Remove Noise From Screen Recording

To remove noise from the speaker audio in your screen capture video, I can recommend a solution using the tools FFmpeg and Audacity as well as some free alternatives. Here's a step-by-step approach.

1. Extract the audio with ffmpeg

Use FFmpeg to extract the audio from your video:

ffmpeg -i input_video.mp4 -vn -acodec pcm_s16le -ar 44100 -ac 2 output_audio.wav

2. Noise reduction with Audacity (Free, open-source)

• Import the extracted audio into Audacity
• Select a portion of the audio that contains only background noise
• Go to Effect > Noise Reduction
• Click "Get Noise Profile"
• Select the entire audio track
• Go to Effect > Noise Reduction again
• Adjust settings and preview until satisfied
• Click "OK" to apply

Export the cleaned audio: File > Export > Export as WAV

3. Recombine audio with video:

Use FFmpeg to merge the cleaned audio with the original video:

ffmpeg -i input_video.mp4 -i cleaned_audio.wav -c:v copy -c:a aac -map 0:v:0 -map 1:a:0 output_video.mp4

Alternative free, video editing tools

1. DaVinci Resolve (Free version)

• Powerful video editor with built-in noise reduction
• Import video, separate audio, apply Fairlight FX > Noise Reduction
• Export the final video

2. Kdenlive (Free, open-source)

• Video editor with basic noise reduction capabilities
• Import video, separate audio, apply Audio Effects > Noise Reduction
• Export the final video

3. Olive Video Editor (Free, open-source)

• Another video editor with audio filtering options
• Import video, separate audio, apply audio effects
• Export the final video

For best results, experiment with different tools and settings. The effectiveness of noise reduction depends on the type and amount of noise in your original recording.

Noise removal from CLI alternatives

There are CLI (Command Line Interface) tools available for macOS that can help you remove noise from audio. Here are some options:

1. FFmpeg with FFmpeg-normalize

FFmpeg itself doesn't have advanced noise reduction capabilities, but when combined with FFmpeg-normalize, you can apply some basic noise reduction.

First, install FFmpeg and FFmpeg-normalize if you haven't already:

brew install ffmpeg
pip install ffmpeg-normalize

Then, you can use this command:

ffmpeg-normalize input_audio.wav -o output_audio.wav --normalization-type ebu --target-level -23 --audio-codec pcm_s16le --audio-bitrate 192k --keep-loudness-range-target --loudness-range-target 7 --true-peak -2 --offset 0.5

This command normalizes the audio, which can help reduce some background noise.

2. SoX (Sound eXchange)

SoX is a powerful command-line audio processing tool that includes noise reduction capabilities.

Install SoX:

brew install sox

Use SoX for noise reduction:

sox input_audio.wav output_audio.wav noisered noise_profile 0.21

Note: You'll need to create a noise profile first:

sox input_audio.wav -n trim 0 0.5 noiseprof noise_profile

This captures the first 0.5 seconds of the audio as the noise profile.

3. AFNI's 3dTcorrMap

AFNI is a set of C programs for processing, analyzing, and displaying functional MRI (fMRI) data, but it includes some audio processing tools.

Install AFNI:

brew install --cask afni

Use 3dTcorrMap for noise reduction:

3dTcorrMap -prefix output_audio.wav -input input_audio.wav -mask_only_targets

4. RNNoise

RNNoise is a noise suppression library based on a recurrent neural network. While it's not a standalone CLI tool, you can use it with FFmpeg if you compile FFmpeg with RNNoise support.

Here's a general approach (requires advanced setup):

ffmpeg -i input_audio.wav -af arnndn=m=./rnnoise-models/sh.rnnn output_audio.wav

Note: that this requires compiling FFmpeg with RNNoise support, which is a more advanced process.