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• ffmpeg - Specifying timecode for a video in drop frame rate

  21 février 2018, par user2808584

  I want to create a copy of an existing video.mxf and give it a new starting timecode. This timecode is drop frame rate, and at 59.94fps (the same as in video.mxf). I know that this means that the first four frames (00, 01, 02, 03) are skipped in drop frame rate, at the start of every minute that is not a multiple of 10. I run

  ffmpeg -i video.MXF  -metadata timecode=00:08:00;04 -codec copy video_newTC.MXF  

  While ffmpeg executes this, there is a "timecode" entry that says "00:08:00 ;04". I then run :

  ffprobe video_newTC.MXF

  and the "timecode" entry says "00:08:00 ;20".

  It seems that for every full minute in the specified timecode, ffmpeg adds an additional 2 frames to whatever I specify (I could understand 4 frames, since 00->03 are skipped...). If the timecode that ffmpeg calculates passes the full-minute mark, an additional 2 frames are added. E.g. specifying the timecode as "00:07:59 ;59" results in ffmpeg giving video_newTC a starting timecode of "00:08:00 ;17" (59 + 16 + 2). Can anyone shed some light on what ffmpeg is doing ?

• FFMPEG command from Python 3.5 does not actually create audio file

  20 décembre 2017, par Nathan Blaine

  I have a Django web application that accepts user uploaded videos/audio and saves them into a folder ’../WebAppDirectory/media/recordings’.

  I am then using a speech to text API to get a rough transcription of the audio. This is working fine for .wav and .mp4 files, but the web app also accepts videos (.MOV) that I would like to first convert to .wav, then pass off to the API.

  Using ffmpeg from my command line like this

  ffmpeg -i C:\Users\Nathan\Desktop\MeetingRecorderWebAPP\media\recordings\upload_sample.MOV -ab 160k -ac 2 -ar 44100 -vn upload_sample.wav

  Correctly creates the .wav file from the original .MOV.

  However, when I run this from python with

  subprocess.check_call(command, shell=True)

  ffmpeg responds with

  File ’upload_sample.wav’ already exists. Overwrite ? [y/N]

  While Python tells me

  FileNotFoundError : [Errno 2] No such file or directory : ’C :\Users\Nathan\Desktop\MeetingRecorderWebAPP\media\recordings\upload_sample.wav’

  It is also worth noting that I do not see a ’upload_sample.wav’ file in the media/recordings/ directory.

  This leads me to believe that maybe Python and ffmpeg are looking in different folders, but I am not sure where I am going wrong. When I print the command from the subprocess.check_call and copy/paste it into cmd, the file is created as expected.

  Hoping someone with some experience with ffmpeg/Python subprocess can help shed some light ! Here are the files I am working with :

  Folder Structure

  DjangoWebApp
  
  |---media
  
  |---|---imgs
  
  |---|---recordings
  
  |---|---|---upload_sample.MOV
  
  |---uploaded_audio_to_text.py

  uploaded_audio_to_text.py

  import speech_recognition as sr
  
  from os import path
  
  import os
  
  import subprocess
  
  
  
  
  
  def speech_to_text(file_name):
  
      AUDIO_FILE = path.join(path.dirname(path.realpath(__file__)), 'media','recordings', file_name)
  
      print("Looking at path: ",AUDIO_FILE)
  
      # get extension
  
      AUDIO_FILE_EXT = os.path.splitext(AUDIO_FILE)[1]
  
  
  
      if(AUDIO_FILE_EXT == '.MOV'):
  
          print("File is not .wav: ", AUDIO_FILE_EXT, "found. Converting...")
  
          # We will use subprocess and ffmpeg to convert this .MOV file to .wav, so we can send to API
  
          temp_wav = os.path.splitext(file_name)[0] + '.wav'
  
          print("New audio file will be: ", temp_wav)
  
          # build CMD ffmpeg command
  
          command = "ffmpeg -i "
  
          command += AUDIO_FILE
  
          command += " -ab 160k -ac 2 -ar 44100 -vn "
  
          command += temp_wav
  
  
  
          print("Attempting to run this command: \n",command)
  
          print(subprocess.check_call(command, shell=True))
  
          print("Past Subprocess.call")
  
          AUDIO_FILE = path.join(path.dirname(path.realpath(__file__)), 'media','recordings', temp_wav)
  
          print("AUDIO_FILE now set to: ", AUDIO_FILE)
  
  
  
      else:
  
          # continue with what we are doing
  
          pass
  
  
  
  
  
      r = sr.Recognizer()
  
      with sr.AudioFile(AUDIO_FILE) as source:
  
          audio = r.record(source)  # read the entire audio file
  
          text_transcription = "Sentinel"
  
          # recognize speech using Microsoft Bing Voice Recognition
  
          BING_KEY = "MY_KEY_:)"
  
          try:
  
              text_transcription = r.recognize_bing(audio, key=BING_KEY)
  
          except sr.UnknownValueError:
  
              print("Microsoft Bing Voice Recognition could not understand audio")
  
          except sr.RequestError as e:
  
              print("Could not request results from Microsoft Bing Voice Recognition service; {0}".format(e))
  
  
  
      return text_transcription
  
  
  
  
  
  #my tests
  
  my_relative_file_path = "upload_sample.MOV"
  
  print(speech_to_text(my_relative_file_path))

  Console output (traceback and my print()’s)

  Looking at path:  C:\Users\Nathan\Desktop\MeetingRecorderWebAPP\media\recordings\upload_sample.MOV 
  
  File is not .wav:  .MOV found. Converting... 
  
  New audio file will be:  upload_sample.wav Attempting to run this command:
  
   ffmpeg -i C:\Users\Nathan\Desktop\MeetingRecorderWebAPP\media\recordings\upload_sample.MOV -ab 160k -ac 2 -ar 44100 -vn upload_sample.wav 
  
  ffmpeg version git-2017-12-18-74f408c Copyright (c) 2000-2017 the FFmpeg developers   built with gcc 7.2.0 (GCC)   
  
  ----REMOVED SOME FFMPEG OUTPUT FOR BREVITY----
  
  File 'upload_sample.wav' already exists. Overwrite ? [y/N] y 
  
  Stream mapping:   Stream #0:1 -> #0:0 (aac (native) -> pcm_s16le (native)) Press [q] to stop, [?] for help Output #0, wav, to 'upload_sample.wav':   Metadata:
  
      major_brand     : qt  
  
      minor_version   : 0
  
      compatible_brands: qt  
  
      com.apple.quicktime.creationdate: 2017-12-19T16:06:10-0500
  
      com.apple.quicktime.make: Apple
  
      com.apple.quicktime.model: iPhone 6
  
      com.apple.quicktime.software: 10.3.3
  
      ISFT            : Lavf58.3.100
  
      Stream #0:0(und): Audio: pcm_s16le ([1][0][0][0] / 0x0001), 44100 Hz, stereo, s16, 1411 kb/s (default)
  
      Metadata:
  
        creation_time   : 2017-12-19T21:06:11.000000Z
  
        handler_name    : Core Media Data Handler
  
        encoder         : Lavc58.8.100 pcm_s16le size=    1036kB time=00:00:06.01 bitrate=1411.3kbits/s speed=N/A     video:0kB audio:1036kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.007352% 
  
  0 
  
  Traceback (most recent call last): Past Subprocess.call   
  
  File "C:\Users\Nathan\Desktop\MeetingRecorderWebAPP\uploaded_audio_to_text.py", line 53, in <module> 
  
  AUDIO_FILE now set to:  C:\Users\Nathan\Desktop\MeetingRecorderWebAPP\media\recordings\upload_sample.wav
  
      print(speech_to_text(my_relative_file_path))   
  
  File "C:\Users\Nathan\Desktop\MeetingRecorderWebAPP\uploaded_audio_to_text.py", line 36, in speech_to_text
  
      with sr.AudioFile(AUDIO_FILE) as source:   
  
  File "C:\Users\Nathan\AppData\Local\Programs\Python\Python36-32\lib\site-packages\speech_recognition\__init__.py", line 203, in __enter__
  
      self.audio_reader = wave.open(self.filename_or_fileobject, "rb")   
  
  File "C:\Users\Nathan\AppData\Local\Programs\Python\Python36-32\lib\wave.py", line 499, in open
  
      return Wave_read(f)   
  
  File "C:\Users\Nathan\AppData\Local\Programs\Python\Python36-32\lib\wave.py", line 159, in __init__
  
      f = builtins.open(f, 'rb') 
  
  FileNotFoundError: [Errno 2] No such file or directory: 'C:\\Users\\Nathan\\Desktop\\MeetingRecorderWebAPP\\media\\recordings\\upload_sample.wav'
  
  
  
  Process finished with exit code 1
  
  </module>

• Encode HEVC/H.265/HDR Video for YouTube from 10bit Pro-Res using FFmpeg

  30 janvier 2018, par Rodrigo Polo

  I want to have an HDR YouTube video published, my source file is either an Apple ProRes or DNxHR using a chroma subsamplig 4:4:4 or full RGB, both 10bit, so the original source file has all what is needed in order to be encoded into a 10bit 4:2:0 H.265/HEVC (HDR).

  I have followed some answers listed here, reviewed lots of different approaches, tried out many different commands without success, colors aren’t right when using only FFmpeg, to much red, when using only Adobe to encode into H.264 with the recommended settings on their support page, the results is darker, here are the commands I’ve using :

  I have tried this :

  ffmpeg \
  
  -i input.mov \
  
  -c:v libx265 \
  
  -tag:v hvc1 \
  
  -crf 21 \
  
  -preset fast \
  
  -pix_fmt yuv420p10le \
  
  -x265-params "colorprim=bt2020:transfer=smpte2084:colormatrix=bt2020nc:master-display=G(13250,34500)B(7500,3000)R(34000,16000)WP(15635,16450)L(10000000,10):max-cll=1000,400" \
  
  -c:a libfdk_aac \
  
  -b:a 128k \
  
  -ac 2 \
  
  -ar 44100 \
  
  -movflags +faststart \
  
  output.mp4

  And this :

  ffmpeg \
  
  -y \
  
  -hide_banner \
  
  -i input.mov \
  
  -pix_fmt yuv420p10le \
  
  -vf "scale=out_color_matrix=bt2020:out_h_chr_pos=0:out_v_chr_pos=0,format=yuv420p10" \
  
  -c:v libx265 \
  
  -tag:v hvc1 \
  
  -crf 21 \
  
  -preset fast \
  
  -x265-params 'crf=12:colorprim=bt2020:transfer=smpte-st-2084:colormatrix=bt2020nc:master-display="G(13250,34500)B(7500,3000)R(34000,16000)WP(15635,16450)L(10000000,1)":max-cll="1000,400"' \
  
  -c:a libfdk_aac \
  
  -b:a 128k \
  
  -ac 2 \
  
  -ar 44100 \
  
  -movflags +faststart \
  
  output.mp4

  I have also tried using MKVToolNix in order to insert the metadata into the encoded HEVC/H.265 file with the following command :

  /Applications/MKVToolNix-9.7.1.app/Contents/MacOS/mkvmerge \
  
  -o output.mkv \
  
  --colour-matrix 0:9 \
  
  --colour-range 0:1 \
  
  --colour-transfer-characteristics 0:16 \
  
  --colour-primaries 0:9 \
  
  --max-content-light 0:1000 \
  
  --max-frame-light 0:300 \
  
  --max-luminance 0:1000 \
  
  --min-luminance 0:0.01 \
  
  --chromaticity-coordinates 0:0.68,0.32,0.265,0.690,0.15,0.06 \
  
  --white-colour-coordinates 0:0.3127,0.3290 \
  
  input.mp4

  But the result is the same and YouTube don’t recognize the file as an HDR file, it does only with the first FFmpeg command and with the file encoded with Adobe Premiere, but the colors don’t look well, so, maybe I’m getting some concept wrong, thanks for your help.