Record noise free audio or remove noise from already recorded audio/video

Steps for recording noise-free AUDIO or removing noise from a recorded AUDIO file:

When you record an audio it is usually very unclear and full of background in Ubuntu. Following steps will help you remove the noise from audio to a great extent:

• First of all you will need to install SOX package. To install "sox" open the terminal and run the following command:
  

  sudo apt-get install sox 

• Record the audio in a file original.wav :

  rec -c 1 -r 16000 -b 16 original.wav

  • This command records audio until ctrl+C is pressed.
  • -c defines that sound is recorded in a single channel, -r defines 16000 sample-rate and -b defines 16-bit sample encoding. 

• Amplify the audio if it is not audible.

  sox -v 256.0 original.wav amplified.wav

  • This command amplifies 256 times (amplification works on logarithmic scale)
  • Amplified audio is saved in other file with name amplified.wav

• Trim out a noise sample from it :

  sox amplified.wav noise.wav trim 0 0.5

  • This command will trim out noise of length 0.5 seconds starting from 0 seconds and save it to the file noise.wav

• Create the noise profile :

  sox noise.wav -n noiseprof noise.prof

• Create cleaned audio after removing noise :

  sox amplified.wav cleaned.wav noisered noise.prof 0.2

  • You can set the noise removing parameter to any value. Usually 0.2 to 0.3 gives better results.

You can play the cleaned audio from terminal itself using the command :

play cleaned.wav

Steps for recording noise-free VIDEO or removing noise from a recorded VIDEO file:

Following steps refer to the steps for recording noise-free video:

• First of all you will need to install FFMPEG package. To install "ffmpeg" open the terminal and run the following commands:
  

  sudo add-apt-repository ppa:kirillshkrogalev/ffmpeg-next
  sudo apt-get update
  sudo apt-get install ffmpeg

• You can record onscreen video using Simple Screen Recorder. To install "simple screen recorder" run the following commands:
  

  sudo add-apt-repository ppa:maarten-baert/simplescreenrecorder
  sudo apt-get update
  sudo apt-get install simplescreenrecorder

• Split the audio and video streams :

  ffmpeg -i original.mp4 -qscale 0 -an tmpvid.mp4
  ffmpeg -i original.mp4 -qscale 0 tmpaud.wav

  • First command stores the video stream to the file tmpvid.mp4
  • Second command stores the audio stream to the file tmpaud.wav

• Now remove noise from the audio file tmpaud.wav following above steps.

• Merge back the audio and video and audio :

  ffmpeg -i cleaned.wav -i tmpvid.mp4 -qscale 0 -strict -2 cleanedvid.mp4

  • This command will merge the audio from cleaned.wav and video from tmpvid.mp4 to the file cleanedvid.mp4