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• playing, decoding, seeking, audio from command line

  25 août 2017, par AbstractDissonance

  There are various way to use audio, I would like to find several different audio players that can do the following easily, from the command line :

  1. Carry out the standard audio function : Play, pause, stop, seek(absolute), volume(absolute), mute.

  2. Be able to decode and get the raw data of the audio input so one can display a waveform.

  — Correct answers will provide the player, the command line to do the functions and/or how one can interact with it programmatically if necessary.

  e.g.,

  Program : FFmpeg
  decode : pipe out using -i <filename> -f s16le -ac 1 -</filename>
  play : ffplay -nodisp then send keys to wmproc(keys don’t work without window open and -nodisp closes window, so much wm the keys)
  stop, pause, etc are the same. Does not have a way to absolutely seek or set volume.

  Other programs might be vlc, etc.

  The reason I am asking this is because I would like to provide several options for my program to use what the user might already have without having to require shipping or downloading dlls(i.e., hard dependencies).

  Bonus points for being able to control pitch and speed.

• Merge commit ’3399a26d3f57d462e839c0ee51223ae9aca20852’

  25 juin 2016, par Clément Bœsch

  Merge commit ’3399a26d3f57d462e839c0ee51223ae9aca20852’
  * commit ’3399a26d3f57d462e839c0ee51223ae9aca20852’ :
  
    nvenc : allow setting the number of slices
  
    nvenc : De-compensate aspect ratio compensation of DVD-like content.
  
    nvenc : list the major contributors in the copyright header
  
    configure : Don’t require nonfree for nvenc
  
    nvenc : drop the hard dependency on CUDA
  
    nvenc : only support HW frames when CUDA is enabled
  
    nvenc : write the VUI signal properties for HEVC
  
    nvenc : only write the VUI signal type fields if they are set
  
    nvenc : Generate bufferingPeriod/pictureTiming SEI
  
    nvenc : Delay frame output to increase encoding speed
  
    nvenc : add support for lossless encoding
  
    nvenc : Generate AUD NAL units for better compatiblity
  
    nvenc : fix the rc option definitions
  All these commits are noop as requested by Timo Rothenpieler.
  <BtbN> andrey_turkin, ubitux, yeah, I like the current state of nvenc in
  
  ffmpeg, I think most remaining differences should be merged on the libav
  
  side of things. At least I’m not aware of anything that’s missing in
  
  ffmpeg.
  Merged-by : Clément Bœsch <u@pkh.me>
  

• Python : How to use ffmpeg to read videos(video file or rtsp) and display them using OpenCV ?

  22 août 2019, par ToughMind

  I know that if we want to read video file or USB camera or rtsp stream, we can use cv2.VideoCapture.
  But for some reason, I want to use ffmpeg to do the thing and process obtained images using opencv. So the pseudocode would be :

  import cv2
  
  import ffmpeg
  
  
  
  videoFile = 'XXX.mp4'
  
  
  
  video = ffmpeg.XXX(videoFile)
  
  
  
  while True:
  
      frame = video.read() # this read() function is made up by me
  
      frameCV = ffmpeg2cv(frame) # this ffmpeg2cv() function is made up by me
  
  
  
      cv2.imshow('frame', frameCV)

  I have searched a something like https://github.com/kkroening/ffmpeg-python. But I still not know how to do this. I think ffmpeg is too hard and there are few online docs unlike opencv. So please help.