrogram then it gives an error -

  


  TypeError: array([nan, nan, nan, ..., nan, nan, nan], dtype=float32) has type numpy.ndarray, but expected one of: int, long, float


  


  To extract raw audio using(this is similar to what is done in dmvr lib, https://github.com/deepmind/dmvr/blob/master/examples/generate_from_file.py)

  


  cmd = (
      ffmpeg
      .input(video_path, ss=start, t=end-start)
      .output("pipe:", ac=1, ar=sampling_rate, format="s32le")
  )

  audio, _ = cmd.run(capture_stdout=True, quiet=True)

  audio = np.frombuffer(audio, np.float32) "


  


  To get melspectrogram -

  


  mel_spec = librosa.feature.melspectrogram(audio,sr=16000,hop_length=10,n_mels=128,window=25)


  


  Errors

  


  C:\Users\Shreya Gupta\IS-Project\generate_from_file.py:142: FutureWarning: Pass y=[-6.5381321e+37  1.5676004e-38  7.2428216e-37 ...  2.6283893e-37
  2.5346798e-36  1.9253581e-37] as keyword args. From version 0.10 passing these as positional arguments will result in an error
  mel_spec = librosa.feature.melspectrogram(audio,sr=16000,hop_length=10,n_mels=128,window=25)
C:\ProgramData\Anaconda3\lib\site-packages\librosa\core\spectrum.py:2563: RuntimeWarning: overflow encountered in absolute
  np.abs(
C:\ProgramData\Anaconda3\lib\site-packages\librosa\core\spectrum.py:2563: RuntimeWarning: overflow encountered in square
  np.abs().....
TypeError: array([nan, nan, nan, ..., nan, nan, nan], dtype=float32) has type numpy.ndarray, but expected one of: int, long, float


  


  Could someone please help, thank you !