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• Split list of videos to chunks by silence in Python

  27 mai 2020, par JohnPython

  I have a list of 500 videos that I want split into small chunks by single words.

  



  I was thinking to split it by short silences between words.

  



  Process output is lots of short videos each contains one word.

  



  It would be great if silence length would be adjustable so it can extract words by various talking speech.
Process will run in Google Colab notebook
I tried FFMPEG with no success.

  


• Python : mp3 to wave.open(f,'r') through ffmpeg pipe

  7 avril 2015, par user2754098

  I’m trying to decode mp3 to wav using ffmpeg :

  import alsaaudio
  
  import wave
  
  from subprocess import Popen, PIPE
  
  
  
  with open('filename.mp3', 'rb') as infile:
  
      p=Popen(['ffmpeg', '-i', '-', '-f', 'wav', '-'], stdin=infile, stdout=PIPE)
  
      ...

  Next i want redirect data from p.stdout.read() to wave.open(file, r) to use readframes(n) and other methods. But i cannot because ’file’ in wave.open(file,’r’) can be only name of file or an open file pointer.

      ...
  
      file = wave.open(p.stdout.read(),'r')
  
      card='default'
  
      device=alsaaudio.PCM(card=card)
  
      device.setchannels(file.getnchannels())
  
      device.setrate(file.getframerate())
  
      device.setformat(alsaaudio.PCM_FORMAT_S16_LE)
  
      device.setsetperiodsize(320)
  
      data = file.readframes(320)
  
      while data:
  
          device.write(data)
  
          data = file.readframes(320)

  I got :

  TypeError: file() argument 1 must be encoded string without NULL bytes, not str

  So is it possible to handle data from p.stdout.read() by wave.open() ?
  Making temporary .wav file isn’t solution.

  Sorry for my english.
  Thanks.

• How to overlay images sequence from pipe over a video stream with ffmpeg ?

  7 juin 2018, par Dotan Simha

  I’m trying to figure out an issue with ffmpeg.
  I have the following installation :
   DeckLink Mini Recorder Card (for HDMI input)
   DeckLink Mini Monitor Card (for HDMI output)

  I’ve successfully managed to take the HDMI input from the Decklink card and output is as-is to the output card with the following command :

  ffmpeg -f decklink -video_input hdmi -raw_format yuv422p10 -i "DeckLink Mini Recorder" -f decklink -pix_fmt uyvy422 "DeckLink Mini Monitor"

  I tried to add a complex-filter to add an overlay of an image, with the following command, and it works :

  ffmpeg -f decklink -video_input hdmi -raw_format yuv422p10 -i "DeckLink Mini Recorder" -i ./tools/bin/windows/2.png -y -filter_complex "[0:1][1:0]overlay=10:10" -f decklink -pix_fmt uyvy422 "DeckLink Mini Monitor"

  I’m getting a realtime feed from the decklink recorder, the image is added to the stream, and it outputs it to the output HDMI card. Everything seems to work.

  Now I tried to change the static image path to use stdin (pipe:0), and I have a tool that constantly streaming PNG images to stdout :

  ffmpeg -f decklink -video_input hdmi -raw_format yuv422p10 -i "DeckLink Mini Recorder" -i pipe:0 -y -filter_complex "[0:1][1:0]overlay=10:10" -f decklink -pix_fmt uyvy422 "DeckLink Mini Monitor"

  The result that i’m getting on the output HDMI card is a static image, of the first frame.
  The output of ffmpeg also changes now, and it looks like it stuck of the first-second of the stream :

  ```
  frame= 30 fps=7.4 q=-0.0 size=N/A time=00:00:01.00 bitrate=N/A speed=0.247x

  frames : 30,
  currentFps : 7,
  currentKbps : NaN,
  targetSize : NaN,
  timemark : ’00:00:01.00’
  ```

  It just remains on 00:00:01.00 and never changes.

  I tried to find the issue, and did the following :

  • Tried to stream Decklink Recorder -> static png file overlay -> Decklink Monitor = IS WORKS

  • Tried to stream static png file -> Decklink Monitor = IS WORKS

  • Tried to stream pipe:0 (PNG files) -> Decklink Monitor = IS WORKS

  • Tried to stream Decklink Recorder -> pipe:0 (PNG files overlay) -> RAW AVI file IS WORKS

  The only issue is with :
   Tried to stream Decklink Recorder -> pipe:0 (PNG files) overlay -> Decklink Monitor DOES NOT WORK

  I suspect that Decklink output is more strict, and my pipe:0 with the PNG images is not stable, and the combination of both causes it to freeze.

  Any idea how to solve it ? :(

  Thanks !